siwasir' of iu.w«3 : 
 
 JUL ^19- 
 
 Report of Engineers 
 
 Regarding the 
 
 Disposal of Sewage 
 
 of the 
 
 City of Los Angeles 
 
 California 
 
a.3 
 
 L8°)<bA> 
 
 Contents 
 
 1. Introduction. 
 
 2. Report of City Engineer to Council on June 23, 1921. 
 
 3. Copy of Report regarding North Outfall Sewer taken front' 
 
 Annual Report of City Engineer for year ending Tune 30, 
 1921. 
 
 4. Report of City Engineer to Council on August 27, 1921. 
 
 5. Sewage Disposal in Eastern Cities. 
 
 Published by the 
 
 Los Angeles Sewage Disposal Committee 
 October, 1921 
 
 Book No. 2 
 

 
 Digitized by the Internet Archive 
 in 2017 with funding from 
 
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 https://archive.org/details/reportofengineerOOIosa 
 
Introduction 
 
 After the publication in March, 1921, of the Reference Book for the 
 proposed North Outfall Sewer for the City of Los Angeles, arrangements 
 were made by the City Council to obtain a report from the best sanitary 
 engineers available, as it became apparent that the opposition to the proposed 
 outfall sewer required as much enlightenment on the subject of sewage dis- 
 posal as could be obtained from the highest authorities. Mr. George W. 
 Fuller, of New York City, Professor George C. Whipple, of Harvard Univer- 
 sity, Cambridge, Mass., and Mr. William Mulholland, Chief Engineer of the 
 Los Angeles Water Department, were selected by the Council as a Special 
 Sewage Disposal Commission. The two first mentioned are eminent sanitary 
 engineers of national reputation, and Mr. Mulholland is well known as the 
 builder of the Los Angeles aqueduct. 
 
 This Commission made a very thorough examination of the situation in 
 Los Angeles in April, and submitted the first two parts of its report to the 
 Los Angeles City Council on April 16, 1921. As, however, more data was 
 required by the Commission, the City Engineer, working under its direction, 
 obtained considerable additional information, which was sent east, for its 
 use. The Commission further requested that Major John A. Griffin, City 
 Engineer, and Mr. W. T. Knowlton, Engineer of Sewers, meet them in New 
 York in May and assist in the preparation of their final report: This meet- 
 ing, however, was delayed until the middle of July. 
 
 The report of the City Engineer of January 17, 1921, recommending the 
 North Outfall Sewer, gave the amount of $12,850,000 as the estimated cost of 
 the work, which included the construction of a sewage treatment plant at 
 Hyperion. In the first part of its report the Special Sewage Commission 
 recommended that the proposed Bond Issue be increased to $14,000,000 to 
 provide for improvements at the end of the existing sewer outfall at Hyperion, 
 to insure the outfall sewer being, as far as possible, acid proof, and to enable 
 a start at once on sewage treatment and utilization. The Council, however, 
 in apportioning the different amounts to the various projects which were to 
 be submitted for a Bond Issue election on June 7, cut the amount proposed 
 for the outfall sewer to $12,250,000. On June 7 the election was held and the 
 Sewer Bond Issue was defeated. Only 38% of the total votes cast were in 
 favor of the issue, whereas 67% was required to successfully carry the bond 
 election. 
 
 This defeat made it necessary to submit an alternative plan to provide for 
 the relief of the present overtaxed outfall sewer, and on June 23d the City 
 Engineer submitted a report to the Council outlining such a plan, which is 
 given in full in this publication. In this report of June 23d the City Engineer 
 recommended that the Council at once have him confer with the Eastern 
 members of the Special Sewage Commission, and also investigate the later 
 developments of the sewage disposal plants in Eastern cities. This request 
 was granted by the Council, and Major Griffin, accompanied by Mr. Knowl- 
 ton, made an inspection of the sewage disposal plants in a large number of 
 the Eastern cities. Soon after his return, the City Engineer submitted on 
 August 27th, a report of the sanitary conditions found in the East. This 
 report in a general way confirmed the plan he proposed on June 23d, making a 
 few changes and giving a total estimate of $3,450,000 as the amount required 
 for a bond election for sewage treatment and disposal. It should be thor- 
 oughly understood that this amount will provide for the treatment of only 
 the present flow in the outfall sewer and that at the end of three or four years 
 an additional bond issue will be needed to take care of the excess sewage, 
 
 •5 
 
which unless provided for will again cause the outfall sewer to overflow. If, 
 however, the results attained by the construction of sewage treatment plants 
 during the next three or four years are not successful, an ocean outfall can be 
 built at a minimum expense. 
 
 In the following pages is given the above mentioned reports of the City 
 Engineer for June 23d and August 27th ; also the complete report of the con- 
 ditions he found on the Eastern trip which should be of especial interest on 
 account of the numerous photographs. An abstract of the report of Mr. 
 Knowlton, concerning the North Outfall Sewer, taken from the Annual Report 
 of the City Engineer for the past fiscal year, is also given. It is intended 
 that the complete report of the Special Sewage Disposal Commission will be 
 published as soon as the final report from this Commission has been sub- 
 mitted to the Council. It is to be hoped that the voters of Los Angeles, with 
 these two publications on the disposal of sewage of Los Angeles at hand, will 
 be sufficiently enlightened to comprehend the seriousness of the situation. 
 
 y Engineer to Council 
 
 June 23, 1921 
 
 Office of the City Engineer, Los Angeles, California, June 23, 1921. 
 
 To the Honorable Council of the City of Los Angeles : 
 
 Gentlemen : 
 
 I beg to again call your attention to the condition of the outfall sewer, the 
 flow in which is increasing at such a rate that, unless some relief is provided 
 in. the near future, the outfall sewer will probably be under pressure during 
 most of the day, and will in the middle of the day overflow onto the ground 
 adjoining it in certain portions of the southwestern part of the city before 
 the end of the next two years. On account of the recent defeat of the bond 
 issue for a new outfall sewer, it is necessary to immediately consider the next 
 alternative plan of relieving this overtaxed condition. Even though it will 
 ultimately cost more, its initial expense is about one-third of the outfall 
 sewer cost. This plan consists of having a treatment plant installed near 
 the southeastern portion of the city, where all of the sewage from the main 
 sewer which now crosses the Los Angeles river at Boyle Avenue could be 
 diverted and treated by the activated sludge process. This plan would be 
 in accord with the recommendations of the Special Sewage Commission em- 
 ployed last March by your Honorable Body to report on the matter of 
 sewage treatment and disposal for Los Angeles. As the amount of sew- 
 age which would be so intercepted and treated at this plant at the present 
 time would not exceed 1,000,000 gallons per day, I have considered that a 
 similar process of treatment could be installed at another plant to be built in 
 the southwestern portion of the city, where, at the present time, approxi- 
 mately 10,500,000 gallons of sewage could be diverted through an intercepting 
 sewer from the outfall sewer and treated. 
 
 By the removal of this total flow of 11,500,000 gallons per day from the 
 outfall sewer, it would be temporarily relieved, at least for 18 months, and I 
 have estimated that to divert and treat a total flow of 31,000,000 gallons of 
 sewage per day, the outfall sewer could be relieved for a period of about three 
 years. If, in the meantime, the results obtained by this treatment should 
 prove satisfactory, other units could be added to the plants at each of these 
 locations as required, which would prevent the outfall sewer from again 
 becoming overtaxed, providing subsequent bond issues are voted. The cost 
 
 6 
 
of the necessary diverting sewers required at the present time to take sewage 
 to the proposed treatment plants, together with the cost of units required at 
 said plants for the treatment of 31,000,000 gallons per day, is estimated at 
 approximately $3,250,000. In addition thereto, a sufficient amount should be 
 allowed to pay for the maintenance and operation of the units required for 
 these treatments plants. As the discharge from the end of the present outfall 
 sewer would not be treated by either of these proposed plants, it would be 
 necessary to install either a screening plant or still another activated sludge 
 plant at Hyperion to remove the cause of complaint of the residents of the 
 beach cities on the west coast. The cost of this screening or treatment 
 should be included with the above costs, making a total of approximately 
 $4,150,000, which would be the approximate amount of a bond issue required 
 at this time. These costs, however, to be better determined after a thorough 
 investigation of all the principal eastern plants. 
 
 If this plan for relieving the outfall sewer should be adopted, rather than 
 the construction of the proposed outfall sewer, subsequent bond issues would 
 be required to pay for the cost of additional activated sludge treatment units 
 of sufficient capacity to prevent the outfall sewer from becoming overtaxed, 
 after the increased discharge of sewage from the ever-growing city had 
 reached the maximum flow which could be treated by the plant units installed 
 by the proposed bond issue of approximately $4,150,000, and by subsequent 
 bond issues. 
 
 As shown in my report to your Honorable Body of June 6, 1921, the 
 installation and operation of such treatment plants would prove much more 
 costly to the tax payers of the city of Los Angeles at the end of the thirty- 
 year period, for which the proposed outfall sewer was planned, than would 
 the proposed outfall. This statement is borne out by preliminary estimates 
 of costs I have prepared, which show the amount of money required to be 
 obtained at different intervals (by bond issues) to treat the excess sewage 
 which would overtax the outfall sewer and which must be cared for. These 
 estimates also show that a large deficit would occur annually which will 
 render the project unpracticable from the viewpoint of the financial condition 
 of the City of Los Angeles. 
 
 In order, however, that an extended study of this matter may be obtained, 
 I recommend that I be authorized by your Honorable Body to visit and inves- 
 tigate the different plants of the activated sludge type which have been 
 installed in other cities in the eastern and central portions of the country. 
 Such a study is necessary if I am to prepare plans for such units to be built 
 and operated at a minimum cost, and is in accord with the request of the 
 Special Sewage Commission. 
 
