99 99 99 99 99 ,transcriber's ,note3 ,words in italics are indicated like this4 ,subscripts are indicated like this3 ,h#b,o4 ,the original publication has been replicated faithfully except as listed at the end of the text4 99 99 99 99 99 ,,table ,,of ,,contents ,,introductory4 #dge ,,the ,,concession4 #dgf ,,geology ,,and ,,topography4 #dgf ,,population1 ,,area1 ,,and ,,mortality4 #dgi ,,rainfall ,,and ,,temperature4 #dhj ,,available ,,sources ,,of ,,supply4 #dhd ,,materials ,,for ,,concrete4 #dia ,,estanzuela ,,supply4 #did ,,south ,,distributing ,,reservoir4 #ejf ,,san ,,geronimo ,,gravity ,,supply4 #ead ,,distributing ,,reservoir ,,at ,,obispado4 #ebe ,,comparison ,,of ,,south ,,and ,,obispado ,,reservoirs4 #ecj ,,analyses ,,of ,,estanzuela ,,and ,,san ,,geronimo ,,waters4 #ecb ,,city ,,water ,,distribution ,,system4 #ecb ,,main ,,sewerage ,,system4 #eci ,,main ,,outfall ,,sewer4 #edb ,,sewage ,,disposal ,,works ,,and ,,irrigation ,,lands4 #ede ,,quality ,,of ,,and ,,rates ,,for ,,labor4 #eeb ,,cost ,,of ,,works4 #eeb ,,tariffs ,,and ,,sanitary ,,regulations4 #eec ,,engineers1 ,,etc4 #eef ,,discussion4 #eeg ,,james ,d4 ,,schuyler4 #eeg ,,david ,t4 ,,pitkethly4 #eei ,v4 ,,saucedo4 #efc ,,george ,t4 ,,hammond4 #efg ,,rudolf ,,meyer4 #egf ,,george ,,robert ,,graham ,,conway4 #ehj ,,american ,,society ,,of ,,civil ,,engineers ,,instituted #aheb ,,transactions ,paper ,no4 #aaic ,,the ,,water-,,works ,,and ,,sewerage ,,of ,,monterrey1 ,n4 ,l41 ,,mexico4#a ,,by ,,george ,,robert ,,graham ,,conway1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 ,,with ,,discussion ,,by ,,messrs4 ,,james ,d4 ,,schuyler1 ,,david ,t4 ,,pitkethly1 ,,george ,s4 ,,binckley1 ,,vicente ,,saucedo1 ,,george ,t4 ,,hammond1 ,,rudolf ,,meyer1 ,,and ,,george ,,robert ,,graham ,,conway4 ,,introductory4 #a ,presented at the meeting of ,february #ast1 #aiaa4 ,monterrey1 the ,capital of the ,state of ,nuevo ,leon1 ,mexico1 is built on the site of the old village of ,santa ,lucia de ,leon1 which was established in #aehc by the ,governor of the ,kingdom of ,leon1 ,don ,luis ,carabajal4 ,four years later ,carabajal was imprisoned by the ,inquisition1 and the village of ,santa ,lucia was abandoned by its few inhabitants4 ,in #aeif1 ,captain ,diego ,montemayor1 a resident of ,saltillo1 in the adjoining ,state1 wishing to render a service to his king1 ,philip ,,ii of ,spain1 assembled his friends1 and on ,september #bjth of that year1 proceeded to establish a town on the site of the old village on the northern side of the principal spring at the place4 ,the town was named ,nuestra ,senora de ,monterrey 7,our ,lady of ,monterrey71 after the ,count of ,monterrey 7,ojos de ,santa ,lucia y ,valle de ,extremadura71 the ruling ,governor of ,new ,spain1 as ,mexico was then called4 ,monterrey is approximately in the center of the ,state of ,nuevo ,leon1 #a deg4 #ab' west of ,mexico ,city1 and in latitude #bf deg4 #dj' ,n4 ,it is a distributing railway center on the main line of the ,national ,railroad1 #bgj km4 from the ,rio ,grande at ,laredo1 #a1jbb km4 from ,mexico1 and #ebj km4 from ,tampico by the ,mexican ,central ,railway4 ,it is the center of many large industries1 and is the second largest manufacturing city in the ,republic4 ,,the ,,concession4 ,the works described in this paper were carried out under a guaranteed concession granted by ,his ,excellency1 ,general ,bernardo ,reyes1 ,governor of the ,state of ,nuevo ,leon1 to ,messrs4 ,james ,d4 ,stocker and ,william ,walker1 of ,scranton1 ,pa4 ,the concession is dated ,october #aith1 #aijd1 and is for #ii years from that date2 the works for a complete water and drainage system were to be finished in #c years from the time of their commencement4 ,before the works were designed and begun1 the concession was acquired by ,mr4 ,william ,mackenzie1 of the firm of ,mackenzie1 ,mann and ,company1 ,limited1 of ,toronto1 ,ont41 ,canada1 who1 on ,may #dth1 #aijf1 organized the ,monterrey ,water-,works and ,sewerage ,company1 ,limited 7,compania de ,servicio de ,agua y ,drenaje de ,monterrey1 ,s4 ,a471 under the laws of the ,dominion of ,canada1 of which company he is ,president4 ,mr4 ,mackenzie is also ,president of the ,monterrey ,railway1 ,light1 and ,power ,company1 ,limited1 which was constructing the street railways of ,monterrey concurrently with the water-works4 ,under the provisions of the concession1 the ,government appointed a ,financial ,interventor1 who had authority to examine and check the company's expenditures1 and also a ,technical ,inspector to examine and report on the construction4 ,the duties of these officials also apply to the operation of the system when the construction is finished4 ,the ,government has the right1 after the system has been operated #dj years1 to purchase the entire property1 subject to #f months' notice1 for a sum equal to #af-b_/c times the average annual net proceeds during the #c preceding years4 ,this right may be exercised at the end of #dj years1 or at the end of any #aj-year period thereafter1 up to #ii years from the commencement of operations4 ,,geology ,,and ,,topography4 ,monterrey lies in a plain at the foot of the ,eastern ,sierra ,madre ,mountains which constitute the eastern margin of the ,mexican ,cordilleran ,plateau1 and is surrounded by the magnificent mountains of that group1 among the most notable of which are the beautiful ,mitra and ,silla ,mountains4 ,in the neighborhood of ,monterrey these mountains attain heights of from #b1jjj to #b1djj m41 and are noted for their broken and jagged sky-lines4 ,the leading geological characteristics of the district are the uplifted limestones of the older cretaceous age which form the main mass of the mountains4 ,primarily1 the mountains are compressional folds which1 in the ,sierra ,madre1 near ,monterrey1 are close and vertically compressed4#b ,the drainage areas of the ,santa ,catarina ,river1 which flows through ,monterrey1 and of the ,estanzuela and ,silla ,rivers1 its tributaries1 are of limestone and shale2 originally the shales were above the limestone1 but the convulsion which formed the ,sierra ,madre as an anticlinal fold1 left the originally horizontal strata standing nearly upright1 and subsequent erosion in the upper part of the anticline has exposed nearly vertical strata in many places4 ,the limestone being hard and resisting erosion1 there is generally1 along the line of contact1 an abrupt drop vertically on the face of the limestone to the shale below4 ,in many places this abrupt drop is broken by a limestone talus1 but the line of contact can generally be traced4 ,mining operations in these mountains have revealed the presence of large caves at a considerable elevation1 many of which contain large reservoirs of water1 delivered to them through numerous faults4 ,the river valleys are formed of masses of limestone conglomerate and coarse gravels1 re-cemented in many cases by the lime deposits of the flowing waters4 ,one of the chief characteristics of the subsoil of ,monterrey itself is a local rock called sillar1 which is a superficial deposit of carbonate of lime from the evaporated waters4 ,in some places the sillar is largely mixed with a conglomerate called tepetate1 or impure sillar4 #b ,transactions1 ,am4 ,inst4 ,min4 ,engrs41 ,vol4 ,,xxxii 7#aijb71 pp4 #afc-agh4 ,illustration3 ,,plate ,,ii4--,,general ,,plan ,,of ,,the ,,water ,,supply ,,and ,,drainage ,,works ,,for ,,monterrey1 ,n4 ,l41 ,,mexico4 ,topographically1 the region around ,monterrey is distinguished by the drainage area of the ,river ,santa ,catarina1 which rises in the ,sierra ,madre near the ,laguna de ,sanchez1 at an elevation of #a1hej m41 as shown on ,plate ,,ii4 ,from this ,laguna it follows a tortuous course between precipitous mountains through the ,boca of ,santa ,catarina to ,monterrey1 for a distance of #ij km41 eventually finding its way to the ,san ,juan ,river1 a tributary of the ,rio ,grande4 ,throughout its course it disappears1 flows underground1 and again appears2 and1 except in flood time1 it has a subsurface flow for a distance of #af km4 above the city4 ,in the ,canon of ,santa ,catarina it appears at the surface1 having a normal flow of about #a1dae liters 7#ej cu4 ft47 per sec41 and its waters at that point are divided into two parts and carried into irrigation canals4 ,the drainage area of the river above ,monterrey is #a1daj sq4 km41 and its bed at ,monterrey is between #eah and #ede m4 above sea level4 ,southward from ,monterrey the country rises along the valley of the ,silla for a distance of #ai km41 where the ,silla is separated from the ,san ,juan by a low divide1 the former flowing northward to ,monterrey and the latter southeastward toward ,allende4 ,the ,silla ,valley is bounded on the east and west by the steep ranges of the ,silla and ,sierra ,madre ,mountains4 ,the floor of this valley is gently rolling1 but is cut by many arroyos which carry little or no water during the greater part of the year4 ,the chief feeder of the ,silla ,river is the ,estanzuela1 a stream which derives its waters from several springs coming to the surface near the line of contact between the limestone and the shale1 at elevations of about #hjj and #ijj m4#c above datum4 ,the water-shed of this stream is rich with abundant vegetation due to the precipitation being greater than on the ,santa ,catarina water-shed4 ,to the south of the divide the country is well wooded1 and ,el ,porvenir1 #ce km4 from ,monterrey1 is the garden spot of the ,state of ,nuevo ,leon4 ,here the rainfall is much greater than at any other point near ,monterrey1 and there are many streams which are used for irrigation purposes4 ,monterrey is built on a plain1 chiefly on the north side of the ,santa ,catarina ,river4 ,this plain has a general fall toward the northeast1 and beyond the city it slopes gently northward for several miles toward the ,topo ,grande ,river1 and then southeastward to join the great coastal plain of the ,gulf of ,mexico4 ,the general elevation of the city lies between the #eai- and #eej-m4 contours4 ,the ,plaza ,zaragoza1 in the center of the city1 is #ecc4ij m4 above sea level2 the elevation of the highest part of the city1 at the western boundary1 is #eej4je m41 and of the lowest part1 at the northeastern boundary1 #eah4j m4 above sea level4 #c ,throughout this paper datum refers to the height in meters above the mean sea level of the ,gulf of ,mexico at the ,port of ,tampico4 ,illustration3 ,,plate ,,iii1 ,,fig4 #a4--;,,general ,,view ,,of ,,line1 ,,estanzuela ,,aqueduct4 ,,population1 ,,area1 ,,and ,,mortality4 ,the population of ,monterrey has increased as follows3 ,census of #ahea #ad1fba #ahfa #bf1jjj #ahga #cc1haa #ahha #ci1def #ahia #da1aed #aija #gc1ejh 7,estimated7 #aiji #hf1jjj to #ij1jjj ,the greatest progress1 it will be noted1 was between #ahia-aija1 with an increase of more than #bb1jjj in #aj years4 ,in designing the new works1 provision has been made for the future requirements of a city of #bjj1jjj persons4 ,the actual area within the city limits proper is #ifj4e hectares 7#b1cgd acres71 forming the area to be provided with water and drainage1 but the municipal district extends to many surrounding suburbs1 and covers an area of #cc1geh hectares 7#hc1dbf acres74 ,,table #a4--,,population ,,and ,,death ,,rate ,,of ,,monterrey1 ,n4 ,l41 ,,mexico1 ,,from #aija ,,to #aiji1 ,,inclusive4 ,,deaths ,,from ,,typhoid ,,fever ,popu- ,deaths ,rate --------------------- ,year4 lation4 from all per causes4 #a1jjj4 ,jan4,feb4,mar4,apr4,may4 ---------------------------------------- ------------------ ,census #aija #gc1ejh #b1ife #dj4c #j #b #a #c #d ,estim4 #aijb #gd1ejj #c1cch #dd4h #a #d #b #c #f #aijc #gf1jjj #c1hbe #ej4c #c #b #d #a #j #aijd #gg1ejj #b1ije #cg4d #j #a #a #e #c #aije #gi1jjj #b1iea #cg4d #b #j #j #c #c #aijf #hj1jjj #b1ice #cf4g #a #b #a #c #c #aijg #hb1ejj #c1bfi #ci4f #d #f #c #c #e #aijh #hd1jjj #c1ahh #cg4i #e #b #e #c #h #aiji #hf1jjj #dc1dgg #dj4d #e #a #d #e #ac ,,deaths ,,from ,,typhoid ,,fever4 7,continued7 ,deaths from ---------------------------------- ,typhoid fever ,year4 ,total per year per ,jne4,jly4,aug4,sep4,oct4,nov4,dec4for #ajj1jjj year4 population4 ---------------------------------------- -------------------- ,census #aija #c #f #f #c #f #d #b #dj #ed ,estim4 #aijb #e #c #a #a #b #c #e #cf #dh #aijc #e #c #e #f #af #c #a #di #fd #aijd #c #c #d #a #e #a #j #bg #ce #aije #g #f #c #b #g #b #b #cg #dg #aijf #f #e #c #b #a #b #c #cb #dj #aijg #f #d #d #i #c #j #c #ej #fa #aijh #e #i #g #b #g #d #j #eg #fh #aiji #aa #ae #ab #f #h #c #d #hg #aja #d ,excluding deaths due to drowning in the great flood of ,august #bgth and #bhth4 ,table #a gives particulars of the death rate for #aija to #aiji1 inclusive1 and data relative to the mortality due to typhoid fever4 ,the high death rate is caused by the excessive infantile mortality1 which is so prevalent throughout the whole of ,mexico4 ,the climatic condition of ,monterrey1 with its exceptionally healthy subsoil1 ought to make it one of the healthiest of cities1 if proper care were taken to enforce sanitary laws4 ,the data regarding typhoid mortality are probably understated1 as they were compiled by the writer1 in the absence of any official publications1 from the actual death certificates1 but no special care is taken by the authorities to insure accuracy in such certificates4 ,attention is called to the typhoid rate in ,may1 ,june1 ,july1 and ,august1 #aiji2 this high rate coincides with a scarcity of rainfall and the greatest period of drought experienced in #cj years1 and immediately precedes the great flood of ,august #bgth4 ,it was probably due to the lowering of the ground-water throughout the city and the consequent contamination of the private wells1 which were largely in use during that time4 ,throughout the city the wells are sunk to a depth of about #ab or #ae m41 in order to reach the subterranean waters1 and the cesspools are often in dangerous proximity to them and at a much higher level4 ,the nature of the subsoil1 which is often much fissured and open in the conglomerate and sillar strata1 would make the passage of contamination an easy matter1 and this alone would account for a high mortality due to water-borne diseases4 ,,rainfall ,,and ,,temperature4 ,the precipitation records of ,monterrey and its neighborhood are very meager1 and cannot be relied on for a longer period than from #ahid to #aiji1 inclusive4 ,the records are available from #ahhf1 but in the early years there are many apparent discrepancies1 and they are probably inaccurate4 ,the average rainfall for the #ae years 7#ahid-aijh7 is #ba4id in42 the driest years for this period are as follows3 #ahid1 #ad4ad in42 #aijb1 #ae4bi in42 #aijg1 #ae4bc in42 #aijh1 #ae4aa in4 ,assuming the early records to be correct1 the average rainfall for the period1 #ahhf-aijh1 would be #ai4hf in4 ,at ,saltillo1 which is #ej miles due southwest1 at an elevation of about #a1ebj m4 above sea level1 the average rainfall for the #bc years1 #ahhd-aijh1 inclusive1 is given as #ba in4 ,the maximum year was #ahhi1 with #cc-a_/b in41 and the minimum #aijc1 with #g-a_/b in4 ,at ,carmen1 in the ,state of ,tamaulipas1 #add km4 southwest of ,monterrey1 at an elevation of about #caj m4 above sea level1 the average fall for #ab years is #bd4gj in41 the maximum year being #ahig1 with a fall of #cd4ji in41 and the minimum year1 #aije1 with #ac4da in4 ,illustration3 ,,fig4 #a4--;,,annual ,,rainfall ,,in ,,monterrey ,,covering ,,the ,,period ,,from #ahid ,,to #aiji4 ,fig4 #a shows the annual variation of rainfall at ,monterrey for #ahid-aiji4 ,fig4 #b shows the monthly variation during the same period1 and gives the minimum1 average1 and maximum for each month4 ,from these diagrams it will be seen that the months of least rainfall are ,december1 ,january1 ,february1 and ,march1 with averages of #j4ff1 #j4ei1 #j4gi1 and #j4ic in41 respectively4 ,the months of greatest rainfall are ,august1 with an average of #d4ci in41 and ,september with #d4hg in4 ,the maximum in any month prior to #aiji was #af4ge in41 during ,september1 #aijd4 ,rainfall in #aiji4--,the rainfall in #aiji was unprecedented1 causing the disastrous flood in the ,santa ,catarina ,river1 which will be referred to when describing the works4 ,fig4 #c shows the monthly rainfall for #aijf to #aiji1 inclusive1 and has been plotted to show the variation of rainfall prior to the great precipitation of ,august1 #aiji4 ,in that month there were two heavy falls1 one beginning at midnight on ,august #ith1 and during the following #db hours a fall of #ac4bh in4 was recorded by the gauge at the ,water-,works ,company's general offices1 #aj4bj in4 of which fell1 during the first #bd hours4 ,from #f ,p4 ,m4 to #aa ,p4 ,m41 on ,august #ajth1 #e4jai in4 were recorded1 or an average of #a in4 per hour4 ,illustration3 ,,fig4 #b4--,,monthly ,,rainfall ,,in ,,monterrey ,,covering ,,the ,,period ,,from #ahid ,,to #aiji ,,inclusive4 ,illustration3 ,,fig4 #c4--,,monthly ,,variation ,,of ,,rainfall ,,at ,,monterrey #aijf-aijg-aijh-aiji4 ,after #ac dry days1 another rainstorm began1 at #d ,p4 ,m41 on ,august #beth1 and continued more or less intermittently until ,august #bith4 ,during this #ih-;hour period there was an additional fall of #ba4fa in41 #aa4bg in4 falling in #bd hours4 ,the total precipitation during the month amounted to #cf4jj in4 ,the highest previous record for the month of ,august was in #ahie1 with a fall of #f4fa in4 ,fig4 #d gives the details of the two heavy precipitations in ,august4 ,as no automatic recording gauge was available1 the maximum intensity could only be computed approximately1 owing to the intermittent character of the readings taken from the ordinary rain gauge on the roof of the ,water-,works ,company's office in the city4 ,from the readings thus obtained1 it was shown that the maximum intensity occurred early on the morning of the #bhth1 and was nearly #b in4 per hour4 ,above ,monterrey1 in the ,santa ,catarina water-shed1 it is believed that the precipitation was considerably greater1 but no gauges were accessible during the month4 ,illustration3 ,,fig4 #d4--;,,curve ,,of ,,rainfall ,,at ,,monterrey ,,during ,,august #aj,,th #aa,,th ,,and ,,from ,,august #be,,th ,,to #bi,,th - #aiji4 ,the total rainfall for #aiji amounted to #dg4df in41 of which #ge fell in ,august4 ,this is #ej greater than the previous highest annual record 7#ca4fe in4 in #aijj7 for ,monterrey4 ,temperature4--,fig4 #f gives a record of the temperature at ,monterrey from #aija to #aiji1 inclusive4 ,these records were taken at an altitude of #ebj m4 ,it will be noted that the lowest recorded temperatures are in ,january and ,february4 ,the lowest during these years was #bd deg4 ,fahr41 in ,january1 #aije4 ,the monthly maxima vary between #hj and #aaj deg4 ,fahr4 ,the mean annual temperature is #gb4fe deg4 ,fahr4 7,the mean annual barometer is #bh4b in47 ,illustration3 ,,fig4 #f4--;,,diagram ,,of ,,temperature ,,variation ,,at ,,monterrey1 #aija-ji4 ,,available ,,sources ,,of ,,supply4 ,the question of the best sources from which ,monterrey should be supplied with potable water was one that had been long under discussion1 and was the subject of many investigations prior to the granting of the present concession4 ,several of the original schemes called for an impounding reservoir in the ,canon of ,santa ,catarina and it was on the assumption that a dam would be built that a clause was inserted in the concession for the purpose of making its construction obligatory4 ,the general character of the physical and geological conditions surrounding ,monterrey has already been referred to4 ,a thorough study of these conditions proved that no suitable site for impounding the ,santa ,catarina ,river could be found1 apart from the fact that periodically this river is subject to enormous floods which tear through the steep canon with tremendous velocity4 ,at the site originally proposed for the dam1 a considerable underflow was found1 and later investigations1 carried out under the present concession1 proved that1 although borings were carried to a depth of #ed m41 bed-rock could not be found1 the strata being composed of gravels1 conglomerate and sand4 ,assuming that such a dam could have been built1 the quality of the water draining from a comparatively barren water-shed1 on which many thousands of goats are pastured1 would have made its filtration an absolute necessity before it could be delivered to the consumers4 ,the various available sources from which water could be delivered to the city by gravity were investigated by ,mr4 ,f4 ,s4 ,hyde1 in the autumn of #aije1 and also by ,j4 ,d4 ,schuyler1 ,m4 ,am4 ,soc4 ,c4 ,e41 who was afterward retained as ,consulting ,engineer for the ,company4 ,the various investigations made from time to time showed that the question of a satisfactory supply was one of extreme difficulty1 requiring prolonged observation and study1 more particularly into the character of the underground sources of supply4 ,one of the chief characteristics of many of the streams in the ,state of ,nuevo ,leon1 is their disappearance and reappearance at different points along their routes1 and the ,santa ,catarina ,river1 under normal conditions1 as already remarked1 is a very notable example of a river which is very dry at the surface for many kilometers of its length4 ,in the writer's opinion1 the waters of this and similar rivers in the ,state pass through many open caverns underground1 so that experience gained in the investigation of underflow waters in other places would be insufficient to determine the quantity passing at any point along the river if ascertained by merely computing it from the velocity of the underflow and the area of the water-bearing gravels4 ,the rainfall on the water-shed of the ,santa ,catarina ,river is probably #be greater than at ,monterrey1 and all ordinary rains sink rapidly into the limestone soils and quickly disappear4 ,in another water-shed of a very similar character1 namely1 that of the ,rio ,blanco1 in the southern part of the ,state1 the underflow waters appear at the surface at a place called ,mezquital1 where a metamorphosed sandstone barrier prevents them from disappearing underground4 ,at this point the normal quantity of water is about #e1ffj liters 7#bjj cu4 ft47 per sec41 but it gradually disappears1 and a few kilometers below it has sunk to an insignificant stream1 finally disappearing altogether for about #bj km4 ,in the neighborhood of ,monterrey similar conditions exist with regard to the surface-water supplies1 and investigations1 therefore1 were directed toward obtaining unpolluted supplies from springs and underground sources4 ,santa ,catarina ,sources4--,the chief points from which it was thought desirable to obtain underflow supplies were 7#a7 at the barrier of ,san ,geronimo1 and 7#b7 at the ,canon of ,santa ,catarina1 both shown on ,plate ,,ii4 ,conditions at ,san ,geronimo1 which is only #f-a_/b km4 west of ,monterrey1 were investigated by the ,state ,government in #ahib1 to determine the depth of bed-rock1 the rock on either side of the valley being shale1 with its original bedding planes standing almost vertical4 ,to determine this depth1 borings were made by driving #b-;in4 tubes until it was assumed that bed-rock had been reached1 a method which1 in strata containing so many boulders1 was obviously unreliable4 ,these borings indicated that bed-rock was from #ab to #ae m4 below the surface4 ,if these had proved to be correct1 there is no doubt that a development of the underground water at this point1 by constructing a submerged dam combined with an infiltration gallery1 would have yielded a large supply4 ,in ,march1 #aijf1 the ,company commenced operations at ,san ,geronimo by sinking a well a few meters north of the then dry bed of the river4 ,water was found in considerable quantities a few meters below the surface1 practically at the level of the river1 that is1 #egj m4 above datum4 ,this supply was used for provisional purposes1 and will be referred to later in describing the ,san ,geronimo gravity supply works4 ,between ,august1 #aijf1 and ,january1 #aijg1 #d-;in4 bore-holes were sunk in the river bed and on the high ground to the north with a ,keystone driller outfit4 ,these borings showed bed-rock immediately under the river bed1 at a depth of from #ae to #de m41 but dipping gradually as the borings were carried northward4 ,boring operations were also carried on at ,santa ,catarina1 during ,november and ,december1 #aijf1 and in ,january1 #aijg1 to determine the geological conditions1 and the results are shown on ,fig4 #g4 ,from the area of water-bearing gravels found1 it was proposed to tap the underflow water at the #fcj-m4 level by an infiltration gallery4 ,this would have necessitated a gravitation tunnel #c1jjj m4 long1 and an aqueduct of #ad km41 which it was proposed to carry to one of two distributing reservoirs at ,guadalupe1 on the south side of the river1 opposite ,monterrey4 ,in ,may1 #aijg1 the writer1 after making a study of all the available data which had been accumulated1 had additional borings sunk farther across the valley to the north1 and these revealed a considerable area of water-bearing gravels1 and proved that1 in former geological times1 the ,santa ,catarina flowed about #ejj m4 north of its present position1 and to the back of ,obispado ,mountain1 instead of through the city4 ,this aspect of the subject was discussed with ,mr4 ,schuyler1 who agreed with the writer that1 in the interest of economy1 it was better to tap this supply by an infiltration gallery at the #efj-m4 level1 and bring the water thus obtained to a reservoir to be placed at the western limits of the city1 dividing the city1 for distribution purposes1 into two interchangeable systems1 a high- and a low-pressure1 the high-pressure system being supplied from ,estanzuela1 #ah km4 south of the city4 ,one advantage to be gained from this change was that the scheme was capable of considerable extension1 and any future developments at ,santa ,catarina ,canon would form part of the works to be constructed for both high- and low-pressure districts4 ,illustration3 ,,fig4 #g4--;,,cross-,,section ,,of ,,santa ,,catarina ,,river ,,at ,,santa ,,catarina4 ,the future extension of the ,santa ,catarina sources1 the writer believes1 can be developed best by driving an infiltration gallery #aj m4 below the surface of the ,santa ,catarina ,river1 a little west of the village of the same name1 and then conveying the water through a comparatively short gravitation tunnel and pressure conduit to a main reservoir near ,san ,geronimo having a top water level at an elevation of about #eij m4 above datum4 ,southern ,sources of ,supply4--,the available sources of supply southward from ,monterrey include a number of springs at various points in a distance of #dj km4 ,many of these springs are of uncertain quantity1 and some are quite dry during periods of drought4 ,the chief perennial springs near ,monterrey are those which contribute to form the ,estanzuela and ,diente ,rivers1 both tributaries of the ,silla1 while farther south1 at the ,potrero ,cerna1 near ,el ,porvenir1 there are excellent springs1 at a considerable elevation1 with a minimum flow of from #agj to #bjj liters 7from #f to #g cu4 ft47 per sec4 ,the total quantity of water available from all these springs during the driest season would probably not be less than about #efj or #gjj liters 7from #bj to #be cu4 ft47 per sec4 ,the ,estanzuela springs issue at the foot of the ,sierra ,madre ,mountains1 and have a normal flow of from #ef to #he liters 7#b to #c cu4 ft47 per sec4 in an ordinary dry year2 they probably derive their water1 through the limestone formation1 from the neighboring water-shed of ,santa ,catarina1 as the catchment area of the stream is only #iaj hectares1 and the stream has never been known to fail1 even in the driest periods of prolonged drought4 ,the rainfall on the area is about #cj in4 per annum1 and the catchment area is well wooded and covered with abundant vegetation4 ,the ,el ,diente springs have an ordinary dry-weather flow of about #bh-a_/b liters 7#a cu4 ft47 per sec42 but part of the water is carried underground1 and the real quantity is much greater and could be developed by a small submerged dam carried down to bed-rock4 ,the elevation and the extreme purity of the water of the ,estanzuela ,river made its acquisition very desirable1 and the ,company1 therefore1 purchased the ,federal water rights owned by various members of the ,estanzuela community1 amounting to #ia liters per sec41 and has since acquired a ,federal concession to all the flood-waters of that river4 ,it was decided1 therefore1 to adopt the ,estanzuela ,river as the first step toward developing the water to the south of ,monterrey for a high-pressure supply1 the advantage of the scheme being that from time to time extensions could be made to tap other sources by gravity1 as the demands of the city required4 ,the ,estanzuela scheme1 therefore1 is a preliminary step toward future extensions which will be necessary in this direction as the city grows4 ,the springs near ,el ,porvenir1 and others which contribute to the ,san ,juan ,river1 can be tapped at a sufficiently high level to convey them by a gravity pressure line to the ,estanzuela ,aqueduct near ,mederos4 ,the two sources definitely decided on in ,july1 #aijg1 were those from ,estanzuela and ,san ,geronimo4 ,the works were designed to supply #dj1jjj1jjj liters daily1 which it was assumed would be sufficient for all future developments for a population of #bjj1jjj at a per capita consumption of #bjj liters per day4 ,the present requirements of the city's population1 assuming that all the water was supplied by the ,company1 would be1 at that rate1 which is a very liberal one1 only #ah1jjj1jjj liters daily4 ,this1 it was thought1 would be easily met by the ,san ,geronimo source alone1 as it was estimated that it would provide not less than #bj1jjj1jjj liters1 if the infiltration gallery was driven far enough into the water-bearing gravels4 ,the question of a high-pressure water supply for domestic use in a city like ,monterrey is not a serious one1 as practically nine-tenths of the houses are of one story4 ,the increase in the number of large commercial buildings1 however1 will make the demand greater in the future1 and this point has been kept in mind in arranging the division of the distribution systems4 ,,materials ,,for ,,concrete4 ,cement4--,in the early stages of construction the cement for the work was obtained from the ,associated ,portland ,cement ,manufacturers1 ,limited1 of ,london1 which supplied the ,pyramid brand1 from the ,knight1 ,bevan1 and ,sturges ,works1 but later the supply was obtained from a new factory at ,hidalgo1 near ,monterrey4 ,the total quantity of ,portland cement used was #db1ejj bbl4 of ,pyramid and #cb1ejj bbl4 of ,hidalgo4 ,the ,english cement was tested for the ,water-,works ,company in ,london before shipment and again at ,monterrey1 to conform to the ,british ,standard ,specifications2 the ,hidalgo cement was required to pass the ,standard ,specifications advocated by the ,special ,committee of the ,american ,society of ,civil ,engineers4 ,the quality in each case was of the very highest1 no difficulties being experienced at any time4 ,sand and ,rock4--,one of the chief difficulties in connection with the