i ; 
 
 
Cornell University 
 Library 
 
 The original of this book is in 
 the Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924004465559 
 
Cornell University Library 
 TD 525.L98M41 
 
 Report of the State Department of Health 
 
 3 1924 004 465 559 
 
 REPORT 
 
 A PLAN FOR THE DISPOSAL OP SEWAGE 
 
 CITY OF LYNN 
 
 Under the Provisions of Chapter 63 of the 
 Resolves of 1914. 
 
 BOSTON: 
 
 WEIGHT & POTTBE FEINTING CO., STATS 'WlNJEES, 
 
 32 DEENE STEEET. 
 
 1916. 
 
®I)e (irotnmontDeoltl) of 0iaf^0ac\)usttt$, 
 
 REPORT OF THE STATE DEPARTMENT OF HEALTH 
 AND THE MUNICIPAL COUNCIL OF THE CITY 
 OF LYNN UPON THE DISPOSAL OF THE SEW- 
 AGE OF THE CITY OF LYNN. 
 
 Feb. 21, 1916. 
 Toyhe General Court. 
 
 The undersigned members of the Joint Board, consisting of the 
 State Department of Health and the Municipal Council of the City of 
 Lynn, to whom was referred, by chapter 63 of the Resolves of the 
 year 1914, the consideration of a plan for the disposal of sewage in 
 the city of Lynn, have made the necessary investigations and respect- 
 fully submit the following report. 
 
 The Board has considered the various methods of sewage disposal 
 in^practical use by cities and towns and the adaptability of the differ- 
 ent methods of treatment to the conditions now existing in the city of 
 Lynn. A study of these methods and their efficiency, and especially 
 of 'the extent of the works required for satisfactory results, shows 
 clearly that it would be impracticable to locate satisfactory treat- 
 ment works at any available point within the limits of the city; nor 
 could such works be located on any available land in any contiguous 
 municipality without danger of the escape of offensive odors in the 
 neighborhood of a thickly populated district. Experience has shown 
 tHkt where it is practicable to discharge sewage into the sea at some 
 point where an adequate body of water is available for its efficient 
 dilution, it can be disposed of effectually and satisfactorily without 
 danger of creating a nuisance. Furthermore, the most efficient of all 
 systems of sewage disposal at present in use are those in which the 
 sewage is discharged continuously in deep water in a sea way where 
 the volume of tide is ample for its effective dilution at all times. 
 
 In view of the success of such outlets, the engineers of the Board 
 were directed to investigate carefully the practicability of disposing 
 of the sewage of the city of Lynn by this method. The results of their 
 investigations, which have included a careful study of the movement 
 of the tidal currents in the sea in the vicinity of the city, show that 
 a suitable outlet can be reached at a point off the mouth of Lynn 
 Harbor, where the water is 30 feet or more in depth at low tide. Sewage 
 discharged at this point in quantities no greater than are likely to be 
 collected in the sewers of Lynn f of many years in the future would be 
 
diluted at all times before reaching the surface of the sea to an extent 
 comparable with the most efficient practicable methods of treatment 
 now known and would be thoroughly diffused in the water of the sea 
 long before it could reach any shore or flat exposed at low tide. This 
 point is reached about 3 miles from the shore at the present sewer 
 outlet of the city of Lynn and about two-thirds of a mile southwest of 
 Bass Point. 
 
 In accordance with our direction, the engineers have presented a 
 plan for disposing of the sewage of the city at an outlet in this local- 
 ity. The results of their investigations, together with plans of a 
 practicable method for disposing of the sewage at the outlet suggested, 
 are contained in their report, which is appended hereto and is made a 
 part of this report. The estimated cost of the proposed works is in 
 round numbers $800,000, and the estimated annual cost of mainte- 
 nance and operation in the earlier years of the works $9,000. 
 
 The plans provide for discharging the dry-weather flow of sewage 
 at the proposed outlet at all times, together with all of the storm 
 water that it is practicable or necessary to convey to an outlet into 
 the sea. A small amount of sewage mingled with storm water and 
 highly diluted will be discharged occasionally at the present harbor 
 outlet, such discharges taking place not oftener than once or twice a 
 month under ordinary conditions. In our opinion, the occasional 
 discharge of small quantities of highly diluted sewage at the present 
 outlet will not create objectionable conditions in its neighborhood. 
 
 We recommend the adoption of the scheme proposed by the en- 
 gineers for the disposal of the sewage of the city of Lynn, by which 
 the sewage will be pumped at a pumping station, to be located on 
 land owned by the city near the present outfall sewer, to an outlet 
 in deep water off the mouth of Lynn Harbor approximately 3,500 
 feet southwest of Bass Point, as shown on the plan presented here- 
 with. 
 
 Respectfully submitted. 
 
 For the Joint Board, 
 
 A. J. McLaughlin, 
 
 Commissioner of Health. 
 
 GEORGE C. WHIPPLE, 
 
 Chairman, Water & Sewerage Committee, Public Heallh Council. 
 
 GEO. H. NEWHALL, 
 
 Mayw. 
 
 GEORGE A. CORNET, 
 
 Member of Municipal Council. 
 
Missing Page 
 
Missing Page 
 
FINANCIAL STATEMENT. 
 
 Appropriation, $3,000 00 
 
 Total amoimt expended to Feb. 21, 1916, 2,493 38 
 
 BaUnce unexpended at date, $506 62 
 
 A few small bills for maps, plans, etc., as yet not received, are not 
 included in the above. 
 
PROPOSED LEGISLATION. 
 
 An Act to authoeize the City of Lynn to alter and extend its System 
 
 OP Sewage Disposal. 
 
 Be it enacted, etc., as follows: 
 
 Section 1. The city of Lynn, acting through its municipal council, may, 
 for the purpose of removing and disposing of the sewage of said city, make such 
 modifications in its present system of sewers and construct, maintain and operate 
 such additional system of sewers and sewage disposal, — which may include a 
 pumping station, one or more trunk sewers, outfall sewers and other works 
 essential to the proper treatment and disposal of said sewage, — as may be 
 necessary for the proper and convenient discharge of the sewage at some point 
 in Lynn harbor, such modifications or additional system to be in substantial 
 accordance with the plans recommended by the state department of health and 
 the municipal coimcU of the city of Lynn in their report to the le^slature of the 
 year nineteen hundred and sixteen; and said city may for said purposes take by 
 purchase or otherwise any lands, water rights, rights of way or easements in said 
 city deemed necessary therefor: provided, however, that no sewers or other works 
 shall be constructed under authority of this act until plans thereof have been 
 approved by the state department of health after due notice by the commis- 
 sioner of health of the presentation of such plans to said department for ap- 
 proval by publication of such notice, with the time and place of hearing thereon, 
 in such paper or papers and at such time or times as the said department may 
 deem proper; and the department, after the hearing, may reject or approve said 
 plans, or may modify and amend the same and approve them as so modified 
 and amended. 
 
 Section 2. The said city may, for the purposes of this act, carry its sewers, 
 pipes and conduits under any street, railroad, highway or other way in said city, 
 and construct an outfall sewer across the harbor thereof in such manner as not 
 unnecessarily to obstruct the same, and may do any other thing necessary and 
 proper for the purposes aforesaid. 
 
 The said city shall, in respect to all work done and structures built in tide 
 water below high-water mark under authority of this act, be subject to the pro- 
 visions of chapter ninety-six of the Revised Laws and acts in amendment 
 thereof or addition thereto so far as the same are applicable to the subject- 
 matter of this act. 
 
 Section 3. The said municipal council, in order to take any lands in fee, 
 water rights, rights of way or other easements, shall cause to be recorded in the 
 registry of deeds for the southern district of the county of Essex a statement 
 signed by a majority of the mvmicipal coimcil containing a description thereof as 
 
certain as is required in a conveyance of land and specifying that the same are 
 taken under authority of this act; and upon such recording the title to the lands, 
 flats, water rights, rights of way or other easements described in such statement 
 shall vest in the city of Lynn, which shall pay all damages therefor and all other 
 damages sustained by any person or corporation through any action of said 
 municipal council vmder this act. The said council, at the time of such taking, 
 shall notify the owners thereof in writing, and may agree with any person or 
 corporation injured hereunder upon the damages sustained by such person or 
 corporation; and if the damages are not agreed upon, a jury in the superior 
 coxat for said coimty may be had to determine the same, upon petition of either 
 party, in the manner provided by law for determining the damages for land 
 taken for the laying out of highways; but in the case of a taking no suit or peti- 
 tion shall be brought after the expiration of two years from the date of the re- 
 cording of the taking as herein provided; and in all other cases no suit or peti- 
 tion shall be brought atfer the expiration of two years from the time when the 
 cause of action accrues. 
 
 Section 4. The city of Ljmn, for the purpose of paying the necessary ex- 
 penses and Uabilities incurred under this act, may incur indebtedness to an 
 amoimt not exceeding eight hundred thousand dollars, and may issue from 
 time to time bonds or notes therefor; and the debt and loans authorized by this 
 act and the bonds or notes issued therefor shaU not be reckoned in determin- 
 ing the statutory limit of indebtedness of the city. Such bonds or notes shall 
 bear on their face the words, City of Lynn Sewerage Loan, Act of 1916, shall be 
 payable within periods not exceeding fifty years from their respective dates of 
 issue, and shall bear interest, payable semi-annually, at a rate not exceeding iova 
 per cent per annum. They shall be signed by the treasiurer of the city and 
 countersigned by the mayor and by a majority of the municipal council. The 
 city may from time to time sell such securities, or any part thereof, at public or 
 private sale, but they shall not be sold for less than their par value. The pro- 
 ceeds thereof shall be retained in the treasury, and the treasurer shall, upon the 
 order of said municipal council, pay therefrom the expenses incurred for the 
 purposes aforesaid. 
 
 Section 5. The city of Lynn shall, at the time of authorizing the said loan or 
 any part thereof, provide for the payment thereof in such equal annual pay- 
 ments as will extinguish the same within the time prescribed by this act, and 
 when a vote or votes to that effect have been passed the amount required thereby 
 shall without further vote be assessed by the assessors of the city in each year 
 thereafter in the same manner in which other taxes are assessed until the debt 
 incurred by the city is extinguished. Any premium realized in the sale of said 
 bonds, notes or certificates of debt shall be applied to the payment of said loan. 
 
 Section 6. This act shall take effect upon its passage. 
 
REPORT OF THE ENGINEERS. 
 
 Feb. 12, 1916. 
 To the CommiUee of Joint Board on the Disposal of Sewage in the City of Lynn. 
 
 Gentlemen: — In accordance with your direction, we have considered 
 the question of disposing of the sewage of the city of Lynn by various 
 methods in such a manner as to prevent further nuisance therefrom 
 and respectfully submit the following report. 
 
 The resolve under which this investigation has been carried out is as 
 follows: — 
 
 Chapteb 63, Rbsolyes of 1914. 
 
 Resolved, That the state board of health and the mimicipal council of the city 
 of Lynn, acting jointly, are hereby authorized and directed to consider and 
 report a plan for the disposal of sewage in the city of Lynn. It shall be the duty 
 of said board: — 
 
 First, to prepare suitable plans and maps for the disposal of sewage. 
 
 Second, to consider the various methods of disposal of sewage and the appli- 
 cation of such methods to any part of the present sewerage system in said city. 
 
 Third, to employ such engineering and other assistance as may be necessary for 
 carrying but the objects of this resolve. 
 
 Fourth, to ascertain and report the cost of any means of the disposal of sewage 
 recommended by them. 
 
 Said board shall have access to all plans and specifications relative to the 
 sewage disposal of said city. All expenses incurred by said board under the pro- 
 visions of this resolve shall be reported to the governor and council, and all such 
 expenses, when approved by them, shall be paid out of the treasury of the com- 
 monwealth; but the total expenditiu-e shall not exceed three thousand dollars. 
 The commonwealth shall be reimbursed for such expenditures imder this re- 
 solve as shall have been approved by the governor and council, and the same shall 
 be assessed and collected by the treasurer of the commonwealth from said city 
 at the time required for the payment of the state tax of said city. Said boqid 
 shall make all reports required by this resolve to the general court on or before 
 the first Wednesday of January, nineteen himdred and fitteen. 
 
 Careful consideration has been given to various systems of sewag« 
 disposal, and the available data collected by previous commissions, 
 especially the Commission on the Investigation of Lynn Harbor of 
 
10 
 
 1912, have been made use of and supplemented by new studies, sound- 
 ings and observations of tidal currents. The effect of the methods 
 of sewage disposal employed and in operation in many other munic- 
 ipalities has been considered, and examinations have been made of 
 the various sewage disposal works, especially of the sewer outlets dis- 
 charging into the sea where the conditions resemble those which affect 
 the disposal of the sewage of the city of Lynn. 
 
 In treatipg of these questions we have not thought it necessary to 
 refer at length to the insanitary conditions produced at the present 
 time by the discharge of sewage into the harbor of the city of Lynn. 
 That the nuisance is a most serious one is generally recognized and 
 requires no extended description. The first sewers were constructed 
 in the city about the year 1870, and at the present time there are 
 about 87 miles of sewers in use. The construction of a system of 
 intercepting sewers designed to collect all of the sewage of the city 
 and discharge it at a single outlet in Lynn Harbor was begun in 1885 
 and completed in 1892. By this system the sewage is collected into 
 two main sewers, known as the easterly and westerly intercepting 
 sewers, and conveyed to an outlet opposite the end of Commercial 
 Street about 1,600 feet from shore and below ordinary low water. 
 From this point a shallow channel extends to the main channel which 
 forms the outlet of Saugus River. 
 