 The accompanying map shows the general location of the plants which 
 could be installed ; also the proposed outfall sewer, which was planned to 
 provide for the removal of sewage from two of the large sections of a general 
 metropolitan sewerage district, i. e., the central and northern sections. In 
 connection with the plans prepared for a new outfall sewer, I gave much 
 study to the subject of a future metropolitan sewerage district, the north and 
 central sections of which must be provided for at the present time. At some 
 future time, when it becomes necessary to provide for the removal of sewage 
 from that portion of the metropolitan district designated on the maps as the 
 northeast section, which lies between the easterly boundary of the City of 
 Los Angeles and the San Gabriel River, and extends from the mountains 
 southerly to a line along that portion of the Santa Fe Railway which is 
 located between the southeast corner of the city and Los Nietos, an outfall 
 sewer can be planned which will remove the sewage from this section and 
 treat it at some location near the southerly boundary of the section, or carry 
 
 7 
 
it, by an extention of the outfall for this section, southerly along the line of 
 the Los Angeles river to the ocean on the south coast. Sewage from the so- 
 called south section of the metropolitan sewerage district, which is located 
 south of Manchester Avenue and the portion of the Santa Fe Railway above 
 described, could be intercepted by laterals draining into such a proposed 
 outfall sewer. 
 
 With reference to the beach sections shown on the accompanying map, 
 I have considered that local treatment of the sewage of the several cities in 
 these sections can be planned at different locations on the west and south 
 coasts, although it is believed that the sewage of the cities on the west coast 
 can best be collected at Hyperion, as I have reported at various times during 
 the past. 
 
 Since the filing of the first portions of the report of the Special Sewage 
 Commission, I have furnished the Eastern members of this Commission 
 certain data they have requested for the purpose of preparing their final report, 
 and, in connection with this final report, I beg to advise that these engineers 
 have requested that I arrange to meet them in the East, for the purpose of 
 conferring in regard to the details of their proposed plans for the installation 
 and operation of the activated sludge treatment plants herein suggested. 
 
 I recommend that I be instructed by your Honorable Body to proceed 
 forthwith and investigate the latest developments at the principal eastern 
 plants and present to you, at the earliest date possible, complete plans, with 
 estimates, that a bond issue may be called at an early date. 
 
 (No. 78742— J.. A. G.) 
 
 Respectfully submitted, 
 
 JOHN A. GRIFFIN, 
 
 City Engineer. 
 
 Copy ot Report regarding North Outfall Sewer 
 taken from Annual Report of City Engineer 
 for year ending June 30, 1921 
 
 NORTH OUTFALL SEWER 
 1. — Preliminary Work 
 
 At the beginning of the past fiscal year studies were made and reports 
 prepared showing the need of a new outfall sewer. These studies indicated 
 that such a new outfall would be required within a few years, as the amount 
 of sewage discharged into the present outfall sewer was increasing so rapidly 
 that the present outfall would probably become overtaxed before 1924. Fur- 
 thermore, the rapid increase of new buildings west of the present sewered 
 area of the City has indicated that some provision must be made in the near 
 future for an outfall sewer which would render unnecessary the use of cess- 
 pools for all of the district lying between Rimpau Avenue and the cities on the 
 west coast. At the present time a portion of this non-sewered section is not 
 included within the City boundaries, but plans for the annexation of such 
 portions are being made, and it is probable that an outfall sewer for this dis- 
 trict will be needed before such an outfall can be completed. 
 
 In addition to these reasons why a new outfall sewer is needed, the in- 
 crease in the amount of sewage from the industrial district, which is located 
 along the Los Angeles River, has been so great during the past few years 
 that the capacity of that portion of the central interceptor sewer, which is 
 
 8 
 
located on the east side of the Los Angeles River, north of Sixth Street, is 
 becoming over-taxed. 
 
 The need of this new outfall sewer has been referred to in special reports 
 of this department and in almost every annual report since June 30, 1912. As 
 the continued increase in the flow in the present outfall sewer has been care- 
 fully noted from year to year, it became apparent over a year ago that the 
 matter of rights of way for a new outfall sewer should be secured, and to pro- 
 vide for this part of the work an appropriation of $5,000.00 was made by the 
 Council at the beginning of this fiscal year. This amount will pay for a 
 portion of the right of way required for this improvement, but it is probable 
 that an additional amount must be provided before all of the deeds required 
 for the right of way can be obtained. 
 
 2. — Proposed Plans 
 
 Preliminary plans for this new outfall sewer were completed and reports 
 to the Board of Public Works and City Council were submitted in September 
 and November of 1920, also in January, 1921, giving in detail the conditions 
 and reasons why such an outfall sewer was required, and recommending that 
 the matter be submitted to the vote of the people for a bond issue at an early 
 date. The first estimate of cost prepared for the proposed new outfall was 
 approximately $12,200,000. Later, after further consideration to certain de- 
 tails concerning the design and construction of the sewer had been given, 
 this amount was increased to $12,850,000. 
 
 On account of the large amount of money which would be required for 
 this improvement it became apparent when the matter was submitted to the 
 Board of Public Works and the City Council that an educational campaign 
 would be required for the purpose of showing the public the facts as to the 
 need of such an improvement. Furthermore, to have the matter examined 
 and checked by other engineers than the City Engineer, a committee of six 
 local engineers was selected by representatives of prominent civic organiza- 
 tions of the City. This Advisory Board of Engineers, after a careful 
 examination of the plans, reported, after a study of two months, that with a 
 few corrections the plans prepared by the City Engineer were sufficient for 
 the work required. 
 
 In making the necessary studies and preliminary plans for this new out- 
 fall sewer, attention was given to the growth of the different sections of the 
 City and the work, as proposed, was planned to provide for the increased 
 growth of Los Angeles and the probable conditions which would exist in 
 1950. The design of the new outfall sewer provided for a general metro- 
 politan district, and for the extension of the City to the west and north, so 
 that all the area lying west of the easterly boundary line of the City of Los 
 Angeles, north of Manchester Avenue, and south of the northerly boundary 
 line of the San Fernando Valley, would be benefited by the proposed improve- 
 ment. This area would include all of the land lying between the west coast 
 and the mountains to the north of the San Fernando Vallejq Burbank, Glen- 
 dale and Eagle Rock, with the exception of the beach cities, sewage disposal 
 for which cities can be provided if necessary within their own limits, or by 
 treatment at Hyperion. In the report of the Advisory Board of Engineers 
 special attention is called to the areas which would in the future be con- 
 tributary to the proposed sewer, which areas are included in the Los Angeles 
 Metropolitan Sewerage District, for which the proposed outfall sewer was 
 planned. 
 
 3. — Sewage Treatment 
 
 In addition to the plans prepared for the new outfall sewer, studies have 
 been made for the treatment and disposal of the sewage at the ocean. This 
 
 9 
 
part of the proposed improvement has been given considerable attention, 
 examinations being made of sewage treatment plants in various portions of the 
 state, as well as noting the type of treatment described in reports of other 
 cities. After making such studies, the use of a fine screening plant was recom- 
 mended for the treatment of the raw sewage at Hyperion, recommendations 
 for which plant with a report on the use of such screens were also given in 
 the annual report of this department for the year ending June 30th, 1920. 
 
 4. — Land Disposal 
 
 After the plans for the proposed outfall sewer were submitted to the 
 Board of Advisory Engineers, it was found that some opposition to the project 
 arose from persons who objected to the discharge of sewage into the ocean, 
 these persons believing that the City was wasting certain values which might 
 permit a profit to be recovered by the City if the sewage should be treated and 
 then disposed of onto the land through irrigation ditches. In order that such 
 plans might be given careful consideration, detailed studies of the disposal 
 of sewage on land were made. Before the flow in outfall sewers can be used 
 on land, however, it is considered by all that necessary treatment must be 
 given to the flow which would render the sewage free from offense if used for 
 irrigation. Although there are three or four types of treatment which can be 
 considered for this purpose, it was considered that the best form of treatment 
 which could be used was that of the activated sludge process, which renders 
 the effluent practically free from bacteria and produces a sludge that can be 
 dried and used for fertilizing purposes. Studies for the installation of such 
 treatment plants were accordingly prepared and estimates of costs obtained 
 of the different factors required for such a treatment. 
 
 The land to the south and southeast of the city, on which treated sewage 
 effluent could be discharged, would require long distributing conduits, even 
 under the most favorable conditions. Studies for the land disposal of sewage 
 included the planning of sewage treatment plants along the line of the outfall 
 sewers and it was considered that a certain length of new collecting sewers 
 would be required to bring the sewage to such treatment plants. In some 
 cases resort to pumping the sewage would be required, as the land on which 
 disposal was to be made was in some places several feet higher than the 
 sewer. 
 
 In some of the discussions that have occurred during the past year, pro- 
 ponents for the land disposal of the sewage have considered only certain por- 
 tions of the cost required therefor. To properly consider the entire cost, 
 one must allow for the item of collecting sewers required, pumping when 
 necessary, the installation and operation of the treatment plants, and the 
 installation and maintenance of the distributing conduits therefrom. 
 
 As a result of the studies for land disposal, it was found that the present 
 available acreage for such a disposal was sufficient for the present volume of 
 sewage now discharged into the ocean at Hyperion, but that as this volume 
 increased to an amount which would probably be carried by outfall sewers in 
 the future, the land for such a disposal was not obtainable in Los Angeles 
 County. Studies and inquiries made as to whether such land was available in 
 Orange County gave no encouragement to this method of disposal. If, how- 
 ever, the land now available for land disposal of sewage was sufficient in 
 area, it was found that the cost required for the different steps of the process 
 of collecting, treating and distributing the sewage would be more than the 
 probable income to be derived by the sale of the water and solid matter which 
 could be used for fertilizer. 
 