construction work in its initial stages was in procuring satisfactory sand for the concrete4 ,an investigation of the quality of all the available sands in the neighborhood of ,monterrey resulted in the decision to use a manufactured sand obtained from the calcareous shales in the foot-hills opposite the city1 on the south side1 and near the site of one of the proposed reservoirs4 ,a quarry was opened1 and the raw material was delivered by a gravity plane to a crushing plant1 #bcj m4 from the quarry and at a level about #ej m4 lower4 ,the plant consisted of a ,no4 #e ,austin gyratory rock-crusher1 fitted with elevators and revolving screens of various dimensions1 driven by a #aej-;h4p4 ,erie steam engine2 two sets of ,traylor's heavy-duty crushing rolls1 one having #cj by #af-;in4 and the other #ah by #ab-;in4 rolls2 and a ,niagara sand disintegrator4 ,this plant1 except during a short period when the requirements were beyond its capacity1 was able to produce all the sand and rock required for construction purposes4 ,more than #dj1jjj tons of rock were quarried1 the greater part of which was converted into crushed stone and sand4 ,table #b gives the chemical analysis of the chief constituents of the various sands examined4 ,,table #b4--;,,analysis ,,of ,,sands ,,in ,,the ,,neighborhood ,,of ,,monterrey4 ,,key3 ,a3 ,percentage of silica 7absolute71 ,si,o#b ,b3 ,percentage of alumina1 ,al#b,o#c ,c3 ,percentage of sesquioxide1 ,fe#b,o#c ,d3 ,percentage of lime carbonate1 ,ca,c,o#c ,no4 ,location4 ,a ,b ,c ,d ---------------------------------------- ------------------- #a4 ,arroyo ,seco1 near brickyard at ,monterrey #fj4aj #ag4ie #b4hi #h4ja #b4 ,arroyo ,seco1 near brickyard at ,monterrey1 ,no4 #b #db4ib #ad4bf #d4ff #cd4eh #c4 ,near ,garcia ,station1 ,mexican ,national ,r4 ,r41 ,chiquito ,river1 ,no4 #a #ej4bb #i4gb #a4dd #cd4fb #d4 ,near ,garcia ,station4 ,mexican ,national ,r4 ,r41 ,chiquito ,river1 ,no4 #b #dh4g #d4ib #h4bh #ce4dc #e4 ,san ,luis ,potosi #he4jb #e4jj #g4ch #b4ba #f4 ,topo ,grande1 ,pesqueria ,river #dj4bj #e4ae #d4be #df4ej #g4 ,hornos1 near ,torreon #gg4i #ac4a #b4d #d4i #h4 ,salinas ,river1 at ,salinas #da4e #e4g #a4d #dh4b #i4 ,pits near ,caballeros1 on ,tampico ,branch of ,mexican ,central ,r4 ,r4 #gc4d #e4f #d4d #aj4a #aj4 ,santa ,catarina ,river1 near ,san ,geronimo 7washed sand7 #ab4dj #b4jf #a4ad #ha4gj #aa4 ,santa ,catarina ,river1 at ,monterrey #ag4d #b4ej #b4jj #gg4jj #ab4 ,composition of rock1 quarry in foot-hills opposite ,monterrey1 ,monterrey ,water-,works and ,sewer ,company's property #dj4dd #ae4gj #b4bj #cd4cj #ac4 ,manufactured sand from above quarry 7run of crusher7 #ea4hj #ab4ad #h4g #cb4f ,the chief sands used for ordinary building purposes in ,monterrey are ,nos4 #aj and #aa1 which are procured from the bed of the ,santa ,catarina ,river4 ,as these sands contain large proportions of lime carbonates1 which make them very undesirable for important structures1 their use was limited to relatively unimportant work4 ,the best sands procurable were ,nos4 #e and #i1 but the long distance of the pits from ,monterrey1 and consequently the heavy freight rate1 made their use prohibitive on economical grounds4 ,the best of the available sands1 although it was very fine1 was ,no4 #g1 from ,hornos1 near ,torreon1 as it could be depended on for uniformity and could be obtained f4 o4 b4 cars at ,monterrey for #c4ahe pesos per ton4 #e ,all costs given in this paper are in ,mexican pesos1 one peso being equivalent to #ej cents in ,u4 ,s4 currency4 ,the bulk of the sand and crushed rock used was similar to ,nos4 #ab and #ac1 and reference to the cement sand tests in ,table #c1 will show that the manufactured sands gave very satisfactory results4 ,table #c gives the average tests made with the ,hidalgo cement and various sands1 alone and in combination1 for the purpose of obtaining comparative results2 the mixtures tested were composed of #c parts of sand to #a of cement4 ,,table #c4--,,tests ,,of ,,hidalgo ,,cement ,,with ,,various ,,sands4 ,sand4 ,at #g days4 ,at #bh days4 ---------------------------------------- --------------------- ,ottawa 7,standard7 #cje lb4 #dad lb4 ,monterrey1 #a-a_/b parts1 ,hornos1 #a-a_/b parts #ahh #cac ,monterrey #bec #cfe ,hornos #bjb #cja ,manufactured sand1 ,company's crusher #cgb #eff ,hornos1 #b parts1 ,crusher sand1 #a part #bca #ceb ,hornos1 #a-a_/b parts1 ,crusher sand1 #a-a_/b parts #bfe #cdf ,hornos1 #a part1 ,crusher sand1 #b parts #bdh #cbh ,the ,hornos sand was used during a few weeks in the latter part of #aijh1 when the crusher was unable to produce all that was required4 ,its use was restricted to thick walls which were required to be water-tight1 and it was always used in equal proportions with the crusher dust4 ,,estanzuela ,,supply4 ,illustration3 ,,fig4 #h4--,,location ,,plan ,,of ,,estanzuela ,,dam4 ,intake ,works4--,the intake 7,fig4 #h7 is about #a km4 below the lowest spring and at a point where the maximum flow of the stream was observed4 ,the works consist of a small monolithic concrete dam1 placed obliquely across the stream at an angle selected for the purpose of obtaining a foundation running parallel to the direction of the strata1 which at this point were lying almost vertically across the bed of the stream4 ,above these strata the stream bed was formed chiefly of large cemented limestone blocks and smaller conglomerate4 ,no storage being possible in this valley1 which has a very precipitous fall1 the height of the dam was fixed merely to obtain a small settling basin for sand and debris brought down in time of flood4 ,the dam foundation was excavated to bed-rock1 from which the upper disintegrated portions were carefully removed2 the rock was then stepped1 and dovetailed recesses were left for properly bonding the concrete4 ,the dam is carried well into the banks4 ,its extreme length is #eb m41 its maximum height #d4ej m41 and its greatest thickness #b m4 ,the up-stream face has a batter of #a in #ab1 and the down-stream face1 #a in #h4 ,the top of the wall is #a m4 thick4 ,for the discharge of flood-water there is a weir #aj m4 long1 and it was calculated that with a depth of #a m4 it would discharge about #djj times the ordinary flow1 or about #bc1jjj liters per sec41 but1 in addition1 the whole length of the dam 7excluding that occupied by the gate-house7 was arranged for the discharge of abnormal floods1 one of which1 on ,august #bgth1 reached the enormous quantity of #hb1jgj liters 7#b1ijj cu4 ft47 per sec41 or #hbe cu4 ft4 per sec4 per sq4 mile of drainage area1 a remarkable run-off from so small an area as #iaj hectares4 ,the concrete forming the dam is a #a3c3e mixture4 ,the overflow sill is #fib m4 above sea level4 ,when the dam was completed it was filled to the overflow level1 in order to test the water-tightness of the basin1 which1 when cleared1 was found to be slightly fissured on the north side4 ,the leakage was sufficient to cause a serious loss during periods of drought1 and it was then decided to line the basin with concrete1 so that the stream would enter it without being under a head greater than its own depth4 ,the length of the basin1 measured along the center line of the original stream surface1 is #he m41 and its area is #a1ajj sq4 m4 ,at its upper end it is merely a lined channel1 #e m4 wide at the entrance4 ,the floor of the basin has a fall of #d m4 ,the lining was formed in two thicknesses totaling #cj4e cm4 7#ab in47 of #a3b-a_/b3c-a_/b concrete1 laid in panels approximately #c m4 square1 the upper panels breaking joint with those immediately below2 in this way a very satisfactory and water-tight lining was obtained4 ,a parapet wall1 #de4g cm4 high1 surrounds the basin4 ,for scouring out the basin a #cj4e-;cm4 7#ab-;in47 cast-iron pipe was taken through the dam at the lowest point1 this pipe being provided with a gate-valve encased in concrete on the down-stream face4 ,the gate-house was built in connection with the dam at the north end of the overflow weir1 its inner dimensions being #d4cd by #b4hj m4 ,the substructure1 to the level of the dam1 is of concrete founded on the solid rock1 and the superstructure is of brick rendered with cement plaster4 ,the roof is of framed timber with red ,french tiles4 ,the intake pipe is of cast iron4 #dj4f cm4 7#af in47 in internal diameter1 fitted outside with a movable copper screen which is further protected by a wrought-iron hinged screen to prevent damage from stones1 floating timber1 etc41 during times of flood4 ,inside the gate-house the outlet pipe is provided with a #dj4f-;cm4 7#af-;in47 sluice-valve1 operated from the floor level by a vertical head-stock with worm-gearing4 ,the gate-house has a scour-out pipe 7also operated by a head-stock7 and duplicate copper screens fitted to iron frames4 ,from this house the water is conveyed to the upper portion of the conduit1 which is a #de4g-;cm4 7#ah-;in47 cast-iron pipe4 ,of the total area of land1 #hhe hectares 7#b1ahg acres71 owned by the company1 #cib hectares 7#igj acres7 have been fenced in1 to prevent any contamination of the springs4 ,this fence is formed of five lines of barbed wire protected with stout hog netting at the bottom1 in order to prevent more particularly the entrance of goats1 many thousands of which pasture in the adjoining mountains4 ,on the high ground immediately below the intake1 a #c-roomed stone house has been constructed for the inspector in charge of the intake works1 who also keeps in daily touch with the general office and records the condition of the stream1 particulars of rainfall1 etc4 ,aqueduct4--,the total length of the aqueduct1 from the intake dam to the ,south ,reservoir1 is #ah1gjj m41 made up as shown in ,table #d4 ,,table #d4--;,,estanzuela ,,aqueduct4 ,description4 ,length1 in meters ---------------------------------------- ----------------------------- ,cast-iron pipes1 #de4g cm4 7#ah in47 in diameter1 along the stream bed of the ,estanzuela ,river #aaj ,concrete tubes1 #ee4i cm4 7#bb in47 in diameter1 to ,mederos 7including #bha m4 of tunnel7 #d1dgc4ha ,cast-iron siphons1 #de4g cm4 7#ah in47 in diameter3 ,calabozos #bci m ,south ,virgen #abd ,north ,virgen #agg ,mederos #dbf ----- #iff ,concrete tubes1 #fc4e cm4 7#be in47 in diameter1 ,mederos to ,south ,reservoir4 #ab1jci4ai ,cast-iron siphons1 #ej4h cm4 7#bj in47 in diameter3 ,necaxa #cae m4 ,san ,augustin #gif ----- #a1aaa ---------------------------------------- ----------------------------- ,total #ah1gjj ,the gradient of the concrete pipes is #j4dc from ,estanzuela to ,mederos1 and #j4ec from ,mederos to the ,south ,reservoir4 ,the calculated discharging capacity of the conduit when running full is #cfd liters 7#ac cu4 ft47 per sec4 for the upper1 and #dfe liters 7#af4d cu4 ft47 per sec4 for the lower section4 ,for these pipes1 the coefficient1 n1 in ,kutter's formula1 was taken at #j4jac4 ,at present the line has been limited by overflows to discharge three-quarters full4 ,the increase in the size of the pipes from ,mederos is for the purpose of receiving the waters of the ,mederos ,river and other springs in the ,san ,pablo and ,aqua ,verde catchment areas1 as shown on ,plate ,,ii4 ,the invert of the concrete conduit where it leaves the ,estanzuela ,river is #fhd4be m4 above datum1 and at the valve-house of the ,south ,reservoir it is #ehi4jj m4 ,the concrete pipes were manufactured and laid under contract with ,mr4 ,arthur ,s4 ,bent1 of ,los ,angeles1 ,cal41 the ,company providing all materials1 labor1 etc4 ,the contractor was paid #aj cents per lin4 ft4 of pipe manufactured and #aj cents per lin4 ft4 laid4 ,he was also responsible for the satisfactory completion of the work4 ,illustration3 ,,fig4 #i4--;,,estanzuela ,,pipe ,,line ,,steel ,,forms ,,for ,,the ,,manufacture ,,of ,,concrete ,,pipe4 ,fig4 #i shows the details of the joint recommended by ,mr4 ,schuyler and adopted for these pipes4 ,the #fc4e-;cm4 7#be-;in47 pipes were #fa cm4 long and #gf mm4 7#c in47 thick4 ,the #ee4i-;cm4 7#bb-;in47 pipes were of the same length1 but #gj mm4 7#b-c_/d in47 thick4 ,for the purpose of strengthening these pipes while hauling them over very rough roads they were reinforced with four rings of ,no4 #f galvanized-iron wire4 ,manufacture of ,pipes4--,the pipes were manufactured under the ,supervision of ,mr4 ,h4 ,stanley ,bent1 at a pipe yard established below the crushing plant1 from which the crushed rock and sand were delivered by gravity in bogies run on narrow-gauge rails4 ,the area of the pipe yard was approximately #a-a_/d hectares1 and it was laid out with parallel lines of #gf-mm4 7#c-;in47 galvanized-iron piping with hose couplings for sprinkling purposes4 ,after trials with aggregates of various sizes1 the concrete for the pipes was proportioned by volume as follows3 ,crushed rock broken to pass through a #ai-mm4 screen #j4acf cu4 m4 ,manufactured sand 7run of rolls7 #j4aai ,portland cement #j4jij ------------ ,total #j4cde cu4 m4 7#ab4b cu4 ft47 ,illustration3 ,,plate ,,iii1 ,,fig4 #b4--,,steel ,,forms ,,for ,,moulding ,,concrete ,,tubes1 ,,estanzuela ,,aqueduct4 ,the above quantity manufactured two #fc4e-;cm4 pipes2 a #ee4i-;cm4 pipe required #j4adae cu4 m4 7#e cu4 ft47 of the material1 in the same proportions4 ,fig4 #i shows the forms for these pipes1 and ,fig4 #b1 ,plate ,,iii1 illustrates the process of moulding4 ,the forms consist of cast-iron bottom rings1 to the proper section of the joint1 and inner and outer steel forms of #c-mm4 plate1 provided with inner and outer locking arrangements4 ,the concrete was poured through a cast-iron hopper which fitted to the top of the outer form4 ,the concrete1 which was mixed very dry1 in a #a_/b-;cu4 yd4 batch1 ,smith mixer1 was thoroughly tamped with a #bb-lb4 tamper1 and worked until it was of a stiff jelly-like consistency1 the wire rings being added as the concrete was placed4 ,the best results were obtained with the minimum quantity of water4 ,the upper joint was moulded with a heavy cast-iron ring4 ,the jacket and core forms were loosened immediately1 and placed over other rings1 a sufficient number of bottom rings being used for a day's work4 ,for the pipes required for curves1 special forms were used to give the necessary bevel to the joint4 ,after #bd hours the finished pipes were lifted from the bottom ring with a special lifter1 and ranged in position for coating internally with a ,portland cement grout to which a little freshly slaked lime was added4 ,the pipes were all numbered1 and were kept moist for #aj days by constant sprinkling4 ,they were not hauled to the work until #bh days after they were moulded1 although this rule was sometimes broken1 to the detriment of the pipes4 ,more than #cb1jjj pipes were manufactured1 but some were used for purposes other than the ,estanzuela ,aqueduct4 ,cost of ,pipes4--,the contractor brought with him experienced concrete pipe makers from ,california1 and these were afterward assisted by ,mexican labor4 ,in a day two tampers could manufacture from #de to #ej pipes of the larger 7#fc4e-;cm171 and from #ee to #fj of the smaller 7#ee4i-;cm47 size4 ,the cost varied from #b4ge to #c4be pesos per pipe for the smaller1 and from #c4ej to #d4jj pesos for the larger size4 ,the approximate cost of manufacturing is as follows3 ,taking1 as a fair example1 one week's work during ,march1 #aijh1 the wages paid to the #gd men comprising the total pay-roll 7though part of this labor was intermittent7 amounted to #iha pesos4 ,this includes a general foreman at #aj pesos per day1 four ,american tampers at #g4ej pesos1 and ,mexican labor varying from #d to #a peso1 and all labor necessary to handle and finish the pipes1 including coating the interiors4 ,during this week there were made #a1abf of the #fc4e-;cm4 and #a1jie of the #ee4i-;cm4 size4 ,the pay-roll includes #ebj pesos for the larger pipes 7#df cents each7 and #dfa pesos for the smaller pipe 7#db cents each74 ,table #e shows the quantities and cost of the materials used in the manufacture of these pipes4 ,,table #e4--;,,cost ,,of ,,concrete ,,pipe4 ,,for #a1abf ,,pipes #fc4e ,,cm4 ,,in ,,diameter4 ,materials4 ------------------------------ ,quantities4 ,cost4 ---------------------------------------- ------------------------------ ,portland cement1 at #h4jj pesos per bbl41 delivered at pipe-making yard4 #dja bbl4 #c1bjh4jj pesos4 ,sand1 at #b4fe pesos per cu4 m4 #he cu4 m4 #bbe4be ,crushed rock1 #ai-mm4 7#c_/d-;in471 at #b4fe pesos per cu4 m4 #fb cu4 m4 #afd4cj ,no4 #f galvanized-wire hoops4 #d rings to each pipe4 #d1ejd #bjc4jj ---------------------------------------- ------------------------------ ,totals4 444 #c1hjj4ee pesos4 ---------------------------------------- ------------------------------ ,cost per pipe4 444 #c4cg pesos4 ,,for #a1jie ,,pipes #ee4i ,,cm4 ,,in ,,diameter4 ,materials4 ----------------------------- ,quantities4 ,cost4 ---------------------------------------- ----------------------------- ,portland cement1 at #h4jj pesos per bbl41 delivered at pipe-making yard4 #cjc bbl4 #b1dbd4jj pesos4 ,sand1 at #b4fe pesos per cu4 m4 #fh cu4 m4 #ahj4bj ,crushed rock1 #ai-mm4 7#c_/d-;in471 at #b4fe pesos per cu4 m4 #ej cu4 m4 #acb4ae ,no4 #f galvanized-wire hoops4 #d rings to each pipe4 #d1chj #ahc4jj ---------------------------------------- ----------------------------- ,totals4 444 #b1iai4de pesos4 ---------------------------------------- ----------------------------- ,cost per pipe4 444 #b4ff pesos4 ,from ,table #e it is seen that the cost of the #fc4e-;cm4 pipes was #c4cg pesos for material plus #j4df peso for labor #c4hc pesos per pipe1 or #f4bf pesos per lin4 m4 7#a4ia pesos per lin4 ft474 ,the cost of the #ee4i-;cm4 pipes amounted to #b4ff pesos for material plus #j4db peso for labor #c4jh pesos per pipe1 or #e4je pesos per lin4 m4 7#a4ed pesos per lin4 ft474 ,the cost of cement included hauling from the bodega to the yard1 a distance of about #e km4 ,at a later date1 after the ,company had commenced using the ,hidalgo cement1 some additional #ee4i-;cm4 pipes were manufactured1 so as to have them on hand as a reserve in case of emergency4 ,in this work only ,mexican labor was used1 as the previous gang had been dispersed1 but the tampers had previous experience4 ,taking the cost of #dah pipes made during one period of #i days1 the detailed cost was as given in ,table #f4 ,,table #f4--;,,cost ,,of #ee4i-;,,cm4 ,,concrete ,,pipes4 ,,for #a1abf ,,pipes #fc4e ,,cm4 ,,in ,,diameter4 ,materials4 ------------------------------ ,quantities4 ,cost4 ---------------------------------------- ------------------------------ ,portland cement1 at #h4jj pesos per bbl41 delivered at pipe-making yard4 #dja bbl4 #c1bjh4jj pesos4 ,sand1 at #b4fe pesos per cu4 m4 #he cu4 m4 #bbe4be ,crushed rock1 #ai-mm4 7#c_/d-;in471 at #b4fe pesos per cu4 m4 #fb cu4 m4 #afd4cj ,no4 #f galvanized-wire hoops4 #d rings to each pipe4 #d1ejd #bjc4jj ---------------------------------------- ------------------------------ ,totals4 444 #c1hjj4ee pesos4 ---------------------------------------- ------------------------------ ,cost per pipe4 444 #c4cg pesos4 ,,for #a1jie ,,pipes #ee4i ,,cm4 ,,in ,,diameter4 ,materials4 ----------------------------- ,quantities4 ,cost4 ---------------------------------------- ----------------------------- ,portland cement1 at #h4jj pesos per bbl41 delivered at pipe-making yard4 #cjc bbl4 #b1dbd4jj pesos4 ,sand1 at #b4fe pesos per cu4 m4 #fh cu4 m4 #ahj4bj ,crushed rock1 #ai-mm4 7#c_/d-;in471 at #b4fe pesos per cu4 m4 #ej cu4 m4 #acb4ae ,no4 #f galvanized-wire hoops4 #d rings to each pipe4 #d1chj #ahc4jj ---------------------------------------- ----------------------------- ,totals4 444 #b1iai4de pesos4 ---------------------------------------- ----------------------------- ,cost per pipe4 444 #b4ff pesos4 ,excavation for ,pipe ,line and ,siphons4--,the excavation for the pipe line and for bridge works1 etc41 was let by contract to ,messrs4 ,scott and ,lee1 of ,monterrey1 under three classifications3 7#a7 ,all material which in the judgment of the ,engineer can be economically loosened with picks and handled with shovels4 7#b7 ,indurated earth or gravel1 shale or rock which can be loosened without blasting1 and 'sillar'1 locally so-called1 whether pure or mixed with other substances1 and whether it requires blasting or not4 7#c7 ,all rock not included in the above which requires drilling or blasting4 ,locally1 this classification is well understood1 particularly ,no4 #b1 as it covers the sillar soils which are common in the neighborhood of ,monterrey4 ,the contract prices were3 ,no4 #a1 #ej cents2 ,no4 #b1 #a4ej pesos2 and ,no4 #c1 #b4ej pesos per cu4 m4 ,these prices were over and above the clearing and grubbing of the line1 which was paid for at the rate of #ajj pesos per hectare4 ,the route of the pipe line being along broken country1 at some points difficult of access1 service roadways1 about #c m4 wide1 for hauling material were constructed1 and1 for about #g km41 a roadway was made along the line of the trench4 ,the prices for the roadway1 under the above classification1 were3 ,for ,no4 #a1 #ce cents2 ,no4 #b1 #a4ej pesos2 and ,no4 #c1 #b4ej pesos per cu4 m4 ,the trenches were excavated #e cm4 below the required finishing depth1 to allow for grading the pipes in selected material1 and were taken out to an average width of #dj cm4 greater than the outside diameter of the pipe1 to allow for their proper jointing1 and also to give sufficient room to roll the pipes in the trenches4 ,the final quantities of excavation were3 ,,trench3 ,no4 #a #aa1aae cu4 m4 ,no4 #b #ah1jif ,no4 #c #f1fej -------------- ,total #ce1hfa cu4 m4 ,,roadways3 ,no4 #a #d1afe cu4 m4 ,no4 #b #a1iii ,no4 #c #cj ------------- ,total #f1aid cu4 m4 ,the route of the pipe line was laid out so as to obtain an average fill of not more than #a m4 over the tops of the pipes1 but in some cases the cuts1 for short lengths1 were #c m4 deep4 ,the excavation for this work began in ,june1 #aijg4 ,hauling ,pipes4--,the pipes were hauled to the site of the work with ox-carts and mule teams4 ,the cost of hauling varied from #be cents per pipe at the lower end1 to #a peso per pipe at the upper and1 comparatively speaking1 inaccessible portion of the line4 ,the weight of each #ee4i-;cm4 pipe was about #ahb kg42 that of each #fc4e-;cm4 pipe was about #baf kg4 ,the breakages in all the pipes cast at the pipe yard amounted to about #a1 due chiefly to unloading them carelessly near the pipe line4 ,pipe ,laying4--,the pipe-laying gang was composed of #g ,mexicans under the direction of an ,american foreman1 who was in charge of several gangs4 ,one gang could lay daily from #fj to #gc m4 7from #ajj to #abj pipes74 ,the following was the ordinary pay-roll for one gang3 #a ,foreman at #h pesos 7proportion74 #b4jj pesos4 #a ,pipe layer at #c pesos4 #c4jj #a ,pipe layer's assistant at #b pesos4 #b4jj #a ,cement mixer at #b pesos4 #b4jj #b ,outside plasterers at #b4ej pesos4 #e4jj #b ,inside plasterers at #b4be pesos4 #d4ej #a ,water boy at #j4ej peso4 #j4ej ----------- ,total4 #bj4jj pesos4 ,this brings the average cost of laying the pipes to #cb4h cents per lin4 m4 ,the pipes were jointed with #a3b cement mortar1 the outer joint being rounded over both pipes for a width of #ab-a_/b cm4 7#e in47 and a height of about #ai mm4 7#c_/d in474 ,in making these joints the pipe layers wore rubber gloves4 ,the joints were kept moist1 and the trench was back-filled with fine1 screened material to a depth of #aj cm4 above the top of the pipe4 ,inside1 the joints were carefully caulked with cement and rendered smooth1 the plasterers working continuously along with the pipe layers1 doing from #bj to #ce m4 at a time4 ,water had to be conveyed to the trenches by barrels on burros1 and during the dry season it was sometimes carried #e or #f km4 ,illustration3 ,,plate ,,iv1 ,,fig4 #a4--,,typical ,,reinforced ,,concrete ,,girder ,,bridge1 ,,estanzuela ,,aqueduct4 ,illustration3 ,,plate ,,iv1 ,,fig4 #b4--;,,elliptical ,,arch ,,bridge ,,carrying ,,estanzuela ,,aqueduct4 ,bridges4--,the line as laid out passed over many gulches and dry arroyos1 and these were crossed with reinforced concrete bridges of varying spans and heights1 two being shown on ,plate ,,iv4 ,these bridges were formed of continuous horizontal girders1 #a4aj m4 deep and #a m4 wide1 with a cantilever overhang at the abutments1 varying in length from #a to #b m41 so as to avoid settlement between the pipes and the bridges4 ,the bottom reinforcement consisted of from #b to #f twisted bars of mild steel1 varying in different spans from #ab4g to #ai mm4 7#a_/b to #c_/d in47 in diameter4 ,the turned up bars were #bh-a_/b mm4 7#a-a_/h in47 in diameter2 they were placed on either side1 carried over the upper part of the beams1 and continued along the end for the overhanging part of the girder4 ,these bars1 when not obtainable of the full length1 were spliced with a lap of #a4b m4 with ,no4 #f galvanized-steel wire4 ,the vertical stirrups were #d4g by #be4d mm4 7#c_/af by #a in471 of mild steel2 they were equally spaced #cj4e cm4 7#ab in47 apart1 and carried all around the girders1 lapping at the center about #ae cm4 7#f in471 all the steel being carefully wired together before placing the concrete4 ,the general type of the piers and abutments is shown by ,fig4 #a1 ,plate ,,iv1 and varies in height with practically every bridge1 the foundations in every case resting on hard rock4 ,the concrete for the girders was a #a3b-a_/b3c-a_/b mixture1 the crushed stone used having all passed a mesh of #ai mm4 7#c_/d in474 ,the piers were of #a3c-a_/b3e-a_/b concrete1 and heavy displacers were embedded within them4 ,the concrete was placed after the pipes had been laid through the form by the pipe contractor1 the joints being kept clear of the bottom to the required distance by small moulded concrete blocks4 ,the tops of the girders were moulded to a slightly segmental form4 ,the bridges were all kept watered for about #ae days1 and the forms were not struck for #bh days after placing4 ,at ,station #ac4d the pipes were carried over a picturesque arroyo on an elliptical arched bridge 7,fig4 #b1 ,plate ,,iv7 of #aa m4 clear span4 ,the abutments of all bridges were protected by rubble walls in cement mortar carried up #fj cm4 above the tops of the girders4 ,the contract price for the concrete work of these bridges1 the ,company furnishing the steel and cement1 was #ad pesos per cu4 m41 and for placing reinforcing steel #ce pesos per metric ton 7#b1bjd lb474 ,there are #di single-span bridges1 the larger spans being #i4aj m42 #h two-span1 and #aa three-span bridges1 their total length1 including the overhang1 amounting to #hgj4ej m41 or #d-a_/b of the whole length of aqueduct4 ,concrete ,aprons4--,at #gf points there were small depressions which did not necessitate the construction of bridges1 and at these places the pipes were encased in blocks of concrete carried up the hillside in the form of an apron having small abutment walls from #a to #b m4 apart4 ,this also served to protect the pipes from scouring action during rainstorms4 ,at the upper end of the line1 near the intake1 the pipe had to be protected by concrete continuously for a distance of about #cjj m41 in order to prevent damage from falling rocks4 ,illustration3 ,,plate ,v1 ,,fig4 #a4--,,ventilating ,,column ,,and ,,entrance ,,manhole1 ,,estanzuela ,,aqueduct4 ,ventilators and ,manholes4--,along the route of the concrete pipe there are #bg ventilators1 one of which1 together with an entrance manhole1 is shown by ,fig4 #a1 ,plate ,v4 ,they consisted of simple concrete columns1 #c4ce m4 high1 above the ground line1 the interior of the shafts being formed of fire-clay pipes1 #ae cm4 7#f in47 in diameter4 ,at each ventilator the pipe was cut and a block of concrete1 the width of the trench1 filled in as a foundation4 ,entrance manholes were also placed at #di points1 at #bg of which they immediately adjoined the ventilating columns4 ,estanzuela ,tunnel4--,at #a1efj m4 from the intake at ,estanzuela1 the conduit is laid through a tunnel #bha m4 long4 ,the tunnel was driven through hard calcareous strata from the open cuttings at each end4 ,the inner dimensions were trimmed to approximately #b m4 high and #a-a_/b m4 wide4 ,at the ends of the tunnel the rock was moderately easy to take out1 but the inner section was very hard and difficult to blast4 ,ordinary hand drilling was adopted1 and the actual cost of driving varied from #bh pesos per lin4 m4 at the ends to #ej pesos in the center4 ,the pipes were laid through the tunnel in the ordinary way1 and back-filled from the center1 so as to give a cover of about #de cm4 above to protect them from falling pieces of shale4 ,illustration3 ,,plate ,v1 ,,fig4 #b4--,,placing ,,concrete ,,pipes ,,in ,,forms ,,for ,,bridge ,,crossing ,,at ,,north ,,end ,,of ,,tunnel1 ,,estanzuela ,,aqueduct4 ,siphons4--,it has already been mentioned that there are #f cast-iron pipe siphons4 ,the head on these varies between #aj and #ch m4 ,all are provided with special inlets and outlets1 forming combined overflow and ventilating chambers1 and have wooden hand-sluices to divert the water when necessary4 ,the bottoms of all siphons are provided with #bj-;cm4 cast-iron scour-out pipes1 fitted with valves1 and carried down to a lower point to obtain a free outlet4 ,the valve-boxes are protected by being placed in heavy concrete chambers carried up above the level of ordinary floods4 ,the siphons are formed of cast-iron socket pipes1 #c4fe m4 7#ab ft47 long1 caulked in the ordinary way with lead joints4 ,the thickness of the #de4g-;cm4 7#ah-;in47 pipes is #ai mm42 that of the #ej4h-;cm4 pipes is #ba mm4 ,on the steep hillsides the pipes are anchored securely to the rock in concrete blocks reinforced with heavy iron chains4 ,in some cases these siphons were difficult of access1 but ox-teams hauled the pipes in a very efficient and satisfactory manner4 ,overflow ,chambers4--,the ordinary overflows1 of which there are #ad1 are similar in design to the siphon inlets4 ,testing1 etc4--,when the line was completed it was tested for water-tightness1 and the loss was found to be about #e1 part of which was probably due to absorption4 ,at a later date it was found that the waters of the ,estanzuela ,river1 which contain #aej parts of calcium carbonate 7,ca,c,o#c7 per million1 deposited a very fine film of lime on the interior of the pipes1 completely filling any pores there might have been4 ,at the present time there is no measurable leakage1 thus proving that the character of the work is very satisfactory4 ,the water was turned into the conduit on ,june #aath1 #aijh1 and delivered to the city on the following day through a by-pass1 before the reservoir was completed4 ,the pipe line is patrolled daily by an inspector with the authority of a gendarme1 so as to prevent the unlawful abstraction of water1 a very necessary precaution in so dry a country4 ,,south ,,distributing ,,reservoir4 ,the distributing reservoir for the ,estanzuela supply is at ,guadalupe1 on the foot-hills to the south of the ,santa ,catarina ,river1 about #b km4 from the center of the city4 ,the reservoir is a covered one1 of reinforced concrete1 and its capacity is #ch1jjj1jjj liters 7#aj1jjj1jjj ,u4 ,s4 gal474 ,illustration3 ,,plate ,,viii1 ,,fig4 #a4--;,,general ,,view ,,of ,,excavation ,,and ,,embankment ,,for ,,south ,,reservoir ,,before ,,lining4 ,excavation and ,embankment4--,the heavy slope of the ground at the