 The outfall consists of two rectangular wooden boxes each 5.7 feet 
 high and 4 feet wide, on either side of which a shallow channel has 
 been dredged to a width of 30 to 50 feet. The boxes are not tight, 
 and at times nearly the entire flow of sewage is discharged at various 
 points along their length, whence it spreads over the adjacent flats, 
 which are at the present time deeply covered with sludge. 
 
 Quantity of Sewage. 
 
 The' quantity of sewage discharged from the sewerage system of the 
 city of Lynn is subject to wide variations on account of the fact that 
 the sewers throughout nearly the entire city receive both sewage and 
 storm water. There are, furthermore, no tide gates on the outfall 
 sewer or on either of the two intercepting sewers; consequently the 
 height of sewage in the lower part of the main sewers is dependent 
 upon the height of the tide and the amount of rain water entering the 
 system. While there are no available records of the quantity of 
 sewage discharged from the city under varying conditions and it is 
 impracticable to measure the sewage without consideirable difficulty, 
 the quantity can be estimated with the aid of such observations as 
 can readily be made with sufficient accuracy for the present purpose. 
 
11 
 
 The average quantity of water used by the city in the year 1914 
 probably amounted to about 6,400,000 gallons per day, exclasive of 
 the quantity supplied to the town of Saugus, and it has been esti- 
 mated that the quantity of water obtained from private sources amounts 
 to about 200,000 gallons per day. Most of this water doubtless 
 reaches the sewers, and there is undoubtedly also a considerable leak- 
 age of ground water into the sewers, as is usually the case in most 
 of the older sewerage systems. Observations of the dry-weather flow 
 in the sewers indicate that it amounts at the present time to about 
 12,000,000 gallons per day. 
 
 If it is assumed that all of the water supplied from public works 
 and private sources reaches the sewers, these measurements would 
 indicate an average leakage of approximately 60,000 gallons per mile 
 of sewer. It is probable that this leakage includes small streams which 
 have been taken into the sewers, and consequently includes a varying 
 amount of surface water at all times. Judging from the plans show- 
 ing the size and slope of the main intercepting sewers, these sewers 
 are capable of conveying to the main outlet a total of 81,000,000 
 gallons per day, and, if running full, would therefore deliver at the 
 outlet 69,000,000 gallons of storm water in addition to the sewage. 
 
 The total area drained by the sewers is 4.3 square miles, so that the 
 sewers appear to be capable of carrying an amount of storm water 
 equivalent to 16,000,000 gallons per square mile per day, or 0.92 of an 
 inch in depth in twenty-four hours over this tributary area, or about 
 0.038 of an inch per hour. This quantity is about four times the 
 storm water capacity provided for in the intercepting sewers of the 
 &ty of Boston. Taken in connection with the temporary storage in 
 the sewers, the system is capable of carrying off the rain water from 
 all ordinary storms in addition to the sewage but is not adequate for 
 the removal of the rain water when a large quantity of rain falls in a 
 short period. Moreover, the capacity of the sewers as here given is 
 based on the discharge at times of low tide. When heavy rain has 
 occurred at a time of high tide, serious flooding of some of the streets 
 of the city has resulted. 
 
 On account of the wide variations in the flow of sewage — rang- 
 ing from a minimum of 12,000,000 gallons per day to a maximum 
 of over 80,000,000 gallons — it would be very difficult to provide for 
 the treatment or disposal of all of the sewage discharged at the present 
 outlet at all times, but such a plan is not essential, since at times of 
 heavy rains little harm is likely to be done, for several years at least, 
 if part of the mingled sewage and storm water is allowed to overflow 
 at the present outlet or at other suitably chosen outlets into the tidal 
 
12 
 
 waters adjacent to the city. Furthermore, the necessity for the dis- 
 charge of any considerable quantity of sewage into the harbor at times 
 of rain can be gradually prevented by the construction of separate 
 conduits for storm water only, which can then be diverted from the 
 sewers and, if unpolluted by sewage, can be discharged without objec- 
 tion into the waters about the city. The system of disposal should be 
 large enough, however, to care for a sufficient portion of the flow to 
 prevent overflow in small storms or thaws and the frequent poUutioj^ 
 of the harbor waters. 
 
 Methods of Sewage Disposal. 
 
 The resolve under which this investigation is made specifically 
 requires the consideration of the various methods of disposal of sew- 
 age and the application of such methods to any part of the present 
 sewerage system of the city, of Lynn. The systems of sewage disposal 
 in use by large cities in this country and elsewhere may be divided 
 into three general classes, — (1) disposal by chemical raethods, (2) 
 disposal by filtration or the so-cjalled bacterial methods, and (3) dis- 
 posal by dilution. All of these various methods are in use by cities 
 and towns within the limits of Massachusetts or in adjacent States, so 
 that their probable efficiency, if applied to the city of Lynn, is easily 
 determinable under practical working conditions. 
 
 Chemical Precipitation. 
 
 Works for the chemical treatment of sewage have been in operation 
 in the city of Worcester for many years, continuously under the 
 charge of competent experts, and the results of this method of treat- 
 ment have been published fully in the reports of the department 
 having charge of the sewers. 
 
 The chemical precipitation works at Worcester have cost about 
 $266,000. The total quantity of sewage treated by this process in the 
 year 1914 averaged 13,555,000 gallons daily, or a slightly larger quan- 
 tity of sewage than the present dry-weather flow from the sewerage 
 system of the city of Lynn. For thp treatment of this sewage 2,075 
 tons of lime were used during the year 1914, or 839 pounds per million 
 gallons of sewage treated. 
 
 Concerning this treatment and its effect, the following statements 
 are quoted from the annual report of the superintendent of sewers of 
 the city of Worcester for the year ending Nov. 30, 1914: — 
 
13 
 
 . . . The sludge produced by chemical precipitation amounted to 18,105,000 
 gallons, an average of 3,660 gallons per million gallons of sewage treated. The 
 actual quantity of dry solids per million gallons of sewage was 0.94 ton. Both 
 quantities are much less than last year and are explained by the greater pro- 
 portion of strong sewage being treated by sand filtration. 
 
 Nearly all the sludge produced by the lime treatment was pressed, only 
 1,425,000 gallons, containing 286 tons of dry solids, were pumped on to the old 
 sludge beds. This was done on only a few occasions to facilitate the operation of 
 the precipitation basins. 
 
 The remainder of the sludge, 16,680,000 gallons, was pumped to the storage 
 basins, about 18 per cent, of clear water drawn off, and the resulting sludge 
 pressed. There was formed 14,954 tons of cake, containing 4,383 tons of dry, 
 solid matter, which was hauled by the troUey motor car to the sludge dimip as in 
 former years. A considerable quantity of this cake is hauled by farmers during 
 the winter months. 
 
 The effluent from chemical precipitation is the best obtained in recent years, 
 being much better than that of last year. This result is best explained by the 
 character of the sewage treated. The removal of total organic matter, measured 
 by albuminoid ammonia, is 39.3 per cent.; of suspended organic matter, 75.1 
 per cent. . . . 
 
 The total cost of the operation of these works in the year 1914 is 
 given in the report as follows : — 
 
 Total. 
 
 Per Million 
 Gallons. 
 
 Cost of chemical precipitation, ^ 
 Sludge pressing. 
 
 Total 
 
 $21,647 79 
 18,219 25 
 
 t4 38 
 4 00 
 
 139,867 04 
 
 S8 38 
 
 > The Worcester sewage contains much iron, which is an advantage in this treatment. 
 
 The cost includes the amount expended for the maintenance of a 
 laboratory in connection with the operation of these works. 
 
 The sewage is delivered to the precipitation works by gravity, and 
 the effluent is discharged also by gravity into the Blackstone' River. 
 It will be seen that under efficient operation by experts at the city 
 of Worcester the total removal of organic matter from the sewage is 
 slightly less than 40 per cent., and of the suspended organic matter 
 about 75 per cent. The effluent from such a works would still be 
 capable of causing objectionable conditions if discharged into the 
 shallow waters about the harbor front of the city of Lynn, and for 
 satisfactory disposal it would require conveyance to some point in the 
 sea where an adequate quantity of water for its proper dilution would 
 
a4 
 
 be available at all times and where the danger of the organic matter 
 causing a nuisance Upon neighboring shores or flats exposed by the 
 tide would be avoided. 
 
 There does not appear to be any suitable place for the location of 
 such a works within the limits of the city of Lynn at a sufficient dis- 
 tance from inhabited sections of the city to avoid serious objections, 
 and the location of such works within the limits of an adjacent city or 
 town is not to be considered unless absolutely essential. It is prob- 
 able, furthermore, that the cost of the treatment of the sewage of 
 the city of Lynn by chemical precipitation would be as great as, or 
 greater than, by other more effective methods, and we have not 
 deemed it necessary, under the circumstances, to consider in further 
 detail the application of this method to the city of Lynn. 
 
 FiLTEATION. 
 
 The second general method of sewage disposal is that of filtrationj 
 or bacterial treatment sometimes so called. This treatment is effected 
 in a variety of ways, the principle being practically the same in each. 
 Two general methods of applying this treatment have been found 
 successful in actual practice in the disposal of sewage in Massachu- 
 setts communities. The first of these methods, and the one which has 
 been longest in use, is intermittent filtration of the sewage through 
 beds of sand or gravel, a method which has been found most efficient 
 and satisfactory for the purification of the sewage of many of the cities 
 and towns of the State. This method is used for the disposal of part 
 of the sewage of the city of Worcester, where upon 75 acres of ffiter 
 beds constructed of sand and gravel a quantity of sewage amounting 
 to an average of 4,630,000 gallons per day was treated during the 
 year 1914. The total cost of these filters, not including land, was 
 about $4,300 per acre. The total cost of maintenance in the year 
 1914 was $20,499.54, or about $12.12 per million gallons of sewage 
 treated. The rate of operation was a little over 60,000 gallons per 
 acre per day, and the purification of all of the sewage of the city of 
 Lynn by this method, if the filters were of equal capacity to those 
 of the city of Worcester, would require an area at. the present time of 
 about 200 acres, with an annual cost for maintenance of upwards 
 of $53,000. 
 
 This method is also used for the purification of a part of the sewage 
 of the city of Brockton, where an average of 2,100,000 gallons of sew- 
 age per day is treated on an extensive area composed of sand and 
 gravel suitable for the purpose. The total cost of these filters, not 
 including land, was about $3,500 per acre, and the cost of mainte- 
 
15 
 
 nance in the year 1913, the last year for which figures are available, 
 was $12.40 per million gallons. The rate of operation of these filters 
 was about 60,000 gallons per acre per day. If lands containing similar 
 soil were available for the disposal of the sewage of the city of Lynn, 
 an area of about 200 acres would be required at the present time at a 
 total annual cost of upwards of $54,000. 
 
 It would no doubt be practicable with such a system of treatment 
 to reduce the area of filters required by preliminary treatment of the 
 sewage in sedimentation tanks, though no material saving in expense 
 would be likely to be effected by any practicable preliminary treat- 
 ment, nor is it likely that a very material reduction in the area of the 
 filters, even in the beginning, would be effected thereby. 
 
 In the case of the city of Lynn there is no area available for this 
 method of treatment within the limits of the city, nor is there any 
 area of such size containing soil suited for this purpose in the region 
 about the city. The filters might be built on the adjacent marshes 
 bordering the Pines or Saugus rivers, provided the tides were excluded, 
 by hauling material from some suitable place, but the cost of such 
 works would be great and their location at any place in the populous 
 region about the city of Lynn would undoubtedly be objectionable. 
 
 The second method of filtration is known as the sprinkling or trick- 
 ling filter and consists in applying the sewage in a fine spray a,t fre- 
 quent intervals to filters 5 to 10 feet in depth composed of broken 
 stone with a diameter usually of 1 to 3 inches. The sewage is com- 
 monly first treated for sedimentation, usually in the two-story sedi- 
 mentation tanks known as Imhoff tanks, and the effluent also requires 
 treatment in settling tanks for the removal of suspended matters 
 therefrom. The results of the operation of such filters show that they 
 are less effective in the purification of sewage than intermittent sand 
 filters, but a sufficient degree of purification could be effected by this 
 method of filtration to render the effluent satisfactory, provided it is 
 subsequently diluted in an adequate body of water. Such works have 
 recently been constructed in the cities of Fitchburg and Brockton, and 
 in the former city have been in operation for about a year, treating an 
 average of about 2,000,000 gallons per day. These works have cost 
 thus far about $320,000 and have an estimated capacity for filtering 
 5,000,000 gallons of sewage per day, or about 40 per cent, of the dry- 
 weather flow of sewage now discharged from the city of Lynn. The 
 tanks have sufficient .capacity for treating effectively about 6,800,000 
 gallons per day, or about half the dry-weather flow of sewage from 
 the city of Lynn. The total area of filters in use is 2.14 acres. The 
 cost of operation thus far has been $11.45 per million gallons. At 
 
16 
 
 the same rate the annual cost of operation of such works at Lynn 
 would be $50,000. 
 