 10 
 
5. — Ocean Disposal 
 
 In contrast to this method of disposal, studies made of the discharge of 
 treated, screened sewage into the ocean at Hyperion indicated that all of the 
 solid and floating matter would be removed and that the effluent from such 
 screening plants would receive such further treatment from the oxygen in the 
 ocean that the amount of bacteria at a distance of one-half mile or more from 
 the point of discharge would be no more than is found along those beaches 
 which are not affected by even remote outfall sewers. It was, accordingly, 
 considered that the screening proposed at Hyperion, together with the oxidiz- 
 ing effect of the ocean, will remove all objections now made by the residents 
 of the beaches on the west coast. In this connection reference should be 
 made to the presence of oil which is found on the west coast beaches as not 
 necessarily coming from the Los Angeles outfall sewer, but probably from 
 the oil well off the coast at Redondo and from other sofirces. 
 
 6. — Opposition to Sewer Bond Issue 
 
 During the months from February to May, inclusive, of this year, the 
 opposition to the proposed sewer bond issue became more pronounced as time 
 went by, and counter-proposals were made by some individuals and organiza- 
 tions, which, supported by the daily press, had the effect of misleading the 
 public. Such proposals referred to the possibility of installing plants where 
 the sewage would be treated by the activated sludge process and also to the 
 construction of a smaller outfall sewer which, it was thought by the pro- 
 ponents, might suffice for a period of ten years. In this connection, reference 
 to the cost of the present outfall sewer was made, as it was thought by the 
 proponents .of such a smaller sewer that a duplication of the present outfall 
 sewer could be constructed at a cost of not over $2,000,000, and that this 
 improvement would be sufficient for the next ten years. Other opposition to 
 the proposed sewer bonds was made by those who had for sale certain 
 processes of sewage treatment which they considered would cause the sewage 
 to be so treated that the solid could be recovered and sold at a price which 
 they thought would more than offset the cost of treatment. 
 
 Regarding these different alternate methods of treatment and disposal, an 
 earnest endeavor has been made to investigate carefully the details of each 
 plan proposed, in order that if the alternate plan should be found feasible, its 
 costs could be considered. As, however, in almost every case it has been found 
 that the process of sewage treatment proposed by such alternate plans has 
 net been given a trial on any municipal working basis, it is not thought that 
 such alternate plans should be considered in contrast with the proposed sewer 
 outfall or the activated sludge treatment until a more detailed investigation 
 covering the installation and operation on a large scale can be made. Further- 
 more, it may be noted from the report of the Special Sewage Disposal Com- 
 mission, which was appointed by the City Council in March, that allowing 
 for the average operating cost of $10.00 per million gallons, with an additional 
 cost of $15.00 per ton for pressing and drying the sludge, the city would lose 
 $1,490,000 annually if the activated sludge method of treatment were adopted 
 for the probable amount of sewage which will come from a population of 
 about 2,500,000 in 1950. 
 
 7. — Special Sewage Commission 
 
 This loss has been computed from the estimates given in the report of the 
 consulting engineers of this commission, who considered that the activated 
 sludge process would produce about one and one-half tons of fertilizer per 
 million gallons and that this fertilizer would contain about four units of 
 organic nitrogen, which would have a value at the plant of $18.00 per ton. 
 
 11 
 
This loss would be increased if allowance were made for the cost of the 
 necessary collecting sewers and for the disposal of the effluent from the plant. 
 On account of the amount of grease and mineral oil contained in the Los An- 
 geles sewage, these engineers reported that the commercial success of the 
 sludge utilization project would be uncertain. 
 
 The assistance of this commission was considered necessary, as the 
 large amount of money required for a new outfall sewer was reaching prac- 
 tically the non-revenue producing bond limit, and opinions of the best sewage 
 experts were requested by the public. In order that the selection of mem- 
 bers of this commission should be properly obtained, the local chapters of the 
 American Society of Civil Engineers and of the American Association of 
 Engineers requested the secretary of each of these national engineering 
 organizations to send to the City Council the names of several prominent 
 sanitary engineers who were qualified to act on such a commission. Upon the 
 receipt of the names of such experts, the City Council, with the assistance of 
 Mr. William Mulholland, who was selected as a member of this commission 
 bv the Council, chose the names of George W. Fuller, of New York City, and 
 Professor George C. Whipple, of Harvard University, in Cambridge, Mass., 
 to act as members of this commission. Accepting the choice made by the 
 Council, the eastern engineers arrived in Los Angeles on April 4, and after 
 two weeks’ careful study of the conditions on the ground, prepared the first 
 part of their report on the matter of sewage disposal for the city. Previous to 
 the departure of these eastern engineers on April 16, this part of the report of 
 this commission was filed with the Council which gave their findings, con- 
 clusions and recommendations. This report, copies of which are on file with 
 the City Clerk, covers the general situation which applies to the Los Angeles 
 conditions, but it does not complete the work for which the comtnission was 
 appointed, as these engineers deemed it necessary to make a thorough study 
 of other findings which have been obtained by this department for their use. 
 At the time of their departure it was thought that the final report of the com- 
 mission would be prepared and submitted before the end of this fiscal year, 
 but on account of the time and amount of work required for the securing of 
 the data requested by these engineers, their final report has not as yet been 
 prepared. 
 
 8. — New Outfall Sewer Demand 
 
 It will be noted, however, from the conclusions published by this com- 
 mission in the first part of their report, that a new ocean outfall should be 
 constructed as soon as possible, in which conclusion the writer must em- 
 phatically concur. A careful, systematic record of the daily flow of sewage 
 in the outfall sewer indicated that the present outfall sewer is carrying its 
 maximum capacity during the middle portion of the day at the present time, 
 and that this condition will probably occur during all of the day before the 
 end of 1923, at which time it is probable that the amount of sewage dis- 
 charged into the outfall sewer will so overtax this conduit that sewage will 
 be forced out of the manhole tops on to the adjacent ground. Unless relief 
 measures to intercept the increasing flow of sewage can be carried into effect 
 before the next rainy season, it is possible that the city may be served with 
 injunction suits for the damage to private property from the overflowing 
 sewage. Such a condition seems almost inconceivable for a city of the size 
 and importance of Los Angeles, but until the opponents to the proposed out- 
 fall sewer can realize that this proposed improvement, although very costly, 
 is the cheapest way for the disposal of the sewage of the City of Los Angeles, 
 it appears that the proposed outfall sewer will be blocked indefinitely and the 
 present outfall will become overtaxed and discharge the sewage which it can- 
 
 12 
 
not carry on to lands in the southwestern part of the city. This condition will 
 probably require the construction of ditches for the removal of the excess 
 sewage unless funds for intercepting sewers which will carry the excess flow 
 in the present outfall sewer to water courses can be obtained. The defeat of 
 the sewer bond election on June 7, 1921, when funds amounting to $12,250,000 
 were proposed for the new outfall sewer and treatment at Hyperion is very 
 regrettable, and makes necessary immediate steps be taken to provide a quick 
 alternative, to prevent disaster. 
 
 Report of City Engineer to Council 
 On August 27, 1921 
 
 Office of the City Engineer, Los Angeles, California, August 27, 1921. 
 
 To the Honorable Council, of the City of Los Angeles. 
 
 Gentlemen : 
 
 I beg to submit the following report of the- inspection I have made of the 
 sewage disposal plants in Eastern cities and of the sanitary conditions I found 
 in those cities which I visited with Mr. W. T. Knowlton, Engineer of Sewers, 
 during the months of July and August. 
 
 The inspection began at Milwaukee where a small experimental plant is 
 now in operation, and their ultimate plant under construction. 
 
 No revenue of any nature is derived from their effluent or sludge, and 
 while it is anticipated that when the big plant is finished some two years 
 hence, the sludge will be reclaimed and sold, it is not anticipated that the 
 revenue so derived will do any more than offset a portion of the cost of such 
 reclamation. 
 
 The next principal stop was made in New York to attend a conference 
 with Mr. George W. Fuller and Prof. Geo. C. Whipple, eastern experts of the 
 Special Sewage Disposal Commission. At this conference I submitted my 
 proposed plan of diverting the sewage to the two small treatment plants, 
 which I had recommended to your Honorable Body prior to leaving here, 
 and my recommendation was concurred in by them. While in New York 
 side trips were made to Allentown, Pa. and Phillipsburg, N. J., and an inspec- 
 tion made of the Landreth Direct Oxidation Process at these points; also a 
 trip to Plainfield, N. J. and New Britain, Conn., at which latter place a Dorrco 
 screen was in use. 
 
 On arrival at Boston I was escorted over the Harbor to each of the 
 sewage outlets by Mr. Harrison P. Eddy, together with several members of 
 the Metropolitan Sewerage Commission and Water Works Department, and 
 observed the effect of the multiple outlet distribution of the sewage field. 
 The daily discharge of sewage into Boston Harbor is more than four times the 
 total quantity carried by our present outfall sewer and receives no treatment 
 whatsoever; the steamers entering and leaving Boston Harbor cross directly 
 through the sewage field. Dependence for dilution and disposal is placed 
 upon tides and salt water. 
 
 Inspection of the sewage plants in operation at Fitchburg and at Wor- 
 cester were next made, after which .Syracuse and Rochester were visited. 
 Imhoff tanks and sprinkling filters are in constant use at both Fitchburg and 
 Rochester, and Worcester is now building a similar treatment plant. At 
 Syracuse an outfall sewer is under construction. 
 