selected site made the circular form the most desirable4 ,on the low side the ground was excavated about #b m4 below the original ground line1 while the excavation at the upper part of the slope was about #ab m4 deep4 ,the excavated material consisted chiefly of sillar and limestone conglomerate1 which when broken up forms a calcareous clay of an excellent character for the formation of embankments1 when proper care is taken4 ,the dimensions fixed for the internal diameter of the finished concrete work of the reservoir were3 #ha m4 7#bfe4fh ft47 at the top1 and a depth of water of #i m41 with sides sloping #ee in #ajj4 ,illustration3 ,,fig4 #aj4--,,south ,,reservoir ,,plan ,,of ,,excavation4 ,fig4 #aj is a plan of the reservoir1 with a cross-section of the excavation and embankment4 ,on the lower side the original ground line was cut down in steps1 and all loose earth1 roots1 etc41 were carefully removed4 ,the floor of the reservoir was chiefly sillar conglomerate1 a hard material that required a considerable amount of blasting for its removal4 ,the embankments were formed in #aj-;cm4 layers of sillar and conglomerate broken into small fragments and then rolled with #c-ton sectional rollers drawn by teams of #d and #f mules1 which assisted in disintegrating the mass thoroughly1 and produced by constant wetting a homogeneous and compact clay4 ,the excavation and embankment were left so that #ae cm4 of trimming could be done at a later date1 immediately prior to the lining of the reservoir4 ,the excavated material amounted to about #cd1jjj cu4 m41 and1 of this quantity1 #ca1ejj cu4 m4 were used to form the embankment2 the remainder was taken to a spoil bank immediately adjoining1 the black earth stripping being separated and reserved for covering the reservoir1 etc4 ,the contract prices for the excavated material placed in the embankment were3 ,pesos per cubic meter ,class #a4--,material which could be removed by plows and scrapers #j4fj ,class #b4--,this consisted chiefly of sillar #a4ji ,class #c4--,limestone conglomerate 7requiring blasting7 #a4fe ,the prices 7for the same classification7 for material taken to the spoil bank1 were #j4dj1 #j4hj1 and #a4dj pesos1 respectively4 ,of the material taken out1 #ae came under ,no4 #a classification1 #hj under ,no4 #b1 and #e under ,no4 #c4 ,the excavation was begun at the end of ,may1 #aijg1 and completed in ,january1 #aijh1 by ,scott and ,lee1 the contractors4 ,the embankments were then allowed to stand until the beginning of ,july1 #aijh1 to permit the whole to become thoroughly settled and consolidated prior to beginning the lining4 ,in ,july the work of trimming the embankments and excavating for the foundations of the reservoir columns was commenced1 under the ,company's own administration1 which completed the entire work4 ,illustration3 ,,plate ,,vi4--,,details ,,of ,,beams ,,and ,,columns ,,for ,,south ,,reservoir4 ,illustration3 ,,plate ,,viii1 ,,fig4 #a4--;,,details ,,of ,,forms ,,for ,,south ,,reservoir4 ,illustration3 ,,plate ,,viii1 ,,fig4 #b4--,,view ,,of ,,western ,,half ,,of ,,south ,,reservoir1 ,,showing ,,final ,,setting ,,up ,,of ,,derrick ,,on ,,central ,,columns4 ,concrete ,lining and ,roof4--,the general arrangement and details of the side-walls1 columns1 and roof are shown on ,plates ,,vi1 ,,vii1 ,,viii and ,,ix4 ,the principal feature consists in dividing the reservoir into radial sections and supporting the roof on #ace primary and #fgj secondary beams1 from #ace columns1 spaced as follows3 ,outer ring1 at #cd4be m4 from center #dj columns4 #b;d #bg4hh #dj #c;d #ba4ea #bj #dth #ae4da #bj #eth #h4gg #aj #fth #b4dj #e --- ,total #ace columns4 ,the inner bottom diameter of the reservoir is #gj4cb m4 7#bcj4fd ft472 the upper inside diameter is #ha m4 7#bfe4fh ft472 the water depth at the overflow level is #i m4 7#bi-a_/b ft74 ,the roof was designed to carry a dead load 7the earth cover7 of #aej lb4 per sq4 ft41 and a live load of #ajj lb4 ,the maximum compressive fiber stress in the concrete was assumed at #eej lb4 per sq4 in4 for the beams1 and at #cej lb4 for the columns1 a low figure1 because of their eccentric loading4 ,the tensile strength of the steel was taken at #ad1ejj and #af1jjj lb4 per sq4 in4 ,the twisted steel used for the column reinforcement was made at the local steel plant1 but for the beams1 etc41 a twisted lug bar1 of higher quality and greater permissible tensile stress1 was used4 ,the total quantity of steel used was #agh tons4 ,it was calculated that the load on the column foundations would not exceed #a-a_/d tons per sq4 ft4 ,with the exception of the side-wall and floor1 all the concrete was reinforced with steel1 of the sizes and spacing shown on ,plate ,,vi4 ,general ,construction and ,erection ,scheme4--,the question of ordinary forms1 requiring very heavy timber work1 was a serious one1 as suitable lumber is very expensive in ,mexico2 and the necessity of finishing this reservoir before the end of the first term allowed under the concession1 which expired on ,december #cast1 #aijh1 led to the adoption of what the writer believes is an original scheme for so large a structure4 ,this scheme was to cast the columns in short sections1 mould the radial and secondary beams as separate members1 and then place them in position with derricks4 ,at the same time1 in the case of the beams1 it was important not to sacrifice either the benefit of that part of the slab which is ordinarily assumed to act as a part of the beam1 or the additional strength due to continuity2 and1 in case of the columns1 the strength due to the reinforcement extending from the foundation to the beams4 ,the ,t-beam section was secured by notching the tops of the moulded members1 with notches #aj cm4 deep1 throughout the lengths of the beams1 as shown on ,plate ,,vi4 ,a computation of the maximum flange increment shows that these notches are sufficient to transfer the flange stresses to the stem1 but1 for additional security1 flat steel bars were bent to a ,z-shape and embedded in the top of the beam1 about #fj cm4 apart4 ,continuity in the beams was secured by carrying the steel to the tops of the beams over all supports1 and1 after erection1 concreting them into the roof slab4 ,the secondary beams1 after casting1 were dropped into recesses left in the radial beams for the purpose4 ,concreting1 ,mixing1 etc4--,the radial beams and column sections were cast as nearly as possible under their ultimate positions2 the secondary beams were cast outside and immediately adjoining the reservoir4 ,the rock and sand was brought from the ,company's crushing plant1 in #c-;cu4 yd41 side-dump cars1 running on a #cj-;in4 track by gravity a distance of #a km41 the last #aej m4 requiring hauling with #f mules4 ,the cars returned all the way to the crusher by gravity4 ,these cars dumped the material into bins on the high ground above the reservoir2 from there it was hoppered into cars which carried to the mixer all the material for one batch of concrete4 ,two ,no4 #a ,smith mixers were used1 and from #be to #cj batches per hour could be handled in each machine4 ,the concrete was transported from the mixers to place in #a_/b-;cu4 yd41 #ah-;in4 gauge1 swivel1 steel dump-cars pushed by two men4 ,all the concrete used in the bottom of the reservoir1 for the main beams1 columns1 and floor1 amounting to about #b1dfj cu4 m41 was dumped through a chute into smaller cars4 ,the chute had so many baffle-plates and bolts that it resembled a gravity mixer1 but1 although it was #ab m4 long1 it effectively prevented the separation of the materials4 ,concrete ,placing and ,moulding4--,the square foundations for the columns were deposited in situ1 a recess being left for the reception of the pedestals1 which were moulded in place afterward4 ,the capitals and pedestals were cast in one piece1 and the columns in #a4ba-m4 7#dh-;in47 sections1 eight #e-;cm4 holes being left in them by using wrought-iron pipes1 held in place by templates and removed when the castings were about #c hours old4 ,the columns were erected by threading them on the #ae4h-mm4 7#e_/h-;in47 reinforcing rods1 which extended from the pedestals up through the capitals4 ,the rods were in two lengths1 arranged to lap alternately at one-fourth1 the center1 and three-fourths of the height of the columns4 ,in erection1 a light timber frame was used in conjunction with the derrick1 and1 as the columns were placed1 the reinforcing steel was grouted solid with #a3b cement mortar4 ,all the erection was done with a combined stiff-leg or guy derrick1 having an #hj-;ft4 boom and a #ej-;ft4 mast1 and fitted with a #cj-;h4p4 ,lambert hoisting engine4 ,the derrick was erected seven times at the circumference1 and its final position was on top of the center columns4 ,the moving of the derrick a distance of about #de m4 and its subsequent erection occupied usually about #dh hours4 ,the erection work was carried on continuously1 day and night1 the placing of the whole of the radial and secondary beams and columns occupying #b-a_/b months4 ,forms4--,as the erection scheme was designed to reduce the cost of forms1 economical construction was of considerable importance4 ,the wall was formed in #dj panels1 about #f m4 wide and #aa4bg m4 high4 ,the chief object in arranging them in this manner was to permit an expansion joint1 #cj cm4 wide1 at each panel2 this joint was not filled until after the completion of the roof1 when the temperature inside the reservoir was uniform and not subjected to such great fluctuations as if exposed alternately to the hot sun and comparatively cool nights4 ,the range of temperature during the construction period sometimes amounted to #hj deg4 ,fahr4 in #bd hours4 ,the expansion joints were left to the last1 when a uniform temperature of about #gj deg4 inside permitted the filling of the joints1 thus avoiding all trouble from expansion cracks4 ,the forms are shown in detail on ,plate ,,vii4 ,they consisted of shutters stiffened with four trapezoidal trusses4 ,the bottom posts of the trusses were fixed in holes formed in the foundation block2 they were propped back from the embankment at the top1 and secured to anchorages by iron rods4 ,six sets of these forms were used to construct the whole wall4 ,the concrete was placed in position through stove-pipe chutes1 #bj cm4 in diameter1 in continuous layers1 the workmen treading and spading it well as it was deposited4 ,the forms were allowed to remain #d or #e days1 and were then struck and removed to another section4 ,the pedestals and capital forms were of lumber1 and five of each were used to cast the total number required4 ,in the column sections the outer steel forms used in the manufacture of the ,estanzuela pipes were adapted for this purpose4 ,the radial beam forms1 shown on ,plate ,,vii1 were arranged with internal wedge-shaped blocks to mould accurately the recess for the secondary beams4 ,the bottom forms were left attached to the beams for #bh days1 but the sides and ends were removed after #bd hours4 ,eight forms were sufficient for the whole #ace beams4 ,for the secondary beams1 #bi forms were used for the #fgj beams1 the bottom lumber also being left until they were mature for handling4 ,by referring to the cross-section of the secondary beam1 it will be noticed that it is jug-shaped1 shelves being left on either side for the support of the roof forms1 which were placed after the secondary beams had been properly grouted to the radial ones4 ,the lagging was laid diagonally1 so that the short diameter was slightly greater than the distance between the beams4 ,this greatly facilitated the removal of the lagging1 as it was merely necessary to strike the wedge-shaped fillets beneath1 and turn them clockwise1 after tearing out the end lagging4 ,illustration3 ,,plate ,,ix1 ,,fig4 #a4--,,view ,,of ,,separately ,,moulded ,,secondary ,,beams ,,in ,,yard ,,below ,,south ,,reservoir4 ,illustration3 ,,plate ,,ix1 ,,fig4 #b4--,,setting ,,primary ,,beams1 ,,south ,,reservoir4 ,the writer believes that the adoption of forms of this type1 rather than the ordinary kind1 led to a saving of lumber of about #djj1jjj ft4 b4 m4 ,during the erection and placing of the concrete1 all the joining surfaces were carefully picked and cleaned1 particular care being taken at the junction of the secondary with the radial beams1 and the upper surfaces of all beams before laying the roof slab4 ,after the greater part of the roof was completed1 the floor was laid in those sections where it was protected from the sun's rays4 ,the concrete was placed in two #ae-;cm4 thicknesses1 and the work was carried on night and day1 without any joints4 ,the laying of the floor occupied #h days1 or an average of nearly #ajj cu4 m4 daily4 ,illustration3 ,,plate ,x1 ,,fig4 #a4--,,view ,,of ,,completed ,,section ,,of ,,south ,,reservoir4 ,,expansion ,,joints ,,in ,,side-,,wall ,,not ,,yet ,,filled4 ,proportions of ,concrete4--,all the concrete work was brought to a smooth face by careful spading1 no plastering being used throughout the reservoir1 except in the superstructures4 ,the work was kept well watered in every case for about #ae days4 ,the whole of the concrete work in connection with the reservoir was completed in #e-a_/b months4 ,the concrete for the columns and foundations was a #a3c3e mixture1 the aggregate consisting of equal parts of #ai-mm4 7#c_/d-;in47 and #ch-mm4 7#a-a_/b-;in47 crushed stone4 ,the remainder of the concrete1 except that for the roof1 was a #a3b3d mixture1 the aggregate also consisting of equal parts of #ai-;and #ch-mm4 stone4 ,with the exception of a short length of the side-walls1 the sand used was that manufactured by the ,company4 ,when the crushing plant was unable to produce all the sand required1 the ,hornos sand 7see ,table #c7 was used in the side-walls in equal proportions with the crusher sand4 ,reservoir ,outlet and ,entrance ,tower4--,the outlet1 #fa cm4 7#bd in47 in diameter1 leads from a well in the center of the reservoir and passes under the floor and embankment to an outside valve-pit1 #hi m4 from the center4 ,this pipe was laid in a trench in a solid cutting before the construction of the embankment1 and was encased in #a3d3h concrete4 ,where it passes under the embankment a #a3b3d concrete cut-off wall1 #c4f m4 wide1 #b4e m4 high1 and #a m4 thick1 was placed across it at right angles4 ,the cast-iron pipe is curved upward in the central well1 and has a bellmouth on which rests a movable circular copper screen4 ,above the outlet well1 and on the roof of the reservoir1 there is a central tower1 giving access to the interior by a steel stairway4 ,this tower also serves as a main ventilating shaft1 and in it are arranged the guide-screens and gearing for raising them for cleaning purposes4 ,in addition to the ventilation provided in the tower1 #bj circular openings1 #cj cm4 in diameter1 are carried through the roof of the reservoir at the circumference and into the parapet walls4 ,inlet ,gate-,house1 etc4--,the inlet gate-house is above the reservoir and about #ed-a_/b m4 from its center4 ,the conduit enters at #ehi4jj m4 above datum1 and the gate-house contains the valves for controlling the inlet pipe to the reservoir1 the by-pass1 overflow1 scour-out pipe1 and the copper screens4 ,the inlet1 which is #de4g cm4 7#ah in47 in diameter1 is of cast-iron flanged pipes1 carried on iron hangers on the side-wall of the reservoir1 and1 at a point #ij cm4 above the floor level1 it is turned at right angles to the side-wall and carried on concrete piers to the center of the first row of columns4 ,the end of the pipe is closed by a blank flange1 and the water is deflected at right angles through two #cj-;cm4 7#ab-;in47 branches1 for the purpose of setting up a slight circular motion as it enters the reservoir4 ,the valve-pit is clear of the embankment1 and in it are brought together the main supply and by-pass pipes on which are placed two #fa-;cm4 7#bd-;in47 sluice-valves2 and between them there is a #bj-;cm4 7#h-;in47 scour-out pipe1 for emptying the reservoir into an adjoining arroyo4 ,the arrangement of the valves gives complete control over the contents of the reservoir4 ,venturi ,meter-,house4--,fig4 #aa shows the arrangement of the ,venturi meter and its automatic register in a house over the main supply pipe4 ,this house is designed to form a feature of the entrance gateway of the reservoir grounds1 which cover an area of #ab hectares4 ,illustration3 ,,fig4 #aa4--,,venturi ,,meter-,,house4 ,general4--,the roof of the reservoir has been laid out as a garden1 and the embankments are turfed4 ,the intention is to develop the ,company's land as a public park1 as it commands fine views of the city and the surrounding mountains4 ,an inspector's house has been built1 and a private telephone line provides for communication with the ,estanzuela intake and also with the general offices in the city4 ,illustration3 ,,plate ,,xviii1 ,,fig4 #a4--,,view ,,of ,,south ,,reservoir1 ,,looking ,,toward ,,the ,,city4 ,,san ,,geronimo ,,gravity ,,supply4 ,provisional ,supply4--,it has already been stated that the ,company began operations at ,san ,geronimo in ,march1 #aijf1 by sinking a well on the north bank of the ,santa ,catarina ,river at ,san ,geronimo4 ,at this point1 a little later1 a small steam pumping plant1 sufficient to handle about #h1jjj liters per min41 was installed4 ,the lowest depth to which this well was ultimately sunk in water-bearing strata1 was #g m41 the normal level of the water during #aijf and #aijg never falling lower than #efi m4 above datum4 ,tests made from time to time during #aijg-jh1 showed that this well was capable of supplying nearly #aj1jjj1jjj liters 7#bfd1jjj gal47 of water daily4 ,the excellent supply yielded by this well made it desirable to adopt it immediately as a provisional measure1 pending the completion of the larger works forming the western source of supply4 ,to utilize the well to its fullest extent1 a reinforced concrete reservoir1 of #c1jjj1jjj liters capacity1 was constructed on the south bank of the river1 the top water level being #ehe m4 above datum1 that is1 at the same elevation as the proposed reservoir for the ,estanzuela supply4 ,the reservoir is #ec4hj m4 long1 #ba m4 wide1 and has a water depth of #c4be m4 at the overflow level4 ,it is excavated on a steep hill slope1 and has an earth embankment on the lower side4 ,the lining is of concrete1 #bj cm4 thick1 and the roof is of reinforced concrete composed of flat arches springing from beams carried on #df by #ce-;cm4 reinforced columns4 ,there are #fh of these columns1 and they are #c m4 apart longitudinally and #e m4 apart transversely4 ,the roof was not constructed until ,october and ,november1 #aijg1 and prior to that time the necessity of covering the reservoir was amply demonstrated by the growth1 during hot weather1 of considerable quantities of green algae1 which had to be skimmed from the surface of the reservoir every few days4 ,the delivery pipe from the pumping plant was originally of riveted steel and was asphalted4 ,it was #cj cm4 in diameter1 #b mm4 in thickness1 with slip joints1 and where it crossed the river it was encased in concrete4 ,this pipe was afterward replaced by a cast-iron pipe of the same diameter4 ,the supply pipe to the city was also of sheet steel1 #cj cm4 in diameter4 ,for a part of its length it was laid in the high ground of the south bank of the river1 which it crossed near the western limits of the city1 and was then connected to a #cj-;cm1 cast-iron pipe in the distribution system4 ,the total length of the pipe from the reservoir to the city distribution system was #b1hej m4 ,this provisional pipe continued in service from ,october1 #aijf1 until ,august #bgth1 #aiji1 when the river portion was completely swept away1 together with the provisional pump-house at ,san ,geronimo1 during the great flood in the ,santa ,catarina ,river4 ,fortunately1 the permanent supply works were completed at the time1 so that the destruction of this pipe line1 which had already served its original purpose1 had no effect on the supply of water to the city4 ,illustration3 ,,plate ,,xi4--,,section ,,of ,,infiltration ,,gallery1 ,,san ,,geronimo ,,gravity ,,supply4 ,infiltration ,gallery4--,the chief feature of the ,san ,geronimo gravity supply is the infiltration gallery4 ,by referring to the profile on ,plate ,,xi it will be seen that at this place there is a considerable area of what is undoubtedly water-bearing gravel4 ,the main conditions were revealed by the borings previously carried across the valley1 but the profile has been corrected to show the actual conditions as established at a subsequent date by shafts4 ,practically1 the water-bearing strata are not limited merely to the sand and coarse gravels1 as the clay formation lying above and below them is full of small gravel deposits containing considerable volumes of water4 ,the main direction of the underflow is toward the east1 and the hydraulic gradient1 which was established from wells sunk farther west1 was found to be approximately #a1 or practically the same as the average surface of the bed of the river above the line of the infiltration gallery4 ,the general scheme for tapping this underflow was to drive a main gallery at the #efj-m4 level on a grade of #j4je1 which was sufficiently high to take the supply by gravity to the western reservoir1 having a top water level at #eeh4ge m4 above datum4 ,this elevation is sufficient to give an excellent pressure over about #fj of the city1 and a fair pressure to reach the upper stories of the highest houses1 if required1 over the whole supply district4 ,from this gallery it was proposed to sink shafts at frequent intervals1 for a total distance of #cjj m41 carrying them below the gallery level1 to tap any water-bearing gravels there might be in the clay formation underlying the gravels and sands4 ,from the main gallery it was proposed to construct branch galleries up stream on a flat gradient1 so as to obtain the advantage of an increased head due to the steep hydraulic gradient of the underflow water4 ,illustration3 ,,fig4 #ab4--;,,diagram ,,showing ,,variation ,,in ,,water ,,plane #aije ,,to ,,march #aiaj ,,at ,,san ,,geronimo4 ,in investigations of this kind1 it is of first importance to have a continuous record of the level of the water plane1 and ,fig4 #ab has been plotted to show its variation at ,san ,geronimo from the beginning of #aije to ,march1 #aiaj4 ,from ,january1 #aiji1 to ,march #cast1 #aiaj1 these levels are averages of daily readings taken in #i shafts sunk along the proposed line of the infiltration gallery4 ,in #aijb the water plane was standing at #egj4ah m4 above datum1 but from that date until #aije the writer has been unable to find any records4 ,this diagram should be examined together with the rainfall diagram1 ,fig4 #c1 and it will be noticed that the fall in the water plane drops with the general scarcity of the rainfall during #aijg-jh1 and until ,july1 #aiji4 ,the year previous to ,july1 #aiji1 is regarded1 by many competent local observers to have been the longest period of extreme drought in #cj years in ,nuevo ,leon1 and the evidence which the writer has been able to gather regarding stream flow in the neighborhood of ,monterrey supports this view4 ,the total rainfall at ,monterrey for the year prior to ,july #ast1 #aiji1 amounted to #i4ih in41 or #d4af in4 less than the lowest record for any calender year since #ahid1 or1 in other words1 about #de of the average annual rainfall4 ,the lowest point to which the water plane dropped was during ,june and ,july1 #aiji1 when the levels stood slightly above #efe4jj m41 or #e m4 above the level of the floor of the infiltration gallery4 ,during this period pumping tests were made in the various wells1 and from these it was quite clear that the infiltration gallery1 if carried far enough to meet them all1 would yield a supply of from #be1jjj1jjj to #dj1jjj1jjj liters daily4 ,during the great rainfall of ,august1 #aiji1 the water levels rose very rapidly2 the heavy precipitation between ,august #ith and #ajth caused the level to rise to #efh4jj m4 in about #d days1 and #f days after the great flood of ,august #bgth1 the water level1 which had continued rising gradually1 reached #ega4dj m41 and then fell gradually until at the end of ,march1 #aiaj1 it was practically the same as it had been from #aijb to #aije4 ,illustration3 ,,plate ,,xii4--,,san ,,geronimo ,,gravity ,,supply4 ,it should be noticed that the readings were taken in the shafts on the high ground to the west of the present river bed1 and were independent of any flow there might be in the river4 ,during times of ordinary floods in the river1 it was very noticeable that1 notwithstanding the fact that the river water might be turbid to an extreme degree1 the well even in immediate proximity to the river bed did not show the least sign of discoloration4 ,design of ,works4--,plate ,,xii shows the general design of the gravity scheme1 which consists of a main tunnel #eej m4 long and a concrete aqueduct1 #a4jf m4 7#db in47 in internal diameter and #b1caa m4 in length1 discharging into a low-service distributing reservoir at the extreme western limits of the city4 ,the tunnel and aqueduct were laid on a gradient of #j4je1 and the latter was designed to discharge #ee1jjj1jjj liters per day 7#bb4h cu4 ft4 per sec47 if flowing to its full capacity4 ,gravitation ,tunnel4--,this tunnel1 shown on ,plate ,,xii and ,fig4 #ac1 was completed prior to driving the infiltration gallery into the water-bearing gravel1 so that the water encountered in the gallery could be easily drained off by gravity1 thus avoiding a heavy outlay for pumping4 ,the tunnel passes through various strata1 the principal ones being calcareous shale1 conglomerate1 and gravels4 ,the tunneling operations were carried on from #e shafts1 ,no4 #a being #bc m4 deep1 and the others varying from #bj to #aj m4 ,the shafts in loose ground were timbered in the usual way1 having clear inside dimensions of #b m4 ,shaft ,no4 #a1 which was entirely in shale1 was taken out approximately to #c4ce m4 in diameter1 so as to permit it to be lined with concrete having a finished internal diameter of #b4dc m4 ,illustration3 ,,fig4 #ac4--;,,general ,,details ,,san ,,geronimo ,,gravity ,,pipe ,,line4 ,fig4 #ac shows the details of the tunnel1 which was lined with concrete1 the bottom and sides being approximately #bc cm4 7#i in47 thick4 ,the interior dimension is #j4ia m4 at the invert level and #a4jaf m4 at a height of #a4bb m41 the corners between the side-walls and the floor being slightly curved4 ,the arch is formed of two rings of brickwork in cement mortar1 this thickness being increased in some lengths to three rings4 ,where the rock was in good condition1 and not likely to disintegrate easily1 the arch1 for a distance of #ij m41 was left unlined4 ,of the total distance of #eej m41 careful timbering was required for #cjj m4 ,in lining the timbered portion of the tunnel with concrete1 all the timber was removed1 except in loose ground1 where the laggings were left in position4 ,while the tunnel was being driven1 a start was made to drive the north end of the infiltration gallery1 which was in rock for a distance of #dd m4 ,water appeared at about #ce m41 and then the work was temporarily suspended until the gravitation tunnel was completed and a length of the aqueduct had been constructed far enough down stream on the north bank of the river to permit of draining direct to the river4 ,this point was reached at #a1agj m4 from ,shaft ,no4 #a1 and there a temporary overflow chamber was constructed4 ,when the tunnel was completed1 the two intermediate shafts were filled up1 the remaining three being retained permanently4 ,shafts ,nos4 #b and #c were lined with concrete1 #gf cm4 7#cj in47 in internal diameter1 and #bc cm4 thick4 ,they were domed at the top to form circular openings to receive cast-iron covers4 ,progress on this tunnel was slow1 taking from ,december1 #aijg1 to ,november1 #aijh1 to complete1 owing chiefly to difficulties with an incompetent contractor4 ,the contract was subsequently transferred to ,mr4 ,john ,phillips1 of ,mexico ,city 7who was also the contractor for the aqueduct71 who completed it satisfactorily4 ,continuation of the ,infiltration ,gallery4--,when the aqueduct 7to be referred to again7 was completed as far as #a1agj m4 from ,shaft ,no4 #a1 the driving of the infiltration gallery1 which was #b m4 high and #a-a_/b m4 wide1 was continued until gravel was encountered in the roof1 at #dd m4 from the shaft4 ,at this point the rock dipped at an angle of #de deg41 and the gravels contained quantities of large boulders mixed with fine sand2 immediately after encountering the gravel1 a flow of about #ij liters per sec4 was met1 evidently coming through from a pot-hole in the shale4 ,this quantity diminished in about #aj days to about one-fourth1 but gradually increased again as the driving proceeded4 ,the operations of driving the tunnel from #dd m4 forward were begun in the dry season1 in ,february1 #aiji1 and the gravel was encountered for a distance of #bd m41 or up to #fh m4 from the shaft4 ,the center of this gravel bed was about #cj m4 south of the old river channel1 which had been continuously dry at the surface for several years4 ,up to #fh m4 the work was very difficult1 owing to the upper part being of loose gravel and the lower in very contorted shale4 ,the timbering of the tunnel in the full gravel section consisted of heavy square settings1 #a m4 apart4 ,at #fh m4 the clay and gravel formation was met1 and the rate of progress then was about #d or #e m4 a week4 ,a short branch gallery was also driven about #g m4 up stream near ,shaft ,no4 #b4 ,the total distance the infiltration gallery was carried from ,shaft ,no4 #a1 was #ajj m41 when the floods of ,august1 #aiji1 caused its suspension4 ,during the progress of the gallery1 attempts were made to sink a #c-a_/b by #b-m4 shaft at a point along the line of the infiltration gallery1 about #acj m4 from ,shaft ,no4 #a1 but water in such abundance was encountered that it was practically impossible to sink it in the ordinary way more than about #f m4 deep1 the quantity of water to be dealt with amounting to about #bj1jjj1jjj liters daily4 ,seven shafts were then sunk in the high ground to the north of the river1 five of these being on the line of the gallery and two #cj m4 westward4 ,they were sunk during the dry season prior to ,july1 #aiji4 ,these were ordinary timbered shafts1 #b m4 square between the walings1 and were carried to the depths shown on ,plate ,,xi4 ,in ,shafts ,nos4 #e1 #f1 and #g the water was flowing with considerable velocity1 while ,shaft ,no4 #i seemed to have penetrated a different water plane and one which was probably independent of that showing in any of the other shafts1 in which the water was practically at a uniform level4 ,the evidence obtained showed that if the gallery could be carried to ,shafts ,nos4 #f or #g a great abundance of water would be intercepted4 ,owing to the difficulties of sinking ordinary shafts in the wide river channel1 circular shafts were put down4 ,these were #a4cg m4 in internal diameter and #bc cm4 thick1 and were of concrete reinforced with ,no4 #aj vertical rods1 #ai mm4 in diameter1 tied together with ,no4 #f wire4 ,these shafts were provided with steel cutting edges4 ,shaft ,no4 #b was sunk to a