 If thef sewage of the city of Lynn were to be treated in works of 
 this kind, it is probable that the effluent could be discharged into one 
 of the channels of the harbor without creating seriously objectionable 
 conditions. If only the dry-weather flow of sewage were treated, 
 however, large quantities of sewage would still require disposal at times 
 of rain or when snow is melting rapidly, and this sewage might con- 
 tinue to create very objectionable conditions if discharged in the 
 neighborhood of the present outlet. It would probably be necessary 
 to construct the filtration works of sufiicient size to provide treatment 
 for a part of the excess of flow during times of rain, a requirement 
 which might increase materially the cost of the works. One of the 
 phief objections to this method of disposing of the sewage of the city 
 of Lynn, as in the case of other treatment works, is the difficulty of 
 securing a location for the works where danger of a nuisance could be 
 avoided. Experience with such works indicates that the odor there- 
 from may be objectionable for a considerable distance, and there 
 does not appear to be any location within the limits of the city of 
 Lynn where such works could be constructed without objection. It 
 is probable that a suitable location could be found for such works 
 within the limits of one of the adjacent municipalities, if it should be 
 found necessary to adopt this method of disposing of the sewage of the 
 city of Lynn, but a location in an adjacent municipality is hardly to be 
 considered unless no other practicable method is found to be available 
 for the disposal of the sewage of the city. 
 
 The Activated Sludge Method of Sewage Disposal. 
 
 In the course of the experimental work at the Lawrence Experiment 
 Station, Mr. H. W. Clark, chemist of the State Department of Health, 
 began in 1912 experiments upon the treatment of sewage with growths 
 of organisms and aeration. These experiments are described in the 
 annual report of the State Board of Health for the year 1912. 
 
 These experiments have been continued and have been taken up and 
 further developed both at Lawrence and elsewhere in this country and 
 abroad. The results of the experiments thus far made indicate that 
 by aerating sewage in tanks designed for the purpose containing 
 sludge, the sewage, after the sludge in the tanks becomes seeded with 
 the necessary organisms, can within a few hours under- favorable con- 
 ditions be purified apparently nearly to the degree of purification 
 effected by trickling filters. The experiments indicate that the process 
 can be carried on at such rates that it may be a practicable method 
 
17 
 
 for the treatment of the sewage of qities and towns. The process is 
 still in its experimental stage, however, and awaits the tests of practi- 
 cal experience on a considerable scale. So far as the experiments 
 show, a very considerable area of tanks would be required for the 
 treatment of a quantity of sewage such as that requiring disposal at 
 Lynn, and a large quantity of air would be required in the process. 
 It is impracticable at the present time to indicate with certainty 
 whether or not serious odors will attend this process. There seems 
 danger, however, that considerable odor may arise from such works in 
 view of the large quantities of air that must be passed through the 
 sewage. It is very doubtful whether, even if the process should be 
 found to be practicable, it could be used to advantage in the city of 
 Lynn on account of the lack of a favorable site for such works. 
 
 Screening. 
 
 Coarse screens or racks are commonly employed in connection with 
 sewage disposal works, especially where the sewage is pumped or 
 where it passes through siphons or tunnels, for the purpose of remov- 
 ing larger objects which might injure pumping machinery or obstruct 
 pipes or conduits. Such screens are usually constructed of bars set 
 from half an inch to an inch apart and intercept only the larger 
 objects floating in the sewage, including small amounts of paper, 
 rags, etc. 
 
 Fine screening, on the other hand, is a method of sewage treatment 
 designed to remove the smaller organic particles in suspension and 
 thus reduce the quantity of organic matter in the sewage. The screen- 
 ing of sewage for this purpose is carried on at a number of works in 
 this country and at numerous works abroad, commonly in connection 
 with a further process of sewage treatment. In Massachusetts this 
 method is employed at Brockton in connection with sewage disposal 
 works there for the removal of a part of the suspended organic matter 
 from the sewage before its application to the filters. 
 
 The efficiency of screens appears to depend to a considerable extent 
 upon the character of the sewage treated, and their effect is appar- 
 ently much the same as that of sedimentation when treating sewages 
 of the character commonly discharged from cities and towns in Massa- 
 chusetts. The method has certain advantages which may make its 
 employment desirable, especially in cases where the removal of the 
 larger particles of suspended organic matter from sewage is desirable, 
 as, for example, before the discharge of fresh sewage into a river or 
 waterway having an adequate flow for the proper dilution of the 
 sewage. 
 
18 
 
 Disinfection. 
 The disinfection of sewage for the purpose of destroying disease 
 germs by the introduction of a chemical such as hypochlorite of 
 lime is practised at some of the disposal works in this country and 
 abroad, though there is no case in which the sewage or effluent from 
 an existing works in Massachusetts is treated in this way. It is 
 practicable by treating well-clarified sewage effluents to reduce very 
 greatly the number of bacteria contained therein, and the method 
 may be employed to advantage where the effluent is discharged into 
 waters subsequently used for water-supply purposes or into waters 
 in which shellfish are grown. Its efficiency in the treatment of raw 
 sewage containing considerable quantities of suspended matter is com- 
 nionly of little practical value, and its advantages are most valuable in 
 the further improvement of effluents from treatment works where a 
 high degree of purification of the sewage is desirable. The method 
 might possibly be employed in connection with other works for the 
 treatment of the sewage, but in the case of the city of Lynn this treat- 
 ment of the sewage would not improve noticeably the conditions in 
 the neighborhood of the present outlet. 
 
 Disposal by Dilution. 
 The disposal of sewage by dilution is a method commonly em- 
 ployed by cities and towns in Massachusetts situated on the larger 
 rivers or bordering upon the sea. Inasmuch as this method is avail- 
 able to the city of Lynn, a description of the various sea outlets now 
 in use, of the circumstances affecting these outlets, and the results 
 obtained at each is of great practical value in considering the applicabil- 
 ity of this method to the disposal of the sewage of the city of Lynn. 
 
 Boston Main Drainage Outlet. 
 
 The oldest of the important modern sewer outlets through which 
 large quantities of sewage are discharged into the sea is the Moon 
 Island outlet of the main drainage system of the city of Boston, com- 
 pleted and first put in operation in January, 1884. 
 
 The sewers of the city of Boston were constructed originally upon 
 
19 
 
 works, so called, were designed, of which the Moon Island outlet is a 
 part, provision was made for taking all of the dry-weather flow of 
 the various sewers, together with a quantity of storm water equivalent 
 to about one-fourth of an inch of rain in twenty-four hours over the 
 area drained by the sewers. This arrangement was not applied equally 
 throughout the district, however, since there were certain low areas 
 in the southern part of the city subject to flooding at times of heavy 
 rain when the tide was high, and provision was made in the design for 
 favoring these low areas by taking a greater proportion of the flow of 
 storm water therefrom and a smaller quantity from the higher districts, 
 thus relieving to some extent the flooding of streets and buildings in 
 the lower sections of the city. 
 
 For several years after the construction of the works the area tribu- 
 tary to the main drainage system included only that portion of the city 
 of Boston lying south of Charles River. The design provided, however, 
 for the admission of sewage temporarily from neighboring areas and 
 for the subsequent construction of a system of intercepting sewers at a 
 higher level to relieve the main drainage works when the capacity of 
 the latter had been reached. In 1892, upon the completion of the 
 Charles River valley sewer, sewage from the cities of Waltham and 
 Newton, the towns of Brookline and Watertown, and the Brighton 
 district of the city of Boston was discharged into the main drainage 
 system, and still later, by the completion of a sewer in the Neponset 
 valley, sewage was- brought to the Moon Island outlet from the towns 
 of Dedham, Hyde Park and Milton. In the districts added to the 
 main drainage system outside the city of Boston the sewers had been 
 co^tructed on the separate plan and storm water was excluded, but 
 the addition of considerable quantities of sewage reduced the capacity 
 of the main drainage system for the removal of storm water from areas 
 sewered on the combined plan in the city of Boston and caused the 
 discharge of large quantities of mingled sewage and storm water into 
 local waters. 
 
 In 1904 the high-level sewerage system was completed and the sew- 
 age of the Charles and Neponset river valleys, including also the sewage 
 of the high levels in the West Roxbury and Dorchester districts of the 
 city of Boston, was removed to a new outlet known as the Nut Island 
 outlet, near Peddocks Island in Boston Harbor, and the conditions 
 affecting the Moon Island outlet were restored as contemplated in the 
 original design. In more recent years it has been found necessary, m 
 order to prevent the excessive pollution of local waters, to separate the 
 sewage from the storm water in the territory tributary to the Charles 
 River within the limits of the city, and further provision has been 
 
20 
 
 made for the relief of the low areas in the southern districts by pump- 
 ing the mingled sewage and storm water into the harbor at times of 
 heavy rain. In consequence of these changes there has been con- 
 siderable variation in the quantity of sewage delivered at the Moon 
 Island outlet, the maximum quantity having been reached just pre- 
 vious to the completion of the high-level sewer in 1904. 
 
 The average quantity of sewage discharged at the Moon Island out- 
 let amounts at the present time to about 100,000,000 gallons per day. 
 The sewage of the intercepting sewers is all delivered at a pumping 
 station at Calf Pasture, where it is elevated several feet to deposit 
 sewers, so called, which are small settling tanks designed for the sedi- 
 mentation of sand and other heavy matters, and is then conveyed 
 through a tunnel beneath Dorchester Bay to reservoirs at Moon 
 Island, whence it is discharged into the sea, generally in the first two 
 ' hours of the outgoing tide. In consequence of its slow passage through 
 the intercepting sewers and the deposit sewers at Calf Pasture and 
 its storage in the reservoirs at Moon Island previous to discharge, the 
 sewage becomes considerably decomposed and putrefied when it reaches 
 the outlet and has a more offensive odor than that of fresh sewage. 
 
 The sewer outlet at Moon Island is located at the northwesterly 
 corner of the island, and the sewage is discharged at the level of the 
 water. The sewage passes out of the harbor chiefly between Long 
 and Rainsford islands and after each discharge becomes thoroughly 
 mingled with the water of the sea and does not return on the incoming 
 tide. 
 
 Numerous chemical analyses have been made from time to time of the 
 sewage discharged at this outlet and of the waters of the harbor in the 
 region through which the sewage flows, the results of which show that 
 the sewage, while becoming diluted quite rapidly, has a tendency 
 to float away from the outlet upon the surface of the water in a 
 shallow layer, which on the whole, however, notwithstanding the 
 great quantity of sewage discharged, amounting to about -25,000,000 
 gallons per hour, mingles quickly with the water and is usually dis- 
 persed within an hour after the discharge has ceased. 
 
 The following table shows the results of analyses of samples of the 
 sewage and of the sea water within about 1,000 feet of the outlet 
 before and during a discharge in August, 1915: — 
 
21 
 
 
 
 
 
 
 
 
 • 
 
 Pabts in 100,000. 
 
 Bacteria 
 
 
 
 
 
 1 
 
 
 
 Free 
 Ammo- 
 nia. 
 
 ALBUMINOID AMMONIA. 
 
 Chlo- 
 rine. 
 
 per 
 Cubio 
 Cen- 
 timeter. 
 
 
 Total. 
 
 In Solu- 
 tion. 
 
 In Sus- 
 pension. 
 
 Moon Island Wharf, before discharge, . 
 
 .0175 
 
 .0175 
 
 .0130 
 
 .0045 
 
 1,620.0 
 
 
 Sewage flowing from Moon Island reser- 
 voirs. 
 600 feet off gate house, surface, . 
 
 2.4700 
 
 .seoo 
 
 .9590 
 .3760 
 
 .3490 
 .0680 
 
 .6100 
 .3080 
 
 272.0 
 1,260.0 
 
 100,800 
 
 600 feet off gate house, 20 feet below 
 
 surface. 
 At farther limit of sewage field, 1,000 feet 
 
 from outlet. 
 
 .0450 
 .2130 
 
 .0490 
 .1350 
 
 .0275 
 .0590 
 
 .0215 
 .0760 
 
 1,590.0 
 1,570.0 
 
 28,000 
 144,000 
 
 The foregoing samples are probably fairly representative of the 
 conditions at this outlet. As the sewage field moves away from the 
 outlet it passes chiefly around the southerly end of Long Island and 
 continues toward the sea in a northeasterly direction, chiefly between 
 Long and Rainsford islands. On calm days the sewage greatly dis- 
 colors the water for a distance of from half a mile to a mile from the 
 outlet and remains for a time upon the surface of the sea, which is 
 covered with a greasy film. This film is very thin and usually extends 
 well beyond the area otherwise affected by the sewage. The area 
 covered by the sewage or in which sewage is recognizable varies 
 greatly with the condition of the sea. On very calm days the area 
 affected is extensive, covering 600 to 700 acres of the harbor surface , 
 bet'i^een Moon, Long and Rainsford islands. Under ordinary condi- 
 tions, however, the area visibly affected by the sewage is smaller, and 
 when a considerable wind is blowing the area in which the sewage is 
 noticeable is much less than in calm weather. 
 
 Under ordinary conditions the sewage mingles rapidly with the 
 water and quickly ceases to be recognizable after the discharge has 
 ceased. Analyses of the water of the harbor through which this sewage 
 is discharged twice daily show that its effect rapidly disappears and 
 that the sewage does not return on the incoming tide. Analyses of 
 the water from various stations in different parts of the area over 
 which this sewage flows twice daily are given in the following table, 
 the location of the stations at which the samples were taken being 
 shown on the chart which follows the table: — 
 
22 
 
 CQ 
 
 
 § 
 
 ^ 
 
 -si S 
 
 s i 
 o 3 
 
 ttj 
 
 cq .3 
 
 s 
 
 
 I 
 
 1 
 
 K3 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 K 
 
 ffi 
 
 g 
 
 1 1 
 
 1 1 
 
 s 
 
 1 
 
 g. 
 
 ' 
 
 S 
 
 1 
 
 gi 
 
 
 IC 
 
 
 
 IN 
 
 
 CO 
 
 « 
 
 -1. 
 