 A visit to Cleveland permitted a good inspection of the Imhoff tanks 
 being built and of the conditions along the bathing beaches which were near 
 the sewer outlets. Detroit, Toledo and Lima were then seen, in all of which 
 cities large sums are being spent for outfall and intercepting sewers. It was 
 
 13 
 
next noted that the Imhoff tanks and sprinkling filters at Columbus gave 
 satisfactory results, and that this plant was needed to prevent pollution of 
 the Scioto River. At Indianapolis it was noted that a new outfall sewer was 
 to be built and that considerable study was being given to the activated sludge 
 treatment process. 
 
 We inspected at Chicago a large Imhoff tank plant under construction 
 in the Calumet District; also visited testing plants where tannery and corn 
 product wastes were being treated. Along the North Shore at Chicago an 
 inspection was made of the sewer plants at Fort Sheridan and at the Great 
 Lakes Naval Station. After leaving Chicago a visit was made to the State 
 University of Illinois at Urbana, where an experimental sewage plant of the 
 Dorr-Peck type is in operation. The return trip from Chicago to Los An- 
 geles was made by way of New Orleans and Houston, at which latter place 
 two activated sludge plants have been in use since 1918. 
 
 The total mileage covered by the trip amounts to approximately 8,500 
 miles, and covered an investigation of some 35 plants. The total expense, 
 including railroad fares, etc., amounted to $1,152.45, and the balance of $347.55 
 has been returned to you. 
 
 In the following chapters I have given a condensed report of the sewer 
 conditions in each of the cities I visited. From an examination of these con- 
 ditions it will be noted that several of these cities have investigated the dif- 
 ferent methods of sewage treatment and disposal in use, and that the construc- 
 tion of intercepting and outfall sewers is required in most of these cities. Fur- 
 thermore, the discharge of raw sewage into the ocean or into a large body of 
 water is not infrequent, when sufficient dilution can be obtained and floating 
 matter removed. To provide for dilution, the outlet end of the outfall sewer 
 should be at a depth of about 25 to 30 feet, being that used in Boston, Syracuse 
 and Cleveland. In only one or two of the cities visited was any use made of 
 the sludge as a fertilizer, and in those cities the sludge value did not exceed 
 $0.50 per cubic yard. On the contrary, the sludge from the sewage treatment 
 plants is usually wasted or used for filling low land 
 
 A brief summary of the treatment of the sewage in the various cities 
 visited would divide the cities into two general classes ; first, those discharging 
 their sewage into the ocean; and, second, the inland cities. Of the latter, the 
 general plan used for treatment consist of a combination of settling tanks and 
 filters, the only exception being the direct oxidation (Landreth) process and 
 the activated sludge process. Where the sewage was discharged into the 
 ocean, no treatment was required if the suspended matter was taken to sea by 
 the tides. 
 
 In my report to your Honorable Body of June 23rd, I proposed as an 
 emergency measure an alternative plan for relieving the over-taxed condition 
 of the present outfall sewer of Los Angeles, and at the same time demonstrate 
 the recovery theory by installing sewage treatment plants in or near the 
 southeast and southwest sections of the City. These plants were proposed to 
 be built in units having a total capacity of about 31,000,000 gallons per day, 
 which would suffice to relieve the outfall sewer from overflow during the next 
 three or four years. The cost of such plants, together with intercepting sewers 
 required to carry sewage to the plants, was then estimated at $3,250,000. In 
 addition to this cost, I proposed that a sufficient sum be allowed for the opera- 
 tion of these treatment plants, and that a screening plant be installed at Hy- 
 perion to remove all suspended matter from the ocean discharge. The total 
 cost of these plants, including a sum sufficient for three years operation, was 
 estimated at $4,150,000. 
 
 After a careful study of the situation in Los Angeles, following my inspec- 
 tion of the sewage disposal plants in the Eastern cities, I recommend that the 
 
 14 
 
above plan be adopted with the following modification as relates to initial 
 installation and paying for operation costs. 
 
 First: The construction of an intercepting sewer south of and adjacent 
 to the so-called Air Line Railroad, extending from the junction of Arlington 
 Avenue and Exposition Boulevard westerly to the vicinity of Moynier Lane 
 and the Ballona Creek, w'hich sewer will provide for the unsewered districts in 
 the western part of the City between Exposition Boulevard and Hollywood 
 and as far west as the junction of Washington Street and Adams Street; and 
 also for the removal of the excess flow in the present outfall sewer, which is 
 causing the trouble at the junction of Arlington Avenue and Exposition Boule- 
 vard. The cost of this item is estimated at $1,304,000. 
 
 Second: The installation of an activated sludge plant, to be known as 
 the Southwest Sewage Treatment Plan, of 12,000,000 gallons daily capacity at 
 a location near the westerly terminus of the intercepting sewer described in 
 the first item, with provision for discharging the clarified effluent into the 
 Ballona Creek. The cost of this item is estimated at $926,000. 
 
 Third : The installation of an activated sludge plant, to be known as the 
 Southeast Sewage Treatment Plant, of 6,000,000 gallons daily capacity to be 
 located on City property in the southeastern part of the City, with provision for 
 discharging the clarified effluent into the Los Angeles River bed. The cost of 
 this item is estimated at $488,100. 
 
 Fourth : The construction of an intercepting sewer to deliver sewage 
 from the east side of the Los Angeles River to the Southeast plant described 
 in the third item. The cost of this item is estimated at $397,600. 
 
 Fifth : The installation of a fine screening plant at Hyperion of 54,000,000 
 gallons daily capacity, which will remove the suspended matters from the flow 
 of the present outfall sewer, the cost of which plant is estimated at $300,000. 
 
 Sixth : The extension of the ocean end of the present outfall sewer so as 
 to discharge the screened sewage at the bottom of the ocean, the cost of which 
 is estimated at $34,300. 
 
 The total amount of the foregoing six items is $3,450,000, for which I 
 recommend a bond issue be submitted to the people at the earliest possible 
 date. 
 
 In adopting the above program, it should be understood that during the 
 installation of the items above recommended it may be necessary to deliver 
 sewage from the present outfall onto certain areas which should be obtained 
 for this purpose, such temporary disposal, however, to be considered purely as 
 an emergency measure to prevent the overflow of sewage onto city streets, 
 and built-up areas where construction is under way. Furthermore, it should 
 be understood that the above plan will only provide for the removal of the 
 excess flow in the outfall sewer for a period of three or four years and at the 
 end of such period, extensions will have to be made by future bond issues, or 
 if it is found by experience during this period that the results obtained do not 
 warrant the extension of this method of disposal, a change to ocean outfall or 
 other means can be made at a minimum of expense. The yearly cost of opera- 
 tion and maintenance of the treatment plants and screening plant above rec- 
 ommended is estimated at $258,300, for which arrangements must be provided 
 in the annual budget of the City instead of by bond issue. While it is possible 
 that some revenue may accrue from the sales of water and sludge, I have made 
 no allowance for such sales, as such revenue is problematical. 
 
 On account of the great need of securing the earliest possible relief for 
 the present outfall sewer and providing facilities for the ever-growing City, I 
 recommend that your Honorable Body take early action in this matter. 
 
 Respectfully submitted, 
 
 (No. 78742— J. A. G.) JOHN A. GRIFFIN, City Engineer. 
 
 15 
 
Sewage Disposal in Eastern Cities 
 
 (Accompanying report of City Engineer to Council on August 27, 1921.) 
 
 CHAPTER 1. 
 
 Milwaukee, Wis. 
 
 This City has a population of 500,000, which is 100 per cent sewered. 
 The sewage is both industrial and domestic 
 
 The average daily flow is 65,000,000 gallons ; the minimum is 35,000,000 
 gallons and the maximum 80,000,000 gallons. Three-quarters of the total daily 
 flow is discharged into the Kinnickinnic River and one-quarter into Lake 
 Michigan. The use of the river for disposal of so much of the sewage has 
 created such a nuisance that it has been necessary to pump 80,000,000 gallons 
 of water per day from the lake into the river to dilute the sewage. 
 
 At the present time about 200,000 gallons of sewage flow into the lake is 
 treated at the experimental station on Jones Island. 
 
 The sewage contains an average of 300 parts per million of suspended 
 matter and has an average temperature of 52°, varying from 34° to 72°, the 
 corresponding atmospheric temperature being 55°, — 16° and 98°. 
 
 The sewerage system consists of a high and low level system, two-thirds 
 of the total flow being in the high system and one-third in the low. Forty per 
 cent of the sewage is pumped, while the balance is on a gravity basis. 
 
 The intercepting sewers have a length of 35 miles, and were built of con- 
 crete in 1915 with only cement wash for a protection coat. 
 
 The final treatment plant was begun 
 in June, 1921, and will be finished in 
 about two years. 
 
 The experimental work was begun 
 in 1915 and exhaustive research and 
 
 Two Views 
 
 Milwaukee River, Milzvaukee 
 
 16 
 
study has been carried on to date, costing $500,000. The 200,000 gallons now 
 being treated daily at this plant passes through a grit chamber with a velocity 
 between 0.64 and 1.0 feet per second, and then through fine screens, after which 
 it is pumped to two aerating tanks in series, where it is subjected to a four- 
 hour detention period at peak load in the day and eight-hour detention period 
 at night. 
 
 Grit Chambers, Milwaukee 
 
 98% to 82%. This machine is known as 
 the Besco-Ter Meer Centrifuge and is 
 sold by the Barth Engineering & Sani- 
 tation Co., 11 East Forty-eighth Street, 
 New York City. 
 
 This machine now handles from 
 eight to sixteen thousand gallons, or 
 an average of 12,000 gallons of this re- 
 turned sludge per day, or will produce 
 from 9,000 to 10,000 pounds of 82% to 
 83% moisture cake per million gallons. 
 