depth of #a m4 below the infiltration gallery level1 ,no4 #c within #b m41 and ,no4 #d within #d m41 before ,august1 #aiji4 ,the shafts were sunk by digging them out and loading them at the top1 the top of the shafts being kept generally #c m4 out of the ground4 ,shaft ,no4 #c encountered great volumes of water1 and1 in order to enable sinking operations to proceed1 a pumping shaft1 #b-a_/d m4 square1 was sunk a little west of it to draw off the water4 ,notwithstanding the fact that the prolonged period of drought had lowered the general water plane in all the shafts to #efe4jj m4 above datum1 the difficulties of handling the water even at that level were considerable4 ,at the beginning of ,august the work was progressing very satisfactorily1 but the extraordinary rainfall of that month caused the work to be shut down temporarily4 ,effect of the ,floods in the ,santa ,catarina ,river4--,the area of the water-shed of the ,santa ,catarina ,river above ,monterrey is about #a1daj sq4 km4 7#edd sq4 miles71 and its area at ,san ,geronimo1 owing to its configuration1 is practically the same4 ,its general character has already been referred to4 ,on the night of ,august #ajth and early on the morning of ,august #aath1 a big flood came down the river1 flowing at its maximum about #a1acj cu4 m4 7#dj1jjj cu4 ft47 per sec41 due to the heavy rainfall 7,fig4 #d74 ,this flood carried away all the temporary staging around the shafts1 seriously wrecking the temporary pumping station1 as well as destroying the #cj-;cm4 cast-iron pipe1 notwithstanding the fact that it had been encased in a block of concrete #c m4 wide and #a-a_/b m4 thick right across the river2 but no damage was done to the infiltration gallery or to the shafts in the river channel4 ,the effect of the flood on this pipe is shown by ,fig4 #b1 ,plate ,,xxxi4 ,illustration3 ,,plate ,,xxxi1 ,,fig4 #b4--,,profile ,,sketch1 ,,looking ,,up ,,stream ,,on ,,line ,,of #bd-;,,inch ,,main ,,supply ,,pipe4 ,following this flood1 which had caused the loss of #ad lives in the city1 #c miles below ,san ,geronimo1 there was practically no rain for #ac days4 ,then1 on ,august #beth the second heavy precipitation began and continued until ,august #bith1 the details being shown on ,fig4 #d4 ,this precipitation1 therefore1 fell on a water-shed which was completely saturated1 as it had already absorbed a large proportion of the #ac4ch in4 of rain which fell during ,august #ajth and #aath2 and at every point along the river1 prior to ,august #beth1 springs were issuing forth1 and there had been very little evaporation during the intervening dry spell4 ,the writer has calculated that at ,monterrey this flood reached the enormous quantity of #f1fej cu4 m4 7#bce1jjj cu4 ft47 per sec41 a rate equal to #dcb cu4 ft4 per sec4 per sq4 mile of water-shed4#f ,the effect of this flood was to demolish completely about #a1bjj sillar houses 7without taking into consideration the numerous wooden houses7 at ,monterrey1 and to cause a fearful loss of life1 variously estimated between #c1jjj and #e1jjj persons2 the lower figure the writer believes is approximately correct4 ,at ,san ,geronimo the original pumping station was carried away entirely1 leaving practically no trace whatever4 #f ,the writer1 in a brief article contributed to ,engineering ,news soon after the flood 7,september #bc;d1 #aiji71 gave this figure as #bga1ejj1 or approximately equal to a run-off of #ejj cu4 ft4 per sec4 per sq4 mile2 but1 from a later and more complete study of the conditions for many miles above ,monterrey1 he believes the above quantity to be approximately correct4 ,shaft ,no4 #b was apparently destroyed1 while ,no4 #c was turned at an angle of about #ej deg4 down stream and filled up completely with sand4 ,the infiltration gallery1 near ,shaft ,no4 #b1 was completely blocked with fine sand and gravel1 and access could only be obtained as far as #ed m4 ,the profile1 ,plate ,,xi1 shows the change which had taken place in the river bed4 ,the original course of the stream was changed to the north bank1 #ej m4 distant1 the effect of the scouring action of the flood being to lower the general level at this point about #c4fe m41 while the southern portion of the channel was slightly raised4 ,at present 7,april1 #aiaj71 the end of the driven portion of the infiltration gallery is about #ce m4 from the center of the stream1 which is still carrying about #b1bgj liters 7#hj cu4 ft47 per sec4 ,immediately after the flood the flow in the gallery was #dej liters 7#af cu4 ft47 per sec41 and this quantity has remained constant since that time4 ,the probable effect of the flood was to disturb the whole subsurface above the infiltration gallery and put it in motion1 completely cleaning the gravels of their surrounding clay1 which would account for the large infiltration of water in so limited a distance4 ,the water has always been limpid and pure1 but its hardness remains the same as it was prior to the flood4 ,with the copious supply of water from this source1 due of course to abnormal conditions and not likely to be permanent1 the operations of tunneling have been suspended temporarily2 but it is proposed to continue the driving of the gallery1 from a new shaft west of ,no4 #c4 ,the water encountered will be drained off by pumping until the main water-bearing gravels1 in the neighborhood of ,shaft ,no4 #e1 are reached4 ,it is also proposed to reconstruct the #cj-;cm4 high-level pipe line1 from ,san ,geronimo along the high road on the north bank of the river1 so that by pumping water can be delivered to the city system from ,shafts ,nos4 #e1 #f1 and #g1 in the event of a shortness of supply from the ,estanzuela ,river4 ,shaft ,no4 #a4--,shaft ,no4 #a is designed to connect the infiltration gallery with the gravitation tunnel4 ,this shaft has an inner diameter of #b4dc m4 7#h ft47 and is fitted with a special gate-valve4 ,in the bottom of the door of this valve there is a smaller valve1 #cj cm4 in diameter1 so that1 when the infiltration gallery is closed for cleaning out the sump1 the smaller door1 which is operated through the same spindle by a bevel-geared head-stock at the top of the shaft1 can be opened first4 ,space is also left for screens if these should be found necessary4 ,access to this shaft is gained by a reinforced concrete stairway in nine stages4 ,the superstructure is to be supported on reinforced concrete column foundations carried to the firm rock1 owing to the loose condition of the strata at the top of the shaft4 ,aqueduct4--,the construction of the concrete conduit was begun in ,april1 #aijh4 ,fig4 #ac shows the general types4 ,type ,a was adopted in gravel and conglomerate formation1 and ,type ,b where the excavation was in sillar1 the soft nature of this rock permitting it to be excavated exactly to the required external diameter of the concrete lining4 ,the concrete which was without steel reinforcement was a #a3b-a_/b3c-a_/b mixture1 the sand being from the crusher and the aggregate from the river bed1 screened to pass a #be-mm4 mesh4 ,where the conduit crossed the river obliquely1 immediately below the gravitation tunnel1 it was strengthened with mass boulder concrete of ,type ,c4 ,during the great flood this heavy section withstood its effects without damage of any kind1 but beyond this point1 where the conduit had been laid in compact cemented gravels1 the scouring action of the flood on the north bank lowered the level of the gravels from #b to #c m42 the only damage1 however1 was the scouring away of the gravels at the south side of the conduit4 ,to prevent such an occurrence in the future1 the conduit at that point was strengthened with additional concrete for a distance of #aie m41 as shown on ,fig4 #ac4 ,the extra concrete1 amounting to #gcc cu4 m41 was a #a3c3e mixture1 in which was embedded #bj of heavy boulders4 ,the top of this special length now forms a weir for the present river flow4 ,where the conduit enters the bluff on the north side of the river1 at #a1bjj m41 there is an overflow chamber which has a sluice-gate #gf cm4 wide1 arranged so that the conduit can overflow at the present time when running #gf cm4 deep4 ,to deflect the flow in the conduit1 a wrought-iron plate1 provided with a balance weight1 is dropped into a groove on the lower side4 ,the outlet is a #fa cm4 concrete tube1 having its invert above ordinary flood level1 and arranged to be closed by a gate4 ,at #a1ifc m4 the conduit is carried over an arroyo on a segmental arch of #h m4 clear span1 as shown on ,fig4 #ac4 ,there are #e ventilating columns and #e manholes on the aqueduct4 ,illustration3 ,,plate ,x1 ,,fig4 #b4--,,setting ,,forms ,,for ,,san ,,geronimo ,,culvert4 ,the aqueduct terminates in the ,obispado distributing reservoir valve-house1 at a level of #eeh4ej m4 ,the work in connection with this aqueduct was completed by ,december1 #aijh4 ,,distributing ,,reservoir ,,at ,,obispado4 ,the main distributing reservoir for the ,san ,geronimo gravity supply is immediately below the historic ,obispado 7,bishop's ,palace71 at the western limits of the city4 ,the general arrangement and lay-out is shown on ,plate ,,xiii4 ,illustration3 ,,plate ,,xiii4--,,general ,,plan ,,and ,,sections1 ,,obispado ,,reservoir4 ,valve-,house4--,the invert of the conduit from ,san ,geronimo1 where it enters the valve-house1 is #eeh4ej m4 above datum4 ,the valve-house1 which is built in the center of the reservoir1 is shown on ,fig4 #b1 ,plate ,,xviii4 ,one of its special features is the provision of the main overflow at this point instead of within the reservoir proper4 ,the inlet1 main supply tunnel1 independent by-pass overflow1 scour-out pipes1 gate-valves1 and screens1 are all controlled within the valve-house4 ,illustration3 ,,plate ,,xviii1 ,,fig4 #b4--,,view ,,of ,,roof ,,of ,,obispado ,,reservoir1 ,,looking ,,north4 ,reservoir4--,the reservoir is rectangular1 #abf by #ha m4 7#dac4bh by #bfe4fh ft47 at the top1 and has a water depth of #d m4 7#ac4a ft474 ,in the design it was necessary to limit it to the lowest economical depth1 so as to increase the static pressure over the low-pressure district as much as possible4 ,excavation and ,embankment4--,the excavation1 except for a depth of about #a m4 which was in black soil1 was chiefly in a disintegrated sillar stratum of a heavy clayey nature1 the greater part of which could be handled conveniently with plows and scrapers2 the actual foundation on the eastern half required blasting for the final depths4 ,the total excavation amounted to #ef1dgi cu4 m41 of which #g1bee cu4 m4 were placed in the embankment1 the remainder being deposited in the immediate neighborhood of the reservoir4 ,the final trimming of the banks1 which were left #cj cm4 full1 was not undertaken until the lining was begun4 ,the work was done under contract with ,mr4 ,j4 ,s4 ,nickerson1 of ,monterrey4 ,the excavation had only one classification1 and the contract prices were #j4ej peso per cu4 m4 for material carried to spoil banks1 and #a4jj peso for material placed in the embankment4 ,the excavation was begun in ,december1 #aijg1 and completed in ,april1 #aijh4 ,the work was then left standing until the end of #aijh to allow the banks to consolidate thoroughly prior to lining1 which was begun on ,january #dth1 #aiji4 ,concrete ,lining and ,roof4--,plate ,,xiii shows the general plan and sections1 the main feature being the simple division of the reservoir into #bd rows of columns longitudinally and #ae rows transversely1 making a total of #cfj columns1 less the four left out at the central tower4 ,all the columns are #e m4 apart both ways4 ,the roof was designed for a live load of #ajj lb4 and a dead load of #aej lb41 the same as at the ,south ,reservoir4 ,with the exception of the floor1 all the concrete work was reinforced with twisted steel lug bars4 ,the foundation load on the columns for the eastern half of the reservoir is #j4i ton per sq4 ft42 that on the columns for the western half1 where the foundation is of very hard sillar and conglomerate1 is #a4ie tons per sq4 ft4 ,under-drainage of the ,floor4--,to provide for proper drainage in case of seepage1 the floor was underdrained with rubble drains1 #cj cm4 wide and #bc cm4 deep1 filled with large round gravel carted from the bed of the ,santa ,catarina ,river4 ,the total length of these underdrains is #a1afj m4 ,in order to facilitate the detection of any seepage1 they were conducted to a permanent inspection pit outside of the reservoir4 ,main ,distributing ,conduit4--,the main distributing conduit is laid along the inside of the reservoir1 at the inlet end1 and carried on elliptical arches of #b m4 span to a height of #ga cm4 above the finished floor level4 ,this conduit is #gf cm4 high and #de4g cm4 wide1 and it branches in two directions from the inlet tunnel to each side of the reservoir1 its total length being #fi m4 ,in order to prevent any stagnation and to give a continuous circulation1 the water is delivered at eight points1 in the length of the distributing pipe1 through square openings with semicircular tops1 the areas of the openings increasing toward the ends4 ,these inlets are placed so that the current will not strike the roof columns4 ,outlet ,tunnel and ,valve-,house4--,the outlet tunnel is at the north end of the reservoir1 and was excavated in hard sillar rock4 ,the tunnel is lined with concrete #cj cm4 thick1 the finished internal dimensions being #a4eb by #j4ia m4 ,the length of the tunnel is #bb4e m4 to the point where it enters the outlet-house4 ,this house is divided by a wall #de cm4 thick1 which supports a #gf-;cm4 7#cj-;in47 penstock-valve4 ,the supply pipe to the city leaves this chamber in the west wall1 and is also fitted with a #gf-;cm4 penstock-valve4 ,the supply pipe has a copper screen of the same design and dimensions as those in the inlet-house4 ,a #cj-;cm4 7#ab-;in47 scour-out pipe in this chamber provides for draining the contents of the reservoir to a neighboring irrigation ditch1 when necessary4 ,the superstructure of the valve-house is of concrete1 and at the floor level there are bevel-geared head-stocks to raise the valves1 etc4 ,by-,pass and ,supply ,pipes4--,the by-pass and supply pipes are carried below the reservoir embankment to join the main #gf-;cm4 7#cj-;in47 cast-iron distributing pipe to the city4 ,for this short distance they were constructed of concrete1 #gf cm4 in internal diameter1 #aj cm4 7#d in47 thick1 reinforced with #f-a_/b-mm4 square steel longitudinal rods1 #cj cm4 from center to center in the circumference1 and hooped with #f-a_/b-mm4 square steel rods spaced #cj cm4 apart4 ,the concrete forming these pipes was a #a3a-a_/b3b-a_/b mixture4 ,parapet ,walls4--,the parapet walls have #ab piers at each side and #h at each end4 ,in these piers there are ventilating openings branching at the top to each side of the parapet1 with outlets provided with cast-iron screens4 ,this arrangement gives #d sq4 m4 of ventilating space 7exclusive of that provided in the central tower71 equally distributed at #dj points around the walls of the reservoir4 ,general ,construction ,scheme4--,the concrete mixing plant1 which consisted of two ,no4 #a ,smith mixers1 was arranged in connection with the bins and hoppers for the rock and sand on the high ground to the west1 and from there the material was conveyed on a framed timber gangway carried right across the center of the reservoir1 as shown by ,fig4 #a1 ,plate ,,xvii4 ,from this central platform the concrete for the columns was filled from stages placed on the top of traveling towers1 #e m4 high1 which were run between two rows of columns on standard-gauge rails laid on the floor of the reservoir4 ,by this arrangement #bd columns could be filled from each length of track4 ,a main narrow track was also laid right around the reservoir1 with the necessary turn-outs4 ,illustration3 ,,plate ,,xvii1 ,,fig4 #a4--;,,filling ,,primary ,,beams ,,from ,,traveling ,,tower1 ,,obispado ,,reservoir4 ,illustration3 ,,plate ,,xv1 ,,fig4 #a4--;,,construction ,,of ,,west ,,side-,,wall ,,of ,,obispado ,,reservoir4 ,illustration3 ,,plate ,,xv1 ,,fig4 #b4--,,primary ,,beams ,,and ,,columns1 ,,obispado ,,reservoir4 ,illustration3 ,,plate ,,xiv4--,,details ,,of ,,forms ,,for ,,concrete ,,work1 ,,obispado ,,reservoir4 ,the forms for the columns1 primary and secondary beams1 are shown on ,plate ,,xiv4 ,the side forms for the primary beams were struck in #bd hours1 so as to economize lumber2 but the bottom lumber was left in position for #bh days4 ,to avoid much unnecessary timber1 the secondary beam forms were supported at the ends on reinforced concrete corbels cast on the primary beams4 ,for placing the side-walls1 a special traveling form was used1 the details of which are shown clearly on ,plate ,,xiv4 ,at the end of each form an expansion joint of #be cm4 was left to be filled after the roof was placed in position4 ,the concrete was delivered to the wall through stove-pipe chutes1 and carefully spaded by workmen in the limited space between the forms and the embankment4 ,the wall form was removed after #cf hours1 by loosening the jacks and pulling forward the hooked tie-rods4 ,this form is also shown on ,fig4 #b1 ,plate ,,xvi4 ,illustration3 ,,plate ,,xvi1 ,,fig4 #b4--,,traveling ,,side-,,wall ,,form1 ,,obispado ,,reservoir4 ,illustration3 ,,plate ,,xvi1 ,,fig4 #a4--,,preparing ,,floor ,,for ,,concreting1 ,,obispado ,,reservoir4 ,the concreting of the roof slab was carried on continuously1 and1 when partly completed1 the floor was laid in the shade4 ,the bottom layer of the floor1 #ac cm4 thick1 was laid in continuous panels between the columns1 and brought to a fairly smooth surface4 ,on this surface1 after keeping it wet for #aj days and then allowing it to dry thoroughly1 a layer of asphaltum1 supplied by the ,american ,asphaltum and ,rubber ,company1 of ,chicago1 was placed4 ,the work was done by ordinary ,mexican laborers after they had received a few days' instruction from one of the ,asphaltum ,company's superintendents4 ,the surface of the lower layer was kept perfectly clean1 and then received one coat of ,pioneer paint4 ,the asphaltum1 heated in a boiler inside the reservoir to a temperature of approximately #dbe deg4 ,fahr41 was then poured over the floor from buckets1 in a layer approximately #d mm4 thick4 ,where the floor joined the column pedestals1 and at each new panel section1 a double thickness was used4 ,the labor cost of water-proofing1 including superintendence1 etc41 amounted to #c4c cents 7,mexican7 per sq4 m4 for painting with ,pioneer paint1 and #e4d cents for the asphaltum coating1 or a total labor cost of #h4g cents per sq4 m4 for the complete water-proofing4 ,this cost is based on a rate of #h4jj pesos per day for a foreman1 and #a4jj peso for each laborer4 ,it required #ej ,u4 ,s4 gal4 of the paint to cover #bfe4b sq4 m41 and an average of about #f lb4 of asphaltum for #a sq4 m4 ,the upper concrete layer of the floor1 #aj cm4 thick1 was placed so as to break joint with the lower1 and was brought to a smooth surface with wooden floats sheathed with steel and reaching across the panels4 ,in this way a perfectly smooth surface was obtained without any plastering4 ,illustration3 ,,plate ,,xvii1 ,,fig4 #b4--;,,central ,,tower ,,and ,,stairway1 ,,obispado ,,reservoir4 ,the concrete for the beams1 columns1 side-walls1 and floor1 was a #a3b-a_/b3d mixture1 crushed sand and stone being used throughout4 ,in the roof slab the mixture was #a3b3c4 ,the whole of the concrete work of the reservoir was completed in #f months1 by the ,company's own administration1 and the reservoir was first put into service a few days after the great flood of ,august #bgth1 when the ,estanzuela supply main1 crossing the ,santa ,catarina ,river1 was partly destroyed4 ,since that time frequent examinations of the inspection pit1 which is connected by a pipe to the rubble drains under the floor1 have never revealed the slightest leakage4 ,lay-,out of the ,reservoir ,roof and ,grounds4--,the ,company owns about #aa-a_/b hectares of land1 which includes that occupied by the reservoir and its surroundings1 and as this property is in an attractive situation1 commanding fine views of the ,sierra ,madre ,mountains1 the whole of the works have been given a pleasing architectural character1 and the grounds laid out to form a public park for the citizens of ,monterrey4 ,illustration3 ,,fig4 #ad4--,,sketch ,,plan ,,of ,,lay ,,out ,,at ,,obispado ,,reservoir4 ,the general plan of the scheme is shown by ,fig4 #ad and ,fig4 #b1 ,plate ,,xviii4 ,the roof1 which has an area of #a hectare1 has been laid out with walks and grass plots1 and the surrounding embankments have been converted into driveways4 ,above the reservoir a small plazuela of #a_/b hectare has been laid out with a space above it for a band-stand4 ,the whole of the ground has been encircled with carriage drives1 on which it is the intention to plant shade trees4 ,the lay-out of this land also embraced the scheme for protecting the reservoir by draining the surface-water away to the irrigation ditches4 ,,comparison ,,of ,,south ,,and ,,obispado ,,reservoirs4 ,the two reservoirs are practically of the same capacity1 the only difference being the level of the overflows in their relationship to the roof1 which gives the ,obispado ,reservoir a slightly greater capacity4 ,some comparative figures may be of interest1 owing to the differences in type and construction4 ,table #g gives the comparative quantities of material in each reservoir proper1 that is to say1 exclusive of the valve-houses1 lay-out of grounds1 etc4 ,,table #g4--;,,comparison ,,of ,,materials ,,in ,,south ,,and ,,obispado ,,reservoirs4 ,,south ,,reservoir4 ,,obispado ,,reservoir4 ---------------------------------------- - ,quantities1 ,quantities1 ,no4 in cubic ,no4 in cubic meters4 meters4 ---------------------------------------- --------------------------- ,earthwork3 ,total excavation 444 #cd1jjj 444 #ef1dgi ,placed in embankment 444 #ca1ejj 444 #g1bee ,placed in spoil banks 444 #b1ejj 444 #di1bbd ---------------------------------------- - ,concrete3 ,columns 7including foundations7 #ace #a1bdj #cef #edc ,primary beams #ace #ddj #cgd #dfb ,secondary beams #fgj #eae #a1beb #egf ,side-walls 444 #a1bee 444 #gaj ,square ,square meters4 meters4 ,roof slab #e1adj #ebj #aj1bjf #a1jbj ,floor #d1jgj #ghj #i1bjj #b1abj ,parapet walls 444 #ij 444 #afe ---------------------------------------- - ,total concrete 444 #d1hdj 444 #e1eif ---------------------------------------- - ,pounds4 ,pounds4 ,reinforcing steel bars 444 #chg1jjj 444 #chj1jjj ,square ,square meters4 meters4 ,expanded metal in roofs1 slabs1 etc4 444 #e1fia 444 #aj1dij ,the total cost of these reservoirs1 including valve-houses1 by-passes1 and the length of supply pipe where the by-pass joins1 and including all engineering expenses1 etc41 but exclusive of the cost of lands1 planting1 fencing1 and special work in connection with the formation of parks1 was as follows3 ,south ,reservoir3 #cid1jjj pesos1 or #aj1cfh pesos per million liters4 ,obispado ,reservoir3 #cge1jjj pesos1 or #i1cge pesos#g per million liters4 #g ,mexican currency4 ,these rates may be regarded as reasonable when taking into consideration the special difficulties of construction in ,mexico1 and the high cost of all imported material1 on which heavy duties are levied4 ,the value of the materials alone in these reservoirs amounted to more than #gj of their total cost4 ,,analyses ,,of ,,estanzuela ,,and ,,san ,,geronimo ,,waters4 ,table #h shows analyses of the ,estanzuela and ,san ,geronimo waters1 made in ,february1 #aiaj1 by ,messrs4 ,ledoux1 of ,new ,york ,city4 ,the ,estanzuela sample was taken at the valve-house of the ,south ,reservoir1 while that of ,san ,geronimo was taken in ,shaft ,no4 #a of the infiltration gallery when flowing at the rate of about #dej liters per sec4 ,both waters are absolutely free from turbidity4 ,,table #h4--;,,analyses ,,of ,,estanzuela ,,and ,,san ,,geronimo ,,waters4 ,in ,parts per ,million4 ,san ,geronimo ,estanzuela4 ,infiltration ,gallery4 ---------------------------------------- ------------------------- ,total solid matter in solution #bji4jj #cje4jj ,organic and volatile matter ,not weighable4 ,not weighable4 ,,analysis ,,of ,,solids3 ,silica #aj4e #ab4j ,iron and ,alumina ,traces4 ,traces4 ,lime #he4d #aab4f ,magnesia #c4h #bb4f ,soda 7,na#b,o7 #ac4c #bj4b ,potash 7,k#b,o7 #b4j #a4i ,sulphuric ,acid #bd4d #aa4e ,chlorine #b4j #b4h ------------------------------- ,,probable ,,combination ,,of ,,bases ,,acid ,,radicals ,,in ,,the ,,solids3 ,silica #aj4e #ab4j ,iron and ,alumina ,traces4 ,traces4 ,sodium ,chloride #c4c #d4f ,potassium ,sulphate #c4g #c4e ,sodium ,sulphate #bf4c #dj4h ,calcium ,sulphate #ac4c #bb4a ,calcium ,carbonate #adb4g #ahd4h ,magnesium ,carbonate #h4d #di4h ------------------------------- #bjh4b #cag4f ,nitrogen as ,free ,ammonia #j4jjd #j4jcb ,nitrogen as ,albuminoid ,ammonia #j4jjf #j4jbb ,nitrogen as ,nitrites 7,n#b,o#c7 #j4jjb #j4jjb ,nitrogen as ,nitrates 7,n#b,o#c7 #j4ajj #a4he ,total ,hardness 7as ,ca,c,o#c7 #aee4j #bbj4j ,alkalinity 7as ,ca,c,o#c7 #aba4j #ahj4j ,,city ,,water ,,distribution ,,system4 ,illustration3 ,,plate ,,xix4--,,diagram ,,of ,,the ,,main ,,water ,,pipes ,,of ,,monterrey4 ,the distribution system was begun in ,september1 #aijf1 but the general lay-out of the mains was modified in ,july1 #aijg1 in view of the division of the system into two services1 for high and low pressure4 ,plate ,,xix shows in skeleton form the lines of the cast-iron mains4 ,these are laid at the present time along routes containing houses 7excluding wooden shacks7 which can be served immediately4 ,the distribution system is arranged to serve as follows3 ,estanzuela supply #d1aej houses4 ,san ,geronimo supply #h1fjj -------------- ,total #ab1gej houses4 ,this represents1 at the present time1 a division of the city of #cb-a_/b for the ,estanzuela1 and #fg-a_/b for the ,san ,geronimo supply4 ,of the area of the supply district north of ,santa ,catarina ,river1 #eg will be supplied from ,san ,geronimo and #dc from ,estanzuela4 ,the real development of the city1 however1 is northward in the area of the low-pressure supply4 ,the static pressure over the city in the two sections varies as follows3 ,estanzuela supply #he to #ej lb4 ,san ,geronimo supply #ee to #bi lb4 ,the main supply pipe from the ,south ,reservoir is #fa cm4 7#bd in47 in internal diameter1 and this size allows ample provision for future extensions4 ,the supply pipe from the ,obispado ,reservoir is #gf cm4 7#cj in47 in internal diameter4 ,on this main1 in ,calle de ,cinco de ,mayo1 at a distance of #cbj m4 from the reservoir1 has been placed a #gf-;cm4 7#cj-;in47 ,venturi meter1 the recording apparatus being in the house on the side of the road4 ,both these supply pipes are carried well into the city1 and from them the distribution mains are laid2 these are #de4g and #cj cm4 7#ah and #ab in47 in internal diameter1 with intermediate sections of #ae and #aj cm4 7#f in4 and #d in474 ,along ,calle de ,cinco de ,mayo1 where the division between the two services takes place1 two lines are laid1 a #cj-;cm4 for high pressure and a #ch-;cm4 7#ae-;in47 for the low pressure4 ,a duplicate pipe1 #cj cm4 7#ab in47 in diameter1 is also laid in ,calle de ,dr4 ,coss4 ,on ,calle de ,alvarez the low-pressure pipe is #fa cm4 7#bd in471 and the high-pressure1 #de4g cm4 7#ah in47 in diameter4 ,provision is also made for extending the range of the two services to other districts4 ,practically every block is provided with gate-valves to cut off the supply in any direction4 ,on the #gf-;cm4 main1 #fa-;cm4 7#bd-;in47 valves are used1 and are connected by tapers to the pipe4 ,on the #fa-;cm4 mains1 #de4g-;cm4 7#ah-;in47 valves are used4 ,the actual frictional loss by reducing the valve being small1 this method permitted the use of valves of a more convenient size4 ,on all the larger valves there are #ae-;cm4 by-passes fitted with independent gate-valves4 ,illustration3 ,,fig4 #ae4--;,,connection ,,between ,,high-,,and ,,low-,,pressure ,,areas ,,and ,,the ,,intersection ,,of ,,cinco ,,de ,,mayo ,,and ,,alvarez ,,streets4 ,scour-out pipes1 #aj cm4 7#d in47 and #ae cm4 7#f in47 in diameter1 are placed in various parts of the system1 draining to the sewers4 ,air-valves1 both double and single1 are also placed at high points in different parts of the system4 ,reducing ,valves4--,at four points in the system the mains are arranged so that the supply can be interchangeable4 ,fig4 #ae shows the arrangement of the mains at the junction of ,cinco de ,mayo and ,alvarez ,streets1 and is typical of the arrangement at the other points4 ,each reducing valve is placed on a #cj-;cm4 7#ab-;in47 branch main between the two services4 ,these valves adjust themselves automatically to the pressure required1 after they have been properly regulated to the different pressures on either side4 ,to allow repairs to be easily made1 there are ordinary gate-valves at each end enclosed in the same pit4 ,if necessary1 as in case of fire1 any part of the system can be changed into high pressure temporarily by closing the valves against the ,san ,geronimo supply4 ,table #i gives the length of the mains as laid1 and the number of valves4 ,,table #i4--,,length ,,of ,,water ,,mains4 ,,diameter3 ------------------------ ,length1 in meters4 ,number of ,centimeters4 ,inches4 gate-valves4 ---------------------------------------- ------------------ #aj4b #d #di1hca4fh #fgg #ae4b #f #ca1iah4ca #cjf #cj4e #ab #ad1dfa4ca #aag #ch4a #ae #a1ffa4ih #aa #de4g #ah #d1ebb4fa #e #fa4j #bd #b1hbf4ed #aj #gf4b #cj #a1ded4dj ---------------------------------------- ------------------ ,totals #ajf1fgf4hc #a1abf ,the pipes were all cast according to the ,british ,standard ,specification1 in #c4fe-m4 7#ab-;ft47 lengths1 and were supplied by ,messrs4 ,d4 ,y4 ,stewart and ,company1 and ,messrs4 ,dick1 ,kerr and ,company1 of ,kilmarnock and ,london4 ,the valves were all of standard design1 faced with gun-metal1 and were supplied by ,messrs4 ,glenfield and ,kennedy1 ,limited1 of ,kilmarnock1 ,scotland4 ,in the distribution system it is proposed to provide #bjj fire-hydrants1 by arrangement with the municipality1 but only a few of these have been placed4 ,the general type is a double hydrant for two #fc4e-mm4 7#b-a_/b-;in47 streams4 ,these are to be placed at the corner of every block in the business portion of the city2 single-way hydrants will be used in the residential districts4 ,laying ,cast-iron ,pipes4--,table #aj has been prepared to show what can be accomplished with ,mexican labor in laying pipes4 ,in this kind of work the labor was particularly efficient2 after the gangs were once drilled into shape1 the work proceeded systematically1 and at very good speed4 ,all the pipes1 after being laid1 were tested to #aej lb4 per sq4 in4 in the presence of the ,technical ,inspector4 ,table #aa gives the details of the excavation1 the material1 and the average cost1 of laying about #ajf4f km4 of pipes4 ,house ,connections4--,the ordinary house connections1 which are of #ai-mm4 7#c_/d-;in47 galvanized-steel pipe1 are connected to the mains by lead goosenecks and brass corporation cocks4 ,the ,company's obligation under the concession extended to the edge of the sidewalk1 and at this point curb-boxes1 chiefly of the ,hays pattern1 were placed2 but1 subsequently1 owing to the