 
 
 C4 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 W H 
 
 
 
 
 
 
 
 
 
 
 
 BU 
 
 1 
 
 <=> 
 
 1 1 
 
 1 1. 
 
 1 
 
 1 
 
 3 
 
 1 
 
 g 
 
 g 
 
 Ba 
 Cubic 
 
 1 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 "S 
 
 o 
 
 
 
 o 
 
 
 o 
 
 
 o 
 
 
 
 
 ig 
 
 g 
 
 1 1 
 
 ' ' 
 
 g 
 
 
 s 
 
 
 ui 
 
 ' 
 
 
 pq 
 
 g 
 
 1>;^ 
 
 
 
 
 
 t-^ 
 
 
 r^ 
 
 
 
 g 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 05 
 
 o 
 
 o o 
 
 o o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 
 !e 
 
 o 
 
 CO ui 
 
 8 S 
 
 o 
 
 to 
 
 uj 
 
 W3 
 
 o 
 
 O 
 
 
 
 
 i-H Ui 
 
 D- 
 
 ui 
 
 t- 
 
 ■* 
 
 t- 
 
 t^ 
 
 
 
 1 
 
 CO 
 
 ■^ 
 
 t^ t^ 
 
 ■* t-. 
 
 
 
 l> 
 
 t^ 
 
 
 t-. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■£ 
 
 in 
 
 
 
 ui 
 
 
 us 
 
 
 o 
 
 
 
 
 
 t- 
 
 
 
 b- 
 
 
 "O 
 
 
 ta 
 
 
 
 
 ^ 
 
 C4 
 
 
 
 
 
 
 
 
 
 
 
 O 
 
 
 
 o 
 
 
 o 
 
 
 O 
 
 
 
 A 
 
 o 
 
 
 1 1 
 
 1 1 
 
 
 1 
 
 
 1 
 
 
 1 
 
 1 
 
 Sd 
 
 N 
 
 
 
 
 
 
 
 
 
 
 
 5S5 
 
 ■< 
 
 
 
 
 
 
 
 
 
 
 K 
 
 s o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 t3 S 
 
 
 
 
 
 
 
 
 
 
 
 
 1^ 
 
 U 
 
 g 
 
 O lO 
 
 o »c 
 
 o 
 
 lO 
 
 US 
 
 ta 
 
 U3 
 
 o 
 
 A4 
 
 '* s 
 
 °o ^ 
 
 eo 
 
 ■* 
 
 ••iH 
 
 (M 
 
 to 
 
 '.H 
 
 
 
 
 
 
 
 
 
 
 
 
 § s 
 
 S o 
 
 S 
 
 o 
 
 s 
 
 O 
 
 c> 
 
 o 
 
 
 3 
 
 
 
 
 
 
 
 
 
 
 
 
 OQ 
 
 
 
 
 
 
 
 
 
 
 
 
 ■s 
 
 US 
 
 
 
 O 
 
 
 CO 
 
 
 o 
 
 
 
 
 Q 
 
 
 
 
 
 
 
 
 
 
 
 
 &:< 
 
 co' 
 
 
 
 C<l 
 
 
 CO 
 
 
 N 
 
 
 
 < 
 
 o 
 
 
 
 o 
 
 
 o 
 
 
 o 
 
 
 
 t; 
 
 o 
 
 
 t [ 
 
 1 1 
 
 
 
 
 r 
 
 
 I 
 
 
 13 
 
 CN 
 
 
 
 
 
 
 
 
 
 
 
 o 
 
 HP 
 
 
 
 
 
 
 
 
 
 
 
 S 
 
 <! 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 W 
 
 1 
 
 
 O lO 
 
 g s 
 
 lO 
 
 U3 
 
 
 o 
 
 
 o 
 
 
 
 O OS 
 
 
 
 
 CO 
 
 
 Ca 
 
 
 H 
 
 
 
 in ^ 
 
 
 
 
 (N 
 
 
 
 
 P! 
 
 
 o o 
 
 ^ o 
 
 
 
 
 O 
 
 
 o 
 
 
 Pc. 
 
 ^ 
 
 ■ ■ 
 
 
 
 
 
 
 
 
 
 
 OD 
 
 
 
 
 
 
 
 
 
 
 Distance 
 from 
 Outlet 
 (Feet). 
 
 ^ 
 
 ^ 
 
 o 
 
 ^ 
 
 ^ 
 
 ^ 
 
 g 
 
 ^ 
 
 ^ 
 
 
 
 o 
 
 
 
 
 
 g 
 
 
 
 
 
 
 
 CO 
 
 
 
 M 
 
 ■^~ 
 
 »o 
 
 00 
 
 ^" 
 
 lO 
 
 «? 
 
 in 
 
 
 
 
 
 
 
 
 1-1 
 
 eq 
 
 ,X3 
 
 
 , 
 
 - 
 
 
 
 
 
 
 
 
 -:*( 
 
 CO M 
 
 r- «o 
 
 ca 
 
 Oi 
 
 eo 
 
 Ci 
 
 (M 
 
 CO 
 
 CO 
 
 0» CO 
 
 CO O 
 
 
 O 
 
 eo 
 
 
 M 
 
 o 
 
 n t' c3 
 
 
 CSl 
 
 
 
 
 flO 
 
 
 CO 
 
 (N 
 
 S|& 
 
 
 
 
 
 
 
 
 
 
 la 
 
 
 > — s, 
 
 
 
 
 
 
 
 
 a 
 
 
 
 
 
 
 
 
 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 S 
 
 
 
 
 
 
 
 
 
 
 -ij 
 
 
 
 
 
 
 
 
 
 
 N 
 
 
 
 
 
 
 
 
 
 
 ' 02 
 
 
 
 
 
 
 
 •. 
 
 
 
 
 ^ 
 
 
 
 ifs" 
 
 lO 
 
 TjT 
 
 e<r 
 
 s' 
 
 ^ 
 
 
 
 
 cc 
 
 •*" 
 
 eo 
 
 ■* 
 
 1-4 
 
 -* 
 
 c3 
 
 ^ 
 
Missing Page 
 
28 
 
 From this table it will be seen that at station 31, located 400 feet 
 from the outlet, the surface of the sea was covered with sewage prac- 
 tically in an undiluted condition. At station 3, a distance of 4,200 
 feet from the outlet, two hours after the sewage was discharged, that 
 is, at about the end of the discharge, the quantity of sewage in the 
 water, as indicated by the albuminoid ammonia, was 24 per cent., 
 and as indicated by the free ammonia about 41 per cent., of the 
 amount found at station 31, located 400 feet from the outlet. At 
 station 15, a distance of 8,200 feet from the outlet, the organic matter 
 present in the sea water, as shown by the free and albuminoid am- 
 monia, is no greater than the average of the harbor waters in the 
 inner parts of the harbor. 
 
 During the period when the sea is covered with sewage from this 
 outlet the odor is objectionable when sailing through the sewage field, 
 and this condition prevails for a period of two to three hours on each 
 tide. During the summer season temporary deposits of sludge from 
 the sewage take place along the wall adjacent to the sewer outlet, 
 bu-t these deposits are carried away by the winter storms. There is no 
 evidence that matters from the sewage tend to accumulate upon the 
 bottom of the harbor or the adjacent shores in this region, except the 
 temporary deposits already referred to, caused by the eddying of the 
 sewage against the long wall at the easterly end of Moon Island. 
 
 So far as can be judged from numerous careful examinations, the 
 conditions about this outlet have shown no noticeable change since 
 the works were first established thirty-two years ago. The pollution 
 of a considerable area of the sea to such an extent as to be offensive 
 to flght and smell, as happens in the neighborhood of this outlet at 
 the time the sewage is discharged, especially on calm days, is objec- 
 tionable, and no doubt the objections to this condition will increase 
 with the rapidly increasing use of the harbor as a place of recreation 
 in the summer season and the undoubtedly increasing attention that 
 is paid by the public to objectionable conditions caused by offensive 
 odors. 
 
 Before the outlet was constructed careful observations of the tidal 
 currents were made by means of floats and the probable course taken 
 by the sewage ascertained as carefully as practicable. The actual 
 results have shown the accuracy of the conclusions drawn from the 
 preliminary tests. The outlet represents the first important works 
 constructed in Massachusetts to dispose of large quantities of sewage 
 by dilution in the water of the sea. 
 
24 
 
 North Metropolitan Sewer Outlet. 
 
 The next important sewer outlet constructed for the disposal of 
 sewage into the sea is that of the north metropolitan sewerage system, 
 designed in 1889 and put in operation early in 1894. This outlet is 
 located near the Deer Island beacon at the northerly side of the en- 
 trance to Boston Harbor, and the sewage is discharged at about the 
 level of low water. The sewage brought to this outlet is collected from 
 the cities and towns of Arlington, Belmont, Lexington, Woburn, 
 Winchester, Wakefield, Stoneham, Melrose, Maiden, Everett, Medford, 
 Somerville, Cambridge, Revere and Winthrop, and the Charlestown 
 and East Boston districts of the city of Boston. The sewers in most 
 of the cities and towns of the north metropolitan sewerage district 
 are constructed upon the separate plan, but the sewers in the older 
 sections of the district, especially in Cambridge, Somerville, Chelsea, 
 and the Charlestown and East Boston districts of Boston, are con- 
 structed upon the combined plan and receive both sewage and storm 
 water. ' In this case, as in Boston, the dry-weather flow of sewage and 
 a certain portion of storm water are admitted to the system, and 
 the remainder of the flow at times of storm is discharged into local 
 waters. 
 
 In the course of the investigations relative to the disposal of the 
 sewage of the north metropolitan system, careful studies were made 
 of the volume and movement of the tides near the outer end of Deer 
 Island, the results showing that a much larger volume of water would 
 be available at this point for the dilution of the sewage than is the 
 case at Moon Island and that the velocity of flow of tidal currents is 
 considerably greater than in the smaller channel into which the Moon 
 Island sewage is discharged. 
 
 As a result of these studies the conclusion was reached that the 
 sewage could be discharged to advantage at all stages of the tide with 
 less effect upon the waters of the harbor than if large quantities were 
 discharged at one time, and the plan selected provided for continu- 
 ous discharge at all stages of the tide. The actual results obtained by 
 this method of sewage disposal corresponded to the conclusions reached 
 as the result of the careful preliminary investigations. The sewage 
 brought to this outlet is discharged as it comes, without storage at any 
 point. There are several pumping stations along the line of the main 
 sewer and its tributaries, and while the flow is continuous, on account of 
 the great length of the system, a part of the sewage is many hours in 
 reaching the outlet. The sewers of this system receive large quantities 
 of manufacturing waste from tanneries, rendering works and other estab- 
 
25 
 
 lishments, and the total quantity of sewage discharged in the year 
 1915 amounted to 60,300,000 gallons per day, or about 111 gallons per 
 person connected with the sewers, the total population connected with 
 the sewers amounting to 542,575. On the incoming tide the sewage 
 flows toward the harbor and is noticeable under most favorable con- 
 ditions for somewhat more than half a mile from the outlet. Toward 
 high tide the sewage can be detected in the water on fairly calm days 
 for a distance of three-quarters of a mile, and the oily film known as 
 ''sleek" is usually observable over a larger area. During the outgoing 
 tide the sewage flows directly to sea and is detectable at about the 
 same distances as on the incoming tide, though in a somewhat narrower 
 area. As the quantity of sewage discharged at this point increased 
 it covered a larger area of the sea and was noticeable at times on 
 vessels passing into and out of the harbor and became objectionable 
 to the keepers of the light. It has been decided to extend this outlet 
 to deep water, which is reached within a short distance of the present 
 outlet, and the works for this extension are already under construction. 
 
 Salem and Peabody. 
 
 Following the installation of the outlet of the north metropolitan 
 sewerage system at Deer Island, works were designed for the disposal 
 of the sewage of Salem and Peabody into Salem Harbor near Great 
 Haste Island. These works were designed in 1895 but were not con- 
 structed until 1906. The average quantity of sewage discharged at 
 this outlet in 1915 was 7,560,000 gallons per day. The outlet is lo- 
 (feted at a point in Salem Harbor where the depth of water is 7 feet 
 at low tide, and the sewage is discharged continuously at the approxi- 
 mate rjite at which it is received at the pumping station, the average 
 ra|e of discharge consequently being a little over 300,000 gallons per 
 hour. 
 
 The effect of the discharge of sewage at this outlet has been observed 
 from time to time since it was first used, and samples of the water 
 of Salem Harbor in the neighborhood of the outlet and elsewhere have 
 been analyzed from time to time. An examination of this outlet in 
 1915 shows that the area of the sea visibly affected by the sewage 
 varies greatly with different conditions of wind and tide. With winds 
 of considerable velocity the area affected is limited to less than 1,000 
 feet from the outlet, while in very calm days the sewage is noticeable 
 for a maximum distance of half a mile, though the thin oily film 
 known as "sleek" is noticeable for greater distances. 
 
 There is no doubt that the outlet could be greatly improved and 
 
26 
 
 the area of the sea affected by the sewage very materially diminished 
 if the outlet were extended to deep water, which can be reached at 
 no great distance beyond its present location. 
 
 The Disposal of Sewage from the South Metropolitan System 
 INTO the Sea North of Peddocks Island. 
 