 The total capacity of each of these 
 machines varies from 40,000 gallons to 
 60,000 gallons of returned sludge per 
 million gallons of sewage treated, or, 
 in other words, it will require from 1 
 to 1 y 2 machines per million gallons of 
 sewage treated. 
 
 The amount of air used at the pres- 
 ent time averages \ l / 2 cubic feet per 
 gallon of sewage treated, has a press- 
 ure varying from 6.9 to 7.1 pounds per 
 square inch, and this is diffused 
 through filtros plates at a ratio of 1 to 
 4.4. In the new plant it is planned to 
 reduce the air to 1.1 cubic feet per gal- 
 lon treated. 
 
 From the aeration tanks the sewage 
 flows over a weir to a settling chamber 
 having a Dorr thickener. From the 
 chamber the clarified effluent flows to 
 the lake and 18% of the settled sludge 
 is returned to the aerating tanks. The 
 balance of the sludge is then pumped 
 into a centrifuge dryer where the per- 
 centage of moisture is reduced from 
 
 Activated Sludge Plant , Milwaukee 
 
 17 
 
This machine operated on 
 15-minute to 20-minute inter- 
 vals and produces approxi- 
 mately 100 pounds of cake 
 83% moisture every 15 to 20 
 minutes. 
 
 The present treatment plant 
 was put into operation in 
 October, 1920, and removes 
 90% of the suspended solids, 
 98%of the bacteria with an 
 effluent of 72 hours stability. 
 This stability would permit 
 the effluent from either of our 
 proposed plants to reach the 
 ocean before becoming putrid, 
 but will not prevent algae from 
 growing along the canals. 
 
 To date no cost data is avail- 
 able except Mr. Hatton’s esti- 
 mates, i. e., initial installation 
 at $55,000.00 per million gal- 
 lons and $35.00 per million gal- 
 lons operating cost. 
 
 Activated Sludge Plant , Milwaukee 
 
 18 
 
Traveling Brushes, Allentown 
 
 The screenings are removed from the screens by traveling brushes and dis- 
 posed of in an incinerater. 
 
 The sewage is then passed through a grit chamber and into the electrical 
 unit for treatment, the flow being measured by a Venturi meter. Each electric 
 unit consists of an airtight chamber having a length of 28 feet, and a depth of 
 20 inches. This chamber contains the electrolytic plates by which the sewage 
 
 Electrolytic Plant, Allentown 
 
 ALLENTOWN, PA. 
 
 Chapter 2. 
 
 Allentown has a population of 85,000, 30,000 to be sewered by plant just 
 completed as soon as the system can be installed. 
 
 The sewage is domestic with slight industrial waste. The average daily 
 volume to be treated is estimated at 2,000,000 gallons, the maximum 3,000,000 
 gallons, and the minimum 1,500,000 gallons. 
 
 The plant is designed on the basis of 100 gallons per capita, and consists of 
 three units of the Landreth Direct Oxidation Process each of 1,000,000 gal- 
 lons capacity. 
 
 This type of treatment includes the use of a fine screen to remove all par- 
 ticles greater than ]/<&” in diameter. 
 
 19 
 
is subjected to electrical action. Into these chambers is introduced 700 to 
 1,000 pounds of lime (Cal. Oxide) per million gallons per day. 
 
 The effluent will be discharged into concrete settling tanks, from which 
 the sludge will be drawn to sand drying beds and the clarified effluent run 
 into the creek. 
 
 Settling Tanks , Allentown 
 
 The operation of this plant will require 126 K. W. hours per million gal- 
 lons per day, and the cost of power is 2c per K. W. H. The cost of lime is 
 $8.30 per ton. The power required for operation of the mechanical units of 
 the plant is as follows: 
 
 ]/ 2 horse power for lime feeder. 
 
 ]/ 2 horse power per million gallons daily for screens. 
 
 1 H. P. for water pump to mix lime. 
 
 1,500 watts for paddles per million gallons daily=l K. W. 
 
 1-25 H. P. motor used about 3 hours daily for pulverizing lime, 2j4 K. W. 
 per million gallons daily. 
 
 The total cost of this plant was $205,000.00 without any sewers, of which 
 $134,576.00 was paid to the Landreth Co. for machinery and labor. 
 
 The screenings are estimated at four cubic feet per million gallons per day, 
 and will contain 95% moisture. 
 
 This plant was finished on June 1st, 1921. 
 
 20 
 
CHAPTER 3. 
 
 Phillipsburg, Pa. 
 
 Phillipsburg has a population of 20,000 with 17,000 now served. Character 
 of sewage, 15% sanitary and 85% industrial. 
 
 Average daily volume is 500,000 gallons 
 Maximum daily volume is 800,000 gal- 
 lons. Minimum daiiy volume is 200,- 
 000 gallons. 
 
 The plant is a duplicate of the Allen- 
 town plant. On the day of my visit, 
 
 July 20, 1921, only one electric unit- 
 was in operation and the meters in- 
 dicated 72 volts, 33 amperes and 1,300 
 watts. 
 
 No data was available regarding sus- 
 pended matter excepting a report of 
 October 19, 1920, which gave the aver- 
 age daily volume of inflow of 52.9 ppm 
 and 44.2 ppm in the effluent. It was 
 stated that the sludge would have a 
 weight of 1,508 pounds per million 
 gallons dry basis, and 8,880 pounds per 
 million gallons on wet basis. 
 
 The sewage as it entered the plant 
 looked about like pure water with only 
 a trace of fecal matter. After treatment 
 in the units the grease and oil scum 
 was very apparent and was intercepted 
 by barrels and diverted to coke beds. Buildings Adjacent to Plant 
 
 The effluent as it entered the settling tanks was muddy, and after being 
 detained in the settling basins for four hours overflowed the weir like clear 
 water and was discharged into an adjoining creek. The dried sludge resem- 
 bled clay and was used for filling on land. 
 
 There was practically no odor con- 
 nected with the plant, which is located 
 adjoining several houses. 
 
 The cost and amount of electricity 
 for this plant is substantially as given 
 for the Allentown plant except that 
 electricity is 3 cents per K. W. hour 
 and lime $10.90 a ton. 
 
 Mr. C. P. Landreth stated that he 
 has no interest in the method or 
 amount of treatment given to the ef- 
 fluent or sludge beyond his electric 
 units. 
 
 This Landreth Process has also been 
 used at Elmhurst, N. Y., where one 
 million gallons daily are treated. An 
 experimental plant of one million gal- 
 lons daily was also in operation in 1918 
 in Easton, Pa., but later dismantled. 
 
 Sewage Plant , Phillipsburg 
 
 21 
 
CHAPTER 4. 
 
 Plainfield, N. J. 
 
 The Plainfield plant treats sewage from Plainfield, North Plainfield and 
 Dunellen. 
 
 The total population tributary is 35,000, and the flow is 3,300,000 gallons 
 per day. 
 
 This plant consists of fine screens, Imhoff tanks, sprinkling filters, secon- 
 dary tanks and sludge beds. Taylor nozzles are used in the filter beds which 
 have a depth of six feet. 
 
 The filters are of lp 2 -inch crushed rock. The final effluent contains about 
 30 ppm of suspended solids and is run into an adjacent creek. 
 
 A 10-foot diameter Reinsch-Wurl screen was installed in 1918. 
 
 The sludge was spread on lowlands and plowed under. 
 
 A slight odor was noticeable around the plant. 
 
 Sprinkling Filters , Plainfield 
 
 CHAPTER 5. 
 
 New Britain, Conn. 
 
 The population is 55,000, of which 44,000 are served. 
 
 Sewage consists of domestic and industrial and is delivered through an 
 outfall four miles long. 
 
 Drum Screens, New Britain 
 22 
 
Its average daily volume is 4,000,000 gallons. 
 
 Its maximum daily volume is 6,000,000 gallons. 
 
 Its minimum daily volume is 1,200,000 gallons. 
 
 The sewage contains an average of 110 ppm of suspended matter, of 
 which 20% is removed by a fine screen having 1/16" x y 2 " slots, the percentage 
 of openings being 24.6%. The length of the screen is 8 feet; its diameter is 
 4 feet 10 inches (the same as proposed at East San Pedro). It revolves at the 
 rate of 22 RPM or 330 feet surface speed per minute. This operation required 
 1.56 h. p. A3 h. p. motor is used. 2 h. p. thereof being required for the con- 
 veyor for screening and screen and 1 
 
 23 
 
Screening Elevator, New Britain 
 
 Screening Elevator, Nezv Britain 
 
 24 
 
Sewage Discharge on Filter, New Britain 
 
 This screen was run for 7 days without stopping and tests made by me 
 show no clogging. 
 
 The screenings average 32 cu. ft. per mil. gals, and contain 85% moisture, 
 which is equivalent to 330 lbs. (dry weight) per mil. gals. 
 
 At the time the photographs were taken 4 y 2 mil. gals, per day were pass- 
 ing the screen. 
 
 The plant was built in March, 1921. The effluent from the screen is dis- 
 charged onto filter beds having an area of 37 acres which are 6' deep of sand 
 and gravel in clay pits. They are subdrained into the Mattabesset River. 
 
 Diversion Chamber, New Britain 
 
 CHAPTER 6 
 Boston, Mass. 
 
 Boston and adjoining cities dispose of their sewage through three outfalls. 
 The north side at Deer Island, the City proper at Moon Island, and the south 
 side at Nut Island. 
 
 At Deer Island the average daily volume is 70 million gallons. 
 
 25 
 
Walls and Channels of Settling 7 
 
 Settling Tanks, C 
 
 26 
 
et Treatment Plant, Chicago 
 
 lumet Treatment Plant, Chicago 
 
 ment Plant, Chicago 
 
28 
 
At Moon Island the average daily volume is 100 million gallons. 
 