metering of every house service in the city1 the control of the ,company extended to the meter1 which1 as a rule1 is placed immediately inside of the house4 ,owing to the rapid deterioration of the house service pipes in some districts of the northern part of the city1 where the soil is formed of decaying organic matter1 it has been decided to use lead pipe entirely from the main to the meter4 ,damage ,due to ,floods4--,during the night of ,august #bgth1 the main #fa-;cm4 pipe1 under the river bed of ,santa ,catarina1 at the point where the main entered the city1 was destroyed for a distance of #acj m41 due to the scouring away of a whole block of city property4 ,the ,venturi meter register chart at the ,south ,reservoir showed that the break occurred a few minutes before midnight4 ,the location of this pipe is shown by ,fig4 #e2 its broken end was in proximity to an old bridge pier4 ,fortunately1 at the time of the flood1 the ,obispado ,reservoir works were completed1 and the whole city was supplied with water from ,san ,geronimo within #dh hours4 ,as only about #a1ejj services had then been connected1 this delay was not serious2 in fact1 in the lower part of the city1 the water in the mains was sufficient until the ,san ,geronimo supply could be connected4 ,to make a temporary connection to conduct the high-pressure water to the city1 a #ae-;cm4 steel pipe was placed above ground1 on the line of the main1 for a distance of #ajj m4 ,this pipe was supported by a cable1 #cj mm4 in diameter1 and by timber trestles4 ,by limiting the supply district1 this pipe was of sufficient capacity to serve until the large main could be safely restored4 ,,table #aj4--;,,cost ,,of ,,laying ,,and ,,jointing ,,cast-,,iron ,,pipes1 ,,excluding ,,lowering ,,and ,,testing4 ---------------------------------------- ------------------------ #gf ,,cm4 7#cj ,,in47 ------------------------------------- ,employees4 ,rate for ,total ,total cost ,no4 of ,cost per #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #d #ab4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #bj #j4dih ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #ab #ab4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 444 #bb #cf4ej 444 444 ---------------------------------------- --------------------- #fa ,,cm4 7#bd ,,in47 ------------------------------------- ,employees4 ,rate for ,total ,total cost ,no4 of ,cost per #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #e #ae4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #be #j4daj ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #aj #aj4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 444 #ba #cg4ej 444 444 ---------------------------------------- --------------------- #ej ,,cm4 7#bj ,,in47 ------------------------------------- ,rate for ,total ,total cost ,no4 of ,cost per ,employees4 #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #d #ab4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #ce #j4bhg ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #ab #ab4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 #bb #cf4ej 444 444 ---------------------------------------- --------------------- #de4g ,,cm4 7#ah ,,in47 ------------------------------------- ,rate for ,total ,total cost ,no4 of ,cost per ,employees4 #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #d #ab4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #dj #j4bba ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #h #h4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 #ah #cb4ej 444 444 ---------------------------------------- --------------------- #ch ,,cm4 7#ae ,,in47 ------------------------------------- ,rate for ,total ,total cost ,no4 of ,cost per ,employees4 #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #d #ab4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #de #j4aif ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #h #h4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 #ah #cb4ej 444 444 ---------------------------------------- ---------------------- #cj4e ,,cm4 7#ab ,,in47 ------------------------------------- ,rate for ,total ,total cost ,no4 of ,cost per ,employees4 #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #d #ab4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #fj #j4adg ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #h #h4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 #ah #cb4ej 444 444 ---------------------------------------- --------------------- #ae ,,cm4 7#f ,,in47 ------------------------------------- ,employees4 ,rate for ,total ,total cost ,no4 of ,cost per #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #d #ab4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #ajj #j4jhb ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #f #f4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 #af #cj4ej 444 444 ---------------------------------------- --------------------- #aj ,,cm4 7#d ,,in47 ------------------------------------- ,employees4 ,rate for ,total ,total cost ,no4 of ,cost per #aj-;hour ,no4 of labor4 pipes linear day4 men4 ,pesos4 laid4 meter4 ,pesos4 ,pesos4 ---------------------------------------- --------------------- ,foreman #d4ej #a #d4ej 444 444 ,caulkers #c4jj #d #ab4jj 444 444 ,lead pourers #b4jj #b #d4jj 444 444 ,lead melter #a4ej #a #a4ej #aej #j4jegd ,pipe cutter #b4jj #a #b4jj 444 444 ,peons #a4jj #f #f4jj 444 444 ,water boy #j4ej #a #j4ej 444 444 #af #cj4ej 444 444 ---------------------------------------- --------------------- ,,table #aa4--;,,cast-,,iron ,,water ,,pipes4--,,cost ,,of ,,materials ,,and ,,laying ,,at ,,monterrey4 ,,materials ,,per ,,standard ,,length ,,of ,,pipe 4 ,key3 cm centimeter in inch mm millimeter kg kilogram m linear meter ---------------------------------------- ---------------------------- ,,pipe ,weight ,cost_/ ,,lead ,,oakum ,,charcoal ,total ,,diameter ,thick- of piece ---------------------------- ,ma- ---------- ness ,pipe fob ,mon-,weight ,cost ,cost ,cost terial terrey ,cost cm in mm kg pesos kg pesos pesos pesos per m ---------------------------------------- -------------------------- #aj #d #aj4c #aji #aa4fe #b4j #j4cg #j4jbe #j4jebe #c4cj #ae #f #aa4a #afc #ae4gd #c4g #j4fg #j4jfge #j4jfe #d4ea #cj4e #ab #ae4h #dfc #gf4ej #g4i #a4dd #j4abbe #j4a #ba4ce #ch #ae #ag4d #fhj #gi4cf #aj4f #a4id #j4age #j4ab #bb4cj #de4g #ah #ai4j #hga #ij4bh #ac4d #b4db #j4bcge #j4acge #be4db #fa #bd #bb4b #a1bfa #aag4fj #ah4h #c4db #j4cce #j4age #cc4bj #gf #cj #be4d #a1idf #aii4je #bd4e #d4db #j4dd #j4babe #ee4gg ---------------------------------------- -------------------------- ,,labor4 ,key3 cm centimeter1 in inch1 m meter ---------------------------------------- ------------- ,total ,,diameter ,cubic ,cost ,back- cost1 ,,of ,,pipe3 ,width,depth meters of fillingexca- of per exca- and re-vation ----------trench linearvationmoving back- ,continues meter per surplusfilling cm in m m lin4 m,pesos etc4 ,pesos ---------------------------------------- ------------ #aj #d #j4ee #j4ij #j4ej #j4fj #j4ah #j4gh #ae #f #j4fj #a4jj #j4fj #j4gb #j4bb #j4id #cj4e #ab #j4fe #a4bj #j4gh #j4id #j4bi #a4bc #ch #ae #j4gj #a4cj #j4ia #a4aj #j4cd #a4dd ,below #de4g #ah #j4hj #a4dj #a4ab #a4cd #j4da #a4ge #fa #bd #a4jj #a4ej #a4ej #a4hj #j4ee #b4ce #gf #cj #a4aj #a4fj #a4gf #b4aa #j4fe #b4gf ---------------------------------------- ------------ ---------------------------------------- -- ,,hauling ,,per ,cost ,total ,total of hauling excava- ,,linear ,,meter laying and tion and per laying laying1 --------------- linear per labor1 ,haul- ,misc4 meter linear complete ing ,pesos meter ,pesos ,pesos ,pesos ,pesos ---------------------------------------- - #j4jbge #j4jje #j4jf #j4jibe #j4hgbe #j4de #j4jje #j4hbe #j4acbe #a4jgbe #j4ah #j4jjge #j4adge #j4cce #a4efe #j4bgbe #j4ja #j4ai #j4dgge #a4iabe #j4bgbe #j4ja #j4bde #j4ebge #b4bgge #j4hbe #j4jh #j4da #a4cae #c4ffe #j4hc #j4aj #j4ec #a4df #d4bb ---------------------------------------- - ,,note4--,the above costs of earthwork are based on the following rates and percentages over the whole city3 ,earth1 per cubic meter #j4ce pesos #ej ,soft sillar #j4ge #bj ,hard sillar #a4ej #bj ,rock 7chiefly conglomerate7 #d4jj #aj ,,summary ,,of ,,table #aa4 ---------------------------------------- --------------------- ,,diameter ,total labor ,materials4 ,total cost ,,of ,,pipe 3 cost4 ,pesos4 per linear ----------------------- ,in pesos4 meter1 in ,centimeters4 ,inches4 pesos4 ---------------------------------------- -------------------- #aj #d #j4hgbe #c4cj #d4agbe #ae #f #a4jgbe #d4ea #e4ehbe #cj4e #ab #a4efe #ba4ce #bb4iae #ch #ae #a4iabe #bb4cj #bd4babe #de4g #ah #b4bgge #be4db #bg4fige #fa #bd #c4ffe #cc4bj #cf4hfe #gf #cj #d4bb #ee4gg #ei4ii ---------------------------------------- -------------------- ,the flood destroyed about #a1bjj houses in the neighborhood of the river4 ,in a number of blocks the smaller mains were scoured away1 but considerable salvage was done afterward1 and1 as it is the intention of the authorities not to permit rebuilding along the flood-path of the river1 these mains do not require reconstruction4 ,,main ,,sewerage ,,system4 ,the ,company's obligations1 as far as drainage is concerned1 were limited to the removal and disposal of sewage1 no provision being required for storm-water1 which is allowed to find its way to the natural watercourses4 ,apart from that fact1 however1 the best system for a city like ,monterrey1 where rainfall for many months at a time is very scarce1 is the strictly separate system4 ,in the design advantage was taken of the natural topography of the drainage district1 which is almost an ideal one for a gravitation system of sewers1 the general fall in all directions being northeast2 it was also in this direction that the best available land could be obtained for disposal purposes4 ,illustration3 ,,plate ,,xx4--,,diagram ,,of ,,the ,,main ,,sewers ,,of ,,monterrey4 ,plate ,,xx shows in skeleton form the general lay-out of the sewers4 ,two drainage districts are arranged1 divided by ,calle de ,washington1 which may be regarded as practically the center of the city1 and each of these districts has an independent main collector connecting to the outfall sewer at the northeast extremity of the city4 ,the system has been designed so that extensions may be made and may cover any part within the city limits2 the main collectors are large enough for the whole area when fully built up4 ,the sewers are designed on a very liberal basis1 namely1 on the assumption that when flowing half full the quantity to be dealt with will be #chj liters per capita per day1 with a maximum rate of flow of #bjj per cent4 ,it was assumed that each house would be occupied by #g persons and have a frontage of #ab-a_/b m4 ,the minimum velocities in the sewers1 when running full1 vary between #j4ia and #a4e m4 per sec41 with the exception of a few blocks4 ,the minimum size adopted was #bd4c cm4 7#h in47 in internal diameter4 ,the sewers of diameters between #bd4c and #ej cm41 are #j4ia m4 7#cf in47 long1 and are of salt-glazed vitrified clay1 imported from ,san ,antonio1 ,tex4 ,table #ab gives the details of the length of the various sewers laid4 ,,table #ab4--,,length ,,of ,,sewers4 ---------------------------------------- ----------------------- ,,diameter3 --------- ,kind4 ,length1 cm in4 in meters4 ---------------------------------------- ---------------------- #bd4c #h ,fire-clay #ch1ccb4he #be4d #aj #af1djj4fi #cj4e #ab #g1iec4ae #ch4a #ae #d1hej4ef #de4g #ah #b1jbc4dj #ej4h #bj #a1dej4ec #ee4i #bb ,reinforced concrete tubes1 #f4i cm4 thick #c1acd4bj #fa4j #be #g4f #ceg4dj #fh4f #bg ,brick and concrete #dhd4je #gf4b #cj #ffb4fi ,total #ge1fdi4ae ---------------------------------------- ---------------------- ,the greater number of the manholes are of brickwork1 #bc cm4 thick1 and have concrete inverts4 ,they have a diameter of #a4b m41 which is reduced to #j4fa m4 at the top1 and each is provided with a heavy cast-iron frame and closed cover weighing about #aij kg4 ,there are #eba manholes1 and they are placed at every block and on long lines about #hj m4 apart4 ,illustration3 ,,fig4 #af4--,,standard #cjj-;,,gal4 ,,flush ,,tanks4 ,the sewers are flushed with #ae-;cm4 7#f-;in47 automatic flushing siphons of the ,miller pattern with #bj-;cm4 7#h-;in47 discharge pipes4 ,there are #bgh of these siphons1 and they are placed in flush-tanks 7,fig4 #af7 built of brickwork and plastered with #a3a cement mortar4 ,their capacity varies from #hjj to #a1bjj liters1 and they discharge from #bb-a_/b to #bh-a_/b liters per sec4 ,they are timed to flush once in #bd hours4 ,the system is at present ventilated by #bc-;cm4 7#i-;in47 steel ventilating columns 7,fig4 #af71 with ornamental cast-iron bases4 ,there are #bbj of these columns4 ,most of them are #g4he m4 above the level of the edge of the sidewalk1 and are connected to special #ae-;cm4 branch pipes leading from the sewer on the outside of the flush-tanks4 ,in the center of the city they are provided with extension lengths1 giving a total height of #ab m4 ,table #ac gives the particulars of the average distributed cost of laying the #ge4f km4 of sewers4 ,,table #ac4--;,,average ,,cost1 ,,per ,,linear ,,meter1 ,,for #ge4f ,,km4 ,,of ,,sewers1 ,,for ,,materials ,,and ,,labor ,,complete4 ---------------------------------------- -------------------------- ,,internal ,cost of ,,earthwork ,,and ,,labor3 ,total ,,diameter mater- --------------------------- cost of ,,of ials ,cost of ,cost of sewer ,,sewers4 includ- ,average excavation1labor complete ,kind of ---------- ing depth including in per ,sewer4 #aj-;cm4 of back- laying linear 7#d-;in47 sewer filling1 7includ- meter4 cm4 in4branches removing ing every m4 surplus1 hauling1 #d-a_/b m4 etc4 etc474 ,pesos4 ,pesos4 ,pesos4 ---------------------------------------- ----------------------- ,fire-clay #bd4c #h #b4jj #b4aj #c4df #j4ba #e4fg #be4d #aj #b4gh #b4be #c4ig #j4bfbe #g4jabe #cj4e #ab #c4fd #b4ej #d4gje #j4cje #h4fe #ch4a #ae #f4ad #b4ge #e4ej #j4dcge #ab4jgge #de4g #ah #h4hj #c4jj #f4gde #j4fde #af4ai #ej4h #bj #aa4cj #c4ej #h4bge #j4hae #bj4ci ,concrete #ee4i #bb #e4ic #c4ej #i4ai #a4cbe #af4dde #fa4j #be #g4cj #c4ge #aa4bde #a4fhe #bj4bc ,one brick thick on #fh4f #bg #g4ag #c4ge #aa4gce #c4ic #bb4hce concrete #gf4b #cj #g4ibe #d4jj #ad4ec #d4eae #bf4ig founda- tions ---------------------------------------- ----------------------- ,illustration3 ,,fig4 #ag4--,,sketch ,,showing ,,disconnecting ,,trap ,,on ,,house ,,drain4 ,the house connections are chiefly of #aj-;cm4 7#d-;in47 pipes1 laid on a minimum gradient of #b-a_/b1 from oblique branches on the sewer to siphon intercepting traps near the house1 as shown by ,fig4 #ag4 ,from this trap a #aj-;cm4 fire-clay inspection pipe is carried up and capped at the sidewalk level with a cast-iron box having a locked cover4 ,from this inspection pipe a branch is connected to a cast-iron fresh-air inlet1 in most cases set in the wall of the house1 the inlet being #cj cm4 above the level of the pavement4 ,effect of the ,flood on ,sewers4--,the flood of ,august #bgth and #bhth1 #aiji1 partly destroyed one of the main collectors1 which was laid along the banks of the river and encased in concrete4 ,this has now been relaid farther north1 and out of the way of any future floods4 ,the total length of the new sewers replacing those damaged amounts to #abjj m41 and they vary in internal diameter from #bj to #ee4i cm4 7#h to #bb in474 ,,main ,,outfall ,,sewer4 ,the direction of the main outfall sewer was determined after a thorough study of all the available land lying to the north and northeast of the city1 as it was the intention of the ,company to utilize for irrigation purposes the sewage and any surplus waters that might be developed4 ,the best available site was found to be about #ab km4 north of the city1 a little northwest of the village of ,san ,nicolas de los ,garzas1 as shown on ,plate ,,ii4 ,the long length of outfall required was justified by the cheap cost of the land and its excellent character for sewage irrigation4 ,the sewer was designed for a capacity of #ij1jjj1jjj liters a day 7#cf4gf cu4 ft4 per sec47 in order to allow for conveying surplus waters as well as sewage4 ,illustration3 ,,plate ,,xxii4--,,outfall ,,sewer3 ,,plan ,,of ,,ground ,,showing ,,sewer2 ,,also ,,details ,,of ,,various ,,sections4 ,the outfall intercepts the two main branches of the city sewers at ,calle de ,allende and ,calle de ,tapia1 and its total length is approximately #aa1ijj m4 ,the chief type adopted is shown on ,plate ,,xxii4 ,it is formed with an invert of radial bricks laid in #a3b cement mortar1 on a foundation of #a3c3e concrete approximately #g cm4 thick4 ,as the ground was chiefly in hard sillar1 only a little concrete was required to mould the bottom to the correct shape4 ,the arch was formed of special radial bricks1 #ae cm4 7#f in47 deep1 laid in cement mortar4 ,these bricks were adopted in preference to concrete1 owing to the heavy cost of sand and rock1 due to the long haul1 and for the purpose of obtaining rapid work4 ,plate ,,xxi shows the sewer arch1 and one of the ventilating columns and manholes4 ,the bricks were obtained from the local brick plant1 and form a very satisfactory material for sewers1 being well burnt1 thoroughly hard1 and absorbing not more than #g-a_/b of their weight of water4 ,the contract prices for the labor on the brickwork were #a4be pesos per sq4 m41 and #a4ch pesos for the arch4 ,illustration3 ,,plate ,,xxi1 ,,fig4 #a4--,,view ,,of ,,arch1 ,,outfall ,,sewer4 ,illustration3 ,,plate ,,xxi1 ,,fig4 #b4--,,ventilating ,,column ,,and ,,manhole1 ,,outfall ,,sewer4 ,the general route of the sewer is very direct1 long straight lines of several kilometers being possible1 and these were joined by curves of approximately #cj m4 radius4 ,the gradient of the sewer invert is #j4b 7#a in #ejj7 which is approximately the general fall of the ground northward from ,monterrey4 ,the total quantity of excavation was as follows3 ,no4 #a1 soft earth #h1ifj cu4 m4 ,no4 #b1 sillar #ah1dib ,no4 #c1 conglomerate rock #i1hbb ------ ,total #cg1bgd cu4 m4 ,the contract prices for this excavation were3 for ,no4 #a1 #cb cents2 ,no4 #b1 #he cents2 and ,no4 #c1 #b4ag pesos per cu4 m4 ,all the excavation was in perfectly dry ground4 ,where the sewer was partly out of the ground it had a foundation of concrete1 #a4ge m4 wide1 from #ae to #bc cm4 thick1 below the bottom of the brickwork1 and carried up to the springing of the arch1 and a well-tamped embankment1 with slopes of #a-a_/b to #a1 to protect the sewer to a height of #cj cm4 7#ab in47 above the arch4 ,for #cdb m4 at the ,monterrey end of the line1 the sewer was constructed in tunnel1 from1 the open end and from two intermediate shafts4 ,the tunnel throughout was in sillar1 and the contract price for excavation was #bd4ej pesos per lin4 m4 ,this work was done without timbering of any kind1 except at the shaft lengths4 ,plate ,,xxii shows the lining of the tunnel1 which was of concrete with a brick invert4 ,at four places the sewer passes under main railway tracks1 which at these points were carried on steel girders supported on concrete abutments1 the sewer being carried under the tracks in the ordinary way4 ,bridges4--,at three points the sewer was carried over arroyos on reinforced concrete girders4 ,no4 #a1 at ,station #e1fjj1 consisted of four #aj-m4 spans2 ,no4 #b1 at ,station #h1cfe1 over the ,estanscia ,arroyo1 consisted of nine #aj-m4 spans2 and ,no4 #c1 at ,station #h1ifj1 over the ,topo ,chico ,arroyo1 consisted of three #aj-m4 spans4 ,one of these bridges is shown on ,plate ,,xxiii4 ,they were designed as two parallel continuous girders with connecting top and bottom slabs4 ,the concrete for the girders was a #a3b-a_/b3c-a_/b mixture1 the sand being from the crusher and the rock gauged to pass a #ai-mm4 7#c_/d-;in47 screen4 ,the inside was rendered with a coat of #a3a cement mortar1 #g mm4 thick1 for water-tightness4 ,illustration3 ,,plate ,,xxiii1 ,,fig4 #a4--;,,forms ,,for ,,main ,,girders1 ,,estanscia ,,bridge1 ,,outfall ,,sewer4 ,illustration3 ,,plate ,,xxiii1 ,,fig4 #b4--,,view ,,of ,,estanscia ,,bridge1 ,,completed4 ,the piers of the ,estanscia ,bridge 7,plate ,,xxiii7 were carried down through soft earth to a stiff clay from #d-a_/b to #f m4 below the surface1 and the foundations were spread so that the pressure would not exceed #a ton per sq4 ft4 ,the ends of the bridges were protected by rubble wing-walls supporting the embankment over the sewer4 ,a #a3c3e concrete was used for the upper part of the piers1 and the lower part was of the same mixture with #cj of large boulders4 ,there are #gj manholes 7,fig4 #ai7 along the line of the sewer1 and they vary from #aej to #bcj m4 apart4 ,the sewer is ventilated with #cj concrete towers 7,fig4 #ah1 and ,fig4 #b1 ,plate ,,xxi71 #b4i m4 high1 having #bj-;cm4 7#h-;in47 shafts4 ,illustration3 ,,fig4 #ah4--;,,details ,,of ,,ventilators ,,on ,,outfall ,,sewer4 ,illustration3 ,,fig4 #ai4--;,,details ,,of ,,manholes ,,on ,,outfall ,,sewer4 ,the works for the outfall sewer were carried out satisfactorily under a contract with ,mr4 ,john ,phillips1 of ,mexico ,city1 the ,company supplying the greater part of the materials4 ,the work was begun on ,march #afth1 and finished on ,november #abth1 #aijh4 ,,sewage ,,disposal ,,works ,,and ,,irrigation ,,lands4 ,for the purpose of disposing of the sewage and using it profitably1 the ,company purchased #iji hectares 7#b1bdf acres7 of land from the ,community of ,san ,nicolas de los ,garzas1 the outfall sewer being carried to the southwestern boundary of the land acquired4 ,this area has a general fall in all directions to the northeastern boundary1 with a gradual fall of about #be m4 across the diagonal of the land4 ,the area purchased was practically virgin land1 only small portions having been cultivated4 ,the greater part was covered with a growth of mezquite trees and small shrubs4 ,the quality of the land is excellent1 if properly irrigated1 and capable of yielding abundant crops of every description4 ,the limits of this land are shown on ,plate ,,ii4 ,sewage ,purification ,tanks4--,for the purpose of obtaining a satisfactory effluent to discharge on the land without causing nuisance1 the ,company built a system of detritus chambers and liquefying tanks at the end of the outfall sewer4 ,one difficulty to be faced1 in designing these works1 was the fact that there were no data regarding the probable quantity of dry-weather sewage1 nor any particulars as to its general character2 there was also the probability that the outfall sewer would have to carry large quantities of surplus water4 ,therefore1 the system was designed so as to be capable of extension if necessary1 and the sizes of the various tanks were limited at present1 because of the septic processes which would be set up in the long length of outfall sewer4 ,the tanks were designed to deal with #aj1jjj1jjj liters of sewage proper per day1 and the channels1 etc41 were proportioned to take the full flow of the sewer if necessary4 ,provision was also made for discharging large volumes of surplus water directly on the land1 independent of the tanks4 ,to do this a by-pass was taken from the sewer a short distance before reaching the site of the tanks4 ,by properly timing the flow1 arrangements could be made to discharge these waters in the early hours of the morning1 by allowing the scour-pipes in the distribution system to be opened at night when the domestic sewage flow was at its minimum4 ,as the area of land available is very great1 the degree of purification in the tanks was relatively unimportant2 the object to be obtained consisted chiefly in distributing on the land an effluent which would be innocuous and clear4 ,the general design of the works is shown on ,plate ,,xxiv1 and they consist essentially of a screen chamber1 duplicate detritus tanks1 and three liquefying tanks4 ,there is also a sludge-pit #fbi m4 from the tanks4 ,illustration3 ,,plate ,,xxiv4--,,sewage ,,disposal ,,works ,,at ,,san ,,nicolas ,,de ,,los ,,garzas2 ,,general ,,plan ,,of ,,detritus ,,and ,,liquefying ,,tanks1 ,,with ,,details ,,of ,,the ,,latter4 ,screen ,chamber and ,detritus ,tanks4--,enlarged details of the screen chamber are shown on ,plate ,,xxv4 ,the invert1 where the sewer enters the screen chamber1 is #dhi4de m4 above datum4 ,this chamber has duplicate screens which are fully detailed on ,plate ,,xxx4 ,for cleaning purposes the screens are raised by a steel-framed head-gear1 which is arranged so that they may be lowered to a small traveling bogie1 out of the way of the screen chamber4 ,illustration3 ,,plate ,,xxv4--,,sewage ,,disposal ,,works ,,at ,,san ,,nicolas ,,de ,,los ,,garzas4 ,,details ,,of ,,detritus ,,chambers ,,and ,,inlet ,,channels4 ,illustration3 ,,plate ,,xxvi4--,,sewage ,,disposal ,,works ,,at ,,san ,,nicolas ,,de ,,los ,,garzas ,,detritus ,,and ,,liquefying ,,tanks2 ,,details ,,of ,,distributing ,,channels4 ,illustration3 ,,plate ,,xxx4--,,sewage ,,disposal ,,works ,,at ,,san ,,nicolas ,,de ,,los ,,garzas4 ,,details ,,of ,,screening ,,apparatus4 ,from the screen chamber there are two main channels1 #a4bb m4 wide1 branching to the two concrete detritus chambers4 ,each channel has a square penstock1 so that the sewage can be diverted into either chamber when necessary4 ,the detritus chambers are octagonal in plan1 #d m4 in diameter1 and each is provided with an outlet weir #a4ej m4 wide4 ,at the weir level the chambers have a depth of #a4ge m41 with drainage channels below that level4 ,the coping is #a m4 above the outlet weir of the detritus tanks4 ,to drain off these chambers1 each has a scour-out pipe1 #cj cm4 in diameter1 controlled from valves with spindles carried above the coping level4 ,each of these pipes is connected to a central chamber1 and leads to a #ef-;cm4 7#bb-;in47 sludge-pipe4 ,the chambers as designed are of smaller capacity than those usually provided1 but1 as all surface water is strictly excluded from the sewerage system1 the quantity of detritus reaching the chambers may be small4 ,the velocity through them when both are in use will be approximately #j4jhb m4 7#j4bg ft47 per sec4 ,from these chambers the sewage is carried to the three liquefying tanks by a main channel1 #aa4e m4 long and #a4ej m4 wide4 ,illustration3 ,,plate ,,xxvii1 ,,fig4 #a4--;,,cast ,,concrete ,,beams ,,being ,,placed ,,in ,,position1 ,,liquefying ,,tanks4 ,illustration3 ,,plate ,,xxvii1 ,,fig4 #b4--;,,inlet ,,weirs ,,to ,,liquefying ,,tanks1 ,,during ,,construction4 ,illustration3 ,,plate ,,xxviii1 ,,fig4 #a4--,,view ,,of ,,liquefying ,,tanks1 ,,from ,,inlet ,,end4 ,the tanks are of concrete and have reinforced concrete roofs4 ,each is #ff m4 long and #f m4 wide2 the minimum depth for the sewage is #a4ej m4 at the outlet end1 and #b4be m4 at the inlet1 increasing to a maximum depth of #b4ge m4 at the lowest depth at the scour-out channel4 ,their combined capacity is #b1ejj1jjj liters1 which is equivalent to #f hours' flow of the quantity of sewage for which they were designed4 ,the sewage passes from the main channel1 through penstock-valves which control the flow1 into one or the other of the tanks4 ,from these valve openings it flows over concrete weirs1 #e m4 long1 and is deflected to the bottom of the tank by a reinforced concrete scum-plate1 extending across each tank1 with a clearance of #ae cm4 at each end4 ,this scum-plate is #a4e m4 deep and #aj cm4 thick1 and is placed #dj cm4 from the end walls4 ,illustration3 ,,plate ,,xxix4--,,sewage ,,disposal ,,works ,,at ,,san ,,nicolas ,,de ,,los ,,garzas2 ,,details ,,of ,,outlet ,,channels ,,and ,,weir ,,box4 ,the details of the concrete division and outside walls are shown on ,plate ,,xxix4 ,the floor was constructed in two layers1 and its surface is divided into #f channels formed by small walls1 #bj cm4 wide and #ae cm4 deep1 the object of these channels being to facilitate the cleaning of the floor by scouring it out to a specially arranged channel at the deepest point of the tank1 near the inlet end4 ,each scour-out channel has a #cj-;cm4 7#ab-;in47 gate-valve1 controlled from the roof of the tank1 the three scour-pipes meeting in a concrete chamber outside of the tanks1 from which a #ef-;cm4 7#bb-;in47 concrete pipe discharges the contents of the tanks to the sludge-pit during cleaning operations4 ,the velocity through the tanks1 when they are used in combination1 is #j4jbec m4 7#j4jhc ft47 per sec41 the tanks being made as long as economically possible1 in order to obtain this low velocity and thus permit the proper sedimentation of the suspended matters4 ,the roof of each tank is #a m4 above the weir level4 ,each tank has four ventilating columns1 #c4g m4 high and #cj cm4 in diameter1 vitrified clay pipes1 with an exterior casing of contrete1 being used for the shafts4 ,the roof is enclosed within parapet walls1 and is covered with a layer of earth #be cm4 thick4 ,the outlet channel from the tanks leads to a measuring chamber1 #c m4 square1 as shown on ,plate ,,xxix4 ,this chamber is fitted with penstocks1 #a4hc m4 wide1 and measuring weirs4 ,from this chamber the sewage is delivered to two main irrigation ditches1 which distribute the sewage in two directions1 one northward and the other to the western extremity of the lands4 ,construction of ,tanks4--,the excavation for the tanks was in soft earth for a depth of #a-a_/b m42 the lower depths were in a firm foundation of sillar and calcareous clay4 ,the total excavation in the tanks1 channels1 etc41 was #h1cce cu4 m41 and the actual cost was #de-c_/d cents per cu4 m4 ,to facilitate the construction1 about six-tenths of the concrete beams were cast as single monoliths and placed in position by sliding them across the tanks on temporary timbers4 ,the remainder of the beams1 the roof1 and the slab were placed in position in the ordinary way with timber forms4 ,the total quantity of concrete placed was #a1cfj cu4 m4 ,a #a3b-a_/b3d-a_/b concrete was used for the walls1 channels1 etc41 and a #a3b3c mixture for the roof slab and beams4 ,table #ad gives the average cost per cubic meter for all the concrete work4 ,,table #ad4--;,,average ,,cost ,,per ,,cubic ,,meter ,,for ,,concrete ,,in ,,tanks4 ---------------------------------------- ----------------------- ,pesos per ,pesos per cubic cubic meter4 meter4 ---------------------------------------- ----------------------- ,,labor 3 ,mixing and placing #e4bj ,carpenter work in forms1 framing1 etc4 #d4bj ,total labor cost #i4dj ,,materials 3 ,screened gravel #d4jd ,sand 7from neighboring arroyo7 #d4ih ,cement 7including hauling7 #ae4ai ,lumber1 nails1 and other supplies #a4ij #bf4aa ---------------------------------------- ----------------------- ,total cost of concrete per cubic meter #ce4ea ---------------------------------------- ------------------------- ,sludge-pit4--,the sludge-pit1 used when cleaning out the tanks1 is carried #fci m4 northward1 far enough to get the available fall to drain the bottom of the detritus chambers and liquefying tanks4 ,the drainage pipe was formed of #ef-;cm4 7#bb-;in47 concrete tubes4 ,the sludge-pit is merely an excavation in the earth #bj m4 square and #b m4 deep1 the sides having a slope of #a-a_/b to #a4 ,an overflow drains the pit to an irrigation ditch1 the solid matter being allowed to settle and the liquid to drain off4 ,from time to time it is proposed to dig out the solids