 The sewage disposal works of the south metropolitan system were 
 designed in 1899-1900 and completed in 1904. The system receives 
 the sewage of the cities and towns in the Charles and Neponset river 
 valleys formerly tributary to the Boston main drainage system, the 
 sewage of the higher districts in the southerly part of the city of 
 Boston, and the sewage of the city of Quincy. The estimated popu- 
 lation connected with the sewers in this system in 1915 was 300,435, 
 and the total quantity of sewage discharged during the year 1915 was 
 52,300,000 gallons per day, or 174 gallons per person connected with 
 the sewers. The main sewer operates wholly by gravity, but the sew- 
 age of the Charles River valley district, and of a portion of the Back 
 Bay district of the city of Boston tributary to this system, is pumped 
 into the upper end of the high-level sewer at Roxbury. A part of the 
 sewage of Quincy also is pumped into the main sewer in that city. 
 The sewer terminates at Nut Island, whence two pipes are laid be- 
 neath the bottom of the sea to outlets into the deep channel known as 
 Nantasket Roads in the southerly part of Boston Harbor, one outlet 
 being located 1 mile noi:th of Nut Island and the other 1,500 feet 
 easterly therefrom. The depth of water over the westerly outlet at 
 low tide is 27 feet and over the easterly outlet 30 feet. 
 
 In the course of the studies which led to the selection of these out- 
 lets the experience acquired in the disposal of sewage at the sewer 
 outlets already described was carefully considered, especially the rapid 
 disappearance of the sewage when thoroughly diffused in water, and 
 the outlets were placed at the bottom of the sea at a point where 
 a large quantity of water is available for dilution at all times in order 
 to secure a greater diffusion of the sewage than takes place where the 
 outlet is located near the surface of the sea. The results of the dis- 
 charge of sewage at these outlets show the great advantages in the 
 dilution of the sewage obtained where the discharge takes place at a 
 considerable depth as compared with discharge near the surface of the 
 sea. In order to determine the degree of dilution of the sewage that 
 takes place before it reaches the surface and the condition of the sea 
 water immediately over the outlets, samples of water were taken very 
 carefully immediately over the outlet in use at different times in the 
 past year. In the first test, made on Aug. 25, 1915, samples were 
 
27 
 
 collected from a tug when passing immediately over the outlet. The 
 results of the analyses show that the quantity of free and albuminoid 
 ammonia present in the water at this time amounted to about 5 per 
 cent, of that found in the sewage, while the maximum number of 
 bacteria was less than 2 per cent, of the number present in the sewage. 
 It was found, however, at this time that the effect of the sewage upon 
 the sea water near the outlet diminished with very great rapidity as 
 the distance from the outlet increased, and later on additional samples 
 were taken with the aid of rowboats immediately over the outlet 
 itself. 
 
 The results pf these tests with analyses of the sewage flowing from 
 the sewer at this time, together with samples taken at different depths, 
 are shown in the following table: — 
 
 Table showing Atwlyses of the Sewage and of the Water immediately over the Nut 
 Island Sewer Outlet, Oct. 14-, 1915. 
 
 
 
 Parts in 100,000. 
 
 Bacteria 
 
 
 
 
 
 
 
 
 
 Hoiir 
 
 4..M, 
 
 Free 
 Ammo- 
 nia. 
 
 AI/BUMIsroID AMMGKIA. 
 
 Chlo- 
 rine, 
 
 Cubic 
 Cen- 
 timeter. 
 
 
 Total. 
 
 In Solu- 
 tion. 
 
 In Sus- 
 pension. 
 
 Sewage, .... 
 
 8.30 
 
 1.7600 
 
 .4500 
 
 .1400 
 
 .3100 
 
 53.5 
 
 610,000 
 
 Surface over outlet. 
 
 9.13 
 
 .1440 
 
 .0590 
 
 .0280 
 
 .0310 
 
 1,560.0 
 
 316,800 
 
 Surface over outlet, 
 
 9.33 
 
 .1950 
 
 .0725 
 
 .0305 
 
 .0420 
 
 1,620.0 
 
 290,400 
 
 Surface over outlet. 
 Surface over outlet,' 
 
 9. S3 
 
 .2400 
 
 .0770 
 
 .0385 
 
 .0385 
 
 1,540.0 
 
 277,200 
 
 10.13 
 
 .1220 
 
 .0550 
 
 .0235 
 
 .0315 
 
 1,570.0 
 
 38,200 
 
 10 feet below surface, . 
 
 10.20 
 
 .0750 
 
 .0340 
 
 
 - 
 
 1,650.0 
 
 25,080 
 
 20 feet below surface, . 
 
 10.25 
 
 .0480 
 
 .0175 
 
 
 
 1,690.0 
 
 
 In the above tests the maximum amount of albuminoid ammonia 
 found in any of the samples collected immediately above the outlet 
 was 14 per cent, of the amount present in the sewage, while the aver- 
 age quantity of free ammonia obtained in the surface samples was 10 
 per cent, of the amount found in the sewage. The maximum amount 
 of free ammonia found in any sample was 17 per cent, of that of the 
 sewage, ,and the average amount 14 per cent. 
 
 Samples were collected at the same time in the line in which sewage 
 was flowing from the outlet and at various distances therefrom. The 
 average results of the analyses of several samples at each station are 
 shown in the following tables : — 
 
28 
 
 Samples of Harbor Water collected in Path taken by the Sewage from the Nut 
 
 Island Outiet. 
 
 
 Hours 
 after 
 Dis- 
 charge. 
 
 MiUs 
 
 from 
 
 Outlet. 
 
 Feet 
 
 from 
 
 Outlet. 
 
 Pabts in 100,000. 
 
 Bacteria 
 
 Cubic 
 Cen- 
 timeter. 
 
 Station. 
 
 Free 
 Aniino- 
 
 nia. . , 
 
 Total 
 , Albu- 
 minoid 
 
 Am- 
 monia. 
 
 Chlo- 
 rine. 
 
 Screen house (sewage), . 
 
 
 
 
 1.7600 
 
 .4500 
 
 53.5 
 
 610,000 
 
 A (at outlet), . 
 
 
 
 
 .1763 
 
 .0659 
 
 1,572,5 
 
 230,650 
 
 B, . . . . . 
 
 0.50 
 
 0.04 
 
 200 
 
 .0555 
 
 .0210 
 
 1,670.0 
 
 20,080 
 
 C, . .... 
 
 1.00 
 
 0.05 
 
 260 
 
 .0242 
 
 .0165 
 
 1,710.0 
 
 525 
 
 D, . . 
 
 1.50 
 
 0.27 
 
 1,400 
 
 .0330 
 
 .0177 
 
 1,765.0 
 
 46,220 
 
 E, . . 
 
 2.62 
 
 0.47 
 
 2,500 
 
 .0165 
 
 .0145 
 
 1,720.0 
 
 850 
 
 G, . . ... 
 
 2.87 
 
 0.66 
 
 3,500 
 
 .0130 
 
 .0140 
 
 1,730.0 
 
 180 
 
 Samples of Harbor Water collected from Points outside Path of Sewage from the 
 
 Nut Island Ovilet. 
 
 
 
 
 
 
 
 
 
 
 Hours 
 after 
 Dis- 
 charge. 
 
 Miles 
 
 from 
 
 Outlet. 
 
 Feet 
 
 from 
 
 Outlet. 
 
 Parts in 100,000. 
 
 Bacteria 
 
 Cubic 
 Cen- 
 timeter. 
 
 Station. 
 
 Free 
 Ammo- 
 nia. 
 
 Total 
 Albu- 
 minoid 
 Am- 
 monia. 
 
 Chlo- 
 rine. 
 
 F, . . . 
 H, . . . 
 
 1 
 
 J, . . . 
 
 2.70 
 2.95 
 3.12 
 3.28 
 
 0.82 
 0.43 
 0.23 
 0.28 
 
 4,300 
 2,300 
 1,200 
 1,500 
 
 .0100 
 .0170 , 
 .0120 
 .0115 
 
 .0175 
 .0115 
 .0095 
 .0130 
 
 1,740.0 
 1,720.0 
 1,740.0 
 1,750.0 
 
 700 
 
 4,800 
 
 130. 
 
 400 
 
 It will be noted that in the sample collected at Station D, 1,400 
 feet from the outlet, the amount of free ammonia represents less than 
 2 per cent, and the amount of albuminoid ammonia 4 per cent, of the 
 quantity present in the sewage. 
 
 The remaining samples collected at greater distances show the pres- 
 ence of very much smaller quantities of organic matter, and numerous 
 examinations along the path which this sewage takes, determined with 
 the aid of floats and at various times, fail to show a quantity of free 
 ammonia exceeding 0.0170 parts in 100,000 or an amount of albumi- 
 noid ammonia exceeding 0.0175 parts in 100,000. A comparison of the 
 analyses of harbor waters in the immediate neighborhood of this outlet 
 
29 
 
 and along the course followed by the sewage with waters in other parts 
 of the harbor shows that, except within a distance of about 1,400 feet 
 from the outlet, the quantity of free and albuminoid ammonia in the 
 water is no greater at the surface of the harbor and at points 20 feet 
 below the surface than is found in the harbor waters at points far 
 removed from sewer outlets. 
 
 Samples of Harbor Waters collected at Points remote from Sewer Ovilets. 
 
 [Parts in 100,000.1 
 
 
 , . Fhpb Ammonia. 
 
 Albuminoid 
 Ammonia. - 
 
 
 Surface. 
 
 Twenty 
 Feet 
 below 
 
 Surface. 
 
 Surface. 
 
 Twenty 
 Feet 
 below 
 
 Surface. 
 
 Hingham Bay ' . 
 
 In the outer channels of harbor along a line running approx- 
 imately northwest from Point Allerton. 
 Off Outer Brewster Island 
 
 .0159 
 .0178 
 .0065 
 .0060 
 
 .0169 
 .0132 
 .0115 
 
 .0137 
 .0160 
 .0120 
 .0135 
 
 .0141 
 .0160 
 .0165. 
 
 
 
 
 The total number of bacteria found in the sample of sea water col- 
 lected off Nahant was 300 per cubic centimeter. Samples taken from 
 the sea several miles beyond Outer Brewster Island on the incoming 
 tide indicate that the quantity of free ammonia in the water of the sea 
 many miles from the coast is 0.0025 of a part in 100,000 and the 
 bacteria 25 per cubic centimeter. 
 
 Comparisons of the foregoing tests show very clearly that the waters 
 of the harbor generally are higher in bacteria and in organic matter, 
 as shown by the free and albuminoid ammonia, than the waters of 
 the sea, a condition which is inevitable in view of the large quantity 
 of waste matter that must find its way into the waters near the coast, 
 not only from sewer outlets but from the sewage and waste from 
 vessels, and especially from rivers and other waters flowing into the 
 sea from populous areas such as those which surround Boston Harbor. 
 The examination of 'the sea beyond a distance of 1,400 feet from the 
 Nut Island outlet at the time the recent test was made failed to show 
 any sewage matter or other effect objectionable to the senses. Further- 
 more, the analyses of the water in the region beyond this limit, when 
 compared with waters along the beaches used by large numbers of 
 bathers in the summer season, indicate that, so far as pollution goes 
 or any visible effect of the sewage, the condition of the harbor water 
 was better beyond a distance of 1,400 feet from this sewer outlet than 
 
30 
 
 the waters used by large numbers of bathers at the beach resorts near 
 the city. 
 
 A comparison of the results of analyses of the waters from different 
 bathing beaches with the analyses of waters about the Nut Island 
 sewer outlet at the time of the test in October last is shown in the fol- 
 lowing itable: — 
 
 Table showing Comparison of Analyses of Sea Water off the Nut Island Outlet with 
 Sea Water at Popular Beaches. 
 
 Nut Island Outlet. 
 
 Distance from Outlet. 
 
 Free Ammonia 
 (Parts in 100,000). 
 
 Bacteria 
 
 Miles. 
 
 Feet. 
 
 (per Cubic Centimeter) . 
 
 0.47 
 0.66 
 
 2,500 
 3,500 
 
 .0165 
 .0130 
 
 850 
 180 
 
 Samples collected at the Surface of the Sea at Various Points in Front of Bathhouse at 
 
 Nahant Beach. ' 
 
 
 Free 
 Ammonia 
 (Parts in 
 100,000). 
 
 Bacteria 
 
 (per Cubic 
 
 Centimeter) . 
 
 B. CoLi.» 
 
 Analysis 
 Number. 
 
 0.1 Cubic 
 
 Cen- 
 timeter. 
 
 1.0 Cubic 
 
 Cen- 
 timeter. 
 
 10.0 Cubic 
 
 Cen- 
 timeters. 
 
 100 Cubic 
 
 Cen- 
 timeters. 
 
 124963 
 124964 
 124965 
 124966 
 124967 
 
 .0500 
 .0200 
 .0100 
 .0720 
 .0145 
 
 200 
 101 
 100 
 432 
 500 
 
 
 
 
 ■ 
 
 
 
 
 
 
 
 
 
 +3 
 
 
 
 
 + 
 + 
 
 +8 
 
 
 
 -l-s 
 
 + 
 + 
 
 Samples from Surf along Revere Beach, July 18, 1915. 
 
 124968 
 
 .0520 
 
 1,200 
 
 +s 
 
 +B 
 
 + 
 
 + 
 
 124969 
 
 .0590 
 
 3,700 
 
 
 
 +s 
 
 + 
 
 +s 
 
 124970 
 
 .0550 
 
 2,100 
 
 
 
 + * 
 
 + 
 
 -H 
 
 124971 
 
 .0570 
 
 2,400 
 
 
 
 + 
 
 +8 
 
 + 
 
 124972 
 
 .0490 
 
 1,500 
 
 +K 
 
 -l-s. 
 