 At Nut Island the average daily volume is 65 million gallons. 
 
 An inspection by boat of each of these outlets was made and photos taken 
 of the discharge of sewage. 
 
 At Deer Island no odor was noticeable, while the field was well marked. 
 The depth of water over the end of this outfall is 50 ft. 
 
 At Moon Island, where the sewage is stored until 1 hr. after high tide 
 before it is discharged, the odor was more pronounced, due to surface dis- 
 charge. 
 
 At Nut Island surface conditions were indentical with those at Deer 
 Island, the depth of the water over the sewer outlet being about 30 ft. 
 
 The Moon Island outfall was placed in operation on January 1, 1884. 
 
 The Deer Island outfall was laid in 1891, but extended in 1918, while the 
 Nut Island outfall was completed in 1901. 
 
 29 
 
 
Moon Island Outlet, Boston 
 
 Nut Island Outlet, Boston 
 
 Deer Island Outlet, Boston 
 30 
 
Sludge Beds, Fitchburg 
 
 CHAPTER 7 
 Fitchburg, Mass. 
 
 Fitchburg has a population of 41,000, of which 37,000 are now served. 
 The sewage is domestic and the system is on a separate basis. The average 
 daily volume is 3,000,000 gal. and the maximum 6,500,000 gallons. The 
 sewage is treated as follows : Coarse screens, grit chambers, 5 Imhoff tanks, 
 dosing chamber, sprinkling filters, followed by secondary tanks. The sludge 
 is dried on sand beds and removed after an average of three weeks drying to 
 be used for filling low land areas, with an occasional sale to farmers at 25c 
 per load. The demand for sludge is practically nil. The final effluent is dis- 
 
 Sludge Beds, Fitchburg 
 
 charged into an adjacent creek. The plant has been in operation since 1914. 
 The detention period of flow through the tanks is 10 to 12 hrs. The thick- 
 ness of the partition walls is two inches. The sand filters cover two and one- 
 tenth acres and are 10 ft. deep and permit the handling of sewage at the rate 
 of 30,000 persons per acre. The Gault (Worcester) nozzles are used, and 
 spaced 15 feet apart. The stone used varies from one to two inches. The 
 sub drainage is made through a floor, consisting of 5" by 1^" by 17" blocks 
 
 31 
 
Secondary Tanks, Fitchburg 
 
 Imhoff Tanks, Fitchburg 
 
 Effluent Channel, Fitchburg 
 
 32 
 
Sprinkling Filters, Fitchburg 
 
 resting on edge which gives 43 per 
 cent air space. The sludge beds cover 
 43/100 acres. The Imhoff tanks re- 
 move 60 to 75 per cent of the total sus- 
 pended solids and 99 per cent of settle- 
 able solids. The Hancock ejector is 
 used to remove sludge from the tank 
 between April and December but no 
 scum is removed. The secondary 
 tanks give a clear effluent which is dis- 
 charged down aerating ladders. The 
 plant cost $300,000 and the land $20,- 
 000. The treatment cost is $11.00 per 
 million gallons or $12.00 including care 
 of grounds. No complaint has been 
 made of the plant and no odor was 
 noticeable on day of visit when tem- 
 perature was 80 degrees in shade. 
 
 Aerating Ladders, Fitchburg 
 
 Imhoff Tanks, Fitchburg 
 
 ,33 
 
CHAPTER 8 
 Worcester, Mass. 
 
 The population is 180,000, of which 170,000 is served. The system is 
 a combined one, the average daily volume is 18 million gallons, the maximum 
 54 million gallons and the minimum 12 million gallons. Thirty-eight per cent 
 of the sewer mileage is a combined system, but the total flow consists of 
 domestic, industrial and manufacturing waste from wire mills, carpet works, 
 dye works and tanneries. The present treatment plant consists of two grit 
 
 Grit Chamber , Worcester 
 
 chambers followed by the addition of 625 lbs. of lime per million gallons to 
 the raw sewage, after which this flow is discharged into settling basins. The 
 grit chambers are 40 ft. long, 10 ft. wide and 8 ft. deep and remove 0.10 cu. 
 yds. of grit per million gallons. These chambers are cleaned by hand rakes, 
 the cost of cleaning being $1.95 per cu. yd. When clam shell removal is 
 made, the cost is 85 cents per cu, yd. This chemical treatment is made for 
 only seven hours each day, 8:30 a. m. to 3:30 p. m., and during the remainder 
 of the twenty-four hours the sewage is by-passed to the filter beds which 
 cover 72 acres and are 5 ft. deep. These filter beds contain sand overlying 
 
 Sewage Plant, Wore ester 
 
 34 
 
a system of 6" sub drains spaced 25 ft. to 33 ft. apart. The sand filter effluent 
 shows a removal of 85% organic matter and 95% bacteria. These filters pro- 
 vide for 60,000 gallons per acre per day and the under drains should be relaid 
 at least every five years. Effluent from these filters contain considerable iron. 
 Sludge from the settling tanks amounts to 3500 gallons, 96% moisture, per 
 million gallons of sewage treated and is pumped to drying beds. Lime used 
 cost $14.20 per ton and the treatment costs $9.00 per million gallons, which 
 includes the sludge disposal There is no demand for sludge fertilizer. Owing 
 to complaint from property owners and others on the Blackstone River below 
 the Worcester plant, the City of Worcester is now constructing a new treat- 
 ment plant consisting of twenty-two Imhoff tanks, 36 ft. wide and 90 ft. long 
 which in 1934 are expected to treat 25 million gallons per day, and in 1950, 
 60 million gallons per day. The Imhoff tank effluent will be further treated 
 on 14 acres of trickling filters 9 ft. deep. This new plant is planned to be 
 * ready for use in April, 1924, and its cost is estimated at $2,500,000.00. 
 
 Site for New Plant , Worcester 
 
 CHAPTER 9 
 Syracuse, N. Y. 
 
 Syracuse has a population of 171,717 all of which are served. The sewage 
 is domestic and combined. The flow averages 125 gallons per capita, has a 
 minimum daily volume of 15 to 18 million gallons and an average daily flow 
 of 27 million gallons, including storm water. There are 250 p. p. m. of sus- 
 pended matter in the average daily flow. At the present time this city is 
 building a 90" intercepting sewer and has planned a treatment plant consist- 
 ing of an overflow chamber, screen house, grit chamber, pump house and 
 four Dorr tanks. These tanks are to be 100 ft. diameter and have a depth 
 of 7 ft. at sides and 9 ft. in center. The detention period is to be three- 
 quarters of an hour, which will cause 60% of the suspended matter to be re- 
 moved. The effluent from the tanks is to be discharged 1400 ft. out into 
 Onondaga Lake from which no water supply is taken. The sludge is all 
 wasted on beds on which is discharged waste from the Solway process. This 
 waste is forty times the amount of sludge and four times greater than the 
 amount necessary for sludge disposal. This plant will have a maximum ca- 
 pacity of 55 million gallons per day and all volume above this amount will 
 be by-passed into the lake. The outfall sewer is 60" in diameter and has four 
 24" outlets 24 ft. apart with an open discharge at its end where it is 25 ft. 
 below the water surface in the lake. The proposed plant was designed after 
 
 35 
 
Irondequoit Plant , Imhoff Tanks, Rochester 
 
 Drainage Cannel, Syracuse 
 
 Outfall Sewer, Syracuse 
 
 tests had been made of different kinds of treatment of the flow under the 
 existing conditions for over a period of one year. During this time an ex- 
 perimental tank was installed to get the effect of both storage and detention 
 under varying conditions. This tank was 100 ft. long, 30" wide and 48" 
 deep, with an additional depth of 24" for sludge. The cost of the outfall 
 sewer and plant is estimated at $800,000.00. 
 
 36 
 
CHAPTER 10 
 
 Rochester, N. Y. 
 
 Rochester has a population of 300,000 and is all sewered. The city is 
 divided into three sanitary districts known as the Charlotte, Irondequoit and 
 Brighton. The Charlotte plant will treat sewage of 1200 population and has 
 just been completed. This plant consists of bar screens, grit chambers and 
 one circular Imhoff tank. The screen consists of 2"xj4" bars spaced Y\ of 
 an inch. The grit chamber is 40 ft. long. The Imhoff tank has sludge ca- 
 pacity at the rate of 1 and 6/10 cu. ft. per capita. The gate valves are operated 
 by 3 Nash compressors, size No. 1, under 15 pounds pressure. The sludge is 
 dried on circular sludge beds surrounding the Imhoff tanks and can be by- 
 passed into the outfall sewer. 
 
 The Irondequoit plant 
 was placed in use in 
 1917 and treats 32 and 
 6/10 million gallons 
 per day, which volume 
 contains 324 parts per 
 million of suspended 
 matter. This plant 
 covers 31 and 5/10 
 acres and consists of 
 bar screens, 6 grit 
 chambers, 4 Reinsch- 
 Wurl screens — Imhoff 
 tanks and sludge beds. 
 
 The tank effluent 
 is discharged into 
 Lake Ontario. 
 