and plow them into the land4 ,general4--,to the east of the tanks a #c-roomed house has been built for the inspector4 ,in order to provide a good supply of water for cleaning operations1 a well #bb m4 deep has been sunk and is fitted with pumps operated by an ,eclipse windmill1 #d m4 in diameter1 on a tower #bb m4 high1 which delivers the pump water to a circular wooden tank of #bj1jjj liters capacity4 ,the work in connection with the purification tanks was carried out by the ,company's own staff2 it was begun on ,september #ajth1 #aijh1 and practically completed by the first week in ,january1 #aiji4 ,at the time of writing1 the tanks have to deal with the sewage from a population of only #aj1jjj persons1 as only from #ae to #bj of the connections have been made4 ,the sewage1 therefore1 has been diluted with several times its volume of surplus water1 and the necessary scum on the top of the sewage in the tanks has not yet assumed the usual thick matty condition observed in most systems4 ,as there are no available means in ,monterrey of having proper determinations made of the degree of purification which takes place in the passage of the sewage through the liquefying tanks1 a few simple tests have been made4 ,these tests were limited to the determination of the amount of oxygen absorbed in #d hours1 and show a purification of #ej in passing from the detritus chambers to the outlet4 ,the sewage1 although very black and full of suspended matter as it enters the tanks1 leaves them in a very clarified condition4 ,of the total area of land acquired by the ,company1 #ijd hectares 7#b1bcd acres7 have been leased to the ,monterrey ,railway1 ,light1 and ,power ,company1 for #ii years1 the ,water-,works ,company reserving #e hectares 7#ab acres7 absolutely for future extensions of the sewage works4 ,by giving #ab months' notice1 the ,company also reserves the right to utilize any part of #ade hectares 7#ceh acres7 near the tanks1 should it be required at any time in the future for sewage purification purposes4 ,,quality ,,of ,,and ,,rates ,,for ,,labor4 ,all the work was practically under the direction of ,english-speaking superintendents and general foremen4 ,for the ordinary skilled and low-skilled labor1 ,mexicans were employed exclusively1 and1 on the work1 which was quite new to them1 they proved entirely efficient and satisfactory2 throughout the work1 on which at some periods between #b1jjj and #c1jjj men were employed1 chiefly under the ,company's direct administration1 they were very tractable and willing to do their best1 and no trouble was experienced at any time4 ,the ,mexican peon1 and also the ordinary skilled workman in the north of ,mexico1 is intelligent1 and is excellent for purely routine work1 but he is not adaptable or resourceful in cases of emergency4 ,under intelligent and careful supervision1 however1 it is quite possible to get as good results as could be obtained anywhere4 ,the daily rates of wages for a #aj-;hour day were approximately as given in ,table #ae1 these rates being varied in special cases4 ,,table #ae4--,,rates ,,of ,,wages ---------------------------------------- -------------- ,pesos per day4 ---------------------------------------- -------------- ,general foreman #h4jj to #aj4jj ,foreman #f4jj #h4jj ,cabos #b4jj #d4jj ,masons #c4jj #d4jj ,bricklayers #c4jj #d4jj ,masons and bricklayers helpers #a4ej ,cast-iron pipe jointers 7foreman7 #d4ej caulkers #c4jj helpers #a4ej to #b4jj ,fire-clay pipe layers #a4ge helpers #a4be to #a4ej ,drillers #a4be #a4ej ,carpenters #b4jj #b4ej ,blacksmiths #b4ej ,crane men #f4jj ,peons 7laborers7 #a4jj to #a4be ,boys 7watering concrete7 #j4cg-a_/b to #j4ej ,watchman #a4jj ,timekeepers #bb4jj per week4 ---------------------------------------- -------------- ,,cost ,,of ,,works4 ,table #af gives the main items of the approximate expenditure4 ,these include all expenses for preliminary location1 engineering1 superintendence1 purchase of lands1 water rights1 etc41 but do not include other heavy expenditures chargeable to the concession1 such1 for example1 as general expenses1 interest at the rate of #f during the construction period1 preliminary expenses for investigations1 etc41 items which would increase the total by nearly #be per cent4 ,,table #af4--,,principal ,,items ,,of ,,expenditure4 ---------------------------------------- ------------------------- ,pesos1 ,mexican currency4 ---------------------------------------- ------------------------- ,,estanzuela ,,supply 3 ,aqueduct and dam #ejb1jjj ,south ,reservoir #dbi1jjj ------- #ica1jjj ,,san ,,geronimo ,,gravity ,,supply 3 ,aqueduct1 tunnel1 and infiltration gallery #bbc1jjj ,obispado ,reservoir #dcf1jjj ------- #fei1jjj ,,san ,,geronimo ,,provisional ,,supply 1 including boring operations1 etc4 #acj1jjj ,,city ,,water ,,distribution ,,system #a1aie1gjj ,,city ,,sewer ,,system #a1jcf1jjj ,,outfall 3 ,main outfall sewer #dbe1jjj ,sewage purification works #ge1jjj ------- #ejj1jjj ---------------------------------------- ------------------------- ,total #d1dea1gjj ---------------------------------------- ------------------------- ,as a general statement1 the actual cost of labor is about #cc-a_/c of the total cost of the construction work1 including materials4 ,fig4 #bj shows in graphic form the amount of the labor pay-rolls and the progress of the work during the whole construction period from #aijf to #aiji1 inclusive1 comprising also that done under contract4 ,illustration3 ,,fig4 #bj4--,,progress ,,diagram ,,showing ,,monthly ,,labor ,,pay-,,rolls ,,during ,,the ,,construction ,,period4 ,,tariffs ,,and ,,sanitary ,,regulations4 ,tariffs4--,the tariffs charged for the water and drainage service 7,table #ag7 were approved by the ,state ,government 7which accepts the responsibility for their collection71 under a compulsory ,state law which came into force on ,march #ast1 #aiaj1 for the southern portion of the city1 and on ,july #ast1 for the northern half1 the penalty for non-compliance being a tax of #aj on the monthly rental value of the property1 as assessed by the ,state officials4 ,the basis of the tariffs 7which were published on ,february #bb;d1 #aiji7 is a charge for water varying between #ab and #af cents 7,mexican7 per #a1jjj liters1 with a minimum monthly rate for each different class of property connected to the system4 ,the rate for house drainage is fixed at #hj of the minimum water rate levied on the consumer4 ,the minimum rates have been fixed so that the poorer classes of the community will not be overtaxed1 while at the same time the rate is actually levied on the quantity of water used1 as indicated by the meter4 ,all the services at the present time are metered1 and the meter system will be used throughout4 ,,table #ag4--,,the ,,tariffs4 ---------------------------------------- ------------------------ ,monthly ,liters ,price for ,minimum ,rate for ,total ,class property of #a1jjj monthly drainage rate rental4 water liters4 rate4 service4 payable4 ,pesos4 allowed4 ,cents4 ,pesos4 ,pesos4 ,pesos4 ---------------------------------------- ------------------------ ,i ,up to #bj #g1hjj #af #a4be #a4ji #b4be ,,ii #ba to #dj #ab1ejj #af #b4jj #a4fj #c4fj ,,iii #da to #fj #ah1gej #af #c4jj #b4dj #e4dj ,,iv #fa to #abj #bc1cej #ae #c4ej #b4hj #f4cj ,v #aba to #cjj #cj1jjj #ae #d4ej #c4fj #h4aj ,,vi #cja upward #cc1cej #ae #e4jj #d4jj #i4jj ---------------------------------------- ------------------------ ,notes3 7#ast7 ,the rental for the water meters #e_/h-;in4 size 7#ae-a_/b mm471 which shall always be considered the property of the ,company1 will be #bj cents per month4 ,houses of the first and second classes shall be exempt from paying such rental for one year's time1 counting from this date4 7#b;d7 ,all excess consumption of water over that allowed by the tariff will be charged for at #b cents less than the price shown in the tariff per thousand liters4 7#c;d7 ,extra large houses1 large establishments1 such as colleges1 hotels1 etc41 etc41 having a consumption of #ej1jjj to #fj1jjj liters of water per month1 will pay at the rate of #ad cents per thousand liters4 ,the drainage rate for such buildings will be arranged in proportion to the water tariff1 or #hj of the value of the water4 7#dth7 ,the laundry establishments1 bath-houses1 etc41 when using #ej1jjj liters or upward1 can arrive at some agreement so as to pay #ab cents per #a1jjj liters4 7#eth7 ,groups can be formed of two or more small houses so as to obtain a joint service under the proportion shown in the tariff4 7#fth7 ,any other combination that cannot be entered into under the basis of this tariff1 will be arranged by specially agreed upon prices1 such agreement being as much as possible subject to the basis mentioned4 ,sanitary ,regulations4--,the ,state ,government1 on ,march #ast1 #aiji1 published regulations for the proper installation of the water and drainage services within the houses4 ,at the ,government's request1 a draft of the proposed regulations was submitted by the writer1 who prepared it1 after a study of ,american and ,british sanitary by-laws1 to suit the special conditions of ,monterrey4 ,these regulations were afterward modified by him in collaboration with the ,government ,technical ,inspector and ,financial ,interventor1 and1 in their final form1 though not as stringent as those adopted in many northern cities1 are probably more complete than those in any other ,mexican city4 ,under these regulations only registered plumbers can undertake plumbing installations1 and they have to execute a bond to the satisfaction of the ,alcalde ,primero 7,city ,mayor7 for the sum of #b1jjj pesos as a guaranty of responsibility4 ,for defective workmanship or any infraction of the plumbing regulations1 they are liable to heavy fines1 and can be called on to make good all defects in workmanship1 without extra charge to the owner of the property4 ,the provisions of the regulations are carried out under the supervision of the ,government ,technical ,inspector1 the ,company's obligations extending only to the sidewalk and to the meters placed within the houses4 ,,engineers1 ,,etc4 ,g4 ,s4 ,binckley1 ,m4 ,am4 ,soc4 ,c4 ,e41 was ,chief ,engineer of the ,company from ,february to ,december1 #aijf4 ,the writer was ,chief ,engineer from ,may #ast1 #aijg1 until ,april1 #aiaj1 and is responsible for the design and construction of the works carried out during that period4 ,mr4 ,j4 ,d4 ,schuyler advised the ,company throughout all preliminary studies and investigations1 and acted as ,consulting ,engineer until ,february1 #aijh4 ,the ,technical ,inspector1 on behalf of the ,government1 throughout the whole progress of the works1 has been ,rudolf ,meyer1 ,m4 ,am4 ,soc4 ,c4 ,e41 and the writer wishes to record the valuable assistance the ,company has received from him4 ,in conclusion the writer may be permitted to pay a tribute to the devoted public spirit shown by his ,excellency1 ,general ,bernardo ,reyes1 the ,governor of the ,state of ,nuevo ,leon from #ahhe to ,february1 #aiaj1 and who1 untiring in his devotion to the interests of the city1 was primarily responsible for the inception of the works and their successful completion4 ,,discussion4 ,,james ,d4 ,,schuyler1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by letter74--,for completeness of detail and wide range of subjects of general interest to engineers1 this paper is certainly one of the notable contributions to recent engineering literature4 ,it is a minute and painstaking record of the successful accomplishment of construction work under unusual climatic conditions and difficult circumstances1 and reflects credit on the author1 not only in his capacity as an engineer1 but as a faithful recorder of facts4 ,it was particularly fortunate that he was an eyewitness of the disastrous and extraordinary flood which swept through ,monterrey1 destroying many lives and much property1 and has thus been able to give an intelligent estimate of the maximum discharge of the river during the height of the flood wave of ,august #bgth-#bhth1 #aiji1 when the rate of run-off per unit of area of water-shed drained reached an amount which has seldom been equalled or exceeded1 as far as reliable records extend4 ,it is worthy of note that works deriving their water supply from the source of such torrential floods should have survived with so little actual damage1 and with scarcely any interruption of service4 ,the repair of all damages to the system was estimated to have cost not more than #bj1jjj4 ,as ,mr4 ,conway did not assume charge of construction until ,may1 #aijg1 he was spared the responsibility of deciding on the general plan of securing an abundant supply of pure water from sources permitting of delivery by gravity under adequate pressure for fire protection--a responsibility which devolved on the writer1 assisted by ,g4 ,s4 ,binckley1 ,m4 ,am4 ,soc4 ,c4 ,e41 ,mr4 ,conway's predecessor1 as ,chief ,engineer4 ,not only the water-works1 but the system of sewerage and sewage disposal by broad irrigation were subsequently carried out on the plans submitted to the ,state ,government by the writer in #aijf1 and given provisional acquiescence at that time4 ,there was no lack of water at hand for the supply of a city of that size1 as there are large perennial springs which flow out of the travertine of the plain1 and are used for irrigation in the valley below the city4 ,one of the largest of these1 near the civic center1 has a normal flow of nearly #cj cu4 ft4 per sec42 another nearby1 also within the city limits1 flows some #aj or #ab sec-ft41 while both the ,estanscia and ,robalar springs1 but a few miles below 7shown on ,plate ,,ii71 discharge more than #bj sec-ft41 as nearly as memory serves4 ,besides this supply1 the water to be developed by sinking shafts in certain parts of the plain1 as demonstrated at the brewery and elsewhere1 was apparently a reliable source of large volume4 ,to utilize these sources1 however1 would have involved condemnation of the water-rights in the case of the springs1 depriving present owners of the use of the water1 and this ,governor ,reyes wished to avoid4 ,besides1 it would have necessitated pumping the water for the city in perpetuity1 an expense which the ,governor was equally anxious to save2 hence a gravity supply was made the prime requisite of the plans4 ,until the concession was granted1 and for a year or more afterward1 it was assumed that an adequate supply could only be obtained by the storage of the flood-water of the ,santa ,catarina ,river in a large reservoir2 and the earlier plans of the concessionaires were based on the construction of a high masonry storage dam at the upper end of the narrows1 where the river turns from a western direction to a course almost due east1 between high vertical cliffs of limestone4 ,the concession distinctly provided for such a dam1 and among the plans on file in the ,state ,capitol is one prepared by the late ,e4 ,sherman ,gould1 ,m4 ,am4 ,soc4 ,c4 ,e41 for a masonry weir across the gorge4 ,samuel ,m4 ,gray1 ,m4 ,am4 ,soc4 ,c4 ,e41 also filed a plan and report proposing a capacious1 shallow1 storage reservoir near the city1 to be filled by a large flood-water canal from the ,santa ,catarina ,canon4 ,although the writer could not have anticipated the occurrence of floods of the magnitude of the one of ,august1 #aiji1 which would surely have destroyed any reservoir built in the ,canon1 he was unable to endorse the storage plan of water development1 chiefly because of the uncertainty of the water-tightness of the reservoir in a cavernous limestone formation1 and also because of the probable impurity of water draining from such extensive goat pastures4 ,he1 therefore1 urged the development of the underflow of the river1 which was manifesting itself in the springs referred to4 ,mr4 ,binckley secured two ,keystone drilling machines and proceeded to profile the bed-rock at ,santa ,catarina ,canon and at ,san ,geronimo1 the two places on the stream where the river flows between walls of rock in situ4 ,at both sites the strata were standing nearly vertical across the channel1 and1 by careful sampling and testing1 it was found that in both locations there were thick strata of limestone so highly silicious as to be insoluble1 and hence free from caverns4 ,from this determination it was concluded that all the water which appeared in the valley below must pass through the sections where the borings were made4 ,the results of this drilling1 however1 proved conclusively that the depth to bed-rock at either place was too great to permit of a masonry dam being considered as practical1 and demonstrated the inadequacy of methods which had been used in the earlier investigations when dams were regarded as feasible4 ,the results have also shown that the subterranean supply at the lower cross-section of the river1 at ,san ,geronimo1 is abundant1 and can probably be increased to an indefinite degree by continuing the filtration gallery2 while at ,santa ,catarina the same type of development can be made for a high-source supply1 although requiring a long and expensive tunnel and conduit4 ,,david ,t4 ,,pitkethly1 ,,assoc4 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by letter74--,having been engaged on the design of sewerage systems for some years1 the writer finds this paper of peculiar interest1 particularly the sewerage portion4 ,there are some points in the design1 however1 which do not appear to be clear4 ,the system is described as strictly separate1 and yet the sewers are designed to run half-full1 providing a capacity of #bjj1 the #ajj basis1 or #chj liters per capita1 being #ij1 or #ahj liters1 in excess of the calculated water supply of #bjj liters per capita4 ,it has been the writer's practice to design sanitary sewer systems on the basis of the water consumption1 and to assume the whole daily amount to reach the sewer in #af hours1 thus providing capacity sufficient to care for the maximum or wash-day flow without causing the sewers to run above the calculated hydraulic gradient1 which should be placed within the pipe so as to provide air space for ventilation under all circumstances4 ,the practice of calculating sanitary sewers to run half-full is a good one when ground-water is expected in sufficient amount to fill the remaining portion of the sewer1 but when no ground-water1 or roof-1 or surface-water is allowed to enter the system1 or all precautions are taken to exclude such1 then the system may be designed so that the expected maximum1 or wash-day flow1 will fill the sewer to the desired hydraulic gradient4 ,the method of ventilating the sewers does not seem practicable4 ,the houses are principally of one story1 and yet the stand-pipes on the sewers have openings #be ft4 #i in4 above the sidewalk4 ,are the ventilating or vent pipes of the house plumbing carried to a height to balance this1 or will these chimneys draw the air from the house drains and fresh-air pipes1 breaking the seal in the so-called disconnecting traps1 thus causing the circulation of air in the house piping to be downward through the sewers instead of upward through the fresh-air inlets and vents1 as designed8 ,it is interesting to note that crude sewage1 as well as the liquefying 7septic7 tank effluent1 is to be applied to land for irrigation purposes1 but the application of crude sewage without any attempt at removing the suspended matter1 or the effluent from the septic tanks where only a partial removal occurs1 seems to be bad practice4 ,the author states that3 ,the degree of purification in the tanks was relatively unimportant2 the object to be obtained consisted chiefly in distributing on the land an effluent which would be innocuous and clear4 ,how he expects to obtain such an effluent by passage through screens1 detritus tanks1 and septic tanks only1 is more than the writer can understand4 ,the removal of suspended matter in a septic tank depends on the strength of the sewage1 the time of retention1 the time elapsing between cleaning1 the presence of trade wastes1 etc41 and seldom exceeds #ch per cent4 ,the subject of septic tanks and their effect on sewage is discussed in the ,fifth ,report of the ,royal ,commission on ,sewage ,disposal 7,england1 #aijh71 and the following extracts1 relative to the application of crude sewage to land and the effect of septic tanks on sewage1 seem apropos3 #bc4 99 99 99 ,there are also many cases in which crude sewage has been passed over land1 but the evidence shows that land treatment of crude sewage is liable to give rise to nuisance by the accumulation of solids on the surface of the land4 ,moreover1 in some cases these solids are apt to form an impervious layer1 which interferes with the aeration of the soil1 and so impairs the efficiency of the treatment4 #ca4 99 99 99 ,at that time it was claimed that the septic tank possessed the following1 among other1 advantages3 ,that it solved the sludge difficulty1 inasmuch as practically all the organic solid matter was digested in the tank4 ,that it destroyed any pathogenic organisms which there might be in the sewage4 #cb4 ,as regards the first of these claims1 it is now clearly established that1 in practice1 all the organic solids are not digested by septic tanks1 and that the actual amount of digestion varies to some extent with the character of the sewage1 the size of the tanks relative to the volume treated1 and the frequency of cleansing4 ,at ,huddersfield1 ,mr4 ,campbell estimated that about #ch per cent4 of the solids were converted into gas or digested2 99 99 99 while at ,birmingham1 ,messrs4 ,watson and ,o',shaughnessy say that the figures available indicated a digestion of not more than #aj per cent4 of the suspended matter entering the tanks4 #cc4 ,as regards the second claim1 we find as a result of a very large number of observations that the sewage issuing from the septic tanks is1 bacteriologically1 almost as impure as the sewage entering the tanks4 ,messrs4 ,winslow and ,phelps1 in their interesting paper1 ,investigations on the ,purification of ,boston ,sewage1#h quote a suggestion made by ,stoddart 7#aije73 #h ,water ,supply and ,irrigation ,paper ,no4 #ahe1 p4 #abe4 ,he finds1 in a septic tank of several compartments1 a considerable deposit of sludge in the first compartment1 giving a fairly clear supernatant liquid1 which in the last chamber of all undergoes a secondary decomposition1 leading to the throwing down of an additional precipitate of offensive sludge4 ,what took place in the case referred to by ,stoddart corresponds to the author's observations of the liquid leaving the tanks in a clarified condition1 but the secondary decomposition must take place in some manner1 and1 when it does1 a nuisance seems to be unavoidable where no provision is made to care for it4 ,in view of the experience of others1 some further treatment seems to be necessary4 ,such treatment should include disinfection1 as no method of disposal yet devised has succeeded in reducing materially the pathogenic germs usually to be found in sewage and tank effluents4 ,if the crops to be irrigated are to be eaten1 uncooked1 by mankind1 then disinfection at least is imperative4 ,,george ,s4 ,,binckley1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by letter74--,mr4 ,conway's admirable paper is of special interest to the writer1 as the entire general design of the system1 as well as the extensive hydrological studies and final selection of the sources of water supply1 was completed during #aijf through the joint labors of the writer1 as ,chief ,engineer1 and ,james ,d4 ,schuyler1 ,m4 ,am4 ,soc4 ,c4 ,e41 as ,consulting ,engineer4 ,in this work1 ,mr4 ,schuyler and the writer had the rare privilege of dealing from its inception with the problem of designing a complete and somewhat extensive system of municipal water supply and drainage1 unhampered by any existing works to which the new systems would have to be adapted4 ,it would probably be difficult to find in the ,united ,states a city of #he1jjj inhabitants1 previously totally lacking either a water supply or sewerage system1 which1 under a consistent and harmonious design1 has been provided with both in the degree of completeness and structural excellence exemplified in the works at ,monterrey4 ,the few important changes or amplifications made in the original design1 and the manner in which its detail has been executed is naturally most interesting to the writer1 and this excellent paper should be of very substantial value1 particularly to engineers engaged on similar work in ,mexico or ,spanish ,america4 ,the very novel construction method adopted by ,mr4 ,conway in the roofing of the ,south or ,guadalupe ,reservoir1 seems to the writer rather to invite criticism1 and the fact that in the subsequent construction of the roof over the rectangular ,obispado ,reservoir the customary monolithic concrete construction was apparently reverted to after experience with the separate-unit plan previously used1 would indicate that ,mr4 ,conway reached the same conclusion4 ,the original design of the circular ,guadalupe ,reservoir contemplated just about the same arrangement of columns and roof support as that actually used1 but the writer had expected that the columns would be cast in place1 and that the system of primary and secondary beams would be filled at the same time as1 and integral with1 the roof slab1 the reinforcement being placed in accordance with what may be described as conventional practice4 ,the writer believes that the efficiency of the concrete and steel placed in this manner would be notably higher than under the system actually adopted1 which1 in effect1 is pretty much the same as constructing the supporting system of units of cut stone4 ,if1 with all the elements of structural weakness involved in the multiplicity of mortised joints1 discontinuous reinforcement1 etc41 this construction is strong enough1 it would seem that an important reduction in the dimensions of the members could have been effected by monolithic construction and continuous reinforcement1 without sacrifice of strength4 ,the comparison1 in ,table #g1 of the costs of these two reservoirs1 is interesting1 but very moderately illuminating1 as the comparative unit cost of the most important element in their construction--the concrete--is not given4 ,the total excavation cost for each reservoir is practically the same1 and the general expense1 engineering1 and cost of fittings and accessories presumably so1 but the total cost of the ,guadalupe ,reservoir as given is #ai1jjj 7pesos7 in excess of that of the ,obispado ,reservoir1 while1 in the latter1 there were #gef cu4 m4 more concrete4 ,this certainly indicates a much higher cost of concrete per unit as laid in the ,south 7,guadalupe7 ,reservoir4 ,an actual comparison of the cost per unit of concrete laid under the two systems would be instructive4 ,the writer is interested to observe that the same system of sub-drainage used by him in the construction of the reservoir for the provisional supply of water from ,san ,geronimo1 has been used by the author in the ,obispado ,reservoir4 ,this arrangement of drains under the floor of the reservoir at ,san ,geronimo was devised as a safeguard against damage to the lining through the accumulation of water inside the impervious bank against its back4 ,it was realized that1 in such a climate as that of ,monterrey1 perfect water-tightness of the lining might be difficult to secure or maintain1 and1 if leaks existed1 a sudden draft on the contents of the reservoir might result in serious damage through the static pressure exerted against the lining of the sides or upward thrust against the floor4 ,in the writer's opinion1 such a system of drains is an important element1 as not alone the fact but the quantity of leakage may be determined1 and danger of saturation of the supporting bank avoided--a matter of importance where1 as is sometimes the case1 the material of such a bank is unfit to resist the effects of saturation4 ,the author does not state whether or not this safeguard was omitted in the ,guadalupe ,reservoir4 ,incidentally1 however1 the matter of saturation of the bank is not important in either reservoir1 as the material of which these banks are constructed is such that settlement or failure through saturation is out of the question4 ,it may be remarked1 however1 that in fixing the angle of the sides of the ,guadalupe ,reservoir at #fj deg4 the writer contemplated the same system of constructing the bank as he used in that of the ,san ,geronimo ,reservoir4 ,in this case1 the bank was built up by spreading the material in thin layers1 wetting down1 and rolling and puddling by the passage of the ox-carts used for the transportation of the material1 the wheels of the carts1 and especially the cloven hoofs of the animals1 producing a most excellent effect4 ,the inside slope was built up in this fashion to a much lower angle1 and with a top width considerably in excess of the finished dimensions4 ,the excess material was then picked off to the line1 and exactly to the slope4 ,thus the finished slope presented a surface which was compacted to a degree impossible to attain at or near the surface of the bank as built1 and presenting a support of the best possible character for the concrete lining and coping4 ,v4 ,,saucedo1 ,,assoc4 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by letter74--,the author's description of the water-works and sewerage of ,monterrey1 one of the most extensive schemes in ,mexico1 will be of general interest to engineers1 especially those engaged in hydraulic and sanitary problems4 ,the writer1 having been connected with the works for four years1 knows the local conditions well1 and presents herewith some complementary data on what he considers an important feature1 the subject of floods1 mentioned by the author on different occasions1 especially as certain developments in the works show the importance of such occurrences as a factor in designing4 ,abnormal rainfalls of long duration and high intensity are common in the semi-arid region of ,mexico4 ,they come at irregular intervals1 though tending to coincide with the early fall4 ,the floods of ,august1 #aiji1 were a repetition of similar occurrences in the past2 and1 though there are no numerical records of previous cases1 local traditions and historical state documents describe them as having occurred since the foundation of the city1 at intervals of from #ae to #dj years4 ,the graphic descriptions of the places flooded are in accord with the character of the floods of ,august1 #aiji1 and ,september1 #aiaj4 ,the diagram1 ,fig4 #ba1 is a record of the rainfall during the latter flood1 and was plotted from intermittent readings of standard gauges4 ,it demonstrates that the intensity increased toward the mountains on the south1 which form the tributary water-shed of the ,santa ,catarina ,river1 showing a difference of #aj4ed in4 between the city and the ,estanzuela ,dam1 which is not quite #ab miles to the southeast4 ,illustration3 ,,fig4 #ba4--,,rainfall ,,during ,,floods ,,of ,,september #ad,,th-#af,,th1 #aiaj1 ,,in ,,monterrey4 ,an estimate of the volume of discharge of the river at the time of maximum flood is only a reasonable conjecture which 7without special reference to accuracy7 aims to impress those who have not witnessed such occurrences with the tremendous volume coming from