 + 
 
 + 
 
 124973 
 
 .0380 
 
 2,200 
 
 
 
 + 
 
 + 
 
 + 
 
 124974 
 
 .0280 
 
 5,600 
 
 
 
 + 
 
 +a 
 
 -1- 
 
 124975 
 
 .0115 
 
 7,900 
 
 
 
 + 
 
 + 
 
 + 
 
 1 Samples collected on July 18, 1915, with large numbers of foathera along the beach. 
 '■i -{- signifies presence of B. coli. s signifies presence of sewage streptococcus. 
 
31 
 
 The samples generally were collected about 100 feet from shore, 
 but sample 124975 was collected 600 feet from shore and beyond the 
 line of bathers, these samples being taken at about high tide. 
 
 The appearance and the general condition of the water at these 
 bathing beaches were not objectionable at the time these samples were 
 collected, though a marine growth {Cladophora) was present in a con- 
 siderable quantity in the water along the Nahant Beach. The results 
 show clearly that the waters at the surface of the harbor are not 
 affected in the neighborhood of the sewer outlets at Nut Island by the 
 ordinary quantity of sewage discharged there in such a way as to be 
 noticeable or even detectable by chemical analysis beyond a limit of 
 less than half a mile in the region immediately about the outlet itself. 
 These examinations were made when the rate of discharge was ap- 
 proximately 1,380,000 gallons per hour and when the depth of water 
 over the outlet was about 30 feet. 
 
 Other Deep-sea Outlets. 
 
 In view of the very satisfactory results obtained from the discharge 
 of sewage into deep water north of Nut Island, this practice has been 
 followed in the construction of new outlets into the sea since that time 
 at Swampscott, New Bedford and Manchester. 
 
 At Swampscott the sewage is discharged at a point where the 
 depth of water at low tide is approximately 50 feet, and while the 
 average quantity of sewage discharged at this outlet amounts only to 
 about 1,000,000 gallons per day, the sewage in this case is stored in a 
 reservoir before discharge, so that it has been practicable, by storing 
 ^e sewage as long as possible, to obtain a rate of discharge at this 
 outlet amounting to 3,100,000 gallons per day for a period of one and 
 one-quarter hours. The results of this test were similar to the experi- 
 ence at Nut Island. Observations about the outlet during this period 
 sh6w that the presence of the sewage is not noticeable to sight or 
 smell beyond a very limited area extending some 300 feet from the 
 outlet, and that the quantity of organic matter in the water at a distance 
 of 1,300 feet from the outlet was no greater, as shown by chemical 
 analysis, than is found in waters bordering populous shores remote 
 from sewer outlets. 
 
 A new deep-sea outlet has recently been constructed for the city 
 of New Bedford, the population of which by the census of 1915 
 amounted to 109,568, or about 14,000 more than that of the city of 
 Lynn. This sewer outlet is located at a point 3,300 feet south of the 
 extreme end of Clark's Point in Buzzards Bay, where the depth of 
 water at low tide is about 30 feet. A very careful examination was 
 
32 
 
 made of this outlet on two occasions during the past year, and samples 
 were collected along the line taken by floats launched at the sewer 
 outlet. The results of these observations show that sewage was 
 noticeable only in a limited area in the immediate neighborhood of the 
 outlet and was not traceable with certainty by chemical or bacterial 
 analysis beyond a distance of 1,000 feet. 
 
 The results of the observations at New Bedford and Swampscott are 
 shown in the following table, and the locations of the stations at 
 which samples were taken are indicated on the accompanying chart: — 
 
 Table showing Results of Analyses of Water in the Path of the Sewage from the 
 New Bedford Sewer Outlet. 
 
 Aug. 9, 1916. 
 
 
 Hours 
 after 
 Dis- 
 charge. 
 
 Dis- 
 tance 
 
 from 
 Outlet 
 (MUes). 
 
 Dis- 
 tance 
 
 from 
 Outlet 
 (Feet). 
 
 Parts in 100,000. 
 
 Bacteria 
 
 Station. 
 
 Free 
 Ammo- 
 nia. 
 
 Total 
 Albu- 
 minoid 
 
 Am- 
 monia. 
 
 Chlo- 
 rine. 
 
 Cubic 
 Cen- 
 timeter. 
 
 A (outlet), . 
 
 1 
 
 2, . . . . 
 
 3 
 
 4, 
 
 5, . .... 
 
 0.52 
 1.02 
 1.52 
 1.99 
 2.48 
 
 0.21 
 0.44 
 0.82 
 1.14 
 1.46 
 
 1,100 
 2,600 
 4,300 
 6,030 
 7,680 
 
 .1276 
 
 .0025 
 
 .0025 
 
 .0025 
 
 -1 
 
 .0005 
 
 .0323 
 .0225 
 .0180 
 .0165 
 
 -I 
 
 .0195 
 
 1,589.0 
 1,710.0 
 1,690.0 
 1,690.0 
 
 1,690.0 
 
 
 1 Bottle broken. 
 
 
 
 Sept. U, 1915. 
 
 
 
 
 
 A (outlet) 
 
 - 
 
 
 
 .0207 
 
 .0224 . 
 
 1,697.0 
 
 219,850 
 
 6 
 
 0.32 
 
 0.15 
 
 800 
 
 .0165 
 
 .0205 
 
 1,740.0 
 
 2,650 
 
 7, . . . . 
 
 0.82 
 
 0.35 
 
 1,800 
 
 .0077 
 
 .0125 
 
 1,755.0 
 
 27 
 
 8, . . 
 
 1.32 
 
 0.49 
 
 2,600 
 
 .0045 
 
 .0096 
 
 1,757.0 
 
 17 
 
 9 
 
 1.82 
 
 0.60 
 
 3,150 
 
 .0072 
 
 .0114 
 
 1,735.0 
 
 63 
 
 10, . . . 
 
 2.32 
 
 0.92 
 
 4,900 
 
 .0050 
 
 .0140 
 
 1,757.0 
 
 95 
 
33 
 
 TahU showing Results of Analyses of Water collected from Stations outside the Area 
 affected by Sewage from New Bedford. 
 
 Aug. 9, 1916. 
 
 
 Hours 
 after 
 Dis- 
 charge. 
 
 Dis- 
 tance 
 
 from 
 Outlet 
 (Miles). 
 
 Dis- 
 tance 
 
 from 
 Outlet 
 (Feet). 
 
 Parts in 100,000. 
 
 Bacteria 
 
 Station. 
 
 Free 
 
 Ammo- 
 
 ma. 
 
 Total 
 Albu- 
 minoid 
 Am- 
 monia. 
 
 Chlo- 
 rine. 
 
 Cubic 
 Cen- 
 timeter, 
 
 11, 
 12, 
 
 0.77 
 1.18 
 
 0.61 
 0.65 
 
 3,200 
 3,400 
 
 .0100 
 .0120 
 
 .0145 
 .0160 
 
 1,740.0 
 1,722.5 
 
 - 
 
 
 
 Sept. S4, 1915. 
 
 
 
 
 
 13, . 
 
 0.53 
 
 1.17 
 
 6,180 
 
 .0025 
 
 .0125 
 
 1,750.0 
 
 25 
 
 14, 
 
 2.17 
 
 1.00 
 
 5,280 
 
 .0060 
 
 .0165 
 
 1,750.0 
 
 99 
 
 15, 
 
 2.87 
 
 0.61 
 
 3,200 
 
 .0025 
 
 .0095 
 
 - 
 
 65 
 
 16, ,.,.,. 
 
 3.03 
 
 1.25 
 
 6,580 
 
 .0065 
 
 .0140 
 
 - 
 
 163 
 
 TMe showing Results of Analyses of Water in the Path of the Sewage from the 
 
 Swampscott Sewer Outlet. 
 
 July 19, 1915. 
 
 A (outlet), 
 6, . 
 
 8, . ^' ' t... 
 
 0.83 
 2.07 
 2.90 
 
 0.310 
 0.470 
 0.630 
 
 1,600 
 2,500 
 3,300 
 
 .0758 
 .0085 
 .0045 
 .0085 
 
 .0125 
 .0125 
 .0170 
 
 1,648.8 
 1,690.0 
 1,700.0 
 1,690.0 
 
 .'/f .v.' 
 
 Oct. 1, 1915. 
 
 A (outlet). 
 
 - 
 
 
 - 
 
 .1264 
 
 .0417 
 
 ' 1,702.5 
 
 99,750 
 
 1, . 
 
 0.18 
 
 0.028 
 
 150 
 
 .0405 
 
 .0320 
 
 1,700.0 
 
 38,800 
 
 2, 
 
 0.68 
 
 0.057 
 
 300 
 
 .0330 
 
 .0370 
 
 1,725.0 
 
 21,500 
 
 3, . 
 
 1.18 
 
 0.250 
 
 1,300 
 
 .0127 
 
 .0225 
 
 1,750.0 
 
 2,400 
 
 4, . 
 
 1.68 
 
 0.310 
 
 1,600 
 
 .0033 
 
 .0140 
 
 1,765.0 
 
 13 
 
 S, 
 
 2.18 
 
 0.390 
 
 2,100 
 
 .0030 
 
 .0130 
 
 1,740.0 
 
 66 
 
34 
 
 Tahh showing ResvMs of Analyses of Water collected from Stations otdside the 
 Area affected by Sewage from Swampscott. 
 
 July 19, 1915. 
 
 
 Hours 
 after 
 Di9- 
 
 obaTge. 
 
 Dis- 
 tance 
 
 from 
 Outlet 
 
 (MUes). 
 
 Dis- 
 tance 
 from 
 Outlet 
 
 (Feet). 
 
 Parts in 100,000. 
 
 Bacteria 
 
 Station. 
 
 Free 
 Ammo- 
 nia. 
 
 Total 
 Albu- 
 minoid 
 Am- 
 monia. 
 
 Chlo- 
 rine. 
 
 Cubic 
 Cen- 
 timeter. 
 
 9, . . ; . 
 
 10, ■■'.'■ 
 11, 
 
 2.32 
 0.32 
 
 0.360 
 
 o.i4o 
 
 1.570 
 
 1,900 
 
 740 
 
 8,300 
 
 .0050 
 .0055 
 .0035 
 
 .0085 
 .0110 
 .0110 
 
 1,608.0 
 1,700.0 
 1,700.0 
 
 _ 
 
 1 Eleven minutes before. 
 
 
 
 Oct.l 
 
 , 1915. 
 
 
 
 
 
 12, . . 
 
 2.12 
 
 0.390 
 
 2,100 
 
 .0045 
 
 .0100 
 
 1,740.0 
 
 
 
 13, 
 
 2.33 
 
 0.210 
 
 1,100 
 
 .0025 
 
 .0100 
 
 1,810.0 
 
 22 
 
 14, . 
 
 2.43 
 
 0.230 
 
 1,200 
 
 .0015 
 
 .0100 
 
 1,760,0 
 
 
 
 Comparing the various sea outfalls where sewage is dischargeid into 
 deep water, especially those of the south metropolitan district, New 
 Bedford and Swampscott, it is found that the dilution of the sewage 
 by the time it reaches the surface of the sea is very great, amounting 
 so far as shown by the albuminoid ammonia, to about 85 per cent, 
 in the case of the south metropolitan outlet at Nut Island, where the 
 quiantity discharged at a single outlet amounts to 2,500,000 gallons 
 per hour, to 98 per cent, in the investigations conducted at Swamp- 
 scott, where the discharge during the period of observation was at the 
 rate of 3,000,000 gallons per day, and to 94 per cent, at New Bedford. 
 These comparative results are shown in the following table: — 
 
Missing Page 
 
Missing Page 
 
35 
 
 
 SQ 
 
 
 
 a 
 
 ■l^AomsH 
 
 CO 
 
 g s 
 
 A t 
 
 1 
 
 
 
 ■»tjeo J9J 
 
 O 
 
 o» 
 
 
 
 ■no}»no isAo 
 
 i 
 
 ii 
 
 d d 
 
 s s 
 
 d ^ 
 
 g 
 
 
 
 a 
 a; 
 
 i9?«AV rag 
 
 o 
 
 % 
 
 
 
 e. 
 
 ° S 
 
 es o 
 
 
 
 1 
 
 S 
 a 
 
 •sSBjiag 
 
 1 
 
 O CO 
 
 i i 
 
 
 
 
 S 
 
 
 <o 
 
 eii d 
 
 11 iflj 
 
 
 
 
 
 
 
 
 
 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 •JBAOtaB^ 
 
 00 
 
 □0 «o 
 
 03 1 
 
 . 
 
 
 1 
 
 1 
 
 a 
 
 ■ijnao jaj 
 
 Q> 
 
 o n 
 
 Oi 
 
 
 
 
 
 t* 
 
 U3 o 
 
 U3 O 
 
 
 
 
 S 
 
 ■nenno 13A0 
 
 d 
 
 
 S 3 
 
 
 
 
 ^ 
 
 jaiOAV «9g 
 
 d d 
 
 2 s. 
 