 The grit chambers 
 
 Charlotte Plant, Rochester 
 
 are 90 ft. long and 10 ft. wide and re- 
 move one and one-eighth cu. yds. of 
 grit per million gallons. The sewage 
 has a velocity of flow through these 
 chambers at the rate of 9/10 of a foot 
 per second ; at the time of my visit but 
 one chamber was in operation. The 
 sewage is a combined flow varying 
 from 20. to 80 million gallons per day. 
 The Reinsch-Wurl screen has a slope of 
 30 degrees from the horizontal, which 
 is too steep for effective removal, one 
 screen has $4" slots and another " l /s 
 and two others one-sixteenth inch, the 
 slot length being 2" in all cases. The 
 first two screens mentioned are used 
 for normal daily flow and the latter 
 for storm flows. These screens re- 
 move 6 cu. ft. per million gallons and 
 cost when they were originally placed, 
 $54,000 which included the bridging 
 and electrical work. The screens show 
 
 Charlotte Plant, Gate P'alves, Rochester 
 
 S7 
 
Irondequoit Plant Grit 
 Chambers , Rochester 
 
 Brighton Plant, Rochester 
 
 38 
 

 Charlotte Plant , Rochester 
 
 marked signs of wear and required re- 
 placement after being in use 560 days. 
 The brushes are replaced every two 
 years. There are five double Tmhofi 
 tank units and the flow' into these units is regulated by forty Hydraulic gate 
 valves. These tank units are 62 ft. long and 24 ft. wide and the flow has a 
 velocity of one ft. per second. The tanks remove about 43% of suspended 
 solids and 71% of settleable solids, there being about 300 parts per million in 
 the influent. At the time of my visit there w^as 3 inches of scum in the tanks 
 and no scum had been removed since March. The age of sewage reaching 
 the plant varies from one to 12 hours. The sludge averages 1.08 cu. yds. per 
 million gallons and is removed from the drying beds every thirteen days and 
 sold at 75c per load or 50c. per cu. yd. When drawn off from the tanks the 
 sludge contains from 79 to 86% moisture and when removed from sludge 
 beds 50 to 65%. The cost of this plant w r as $1,000,000, and in 1920 it cost 
 $30,000 to operate. There are employed at the plant, one superintendent, 
 one chemist and assistant, and two laborers on 8 hr. basis. At the tanks there 
 are one foreman and twelve laborers. 
 
 
 The Brighton plant 
 was placed in use on 
 March 1st, 1916, and 
 has an average daily 
 volume of one to one 
 and a half million 
 gallons. The sewers 
 are built on a separate 
 f system. The plant con- 
 sists of grit chambers, 
 Imhoff tanks, sludge 
 beds, 1 acre of sprink- 
 ling filters and final 
 settling basins. The 
 
 Brighton Plant , Rochester 
 
 
 39 
 
filters contain one inch and two inch stone and are six feet deep. Six-inch 
 sub drains are used, the nozzles are Columbus type and spaced 14 ft. in 
 triangles. The final effluent has a stability of more than 10 days and there 
 is a removal of 80% of suspended solids. The cost of this plant was $118,000, 
 
 I rondo ’quoit Plant, Sludge Beds, Rochester 
 
 plus $2,000 for laboratory or a total of $120,000. The fall of 75 ft. from the 
 head chamber to the plant provides for the electricity for the plant, there 
 being 21 horsepower for each six second ft. of sewage flow. This plant 
 uses three men for operation. The Imhoff sludge amounts to 540 cu. yds. per 
 year. 
 
 CHAPTER 13 
 
 Cleveland, Ohio 
 
 Cleveland has a population of 800,000, of which 90 to 95% is served. The 
 sewage is combined and contains 250 parts per million of suspended matter. 
 The daily volume to be treated is 125 gallons per capita. There are four sani- 
 tary districts — westerly, easterly, southerly and a low level section ; 40% 
 of the sewage of the city is discharged into the Cuyahoga River, thence into 
 Lake Erie, so that this river is very black and septic. The Westerly plant 
 is under construction and consists of coarse screens, grit chambers and Im- 
 hoff tanks. The tank effluent is to be discharged into the lake through a 
 submerged outfall of the multiple outlet type, at a depth of about 30 ft. and 
 about 3^ m he from shore. It is proposed to dump the tank sludge into the 
 
 Westerly Plant, Cleveland 
 
 40 
 
Westerly Plant, Imhoff Tanks, Cleveland 
 
 lake by barges. The estimated cost of 
 this plant is $1,100,000. This plant is 
 within a half mile of a popular bathing 
 beach. At the present time the sewage 
 is discharged after dosing with 6 parts 
 per million of chlorine, into the lake at 
 a distance of 1400 ft. 
 
 The Easterly plant is under con- 
 struction and consists of parallel grit 
 chambers, each with its own bar 
 screen, and an open outfall into Lake 
 Erie. Raw sewage averaging 52 
 million gallons per day is now dis- 
 
 Westerly Plant Outfall Sewer, 
 Cleveland 
 
 Westerly Plant,. Imhoff Tanks 
 
 41 
 
Easterly Plant, Grit Chambers and Outfall, Cleveland 
 
 Westerly Plant, Cleveland 
 
 Westerly Plant, I mho ft Tanks, Cleveland 
 42 
 
charged into the lake 400 ft. off shore. Bathers use the beach within one 
 hundred yds. of the plant and floating solids along the beach are very notice- 
 able. There is no complaint, althoug odors from the outfall are very strong. 
 Within 200 yds. of this plant are high-class residences. The cost of this 
 plant is estimated at $1,250,000. 
 
 The Southerly plant is not as yet built. 
 
 CHAPTER 12 
 Detroit, Mich. 
 
 Detroit has a population of 950,000, and including Highland Park, Ham- 
 tranck, Brownly and Charbereau, over a million. 
 
 There are approximately 81 sq. miles within the city limits. About five 
 years ago work was begun on the construction of a combined sewerage 
 system, discharging into the Detroit River, with a proposed treatment plant 
 for the sanitary sewage, consisting of grit chamber, Imhoff tanks, and pos- 
 sibly chlorination. The site for this plant has been bought but no work done 
 as yet. 
 
 The City is now building 9' and 11' intercepting sewers at the rate of 
 two miles per week costing $1,000,000.00 per month, out of an available fund 
 of $33,000,000.00, $25,000,000.00 of which was obtained by bond issue in Au- 
 gust, 1920. 
 
 Most of the work is built by contract, although some is by the city. 
 
 In 1970 it is estimated that the ultimate population will be 2,664,000 
 when the maximum flow per day will be 879 million gallons and the average 
 493 million gallons, which is an average of 185 gallons per capita. 
 
 The design used for the intercepting sewer was an average of 114 gal- 
 lons per day per acre, the maximum being double the average. 
 
 The average sewage flow in 1920 was 177 gallons per capita, the maxi- 
 mum being 287 gallons per capita. 
 
 No infiltration is expected. 
 
 The proposed treatment of the sanitary sewage will remove 90 to 95% 
 of both settleable solids and suspended matter, the percentage of suspended 
 matter varying with the flow per capita. 
 
 In the past this city has had trouble with large amounts of gas and oil 
 in its sewers, and at times explosions have occurred on this account. It is not 
 expected, however, that oil in Imhoff tanks will interfere unless over 1 y 2 " 
 thick. 
 
 The cost of the proposed treatment by Imhoff tanks is estimated between 
 $6 and $6.50 per million gallons, whereas if activated sludge process were 
 used it would cost $15 per million gallons. 
 
 Electricity cost is from 1 to 1J4 cents per K. W. H. 
 
 It is proposed to use 5 parts per million of chlorine costing $.025 per lb. 
 At present time the flow in Detroit River is 210,000 second feet. 
 
 In the neighboring city of Pontiac, Mich., which has a population of 
 52,000 and a sewage flow of 100 gallons per capita, a sprinkling filter plant 
 has been in use for a year. The sewage has an average detention period of 
 2*4 hours, and 94-96% of the settleable solids are removed. 
 
 CHAPTER 13 
 Toledo, Ohio 
 
 Toledo has a population of 243,000, all of which is served. The sewage 
 is combined. Including the sewage of towns adjacent, which will in time be 
 treated at the site proposed for sewage disposal, the total sewered popula- 
 
 43 
 
tion will be 300,000. Intercepting sewers have been planned for which 
 $1,500,000 are now being spent for construction. Toledo has bonded itself 
 for $2,800,000.00 so that a balance is left for future work. 
 
 No sewage treatment is proposed at present time as conditions are such 
 that proper dispersion of sewage into the Maumee River will enable suf- 
 ficient dilution for several years. 
 
 CHAPTER 14 
 Lima, Ohio 
 
 Lima has a population of 41,000. Intercepting sewers are being con- 
 structed to eliminate the discharge of raw sewage into Hog Creek, a stream 
 which flows across the city and which is in a very insanitary and septic 
 condition. The sewers are for combined flow and vary from 3'6" at upper 
 end to 7' at outlet. 
 
 In two sections visited, segment block (Robinson type) was used, and 25 
 bbls. of cement costing $2.50 per bbl. were required per 100 lin. ft. of 6' 6" 
 sewer. Very little sheeting was used and trench in hard clay readily cut to 
 required shape. A force of 2 masons on invert, 1 mason on arch, and 19 
 laborers was employed. Masons are paid $8.00 to $14.00, and labor from 
 35 cents to 58 cents. Trenching machine on 4' 6" sewer averaged 70 lin. 
 ft. per 8 hrs. in 21' depth. In 18' cut, 6' 6" sewer averaged 30-40 ft. per day, 
 and with no water 6' 6" sewers in 20' cut averaged 60 lin. ft., whereas 4' 6" 
 sewers averaged 80 lin. ft. 
 
 Prices paid for the Robinson segment block in August, 1919 f. o. b. job : 
 
 36" 
 
 $2.44 
 
 66" 
 
 $6.00 
 
 42" 
 
 2.99 
 
 72" 
 
 6.84 
 
 54" 
 
 4 22 
 
 78" 
 
 7.46 
 
 60" 
 
 5.59 
 
 84" 
 
 9.35 
 
 CHAPTER 15 
 Columbus, Ohio 
 
 Columbus has a population of 237,000, 80% of which is sewered. One- 
 half of the city is on the combined system and one-half on the separate. 
 