barren steep surfaces previously saturated4 ,the original computation1 referred to by the author1 was obtained from the average of two different methods which gave results close to each other4 ,in one method the extent and nature of the water-shed were considered1 together with the maximum period of precipitation that occurred1 sufficient to gather a maximum volume of water in the river4 ,in the other method the volume was derived from a cross-section of the wetted perimeter of the river at the time of maximum flow1 in combination with velocity approximations obtained by using rough floats4 ,this gave #bga1ejj cu4 ft4 per sec4 ,the figure submitted by the author1 #bce1jjj cu1 ft4 per sec41 is in accord with the proposed formula#i for impervious surfaces by ,c4 ,e4 ,gregory1 ,m4 ,am4 ,soc4 ,c4 ,e4 ,in the first and last methods1 the intensity1 a governing factor1 is more or less of an assumption1 and the cross-sectional method is also unreliable1 as the river-bed was greatly disturbed1 due to the high velocity of the water1 which deepens the channel to a considerable extent at times of maximum flood1 the gravels being redeposited during the period of subsidence4 ,such was the case during the flood of ,september1 #aiaj1 when the depth of gravel above the roof of the ,san ,geronimo ,infiltration ,gallery was diminished to such an extent that it was so inefficient as a filter for the flood as to permit the percolation of turbid water into the underground supply4 #i ,transactions4 ,am4 ,soc4 ,c4 ,e41 ,vol4 ,,lviii4 p4 #deh4 ,during the floods of ,august1 #aiji1 ,shafts ,nos4 #b and #c were damaged beyond repair1 and sand and gravel1 entering through them1 blocked up the gallery to within about #aej ft4 of ,shaft ,no4 #a4 ,the interior timbering probably collapsed1 due to cavings and disturbance in the river-bed during the period of maximum flood1 but no explorations have been possible on account of the great quantity of water still coming through 7at present more than #fej liters per sec474 ,for this reason the work of driving the gallery1 as well as lining ,shaft ,no4 #a1 has been suspended4 ,illustration3 ,,plate ,,xxviii1 ,,fig4 #b4--,,view ,,of ,,santa ,,catarina ,,river ,,in ,,flood1 ,,on ,,august #bh,,th1 #aiji4 ,illustration3 ,,plate ,,xxxi1 ,,fig4 #a4--;,,flush-,,tank ,,carried ,,down ,,by ,,flood ,,of ,,august #bg,,th-#bh,,th1 #aiji4 ,illustration3 ,,plate ,,xxxi1 ,,fig4 #b4--,,view ,,showing ,,scouring ,,effect ,,of ,,flood ,,on ,,san ,,geronimo ,,aqueduct4 ,illustration3 ,,plate ,,xxxii1 ,,fig4 #a4--,,view ,,of ,,santa ,,catarina ,,river ,,after ,,the ,,flood4 ,illustration3 ,,plate ,,xxxii1 ,,fig4 #b4--,,view ,,of ,,santa ,,catarina ,,river ,,flowing ,,through ,,low-,,lying ,,streets1 #h ,,days ,,after ,,the ,,flood4 ,on reaching the city1 the flood of ,august1 #aiji1 swept away two streets adjoining the river4 ,these streets had been built on made ground1 in what was originally the river-bed4 ,the sewers and water mains laid in them were destroyed entirely1 and some #dfj ft4 of the #bd-;in4 cast-iron pipe1 buried under the river-bed at a depth of #h ft41 were carried away4 ,in relaying this portion of the main1 and for protecting the remainder of it across the river1 it is now proposed to encase it in a solid rubble concrete block1 #h ft4 square1 which will impart weight and stability against the scouring effect of floods4 ,the ,south ,reservoir is circular in shape1 with an interior diameter of #afe4fh ft4 at the top1 and is partly excavated in the ground and partly completed by an embankment of vast proportions 7,fig4 #aj74 ,right after the flood of ,august1 #aiji1 a wet spot appeared on the northeastern toe of the embankment1 and it was supposed for some time that it was the effect of the saturation produced by the preceding rains1 but1 as it persisted for several months1 it was obvious that its origin was in the interior of the reservoir1 which was emptied when the writer took charge of the work4 ,the first inspection revealed a horizontal crack in the concrete lining1 about #caj ft4 long and extending about #aec deg4 around the circumference on the north side4 ,throughout its length it coincided with the line of cut and fill4 ,vertical cracks1 coinciding with the panel points in the lining1 had also developed1 and extended from the main horizontal crack to the roof4 ,the circumstances originating this development can be conjectured by considering the position of the main crack1 its characteristic features1 and the conditions that preceded its formation4 ,the coincidence of the crack with the joint of cut and fill1 points to this line as a source of danger4 ,an examination showed1 besides1 that the fracture was clean and sharp1 ranging in thickness from a hair line at the ends to #c_/af in4 at the center1 and that its upper border projected over the lower one perceptibly1 a proof that horizontal motion had taken place4 ,the vertical cracks were a secondary effect1 the consequence of the displacement immediately after it was scoured4 ,a fracture was discovered in the floor of the reservoir4 ,it started at the center and branched out into two diverging lines in a radial direction4 ,the circumstance of two abnormal rainfalls1 giving #ce in4 in #i days1 the precipitation being concentrated in two periods1 not far apart1 of #db hours and #ih hours1 respectively 7,fig4 #d71 together with lack of provision for shedding the water from the roof of the reservoir and from the surrounding embankment1 lead to the inference that the latter became saturated1 increasing thereby in weight and decreasing in stability1 especially in its steep inner face4 ,a settlement and the consequent horizontal displacement1 under these conditions1 was natural4 ,the concrete lining1 only #af in4 thick at that height1 was not sufficient to sustain the resulting strain1 and the main fracture developed1 permitting the stored-up water to leak into the bank4 ,in time this seepage found its way under the bottom of the reservoir1 softening the ground and producing a slight settlement which caused the crack in the floor4 ,had under-drainage been provided1 as at the ,obispado ,reservoir1 the actual conditions would have been noticed earlier4 ,however1 as the embankment is of vast proportions1 stable in itself to sustain with a large margin of safety the weight of the stored-up water1 there was no actual danger of failure1 except for the fact that the material forming the structure1 on account of its calcareous nature1 is dissolved by water4 ,long exposure to this condition would1 in time1 open passages in the embankment1 and it is certain that there would be cavings in its interior4 ,the necessary grouting has been done1 and provision is being made for water-proofing the interior of the reservoir and shedding the water from the roof and from the embankment1 thus relieving the structure of the consequent strain4 ,another place in the works where floods have had a damaging effect is the ,estanzuela intake basin1 which1 when the dam was completed1 was filled to the overflow level in order to test its water-tightness4 ,as this basin1 when cleaned1 was found to be slightly fissured on the north side1 it was decided to line it with concrete4 ,as shown in ,fig4 #h1 the lining does not cover its entire area1 but only the central portion1 leaving a strip on either side without protection4 ,the flood of ,september1 #aiaj1 coming in greater volume than the previous ones of ,august1 #aiji1 in passing through the narrow gorge at the entrance1 undermined the lining in those places where it was not founded on solid rock4 ,figs4 #a1 #b1 and #c1 ,plate ,,xxxiii1 show some of the damage caused by this flood4 ,the buoyant effect of the water and the impact of large rolling boulders caused fractures all over the surface1 and lifted the concrete lining bodily2 but the dam proper1 being founded on rock bottom1 did not suffer any injury4 ,in the future1 in order to avoid the seepage of the ordinary supply1 alluded to by the author1 the water will be carried to the valve-house in an open rubble concrete channel1 lined with cement mortar and built high up against the western hillside4 ,the remainder of the basin will be paved with large boulders4 ,illustration3 ,,plate ,,xxxiii1 ,,fig4 #a4--;,,estanzuela ,,dam3 ,,broken ,,concrete ,,basin ,,lining4 ,illustration3 ,,plate ,,xxxiii1 ,,fig4 #b4--;,,estanzuela ,,dam3 ,,broken ,,concrete ,,basin ,,lining1 ,,east ,,side4 ,illustration3 ,,plate ,,xxxiii1 ,,fig4 #c4--;,,estanzuela ,,dam ,,sept4 #bf1 #aiaj3 ,,view ,,of ,,shearing ,,fractures ,,of ,,wall ,,and ,,lining ,,after ,,flood ,,sept4 #ad-ag1 #aiaj4 ,in conclusion1 the writer wishes to emphasize the point that1 notwithstanding the severity of the test1 relatively small damage was inflicted on the extensive works carried out under the author's design and direction4 ,a test so severe that it caused serious damage and immense losses in the entire region1 washing away kilometers of railroad track and destroying practically all the bridges within reach of the flood1 is an occurrence of paramount importance1 and should be remembered as a leading factor in the design of engineering works4 ,,george ,t4 ,,hammond1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by letter74--,in a country1 such as that described in this paper1 where water is valuable1 and a shortage is at times possible1 where the majority of the population is very poor1 and water and sewage discharge are both to be paid for on a basis of volume1 the question of the expected quantity of daily water supply and sewage flow per capita is of primary importance4 ,this question1 notwithstanding its difficulty1 should be given a first place in the studies for water-works and sewerage projects1 and should never be lost sight of in the design1 which should be such that1 while proper for the expected future flow for a reasonable time1 should also be proper and economical for conditions which at present obtain and may change but slowly4 ,it is desirable1 of course1 to get as much capacity in works as one can for the outlay1 but there are instances where one can get too much for the money1 as where a larger pipe than is necessary is used for a sewer1 merely because it costs about the same as a smaller one1 and as a result the cost of maintenance is permanently increased4 ,the water-works were designed to supply #dj1jjj1jjj liters 7#aj1ehb1jjj gal47 daily1 which it was assumed would be sufficient for all future developments in ,monterrey for a population of #bjj1jjj at a per capita consumption of #bjj liters 7about #ec gal47 per day4 ,the present population of the city is given as less than #ij1jjj1 there having been an increase of #bb1jjj in ten years 7#ahia-aija71 but it is evident that in the last ten years 7#aija-aiaa7 this rate of increase has not continued4 ,taking into account all the data known to the writer1 it does not seem that the city will attain a population of #bjj1jjj in a great many years1 if it ever does2 but this is a matter of personal opinion1 and is only stated as such4 ,the present requirements of the city's population1 assuming that each person uses #bjj liters 7#ec gal47 per day1 would be1 at that rate1 which is a very liberal one1 only #ah1jjj1jjj liters 7#d1gfb1jjj gal47 per day1 or less than half the amount which may be provided4 ,if the water were not to be metered and the sewage discharge paid for by measure1 it is possible that the free use of water might lead to the usual waste with which all are fairly familiar2 but the use of meters1 and the rates charged1 will reduce the water consumption to a minimum4 ,this end will especially result from ,section #e of the ,tariffs which provides that3 ,groups can be formed of two or more small houses so as to obtain a joint service under the proportion shown in the tariff4 ,this provision will keep down the per capita supply1 among the majority of the people1 to about #cg-a_/b liters 7#aj gal47 per day4 ,a similar provision led to abuse in ,santiago de ,cuba1 as well as in other ,cuban cities1 where one householder1 taking water1 frequently delivers it to adjoining houses and tenements through rubber hose4 ,as many as ten or twelve families are sometimes found to be supplied from one tap in this manner4 ,indeed1 it may be stated as a rule1 having but few exceptions1 that where water is paid for by meter its use is always restricted4 ,the water mains and distribution system1 however1 are so well laid out1 and the whole design is so good1 that the writer would not anticipate much difficulty because it is on rather too liberal lines for the present or probable future4 ,it may1 perhaps1 be argued that it may cost more to keep the mains in such a system clean2 but this extra cost will scarcely be of much moment1 and will be offset by the greater lasting quality of the larger pipes4 ,there is another feature of the problem1 however1 which is not affected favorably by a too liberal forecast of the per capita water supply1 namely1 the sewerage system4 ,if it is assumed that1 using #bjj liters per capita per day1 the total water supply of the city for the present population will be #ah1jjj1jjj liters1 and that this may double in fifty years1 or even amount to #dj1jjj1jjj liters in that time1 it would seem that a rather liberal provision has been made for the water supply1 and that this will scarcely be exceeded by the sewage1 for the latter must come from the water supply1 there being little or no ground-water and no storm-water taken into the sewers4 ,designing the sewers to flow half full for all diameters less than #ah in41 and seven-tenths full for all larger sizes1 it would seem that this would give ample capacity for all time to come in such a city1 and that good practice would not exceed these figures1 it being more desirable that the sewers should not be too large to work well1 than that they should be large enough in all places to meet every possible contingency4 ,if all the sewers of a system are too large1 the condition is incurably bad2 while1 if a few miles prove to be too small1 on account of growth and prosperity not anticipated by the designer1 it will be easy enough to relay such parts when this becomes necessary4 ,mr4 ,conway states that3 ,the sewers are designed on a very liberal basis1 namely1 on the assumption that when flowing half full the quantity to be dealt with will be #chj liters #ajj gal4 per capita per day1 with a maximum rate of flow of #bjj per cent4 ,if the writer understands this statement correctly1 it means that the sewers1 flowing half full1 will carry #chj liters per capita in #ab hours1 or are designed with #bjj of the capacity required to take the assumed flow in #bd hours4 ,it was assumed that each house would be occupied by #g persons and have a frontage of #ab-a_/b m4 7about #da ft471 that is1 about #gjj gal4 per day per house1 the maximum flow rate being #bjj1 or at the rate of #gjj gal4 per house in #ab hours4 ,it is to be remembered that nearly all the houses are of one story1 and that1 as a rule in tropical and sub-tropical countries1 the per capita use of water diminishes with some function of the increasing number of inhabitants in one house4 ,most of the water is used in the kitchen1 and where there are #g persons instead of #e1 the quantity used by the smaller number will generally serve the larger4 ,the writer is unable to understand how this quantity of sewage will be produced1 especially as the author states that1 as far as the company is concerned1 it is limited to the removal and disposal of the sewage1 and is not required to provide for storm-water4 ,he also states that3 ,apart from that fact1 however1 the best system for a city like ,monterrey1 where rainfall for many months at a time is very scarce1 is the strictly 'separate system'4 ,the minimum velocities in the sewers1 when running full1 vary between #j4ia and #a4e m4 7from #c to #e ft47 per sec41 and will be the same flowing half full4 ,from the foregoing data it will be observed that3 7#a7 ,the water supply is the only source from which sewage flow is anticipated2 7#b7 ,the water supply is very liberally estimated at #bjj liters 7#ec gal47 per capita daily2 7#c7 ,for purposes of sewer design1 the daily flow of sewage expected 7all of which is derived from the water supply of #bjj liters per capita7 is estimated at #chj liters per capita1 with a maximum rate of flow of #bjj 7or at the rate of #gfj liters per capita71 and with this quantity the sewers are designed to flow only half full2 7#d7 ,the gradients are such that a velocity of from #c to #e ft4 7#j4ia to #a4e m47 per sec4 will be secured in the sewers flowing half full with the above quantity of flow per capita4 ,the writer does not agree with this method of computation1 as he feels sure that it will give sewers which are too large1 with grades too steep for the best obtainable results4 ,his experience1 extending over more than twenty years in sewer design and hydraulic work1 convinces him that the method pursued is wrong in principle4 ,the principles involved in sewer design are first of all hydraulic4 ,the quantity of flow1 in the nature of things1 cannot be forecasted accurately2 success depends on getting the nearest possible approximation to average conditions4 ,if #bjj liters per capita per day is a liberal allowance1 and #dj1jjj1jjj liters per day is a liberal expectation at this rate for double the present population1 and the sewers are designed to flow half full only1 why should this again be doubled8 ,the design of a sewer system for a city such as ,monterrey is1 in fact1 a very difficult problem1 especially as the quantity of sewage will be very limited1 flush-water will have to be used in considerable quantities1 and water in that part of the world is precious at all times and often scarce4 ,under these circumstances1 the size or shape of the pipes selected for the lateral sewers1 should have been such as would more nearly agree with the requirements than does the #h-;in4 circular4 ,a4 ,p4 ,folwell1 ,m4 ,am4 ,soc4 ,c4 ,e41 writing of the #h-;in4 circular size1 states3#aj #aj ,sewerage1 by ,a4 ,p4 ,folwell1 ,m4 ,am1 ,soc4 ,c4 ,e4 ,to secure a flow in this pipe having an average depth of #d inches would require the sewage from a population of #f1ejj4 ,in general it may be said that the ordinary depth of flow in any sewer should not be less than #b inches1 nor should it be less than #a_/b the radius of the invert1 since if it is so there is much more danger of deposits forming along the edges and even in the center of the stream4 ,it will sometimes be impossible to meet this requirement fully1 but it should be kept in mind as extremely desirable4 ,sewers of small size should be proportioned throughout the system so that the depth of the minimum daily flow in the invert1 and the velocity of flow1 will be the best possible to prevent deposits4 ,the transporting power of water is dependent mainly on the depth of flow1 a minimum velocity being selected rather than a minimum depth of flow4 ,to those who have had charge of the maintenance of sewers1 as well as of their design and construction1 this principle seems so obvious that it is always a surprise to see it disregarded by designers1 who in these days seem inclined to consider sewerage as a system of grades and sizes of pipes installed for ideal1 rather than for actual1 conditions4 ,messrs4 ,staley and ,pierson have well stated the principle involved as follows3 ,a stream having a depth of flow sufficient to immerse solid matter held in suspension1 to a certain extent lifts it and carries it forward4 ,the entire surface is also exposed to the action of the current4 ,a stream having an equal velocity but a less depth in proportion to the diameter of the solid matters to be transported1 evidently has less transporting power4 99 99 99 ,an amount of sewage which can be properly transported by a circular sewer of a given size1 cannot be as efficiently transported by one of larger diameter4 ,from some strange idea1 which is apparently without foundation in logic or based on any actual justification from experience1 it has of late years become the practice of designing engineers to make the #h-;in4 circular pipe the smallest size for sewers2 and it is not improbable that the designer of the ,monterrey system has merely followed this example4 ,it has also become the frequent practice of designers to give every length of sewer all the grade possible1 regardless of the fact1 taught both by hydraulics and experience1 that the best grade is that which will give as much depth of flow as is consistent with a scouring velocity4 ,some years ago it was the standard practice1 in the strictly separate system of sewers1 to use the #f-;in4 pipe as the minimum size1 and1 as far as the writer has been able to discover1 after giving the matter a rather extensive investigation1 the #f-;in4 size has given excellent results wherever its use was proper4 ,in places where it has not succeeded there were excellent reasons why it should not have been selected1 and these could easily have been observed at the time the designs were made4 ,the best sizes for the sewers in a given system is always a matter to be determined by local conditions2 but there seems to be no reason why the #f-;in4 size should not be used where the flow is so slight that the #h-;in4 will not work well2 or where the velocity must of necessity be so great that a flotation depth of flow cannot be maintained in the larger size4 ,as to likelihood of clogging and stoppage1 the writer's opinion1 based on the maintenance of three rather extensive systems in different parts of the ,united ,states1 in each of which the #f-;in4 size comprises more than #ge of the whole length of pipe1 and of three other systems1 one having #ab-;in4 and two having #h-;in4 as the minimum sizes1 is that the #f-;in4 size1 where properly used1 is less likely to become clogged than either of the others used improperly4 ,the cost of maintaining the #f-;in4 pipe lateral1 under these circumstances1 is much less than that of maintaining the #h-;in4 lateral4 ,the #f-;in4 pipe is not being used now as much as the #h-;in41 and in most cases this is probably because the capacity of the latter is nearly double that of the #f-;in41 and costs only a few cents more per foot4 ,if there is a sufficient population per acre1 or if1 within #cj or #dj years1 such a population is anticipated as will fill the #h-;in4 pipe half full1 its use1 of course1 is justified and necessary2 but where it is quite evident that this will never occur1 its use is counter-indicated4 ,in ,monterrey1 where the building lots have a frontage of #da ft41 where the houses1 as a rule1 are only one story high1 where the water service is metered and paid for1 and the sewage flow is also paid for1 there seems to be no reason to justify the use of #h-;in4 pipe for the upper reaches of the smallest sewers4 ,the sewage flow to be anticipated will probably never be sufficient to keep an #h-;in4 pipe sewer in a good clean condition at the upper ends of the lines of sewers without excessive flushing2 and the sharper or steeper the grade on which it is placed1 the worse will be the result1 because the sharper the grade1 the thinner the flowing thread of sewage will be drawn out in the invert2 on the other hand1 if the grades are flat1 the slight quantity of sewage flow will be spread out in a sluggish stream1 without sufficient depth1 on the bottom of the #h-;in4 pipe4 ,where a wide surface is given to a small quantity of flowing sewage1 it stagnates slowly along the bottom of the sewer1 leaving frequent deposits to undergo decomposition and create foul air1 if not to choke the sewer1 a result often produced2 and where a circular sewer which is too large for the ordinary flow is given a strong velocity by using steep grades1 the stream1 though flowing rapidly1 is drawn out to such a thin thread that it will not effect the flotation of the solid masses in the sewage brought in at house connections1 and the shallow and thin stream simply flows around such masses until a dam or obstruction forms and the sewage is backed up sufficiently to force the obstruction farther down1 to form another obstruction in a larger pipe below4 ,flushing may possibly keep such a sewer fairly clean2 but1 as usually practiced1 it is effective only for a few hundred feet from the flush-tank2 and the quantity of flush-water required by an #h-;in4 pipe is more than twice as much as that required to keep the #f-;in4 pipe clean4 ,ventilation is better in the smaller sewer than in the larger1 as there is less air to move2 but the elaborate ventilating stacks provided at ,monterrey may take care of this2 and it is evidently a place where ventilation will be needed4 ,the ideal size and shape of cross-section for a sewer is such as will give the best flotation to moving solids which are being carried along by the flow2 and this means the sewer that1 with the expected ordinary or average flow1 will give the best depth in the invert1 when the velocity of flow is sufficient to keep suspended solids1 grit1 etc41 moving at a rate of from #b to #c ft4 per sec4 ,the size1 however1 is limited by practical considerations4 ,the circular pipes cannot well be less than #f in4 in diameter1 because the house connections cannot well be less than #d-;in4 pipe1 and the sewer should be larger than the house connections1 for various practical reasons2 but1 in order to secure flotation and a scouring flow1 the smallest pipe1 or the pipe having the smallest invert radius1 that practical considerations permit1 should be selected4 ,the grade should be such1 and the collecting system so laid out1 that the flow may be conserved as far as possible1 and the sewage flow should be kept of as great a depth in the invert1 or bottom of the sewer1 as safety in self-cleansing velocity will permit4 ,this will save flush-water and prevent stoppages1 and thus reduce the cost of maintenance to a minimum4 ,for good sanitary practice1 the sewers should be designed1 first of all1 to comply with the requirements of the present1 or immediately expected1 ordinary flow1 with some reasonable allowance for the future4 ,they should be neither too large nor too small1 and the grade should neither be too great nor too little1 to secure the best flotation and scouring effects and the best flush-wave action under all circumstances4 ,the use of cement concrete pipe for sewers seems to be growing in favor2 nor is this surprising1 in view of the many improvements made in their design and manufacture4 ,the excellence of the concrete pipe used in ,monterrey and its success1 suggest the query3 ,why was it not used still more extensively8 ,table #ac shows that the cement pipe cost much less than the vitrified tile1 or fire-clay pipe4 ,thus1 the #ch4a cm4 7#ae-;in47 fire-clay cost #f4ad pesos per lin4 m41 the #de4g cm4 7#ah-;in47 cost #h4hj pesos1 and the #ej4h cm4 7#bj-;in47 cost #aa4cj pesos4 ,compared with this1 the concrete pipe was much the cheaper2 the #ee4i cm4 7#bb-;in47 cost #e4ic pesos1 which is less than the cost of the #ch4a cm4 7#ae-;in47 fire-clay2 and the #fa4j cm4 7#be-;in47 concrete pipe cost #g4cj pesos1 which is less than the #de4g cm4 7#ah-;in47 fire-clay4 ,the writer's experience with concrete pipe1 derived mainly from a long service in sewer design and construction in ,brooklyn1 ,n4 ,y41 leads him to believe that at ,monterrey the whole sewer system might1 with advantage1 have been built of concrete pipe1 using an egg-shaped pipe with an area slightly larger than an #h-;in4 circle1 designed for a discharge equal to an #h-;in4 pipe for all the smaller sewers4 ,the invert of such an egg-shaped pipe would fulfill the present requirements in carrying a very small flow with good flotation depth1 better than would a #f-;in4 circular pipe1 and the reserve capacity of the #h-;in4 pipe would be secured without interfering with good present service4 ,egg-shaped pipes1 similar to those used in ,brooklyn1 the writer believes1 would have given far better satisfaction throughout the ,monterrey sewerage system than circular fire-clay pipe1 and would have cost no more1 but probably less4 ,the egg-shaped pipe referred to is made with a flat base and a self-centering joint1 thus insuring perfect alignment1 and a smoother interior surface than can be obtained with fire-clay pipes4 ,brooklyn has about #dej miles of concrete pipe sewers1 of all sizes less than #bd in41 the greater part of which is egg-shaped4 ,there are also about #bej miles of vitrified stoneware circular pipe sewers of similar sizes1 and the cost of repairs and replacing pipe1 over a period of years is about the same per mile for each kind4 ,incidentally1 it may be stated that the annual cost of repairs per mile on both kinds of pipe is very small1 and is only about one-fifth of the cost of repairs per mile on the brick sewers1 of which there are about #bjj miles4 ,the principal advantages and disadvantages of cement concrete pipe sewers may be summed up as follows3 ,,advantages ,,of ,,concrete ,,pipe4 7a7 ,cement concrete pipe is usually less costly than vitrified pipe4 7b7 ,it can be formed in any shape desired4 7c7 ,it is not cracked by vibration1 and resists impact better than vitrified pipe1 for which reason it is a better material to lay near the surface of a street in which there is heavy traffic4 7d7 ,it is not affected by ordinary sewage4 7e7 ,the cost of repairing and maintaining is about the same as for a vitrified pipe sewer4 7f7 ,it can be made in the city or town where it is to be installed1 thus giving the locality the advantage of having some of the money paid for labor in its manufacture spent in the place where the sewers are being put in1 where it is raised as a tax1 etc42 also saving freight charges1 etc4 7g7 ,it can be made under the most careful local supervision and inspection1 of selected material1 by the engineer who is responsible for the success of the work4 ,vitrified pipe can seldom be made in this way4 ,,disadvantages ,,of ,,concrete ,,pipe4 7a7 ,if not carefully made and of the best of materials1 it is subject to failure by disintegration1 etc4 7b7 ,it will not stand strong chemical action1 and therefore the smaller sizes should not be used where they are likely to be exposed to trade wastes containing strong acids4 ,in the larger sizes the quantity of flow mixes so quickly with the trade wastes that this danger is minimized1 and it is very seldom that even the smaller sizes become affected2 but vitrified pipe may be used in places where chemical action is anticipated4 7c7 ,if not properly made1 it will be attacked by steam and hot vapor1 and by animal fats in the sewage2 but1 if properly made1 it is not affected by these4 7d7 ,unless reinforced or made very thick1 it will not stand as great a crushing load as the best vitrified stoneware pipe2 but1 as sewers are not intended to be used under very heavy pressure1 this is not so very important4 ,it is amply strong to withstand any internal pressure or any external crushing load to which it probably will be submitted4 7e7 ,under a considerable head of ground-water1 it may permit water to infiltrate through its walls for a considerable time after it is laid1 thereby temporarily increasing the flow1 which1 if the sewage is to be pumped1 will increase the cost of pumping4 ,this difficulty can be met by using a carefully selected mix of materials in making the pipe1 