 1 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 ^ 
 
 o o 
 
 o o 
 
 
 
 
 
 
 
 
 (?q w 
 
 
 
 
 S 
 
 ■sSBJiag 
 
 ^ 
 
 CO U9 
 
 1 
 
 
 
 
 
 US 
 
 »H d 
 
 i-i d 
 
 
 
 
 ■{BAoniau 
 
 o 
 
 US o> 
 
 o 1 
 
 « 
 
 
 •IHI90 M.! 
 
 a> 
 
 oo r> 
 
 00 
 
 to 
 
 
 
 04 
 
 OS ^ 
 
 oo VA 
 
 l_j 
 
 
 
 •IIBntlO J8A0 
 
 j9?Oj)A Bag 
 
 d 
 
 d d 
 
 5 S- 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■a3BAi.Bg 
 
 t- 
 
 Tt< l-t 
 
 § 1 
 
 « us 
 
 d 
 
 
 o 
 
 
 '^ 
 
 d d 
 
 •■» 3 
 
 «o 
 
 
 
 
 
 a> 
 
 '■1 
 
 1 1 
 
 ■* 
 
 
 
 ■unsQ raj 
 
 OS 
 
 =■ 'r. 
 
 t 
 
 «o 
 
 
 
 t^ 
 
 ^ 04 
 
 ^ to 
 
 Q 
 
 
 
 
 o 
 
 eg o> 
 
 CO 
 
 
 
 
 n 
 
 "n^wo «'^<' 
 
 s 
 
 o o 
 
 O l> 
 
 *! 
 
 
 
 g 
 
 »WM«aS 
 
 
 d d 
 
 "=» s 
 
 
 
 
 IM 
 
 C4 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 o 
 
 s 
 
 ■aaejuag 
 
 00 
 
 1 
 
 1' 
 
 [ 
 
 
 
 
 '-' 
 
 o ' 
 
 ' us 
 
 
 
 
 
 
 
 
 
 
 
 ■IBAOuiag 
 
 CIS 
 
 ■* 1 
 
 I , 1 
 
 1 
 
 
 § 
 
 ■»U90 Jaj 
 
 OS 
 
 o» 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 
 
 «o 
 
 
 o o 
 
 
 
 
 
 t> 
 
 
 C4 
 
 
 
 
 M 
 
 ipono MAO 
 
 ^ 
 
 o o 
 
 3 O 
 
 
 
 
 1 
 
 la^BAi Bag 
 
 d 
 
 d d 
 
 d ^ 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 3 
 
 
 s 
 
 g 
 
 ,o 
 
 
 
 
 
 'aSB^ag 
 
 ^ 
 
 ^ 1 
 
 1 
 
 1 
 
 
 
 
 '^ 
 
 o ' 
 
 a, 
 
 
 
 
 
 
 .9 .9 
 
 a 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 1 
 
 B . 
 
 
 
 
 
 
 & 5 
 
 .3 
 
 
 
 
 
 
 ^-' _2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 
 
 1 
 
 i i 
 1 i 
 
 1 .'i 
 
 2 S. 
 1 i 
 1 " 
 
 i 
 .s 
 
 
 
 
 
 %li 
 
 A 
 
 
 
 
 
 Bs'is 
 
 
 1 
 
 
 
 
 
 H n 
 
 oa' O 
 
 n 
 
 '-5 -a 
 
36 : 
 
 Furthermore, by setting off floats at the various outlets and taking 
 sauries along the path taken by the sewage, as indicated by the 
 floats, it was found that the quantity of organic matter attributable to 
 sewage in the water into which the sewage is discharged, so far as 
 shown by chemical analysis, falls within a period of less than an 
 hour after the discharge of the sewage to an amount comparable with 
 that found in waters bordering populous shores distant from sewer 
 outlets and in waters adjacent to bathing beaches used by large num- 
 bers of people. 
 
 The results of the experience with the various systems of sewerage in 
 the State having outlets into the sea show conclusively that this 
 method of disposal may result in great nuisances where large quanti- 
 ties of sewage are discharged near the shores and in shallow waters. 
 Even when discharged into large tidal volumes the sewage, if dis- 
 charged at the surface, may spread over a considerable area before 
 becoming thoroughly diffused in the water of the sea. But where the 
 sewage is discharged at the bottom of the sea in depths of 30 feet 
 or more of water, where the tidal volume is at all times ample for the 
 dilution of the sewage, the sewage mingles rapidly with the sea water, 
 becoming diluted by the time it reaches the surface of the sea to an 
 extent comparable in degree of purification with that effected by the 
 most efficient methods of sewage disposal. Even when large quantities 
 of sewage are discharged at one point, as at Nut Island in Boston 
 Harbor, the area of surface of the sea over which the sewage can be 
 seen reaches less than half a mile from the outlet, and beyond that 
 distance the effect upon the waters of the sea, as shown by chemical 
 and bacterial analysis, is no different from that which is caused by 
 other conditions, such as pollution from shipping and the natural 
 washings from populated shores. 
 
 Pkacticabilitt of a Deep-sea Outlet fok the City of Lynn. 
 
 Much time and study have been devoted to finding a suitable 
 location for a sea outlet for the disposal of the sewage of the city of' 
 Lynn which would fulfill most economically the conditions required 
 for the efficient disposal of the sewage of the city by this method 
 as shown by experience at sewer outlets already in successful use. 
 The nearest point in the ocean, measuring from the landward end of 
 the present outfall sewer, at which the depth of water at low tide 
 reaches 30 feet is found in the bay between Swampscott and Nahant, 
 distant in a straight line and in an easterly direction from the shore 
 at the present outlet about 11,200 feet, or 2.1 miles. Beyond the 
 point at which the 30-foot sounding is reached the water grows rapidly 
 
37 
 
 -deeper, attaining a depth of 60 feet in a further distance of 0.6 of a 
 mile. It is also practicable to reach a point in the sea where the depth 
 -of water equals 30 feet in a southerly direction from the present outlet 
 at a distance of about 15,000 feet, or 2,8 miles, from the shore at the 
 present outfall. 
 
 In the former case the construction of an outfall sewer to divert the 
 sewage from the present intercepting sewers to an outlet in the bay 
 between Swampscott and Nahant would involve much difficulty and 
 probably a very considerable expense. The most direct route would 
 lie across the present harbor front and thence across the Nahant 
 peninsula and beach to deep water. The greater part of the length of 
 the sewer would have to be laid in the bay, which is exposed directly 
 to the open sea in the direction from which storms cpmmonly blow on 
 this coast and would be a most difficult place in which to carry on 
 the necessary work. 
 
 In the other case the sewer would be laid down the harbor in a 
 southerly direction protected from easterly and northeasterly storms 
 except near the outer end. Considering the conditions, there is no 
 doubt that the latter route would be the more practicable and less 
 ■expensive notwithstanding its greater length. Furthermore, judging 
 from a limited number of float experiments in Nahant Bay, the cur- 
 rents are uncertain, and while a suitable outlet for the sewage of 
 Lynn could doubtless bie found there, it would very probably be neces- 
 sary to locate the outlet at as grea;t a distance from the present out- 
 fall as would be necessary in case the sewage were conveyed to a 
 suitable outlet south of the harbor entrance. We have accordingly 
 -iarestigated carefully the conditions in Lynn Harbor and adjacent 
 waters to determine whether a favorable location for an outlet for the 
 sewage can be found in that region which fulfills the conditions which 
 have been found most favorable for the satisfactory disposal of sewage 
 by discharge into the sea. 
 
 The harbor of the city of Lynn contains extensive areas of flats, the 
 total area exposed at low tide inside of a line drawn from Point of 
 Pines to Black Rock amounting to 830 acres, or 67.2 per cent, of the 
 total area at low water. Two main channels traverse this area, — one 
 along its easterly side leading to the principal wharves with a branch 
 running to the gas works, and the other ?.long the westerly side to the 
 Pines and Saugus rivers with a shallow branch channel leading to 
 the neighborhood of the present sewer outlet. 
 
 The very thorough studies of the Commission on the Investigation 
 •of Lynn Harbor show conclusively that there is -no practicable loca- 
 tion for a sewer outlet in any of the harbor channels at which the 
 
38 
 
 sewage can be discharged without treatment at all stages of the tide 
 with satisfactory results. The tests of the movements of the tides 
 made under their direction at various points in and near the Saugus 
 River channel, and at points in the main channel within 1,500 feet of 
 the present outlet, indicate clearly that, with incoming tides, sewage 
 discharged at any of the points at which tests were made would 
 return upon the flats or adjacent shores and create objectionable 
 conditions. In consequence of the results of these investigations it 
 was recommended that the sewage be stored on the incoming tide and 
 discharged only on the outgoing tide and that it be treated for the 
 removal of suspended matter. 
 
 Float tests were also made by the commission to learn the movement 
 of tides in the outer harbor at a point a little less than a mile westerly 
 from the most northerly pier at Bass Point, Nahant, where the depth 
 of water at low tide is about 20 feet, and at a second point about 
 1,700 feet south of the first, where the depth at low water is 26 feet. 
 Floats discharged at the former location on the incoming tide, with a 
 southwest wind blowing toward Nahant, traveled up the harbor in a 
 northerly direction along the main ship channel at a rate of about 0.6 
 of a mile per hour. At the more southerly point floats started between 
 one and two and one-half hotirs after low tide, with a strong southwest 
 wind blowing 11 to 17 miles per hour directly toward Nahant, moved 
 up the main ship channel in a northerly direction, following a similar- 
 course to those set off at the more northerly point and moving at about 
 the same rate. Floats started at this point from one and one-half 
 to two hours after low tide, with a strong southeasterly and southerly 
 wind, moved in a northwesterly direction for about one and one- 
 quarter hours and then in a northeasterly direction along the Point 
 of Pines channel. These floats moved with an average velocity of 
 about 0.68 of a mile per hour. 
 
 Floats started at the same point at high water, with a southwest 
 wind 7 to 10 miles per hour, traveled to sea in a southeasterly direc- 
 tion at a rate of 0.40 of a mile per hour, and the floats followed the 
 same course with westerly and northwesterly winds. With easterly 
 winds, floats set off at this point after high water moved in a southerly 
 direction at a rate of 0.37 of a mile per hour. 
 
 Further tests have been made under our direction of the movement 
 of floats set off from other points in this vicinity. In these experi- 
 ments three types of floats were used and are designated as surface 
 floats, short floats and long floats. The surface floats consisted of 
 small pieces of wood If inches wide by five-eighths inches thick and 
 8 inches long, which floated on the surface of the water. The short. 
 
Missing Page 
 
Missing Page 
 
39 
 
 floats were of wood If inches square in cross-section and 2 feet, 3| 
 inches long, weighted on the bottom so as to float upright with 1 to 2 
 inches out of the water, with a flag 4 by 6 inches attached to the 
 top. The long floats were 2 by 4 inches in cross-section and 6 feet 
 long, weighted so as to float upright with 4 inches above the water, 
 and also had a 4 by 6 inch flag attached. 
 
 Surface and short floats designed to determine more particularly the 
 force and direction of the surface currents and the influence of the 
 wind were launched at low tide at a point 3,600 feet due west of 
 the most northerly pier at Bass Point, at a point where the water is 
 20 feet in depth at low tide, at a time when a southwest wind was 
 blowing at a rate of about 10 miles per hour. These floats moved 
 toward the main ship channel at a rate of 0.57 of a mile per hour, 
 and other floats of the same kind started later followed the same 
 course at a slightly less rate. With a high northwest wind floats 
 started from the same point after high tide passed southeasterly to sea, 
 the surface floats traveling at a somewhat greater rate than the deeper 
 ones. With northeast winds, 8 to 13 miles per hour, floats started 
 at this point after high tide moved southerly and southwesterly to 
 the open bay at rates of from 0.35 to 0.50 of a. mile per hour. With 
 east and southeast winds blowing at a rate of from 7 to 12 miles per 
 hour, floats launched at this point at high water traveled in a south- 
 westerly direction to sea at rates of about 0.25 of a mile per hour. 
 Floats launched at low water under similar conditions moved westerly 
 and northerly to the Point of Pines channel at a rate of about 0.50 
 of a mile per hour, a rate which required four hours for the floats to 
 arrive opposite the Point of Pines. Surface floats started at a point 
 2,500 feet to the west after low tide, under the influence of a strong 
 northeasterly wind, traveled in a westerly direction at slower rat^s. 
 
 The results of these tests show conclusively that if sewage were dis- 
 charged at some point oil the mouth of the harbor from two-thirds of a 
 mile to a mile west of Bass Point, there would be no tendency under 
 any conditions of wind or tide for the currents into which the sewage 
 would be discharged to convey it in the direction of Bass Point or any 
 portion of the shores in that region. The currents which pass the 
 locality indicated on the incoming tide, whatever the direction of the 
 wind may be, run toward the main harbor channels, and on the out- 
 going tide toward the sea. 
 
 The most favorable location for a sewer outlet in this region is at or 
 near a point about 3,500 feet southwest of Bass Point and where the 
 rates of flow of the currents, as determined both by the United States 
 engineers in earlier studies and in the more recent tests, range from 
 
40 
 
 0.30 to 0.70 of a mile per hour under varying conditions, with an aver- 
 age of about 0.50 of a mile per hour. At this rate, if sewage were dis- 
 charged at the point indicated, the water into which it flows would 
 require more than three hours to reach any shore toward which these 
 currents at any time flow, and more than" two hours to reach any 
 harbor flat exposed at low tide. 
 
 The conditions with regard to the velocity of tides and currents at 
 each of the deep-sea outlets, and the volume of water of the estuary 
 into which the sewage is discharged, are shown in the following table: -^ 
 
 ClTT. 
 
 Locality, 
 
 Average 
 Velocity 
 of Ebb 
 Tide 
 (Miles per 
 Hour). 
 
 Average 
 
 Flow of 
 
 Ebb Tide 
 
 (Cubic Feet 
 
 per Second), 
 
 Boston, . 
 
 Lynn, 
 
 New Bedford, . 
 