 The average daily flow is 26 million gallons, which is treated by a plant 
 consisting of 22 Imhoff tanks 135' long and 25' deep. Sewage is dried on 8 
 open beds in about ten days, and then hauled to dump by gasoline locomo- 
 
 Imhoff Tanks, Columbus 
 
 44 
 
tives. The tank effluent is discharged from a head of 8 feet onto 10 acres 
 of sprinkling filters 5j4' deep consisting of broken limestone. The nozzles 
 are 15' apart, 1" to 3" in diameter. The filter effluent passes through final 
 settling basins into the Scioto River. 
 
 The raw sewage contains 223 P. P. M. of suspended matter, 60% being 
 removed by tanks which remove 95% of settleable solids. 
 
 The total area owned by the city for treatment is 270 acres. 
 
 At present time the flow in the river is less than 5 million gallons daily, 
 but the nearest town down stream is 25 miles distant. 
 
 The plant has been in use since 1916, and the filter operates about 75% 
 of the 24 hours each day. 
 
 Odors at the plant were not strong and came from the sludge beds, which 
 have not sufficient area, as 1.25 sq. ft. per capita should have been used in 
 design rather than 0.44 sq. ft. 
 
 The operation of the plant requires 1 foreman and 5 laborers each day 
 with a chemist and assistant. 
 
 Imhoff Tanks, Columbus 
 
 Sprinkling Filters, Columbus 
 
 45 
 
Argo Plant , Chicago 
 
 CHAPTER 16 
 Indianapolis, Indiana 
 
 Indianapolis has a population of 3 14,000, of which 60,000 is not sewered. 
 The system is a combined one. At the present time an outfall sewer dis- 
 charges raw sewage into the White river, and at this location an experimental 
 plant has been built, where the Dorr-Peck Activated treatment process is 
 being tried. 
 
 It is planned to install a treatment plant elsewhere, and for this purpose 
 a new outfall sewer is to be constructed which will have a maximum capacity 
 of 55,000,000 gallons per day and an average flow of 48,000,000 gallons per 
 day. At the end of this new outfall the sewage is to be screened through a 
 30-mesh drum, consisting of 12 screens, 6 feet in diameter by 7 feet 9 inches 
 face, each of 3,000,000 to 5,000,000 gallons per day capacity. The screens 
 will cost $28,000. 
 
 The sewage contains 250 to 300 pounds of suspended matter per million 
 gallons. 
 
 The treatment plant is to be divided into three units. The city has 200 
 acres of land for the eventual conditions which may be required in 1950. 
 
 CHAPTER 17 
 Chicago, Illinois 
 
 At the Tannery Testing Station, which has been in operation since April 
 1920, the tannery waste of the Griess-Pfleger Tanning Company is being 
 treated by the activated sludge process of the Dorr type. This plant is 
 located at the Halstead Street bridge, over the North Branch of the Chicago 
 river, which contained considerable solid matter and oil on the day of my 
 visit. 
 
 Two and three-quarters cubic feet of air is used per gallon of sewage 
 treated, and the detention period is 12 hours. The Dorr tanks are 12 feet 
 
 46 
 
Settling Tanks, Tannery Testing Station, Chicago General View. 
 
deep and 12 feet in 
 diameter, 405 gallons 
 to be treated per 
 square foot of surface 
 area. 44,000 to 48,000 
 gallons per day are 
 treated by the Dorr 
 tank, and 300,000 to 
 400, (300 gallons per 
 acre per day are fil- 
 tered though cinders 
 and 100,000 to 200,000 
 gallons through sand, 
 the effluent having a 
 stability of 90% and 
 more. The sand beds 
 
 are 3*4 feet deep and 
 the cinder beds 5^4 
 deep. 
 
 In the Calumet dis- 
 trict the population is 
 120,000 and plans have 
 been made for a future 
 population of 300,000. 
 The intercepting sewer 
 for this section is 17 
 feet in diameter, and 
 the sewage is to be 
 pumped, both centri- 
 fugal and impeller 
 pumps being required. 
 
 Wall of Settling Tanks, Calumet Treatment Plant, 
 Chicago 
 
 The sewage is to be treated by a plant to cost $4,500,000 and to contain 
 32 Imhoff tank units, each 103 feet long, 34^4 feet wide and 26 feet deep. Six 
 36-inch pumps and three 72-inch pumps are to be used. 300 gallons of sewage 
 per capita is the estimated flow. 
 
 At Argo, 26 miles west of Chicago, the wastes of the corn products re- 
 finery are being treated by an experimental plant, where the activated sludge 
 process is contrasted with the Dorr-Peck process by having the wastes 
 treated simultaneously by each type. The latter process gives 4.2% to 6.% 
 of nitrogen in the sludge obtained, and required 2.8 cubic feet of air per 
 gallon of sewage treated. A 12-hour detention period is used in both cases. 
 At the present time the plant is treating 43,000 gallons per day in three tanks 
 each 11 feet deep, with a ratio of 1 to 5.75 between filtros plates and surface 
 area. The suspended matter which varies from 600 to 700 parts per million 
 is reduced to only 10 to 12 parts per million. 
 
 Sixty-five thousand bushels of corn per day are used at the Argo plant. 
 
 The flow in the Chicago drainage canal is 7000 second-feet, or approxi- 
 mately 2 second feet per 1000 population. 
 
 48 
 
CHAPTER 18 
 Fort Sheridan, Illinois 
 
 This plant treats the sewage of approximately 3,000 soldiers, and consists 
 of a Doten tank and sprinkling filter 5 feet deep. The filter has under drains 
 12 feet apart and an area of about ^4 an acre, one-half of which was in use on 
 day of visit. The sewage is domestic and amounts to about 400,000 gallons 
 per day. A Sanborn recorder is used to measure the flow. It was noted that 
 some, sprinklers not being in use, the head at these points was about 6 feet. 
 
 Sprinkling Filters , Fort Sheridan 
 
 There was some odor on the beds. The filter bed effluent has, however, 
 further treatment in circular secondary tanks and then discharged into Lake 
 Michigan, after being treated with 24 to 28 pounds of chlorine per million 
 gallons, this being equivalent to three parts per million. Chlorine costs 8c 
 per pound. The effluent from this plant is very clear and free from odor. 
 
 Secondary Tanks, Fort Sheridan 
 
 49 
 
Great Lakes Naval Station 
 
 The sewage from this station is treated through a coagulating plant and 
 then by a rapid sand filter, the beds being under drained. 
 
 On day of my visit there was considerable odor in the effluent. 
 
 CHAPTER 19 
 Urbana, Illinois 
 
 The population of Urbana is about 11,000. The State of Illinois is con- 
 ducting in Urbana experimental studies with the sewage of the adjoining city 
 of Champaign, which has a population of 17,000. This sewage is screened by 
 a small Dorrco screen, having a diameter of about 4 feet and a face of 7y 2 
 inches. The daily capacity of this screen is 250,000 gallons. The slots of 
 the screen are 1/16 of an inch by an inch, are parallel to the direction of 
 flow, and comprise 26% of the total area of the screen. The screenings 
 amount to 85 pounds per 150,000 gallons of wet sewage and contain from 84 
 to 88% moisture. After screening, the sewage is carried through an activated 
 sludge plant of the Dorr-Peck type which requires 7/10 of a cubic foot of air 
 per gallon of sewage. 
 
 Southerly Plant, Houston 
 
 CHAPTER 20 
 Houston, Texas 
 
 This city has 140,000 population, 60% of which are served. The sewage 
 is mostly separate and contains 400 parts per million of suspended solids. 
 The sewage is pumped to two treatment plants, known as the North Side and 
 South Side disposal plants. The method of treatment is the same at each 
 location. The treatment plant consists of activated sludge units, having a 
 capacity of 2,500,000 gallons per day. The North Side plant has four units 
 and the South Side two units. Each unit consists of one main aerating chan- 
 nel 280 feet long, 18 feet wide and 10 feet deep, and ten sedimentation tanks 
 about 22 feet deep. At the South Side plant the maximum flow is 8,500,000 
 gallons per day, the minimum 3,500,000 gallons. The average detention 
 period is two and one-half hours, although this time varies from one and a 
 half to three and a half hours. The filtros plates have a ratio of 1 square foot 
 to each 7 square feet of tank surface. The South Side plant was completed 
 
 50 
 
n January, 1918, at a cost of about $115,000.00 and the North Side plant was 
 :ompleted in May, 1917, at a cost of about $255,000.00. 
 
 The amount of seAvage treated at the North Side plant averages about 75 
 gallons per capita, or a total of 9,000,000 gallons per day, and the effluent at 
 this plant has a stability of 92%. 95% of the suspended solids are removed. 
 
 The effluent contains an average of 4% of nitrates and 12% of ammonia. 
 The cost of operation at the North Side plant averages $11.10 per million 
 gallons, whereas the cost at the South Side plant is approximately $10.80 per 
 million gallons. 
 
 The sludge may have a value of $25.00 per ton and weighs 80% of a ton 
 per million gallons. The sludge is pressed by a Simplex press which has a 
 pressure of 100 to 145 pounds per square inch. 113 presses being used. The 
 sludge is dried by a Buckeye Type “A” Direct-Indirect drier which reduces 
 the moisture to 53j^%. 
 
 The Houston plants are the only ones in the United States which have 
 been using the activated sludge method of treatment. The sludge is disposed 
 of by lagooning, which does not create a nuisance. 
 
 51 
 

 
 mm 
 
 
 
 
Gaylord Bros. 
 
 Makers 
 
 Syracuse, N. Y. 
 
 m jail 21. i m