and by making the joints carefully4 ,infiltration through concrete diminishes rapidly after the sewer is in use2 it occurs in vitrified pipe1 also1 to some extent4 ,the house connection drain adopted in ,monterrey1 with the disconnecting trap1 is very much like one which the writer has seen introduced with very bad result4 ,these are being removed as rapidly as possible by one of his clients1 a sewerage company1 in the ,southern ,states4 ,it has been a fruitful cause of stoppages and bad smells2 the ordinary method now in general use is much better4 ,in the design shown1 it would seem that there may even be some danger that the ventilation of the sewer by the stand-pipes in the streets may force the traps4 ,one is rather surprised to learn that the main outfall sewer is designed with a capacity of #ij1jjj1jjj liters per day1 the present sewage being estimated as not more than #ah1jjj1jjj liters1 and the far future being thought to require only #dj1jjj1jjj liters4 ,why this excessive size8 ,possibly the surplus water which it is to carry is to be discharged into the sewers from the water supply system direct1 and is intended for irrigating the land at the disposal area1 when the sewage is insufficient for this purpose4 ,the author states that all surface water is strictly excluded4 ,the method of sewage disposal gives rise to several questions4 ,it is proposed to use an extensive area for growing crops1 which are to be irrigated with sewage4 ,the paper states that the underlying strata at ,monterrey contain numerous caverns1 and the first question is3 ,what will be the effect on the water supply of other towns lower down the valley8 ,the writer recollects a serious outbreak of typhoid fever in ,bluefield1 ,w4 ,va41 caused by the pollution of the water in similar strata finding its way through unknown underground caverns and channels to the city's water supply4 ,the next question is3 ,what crops will be grown8 ,it is a well-known fact that vegetables grown by the use of sewage as a fertilizer1 are unsafe in a raw state for human consumption4 ,this is well-known to ,european travelers in ,china and ,japan1 where the use of fecal matter as fertilizer renders the various water supplies 7where not filtered and disinfected7 and all green vegetables1 unsafe1 on account of typhoid germs4 ,moreover1 crops not intended for human consumption1 which are grown on lands irrigated by sewage bearing typhoid germs1 etc41 are unsafe for men to handle2 even to store them may cause a dissemination of disease4 ,it is evident1 therefore1 that the whole sewage flow should be in some manner disinfected at least1 if not filtered1 before it is used4 ,the method of sewage disposal and the use of merely settled septic sewage for irrigation seem to be open to objection4 ,the disposal plant is not sufficiently effective to meet the present requirements of sanitary science2 and the sludge-pit will be certain to breed a pest of flies1 if it is not also an intolerable nuisance on account of foul smells4 ,monterrey would seem to be a proper place for the introduction of the ,imhoff tank1 with percolating filters1 and a final settling tank1 the effluent being disinfected1 before entering the latter tank4 ,the flow might then be used safely for irrigation purposes for crops not to be eaten uncooked by man4 ,the writer does not see how the method provided can possibly fulfill the object stated1 to distribute on the land an effluent which will be innocuous and clear1 or how any consequential degree of purification can be obtained in the tanks provided4 ,while there are described in this paper many things to find fault with1 there are also many things to commend4 ,the water supply system1 with its reservoirs1 etc41 seems to be admirable2 and the methods of construction by which the expense for forms was reduced is very interesting4 ,the parking and ornamentation of the grounds over the reservoir roofs cannot fail to benefit the people and popularize the work4 ,,rudolf ,,meyer1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by letter74--,the writer1 as ,engineer for the ,government 7guaranteeing the concessionaires a gross return of #aj per annum on the capital invested71 and as inspector of the various works has had exceptional opportunities to become acquainted1 not only with their construction1 but also with events leading up to the granting of the final concession under which they were built and will be extended4 ,in order to judge of the extent to which the different engineers1 in their turn contributed toward the design of these works1 the writer has thought it desirable to submit a complete statement of all matters relating to the inception1 investigations1 surveys1 tests1 etc41 previous to the adoption of the present plans4 ,data regarding former investigations1 plans1 and concessions which have since lapsed1 have been obtained from the ,government archives4 ,these refer to periods prior to ,mr4 ,conway's engagement1 and anterior to the retaining of ,mr4 ,schuyler by the concessionaires1 and ,mr4 ,binckley's connection with the scheme1 and they are presented here as complementary to the information in the paper4 ,samuel ,m4 ,gray1 ,m4 ,am4 ,soc4 ,c4 ,e41 acting in the interest of some ,american capitalists 7who had been induced by ,col4 ,j4 ,a4 ,robertson1 of ,monterrey1 to look into the merits of a concession acquired by him1 for building these works71 being guided by the ,government's proposition to supply the city with water by damming the flood-waters of the ,santa ,catarina ,river in the narrow gorge through which the stream emerges from the ,sierras1 some eight miles from the city1 had several soundings made and reservoir sites surveyed in the first two box canons up the river1 and prepared and presented to the ,government several alternative projects1 besides the one mentioned by ,mr4 ,schuyler4 ,several different dam sites were designated by ,mr4 ,gray1 whose investigations extended over some two years1 and were finally abandoned after he had designed the general outlay for a complete network of water mains and sewers for the city1 on account of the unwillingness of the ,government at that time1 about #ahig1 to grant any guaranties as to bonds or income to the concessionaire or his assigns4 ,mr4 ,gray did not favor the general scheme of storing flood-waters as a water supply1 but strongly recommended to the attention of the ,government the greater advantages of deriving the supply from subterranean flow in the river1 by an infiltration gallery driven into the water-bearing gravels in the ,santa ,catarina ,canon 7only a short distance above the place where ,mr4 ,binckley afterward established his bore-holes across the river74 ,he proposed to take advantage of the steep slope of the river at a turn in the canon1 and from the lower end drive a tunnel through a projecting rock spur1 which tunnel1 though starting well above the ordinary reach of floods1 would terminate in water-bearing gravel1 at a sufficient depth below the surface of the river-bed to intercept part of the underflow4 ,mr4 ,gray1 through investigations made under his direction1 by ,nathaniel ,turner1 ,m4 ,am4 ,soc4 ,c4 ,e41 had ascertained that there was an abundant subterranean flow1 and work had actually been started on the proposed tunnel4 ,the results of ,mr4 ,gray's investigations were put at the disposal of ,messrs4 ,mackenzie1 ,mann ,co4 by ,mr4 ,robertson1 at whose offices ,mr4 ,binckley prepared the first plans submitted by him for the approval of the ,government4 ,after ,mr4 ,gray's investigations1 ,messrs4 ,mackin and ,dillon 7,f4 ,h4 ,dillon1 ,assoc4 ,m4 ,am4 ,soc4 ,c4 ,e471 under contract with the ,government1 prepared the following plans3 ,for a dam in the ,santa ,catarina ,canon2 for a pipe line1 similar to the one proposed by ,mr4 ,gray1 to a reservoir and settling basin on the left bank of the river 7a short distance above where the provisional pumping station was established afterward by ,mr4 ,binckley71 but on the flat above the bluff skirting the river1 practically at the same elevation as the present high-pressure reservoirs2 for a complete network of water mains and sewers in the city1 indicating the approximate direction in which the sewage would be disposed of1 either by turning it into the river or by spreading it over suitable lands1 the location of which was to be determined later2 and also a complete set of specifications4 ,on these data bids were invited by publication1 and inquiries were received from several parties4 ,finally1 ,messrs4 ,stocker and ,walker1 of ,scranton1 ,pa41 entered into negotiations with the ,government1 and the present concession was agreed upon and granted4 ,messrs4 ,stocker and ,walker engaged the late ,e4 ,sherman ,gould1 ,m4 ,am4 ,soc4 ,c4 ,e41 to prepare a plan for a storage dam in the ,santa ,catarina ,canon1 and submitted plans for water distribution and sewers in the city1 slightly modifying the original plans of ,messrs4 ,mackin and ,dillon4 ,in the fall of #aije1 the concession was acquired by ,messrs4 ,mackenzie1 ,mann ,co41 of ,toronto1 ,canada1 together with all plans1 etc41 presented by the original concessionaires4 ,the new concessionaires stated that they would examine the whole situation again1 for the purpose of presenting modified plans for works4 ,mr4 ,schuyler1 in the interest of the new owners1 had paid one flying visit to ,monterrey when ,mr4 ,gray's projects were brought to his notice1 and the writer had an opportunity to show him the tunnel which had been started4 ,mr4 ,schuyler left for ,brazil and did not return until ,february1 #aijf1 when he was accompanied by the ,chief ,engineer appointed by the concessionaires4 ,messrs4 ,schuyler and ,binckley then prepared plans for the water distribution and sewer systems in the city and for a provisional water supply to be pumped at ,san ,geronimo1 some two miles up the river4 ,the new plans for the city work followed closely the general disposition by ,mr4 ,gray1 the principal difference being that the main reservoirs for the permanent water supply were located to the south instead of to the west4 ,this change was due to the results of an investigation1 made during ,mr4 ,schuyler's absence in ,brazil1 by ,mr4 ,f4 ,s4 ,hyde1 late ,hydraulic ,engineer of the ,necaxa ,water ,power plant1 who1 accompanied by the writer1 visited the whole water-shed of the ,santa ,catarina ,river in ,october1 #aije1 in search of suitable dam sites and prospects of power development4 ,mr4 ,hyde extended his studies to the ,santiago ,canon1 southeast of the city1 recommending finally that the water be brought from that canon1 and that wells be dug in different points of the ,santa ,catarina ,river between ,san ,geronimo and the entrance of the canon1 and tested by pumping1 for the purpose of establishing levels and ascertaining the available amount of underflow1 with a view of determining the location for an infiltration gallery high enough up the river to permit of a gravity delivery and under good pressure in the city4 ,in view of ,mr4 ,hyde's report1 and as the result of a visit to the ,santiago ,canon1 ,mr4 ,schuyler decided to locate the reservoirs south of the town1 intending to bring in water from the southeast1 from springs in the ,santiago ,canon1 and also by infiltration from ,santa ,catarina1 his and ,mr4 ,binckley's scheme of water supply being for the same pressure throughout the city4 ,to supply water during construction1 and partly meet the demands of the city1 ,mr4 ,binckley1 on his arrival1 decided to establish a provisional pumping station at the well in the river nearest to town1 started by direction of ,mr4 ,hyde at ,san ,geronimo4 ,this well was situated within the bed of inundation of high floods1 on a low bank1 at the foot of a conglomerate bluff some #bj ft4 high1 limiting a flat which was above the reach of any flood4 ,it was on the same side of the river as the city1 and there was plenty of good ground on the flat above for the establishment of a reservoir4 ,a slightly shorter pipe line was secured by crossing the river1 building the reservoir 7a substantial concrete-lined and vaulted-over structure7 on the opposite bank1 laying out the pipe line to follow that bank nearly to the city1 and finally crossing back again2 but the result has been that since the flood of ,august1 #aiji1 in which the river crossings were destroyed1 the reservoir remains isolated on the other side of the river from town1 though intended to form part of the permanent works and act as a compensating reservoir for equalizing the pressure of the high-pressure system4 ,fortunately1 the pumping station1 the larger pumps1 and the boilers1 had been moved up the bank 7after a rapid rise in the river on ,august #ajth1 #aiji7 to the new wells established by ,mr4 ,conway on the line of the proposed prolongation of the infiltration gallery4 ,the reservoir1 however1 is left to stand alone on the other side of the river1 and its usefulness will not be restored until a new line is laid across the river1 re-establishing its connection with the new pump line and the new and permanent pipe line to be laid along the north bank from the pumping station to the city4 ,this will free ,monterrey from the constant menace of a water famine4 ,at present its two main water supplies may be cut off by unexpected floods like those of #aiji and #aiaj1 as both supplies are carried across the river1 and though only the cast-iron pipe connecting with the water supply from ,estanzuela was carried away by the flood1 the concrete conduit of the ,san ,geronimo low-pressure supply was seriously threatened4 ,such risks are too great to be carried for any length of time2 besides1 a succession of dry years would cause such a reduction in the ,estanzuela supply as to require an additional reserve in the way of pumping stations drawing on the under-flow of the river1 such as already exists in ,san ,geronimo4 ,afterward1 ,messrs4 ,schuyler and ,binckley submitted preliminary plans and profiles for the projected concrete gravity conduit from ,estanzuela to the reservoir south of the city1 and ,mr4 ,binckley submitted excavation plans for two reservoirs1 only one of which was built1 and from designs by ,mr4 ,conway4 ,stephen ,e4 ,kieffer1 ,m4 ,am4 ,soc4 ,c4 ,e41 was intrusted by ,mr4 ,binckley with the revision of the plans of the water distribution and sewers4 ,the southern half was approved by the ,government and executed according to his plans2 the northern part was afterward revised by ,mr4 ,conway and has been partly built4 ,the final maturing of the project of an infiltration gallery in ,san ,geronimo as a low-pressure gravity supply1 the division of the city into high- and low-pressure districts corresponding to the two supplies1 with one reservoir1 instead of two to the south of the city1 and the other to the west at the ,obispado1 the entire details of both these gravity schemes1 and of the whole sewage disposal scheme1 as well as the modification introduced into the city work for the northern half1 are unquestionably due to ,mr4 ,conway1 independently of the general views which may have been held on those points by other engineers4 ,in ,march1 #aiaj1 ,mr4 ,conway left ,monterrey1 all the principal works being finished4 ,since that time ,vicente ,saucedo1 ,assoc4 ,m4 ,am4 ,soc4 ,c4 ,e41 has put in many additional water mains and sewers in the northern part of the city1 and is finishing the force majeure work caused by the destruction wrought in the districts along the river banks by the extraordinary floods4 ,the writer1 having had an opportunity to watch the earnest efforts of the several engineers connected with these works1 in the course of their design and construction1 resulting without doubt in being the first of their kind built in ,mexico1 has been induced to contribute this discussion in order to bring out clearly the share of each4 ,mr4 ,pitkethly's apprehensions as to the adequacy of the system of ventilation adopted have not been realized1 in part perhaps because the houses1 though generally of only one story1 have such high ceilings that the tops of their vent pipes are generally higher than the ventilating columns at the heads of the branch sewers4 ,,george ,,robert ,,graham ,,conway1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by letter74--,the writer regrets that some features of the works described in this paper have failed to call forth the many useful criticisms which he expected1 and his remarks1 therefore1 are limited to the few points which have been raised4 ,he is particularly indebted to ,messrs4 ,schuyler1 ,meyer1 and ,saucedo for adding supplementary information of value to the paper1 but regrets that he cannot support ,mr4 ,binckley in his claim that the entire general design of the system1 as well as the extensive hydrological studies and final selection of the sources of water supply1 was completed in #aijf1 etc4 ,on ,may #ast1 #aijg1 when the writer assumed responsibility as ,chief ,engineer1 he was unfortunately confronted with the fact that very little data and only a few preliminary and incomplete plans were available4 ,his first duty was to report upon the final sources of supply1 and the recommendations made in his report 7dated ,july #abth71 received ,mr4 7now ,sir ,william7 ,mackenzie's approval during the same month4 ,the final plans1 upon which the approval of the ,state ,government was definitely obtained1 were prepared by the writer during the summer of #aijg1 were submitted to the ,governor of the ,state1 ,gen4 ,bernard ,reyes1 on ,october #aith1 and received his approval on ,december #abth1 #aijg4 ,no works1 with a long preliminary history1 such as those at ,monterrey1 can rightly be said to be due to any one individual2 many engineers contributed to the final result1 and the writer willingly acknowledges his indebtedness to the able men1 who1 for ten years prior to the construction of the works1 investigated the particular problems which were met--problems which were not only of an engineering and physical nature1 but racial and financial4 ,the responsibility of constructing the works in their present form1 and leaving them practically complete1 did1 however1 fall on the writer's shoulders4 ,messrs4 ,pitkethly and ,hammond have criticized the basis of the calculations upon which the sewer system was laid down4 ,in considering this problem1 it is necessary to remember that1 in designing this system1 there was practically no information upon which to base the calculations2 and the writer believed that the wisest course was to anticipate a liberal growth1 and provide a large margin of safety4 ,in designing a sewer system in older and well-established communities1 the engineer is generally able to compile considerable information regarding the probable sewage flow for which it is necessary to provide4 ,in ,monterrey this quantity was absolutely unknown4 ,the writer's practice in other places has been to assume that about #h of the total daily discharge of sewage will flow off in one hour2 and1 from many curves which he has plotted regarding sewage flow in ,british towns1 this rate appears to him to be approximately correct4 ,in ,monterrey1 however1 the old ,mexican traditions are rapidly changing1 and the city is now becoming one of the most ,americanized in ,mexico2 the old one-story houses will give way in time to buildings of several stories--a change1 already noticeable1 which has occurred during the past few years1 particularly in the business portion of the city4 ,taking these facts into consideration1 it is believed that it would be1 not only bad engineering1 but bad business1 for a company whose concession lasts #ii years1 to provide sewers as small as #f in41 as ,mr4 ,hammond would recommend1 and then be called upon1 under the terms of the concession1 to relay larger sewers at a future date1 thus incurring further capital expenditure upon which no ,government guaranty would apply1 and no further revenue be obtained4 ,in matters of this kind1 not only the engineering1 but the commercial1 aspect of the question must be kept in view1 and this point1 the writer must frankly admit1 he has always seriously considered4 ,the writer's experience with reference to the method of ventilating sewers by tall columns extends over many years1 and he still maintains that no other system gives such satisfactory results4 ,in this view he finds considerable support in a recent paper on ,salisbury ,drainage1 by ,mr4 ,w4 ,j4 ,e4 ,binnie1#aa written since the system at ,monterrey was installed1 in which the result of a series of experiments carried on during #aijf-jg are given4 ,at ,salisbury1 ,england1 #fh ventilators1 #f in4 in internal diameter1 #cj ft4 high1 were connected to the main sewer by #f-;in4 stoneware pipes4 ,they were placed about #edj ft4 apart1 and1 from careful anemometer readings1 the following conclusions were reached3 #aa ,minutes of ,proceedings1 ,inst4 ,c4 ,e41 ,vol4 ,,clxxxi1 p4 #cag4 7#a7 ,that four ventilators all lying in the lower portion of the town acted sometimes as air-inlets and sometimes as air-outlets1 and that the other sixty-four acted as air-outlets4 7#b7 ,that the average velocity of the air escaping up these columns was #c4b feet per second1 representing the circulation of #c1fjj1jjj cubic feet of air per diem1 or sufficient to change the air in the sewers every #aj minutes4 7#c7 ,that the average velocity of the current of air in the ventilating-column increases with the size of the sewer to which it is connected1 averaging #b4d feet per second with the #g-;inch sewer1 #c4f feet per second with the #i-;inch sewer1 #c4g feet per second with the #ab-;inch sewer1 and #d4a feet per second with the #ae-;inch sewer in these experiments4 7#d7 ,that the draught in the column is very largely dependent on the wind1 being at its minimum on a still day1 and could therefore be readily increased by the use of a suitable cowl4 7#e7 ,that the draught is very little affected by the sewer-gradients4 ,it was expected that1 in ventilating-columns placed in connection with the upper end of a sewer laid at a steep gradient1 a strong draught would have been obtained4 ,no direct connection1 however1 was traceable4 ,as the result of these experiments1 ,mr4 ,binnie rightly came to the conclusion that this system of ventilation was efficient4 ,mr4 ,hammond anticipates that the house connection trap system at ,monterrey will lead to bad results1 but the writer has seen the system at work in many widely different cities with excellent results4 ,he believes that it is in accord with the best practice of the most eminent sanitarians during the last #bj years1 and has no apology to make for introducing that system in ,monterrey4 ,regarding ,mr4 ,hammond's summary of the advantages of concrete pipes for sewer construction1 the writer is in entire agreement1 and would willingly have introduced them throughout the whole of the ,monterrey system1 but for the fact that it was an exceedingly difficult matter to obtain suitable sand for their manufacture during the early days of construction1 and considerable delays would have arisen if a complete network of such pipes had been used4 ,his later experience at ,monterrey1 when the sand difficulty had been solved1 clearly showed that concrete pipe could be laid down at much less expense than fire clay4 ,both ,mr4 ,pitkethly and ,mr4 ,hammond refer to the system of liquefying tanks used at ,monterrey preparatory to turning the sewage on the irrigation lands1 and both express doubts as to their efficiency4 ,the writer is now separated from his library and notes by many thousands of miles1 and cannot quote chapter and verse as accurately as he would like1 in order to support his views that the system adopted was adequate for dealing with a system such as that at ,monterrey4 ,it must be pointed out that not only was it intended to prevent the sewage from becoming a nuisance1 but that the sewage flow plus a large quantity of surplus water was intended to be used profitably for irrigation purposes4 ,with that object1 the ,company--or rather its allied ,company1 the ,monterrey ,railway1 ,light1 and ,power ,company--obtained the control of #b1bdf acres of the very finest arable land1 with almost perfect natural drainage conditions1 so that this land could be utilized to create a profitable revenue from the use of the sewage4 ,the outfall sewer was accordingly designed to carry sufficient water and sewage to irrigate about #b1ejj acres of land1 which area could be considerably extended if necessary at any future time4 ,most authorities now agree that before turning sewage upon land1 a preliminary treatment is required to remove as much as possible of the suspended matter1 and then reduce the latter by subsidence in liquefying or septic tanks1 so that the quantity remaining in the effluent is so small and finely divided that it may be readily decomposed and oxidized by bacterial action without risk of clogging the surface or interstices of the land upon which it may discharge4#ab #ab ,see ,raikes1 ,sewage ,disposal ,works1 pages #ig-ih4 ,mr4 ,pitkethly quotes ,messrs4 ,watson and ,o',shaughnessy as saying1 in their evidence before the ,royal ,commission on ,sewage ,disposal1 that not more than #aj of the solids are digested in septic tanks1 but it must be remembered that in many other places evidence was given before the same ,commission showing that from #be to #cj was actually obtained4 ,mr4 ,j4 ,d4 ,watson1 in his paper1 ,birmingham ,sewage-,disposal ,works1#ac read in ,march1 #aiaj1 points out that3 #ac ,minutes of ,proceedings1 ,inst4 ,c4 ,e41 ,vol4 ,,clxxxi1 p4 #bei4 ,the much-maligned sewage-farm still may be allowed 7where the conditions are favourable7 to rank as one of the best methods of sewage-disposal4 ,diverse opinions may be held as to what are favourable conditions1 particularly as conditions are sure to vary widely with locality2 but it may be assumed that where there is #a acre of suitable land per #ajj persons1 as in ,berlin and several other important cities1 the efficiently-worked sewage-farm1 when judged solely by the standard of the effluent produced1 is still in the front rank4 ,effluents from such a farm are remarkable for their paucity of micro-organisms1 their low albuminoid ammonia1 and their unvarying character4 ,assuming that not more than #b1jjj acres of the irrigated land at ,monterrey were available for sewage purposes1 this area would represent the sewage treatment of the present population of not more than #de persons per acre1 and on the basis of the design1 that is1 for a population of #bjj1jjj persons1 this represents not more than #ajj persons per acre4 ,in many sewage farms on the continent of ,europe1 the number treated per acre varies between #hj and #bjj persons2 for example1 at ,breslau it is #ahg1 at ,berlin #aje1 at ,brunswick #hh1 and at ,steglitz #ahe4 ,regarding the crops to be grown on the land1 very satisfactory results were obtained from growing ,indian corn1 and two excellent crops per annum were taken from an area of #ejj acres during the period in which the writer was responsible for the works4 ,it was also his intention to grow alfalfa1 and turn a part of the land into a pecan grove1 and1 although he does not share the apprehensions of danger of either ,mr4 ,pitkethly or ,mr4 ,hammond as to growing root crops1 he believes the growth of alfalfa1 ,indian corn1 oats1 barley1 and pecan and fruit trees is eminently suitable for the land1 which is a deep rich loam1 from #d to #h ft4 deep1 overlying the sillar formation referred to in the paper4 ,the writer has seen many sewage farms during the last #ah years1 upon which root crops of excellent quality have been grown1 and not the least suspicion has ever been raised regarding their use4 ,in reference to the adoption of the monolithic form for constructing the ,south ,reservoir1 the writer is so convinced as to its economy that had he to build this reservoir again1 he would adopt the same method4 ,mr4 ,binckley1 in drawing attention to the method of construction1 has overlooked the fact that the cost of forms for a reservoir #cj ft4 deep was a very serious item1 and warranted the adoption of this new method1 not only on account of economy but because of rapidity of construction2 while1 in the case of the ,obispado ,reservoir1 which is very much shallower1 simpler forms could be and were adopted4 ,mr4 ,saucedo's remarks regarding the repetition of the extraordinary floods of ,august1 #aiji1 in ,september1 #aiaj1 are particularly interesting1 and show how abnormal conditions are in so dry a section of ,mexico as the ,state of ,nuevo ,leon4 ,these two floods1 the writer believes1 are among the most instructive in ,north ,america1 particularly when one remembers that prior to #aiji the average rainfall during a period of #ae years1 was less than #bb in4 per annum4 ,,table #ah4--;,,comparison ,,of ,,volume ,,of ,,floods1 ,,etc4 ---------------------------------------- -------------------------- ,maximum ,cu4 ft4 ,annual ,drainage recorded _/sec4 amount ,river4 area1 in flow1 in per of square cu4 ft4 square rain- miles4 per sec4 mile4 fall4 ---------------------------------------- -------------------------- ,santa ,catarina1 ,monterrey1 ,august #bgth1 #aijg #edd #bce1jjj #dcb #bb ,estanzuela1 near ,monterrey1 ,august #bhth1 #aiji #c4e #b1ijj #hbe #be ,tansa1 ,india #eb4e #ce1jjj #fff4g #aja ,krishna1 ,india #cde #aah1jjj #cdb4f #beh ,coquitlam ,river1 ,vancouver #ajj #ab1jjj #abj #adg-ahi ,sweetwater1 ,cal4 #ahf #ah1aej #ii 444 ,delaware1 ,lambertville1 ,n4 ,j4 #f1hbj #bej1jjj #cf4e #de ,colorado1 ,austin1 ,tex4 #cg1jjj #abc1jjj #c4c #bd4e ,ohio1 ,cairo1 ,ill4 #bad1jjj #gjj1jjj #c4c #ed4i ---------------------------------------- -------------------------- ,table #ah1 compiled by the writer1 shows how very extreme the floods of #aiji were compared with those on other rivers1 while those of #aiaj1 referred to by ,mr4 ,saucedo1 although not so great1 would appear to have reached a rate of flow of about #cjj cu4 ft4 per sec4 per sq4 mile of the drainage area4 ,the writer agrees with ,mr4 ,saucedo that in the semi-arid regions of ,mexico and the ,southern ,states1 and also in ,india1 the possibility of these abnormal floods is an important consideration in the design of hydraulic works4 99 99 99 99 99 ,changes ,to ,this ,document ,transcriber's ,note3 ,the table of contents has been added4 ,blank pages have been deleted4 ,illustrations may have been moved4 ,discovered publisher's punctuation errors have been corrected4 ,some wide tables have been re-formatted to narrower equivalents with some words replaced with commonly known abbreviations and possibly a key4 ,some ditto marks have been replaced with the words represented4 ,in addition1 the following changes or corrections were made3 p4 #eja3 but the tampers had haddel #bnd had previous experience p4 #ejh3 shown on ,plates ,,vi to ,,ix,,vi1 ,,vii1 ,,viii1 ,,ixto accomodate links p4 #eaf3 at this place there is a considererableconsiderable area p4 #ech3 based on the following rates and anddel #bnd and percentages p4 #egi3 by crossing the river1 build-thebuilding the reservoir p4 #eej3 ,for ,table #ad3 added ,total materials cost p4 #eff3 respectively 7,fig4 #e77;,fig4 #d71 together with lack of p4 #ehd3 ,table #ag renamed to ,table #ah to avoid duplication4 p4 #ehd3 ,table #agah1 compiled by the writer1 shows how very extreme 99 99 99 99 99