 Deer Island outlet, 
 
 Nut Island outlet. 
 
 Moon Island outlet. 
 
 Inner harbor between Point of Pines and Sandy 
 
 Point. 
 Outer harbor between Bass Point and Revere, . 
 
 Sewer outlet off Clark's Point, 
 
 2.50 
 0.95 
 0.74 
 0.55 
 0.45 
 0.38 
 
 269,000 
 200,000 
 72,000 
 18,000 
 194,000 
 218,000 
 
 Comparing the tidal conditions in the location indicated for an out- 
 let outside of Lynn Harbor with those found at existing main outlets 
 into the sea, it appears that the velocity of the currents is less at 
 Lynn than at the Nut Island outlet but greater than at New Bedford. 
 Comparing the volumes of water about the outlet into which the 
 sewage flows at the various points of discharge, the quantities are 
 much the same at Lynn as at Nut Island and New Bedford. 
 
 The rapidity with which sewage diffuses in the water when dis- 
 charged at a depth of 30 feet or more into tidal reaches of large volume 
 has already been shown by the investigations at outlets already in use, 
 and if the sewage of Lynn should be discharged continuously at the 
 point herein indicated, where the water is 30. feet deep at low tide and 
 the tidal volume is great, there is no reason to anticipate a different 
 result. It has already been shown that the sea water beyond a dis- 
 tance of half a mile from the Nut Island outlet, where the quantity 
 of sewage discharged is more than four times the dry-weather flow 
 from the sewers of Lynn, contains no greater evidences of pollution 
 than are found in the waters near populated shores where no sewage 
 is discharged and in the waters along the beaches used for bathing by 
 large numbers of persons, and that the sewage discharged from the 
 
41 
 
 New Bedford outlet, where the conditions are in all respects similar 
 to those at Lynn, is noticeable by chemical and bacterial tests only 
 •within a few hundred feet of the outlet. 
 
 Judging from these experiences, taken in connection with the in- 
 vestigations at Lynn, it is not to be doubted that sewage discharged 
 at the point indicated would become quickly diffused in the water 
 of the sea and disappear long before the water could reach any shore 
 or flat exposed at low tide. 
 
 We have no hesitation in reaching the conclusion that the sewage of 
 the city of Lynn can be disposed of more effectively and satisfactorily 
 by discharging it at the bottom of the sea in the location indicated, 
 viz., 3,500 feet southwest of Bass Point, continuously as it flows from 
 the sewers without preliminary treatment, than by any other method 
 that it is practicable to adopt, until the quantity of sewage requiring 
 disposal becomes much greater than can be discharged by such works 
 as it seem^ reasonable to construct at the present time. 
 
 Works required for the Disposal of the Sewage. 
 
 Various routes have been considered for an outfall sewer to convey 
 the sewage to the locality deemed most favorable for its disposal 
 and of these the shortest seems likely to be the most economical. 
 By the shortest route the sewer would be laid nearly in a straight line 
 from the neighborhood of the junction of the present east and west 
 intercepting sewers to the location of the proposed outfall and would 
 require the construction of an outfall sewer 15,000 feet in length. The 
 head required for the conveyance of the sewage to this outlet would 
 1)6 too great to admit of its operation by gravity and serve all sections 
 of the city, and in order to deliver all of the sewage a;t this outlet 
 pumping will be necessary. 
 
 'A portion of the city is undoubtedly high enough to admit of the 
 discharge of the sewage by gravity at the proposed outlet without 
 pumping, and' the practicability of disposing of the sewage of these 
 higher levels by gravity, and pumping only that from the lower areas, 
 has received careful consideration. The area of the city in which the 
 height of the sewers is above grade 40, or 25 feet above the- highest 
 tides, comprises about 2.5 square miles, or about 60 per cent, of the 
 total area served by the sewers of the city at the present time. This 
 area is about 1.57 miles long in an easterly and westerly direction and 
 varies from 1.00 mile to 2.27 miles in width. The sewers which drain it 
 slope in various directions, and in order to collect this sewage sepa- 
 rately and to convey it to the outfall sewer by gravity, long lines of 
 intercepting sewers would be required which would necessarily be 
 
42 
 
 operated under pressure beneath the streets of the city, an arrange- 
 ment which appears to be undesirable at the present time. Further- 
 more, the cost of the works for conveying the sewage of these areas 
 to the outfall sewer by gravity would undoubtedly be greater than 
 the cost of pumping the sewage in connection with that of other por- 
 tions of the city. In the future development of the sewerage system 
 of the city a practicable plan may perhaps be worked out for deliver- 
 ing a part of the sewage of the higher areas to the outfall sewer by 
 gravity at a saving in cost over that of pumping the sewage, and in 
 that case the sewage of the higher areas can doubtless be delivered to 
 the main outfall and disposed of by gravity without serious diflBculty. 
 
 The sewers of the city of Lynn are constructed upon the combined 
 plan receiving both sewage and storm water, and the conveyance of 
 all of the sewage flowing in the sewers at times of storm to the pro- 
 posed outlet would be impracticable and, so far as preventing a 
 nuisance in the harbor is concerned, unnecessary. The combined 
 capacity of the present intercepting sewers is, as already stated, about 
 81,000,000 gallons per day, and in excessive rains the sewers are some- 
 times surcharged, especially when a heavy rain occurs at a time of 
 high tide. The outfall works should be large enough to remove a por- 
 tion of the excess of flow at times of rain in addition to the dry- 
 weather flow of sewage. A portion of the mingled sewage and storm 
 water at times of rain can be allowed to discharge in the neighbor- 
 hood of the present outlet without danger of creating objectionable 
 conditions, but the disposal works should be large enough to prevent 
 the overflow of sewage in ordinary rains. 
 
 The provision made for the removal of storm water by the Boston 
 main drainage works amounts to one-quarter of an inch of rain in 
 twenty-four hours over the entire area tributary to the sewers, and 
 this provision has been sufiicient in general to prevent objectionable 
 conditions at overflow outlets discharging into the tidal waters about 
 the city. Such a provision, if applied to the city of Lynn, would 
 require the removal of about 19,000,000 gallons per day of storm 
 water in addition to the dry-weather flow of sewage from the 4.3 
 square miles of sewered area, a total of 31,000,000 gallons per day. 
 With the growth of the city this provision would have a tendency to 
 grow less as the quantity of sewage proper increases and a further 
 allowance is necessary to provide for future growth. 
 
 The population of the city of Lynn has increased from 28,233 in 
 1870 to 89,336 in 1910, or 61,103. The increase in the forty years 
 from 1875 to 1915 was 63,203. If the city should grow at the rate at 
 which it has grown from 1870 to 1915, its population forty years hence 
 
43 
 
 — that is, in 1956 — would be approximately 160,000. This figure 
 seems to be a reasonable estimate of the future growth of the city 
 within the period indicated so far as can now be foreseen. 
 
 Considering the circumstances it is reasonable to assume that the 
 dry-weather flow of sewage will double in the next forty years, and, 
 as the quantity of sewage to be disposed of increases, the capacity of 
 the system for storm water will diminish. The sewers are now ex- 
 tended to somewhat more than one-half of the area of the city avail- 
 able for settlement, and if sewers in the areas hereafter added to the 
 system should be built upon the combined plan, the storm water from 
 an additional area would be brought to the system and the amount 
 of storm water that could be removed in proportion to the whole area 
 would be decreased. It seems safe to assume, however, that as 
 new areas are developed they will be provided with sewers on the 
 separate plan, since that method is not only likely to prove by far the 
 most economical in the future development of the city but also essential 
 if the objectionable pollution of local waters by sewage is to be pre- 
 vented. It will probably be found desirable also to diminish the 
 quantity of storm water admitted to the present sewers. Consider- 
 ing all the circumstances an allowance for the removal by the disposal 
 system of one-half an inch of rain in twenty-four hours over the area 
 at present tributary to the sewers, in addition to the dry-weather flow 
 of sewage, will be a liberal one under present conditions and a greater 
 provision than it would be practicable to make in connection with 
 any system of treatment works without adding materially to the ex- 
 pense of their construction and operation. With such a provision the 
 total number of overflows that would take place during rain storms 
 in an average year would probably average from two to three per 
 month, and the quantity of mingled sewage and storm water dis- 
 charged would of course be much less than the amount being cared for 
 at the same time at the outfall works. The occasional discharge of 
 small quantities of dilute sewage at the present outlet would be un- 
 likely to cause objectionable conditions at any time. 
 
 We have accordingly planned a system of outfall works capable of 
 removing the present dry-weather flow of sewage and an added flow 
 equivalent to one-half an inch 'in depth of rain upon the area now 
 provided with sewers, making a total quantity requiring disposal at the 
 present time of about 50,000,000 gallons per day. This provision will 
 not only be sufficient for present needs but adequate for many years in 
 the future if the sewers in areas hereafter added to the system Are 
 constructed on the separate plan and all storm water and ground 
 drainage so far as practicable excluded therefrom. 
 
44 
 
 Outfall Works. 
 
 The most favorable location for a pumping station to discharge the 
 sewage at an outlet southwest of Bass Point is upon land now owned 
 by the city through which the main outfall sewer now passes to the 
 present point of discharge. Investigations show that a pumping sta- 
 tion can be located east of the main sewer adjacent to the present 
 right of way and the sewage from the outfall sewer diverted thereto 
 without difficulty. The outfall sewer or force main from the pumping 
 station to the proposed outlet could probably best bs laid in a straight 
 line across the harbor, the distance being 15,000 feet as measured from 
 the coast survey charts. 
 
 A pipe 60 inches in diameter will be adequate for conveying 
 50,000,000 gallons of sewage to this outlet whenever in considerable 
 storms the flow in the sewers equals that amount, without excessive 
 loss of head by friction, and should be adequate for many years in 
 the future. The question of constructing a larger pipe in the beginning 
 has been considered but appears unnecessary under existing conditions. 
 It has not been practicable within the time available to make thorough 
 soundings along the line of the proposed outfall sewer to deternline 
 the character of the material likely to be encountered, in the course 
 of its construction. Such borings in Lynn Harbor as are available, 
 however, indicate that the material will consist for the most part of 
 sand and clay with occasional bowlders. 
 
 If the sewer is built in a straight line from the present outfall to the 
 proposed new outlet it will cross the branch harbor channel leading 
 from the Saugus River channel to the gas works and will cross the 
 main harbor channel near its outer end. The depth of water in the 
 channel at the gas works at the present time is 4 feet at low tide and 
 in the outlet channel 14 to 19 feet. Since it is probable that these 
 channels will be deepened in the future it is necessary to make some 
 allowance for these enlargements. 
 
 Plans have been made for a main channel of 35 feet depth in Lynn 
 Harbor, but the construction of the main channel to that depth seems 
 unlikely at least in the near future. The outlet pipe can be so laid as to 
 avoid crossing the outlet channel until the neighborhood of the outlet 
 is reached, but this would involve the construction of a somewhat longer 
 sewer. Considering the circumstances, we have estimated that the 
 main sewer will be laid in a straight line and at sufficient depth to 
 allow for the deepening of the branch channel leading to the gas works 
 to a depth of 15 feet and the main harbor channel to a depth of 35 
 feet. The possibility of difficulty in the operation of the main sewer 
 
45 
 
 due to lowering the grade in passing under these channels has been 
 considered, but such difficulty is unlikely and in any case could be 
 easily remedied. The outfall works then will consist of a new main 
 sewer to replace the present structure laid from the junction of the 
 present east and west intercepting sewers to a point 120 feet easterly 
 therefrom, at the terminus of which will be placed a gate to regulate 
 the flow when desired and a back-water gate to keep out the tide. 
 Beyond this latter gate the sewer will connect with the present outfall 
 for the discharge of storm water. From this sewer just above the gate 
 a branch sewer will be laid to the pumping station, a distance of 58 
 feet. At the upper end of this sewer a gate is provided for regulating 
 the flow whenever necessary.. The design of thip pumping station 
 provides for screening the sewage through coarse screens formed of 
 bars set three-quarters of an inch ap^rt before it passes to the pumps. 
 The screen is intended to arrest only the larger matters which might 
 interfere with the operation of the pumps. Where sewage is collected 
 in a comparatively large system and passed through pumps, as will 
 be necessary in this case, there is unlikely to be serious visible evi- 
 dence of sewage matter at the sewer outlet* and further screening than 
 that suggested does not appear to be necessary at the present time. 
 If preliminary treatment of the sewage before discharge should ever 
 be found desirable in the future, screens can be installed in connection 
 with . the works here proposed, but in case preliminary treatment is 
 necessary it is probable that tank treatment would be found more 
 efficient and economical. The design provides for four pumps, two of 
 which designed for the removal of the dry-weather flow will have a 
 4bpacity of about 13,000,000 gallons per day each and two a capacity 
 of about 29,000,000 gallons each, so that three pumps working together 
 will always be adequate for the removal of as much as 50,000,000 
 gallons per day. , 
 
 The pumping works have been designed for the use of electric 
 power which can apparently be obtained from the adjacent electric 
 light company's works at a reasonable cost. The motors are placed 
 at sufficient height to prevent danger of injury from flooding or from 
 an excessively high tide, and the design includes provision for the 
 ready removal of the machinery whenever necessary or desirable for 
 renewal or repairs. A Venturi meter has been provided for in the 
 plan to be placed just beyond the pumping station, so that the quan- 
 tity of sewage pumped can be readily ascertained and the cost of the 
 work determined. Allowance has been made in the plan of the force 
 main for a second pipe to the sea should an additional outlet be- 
 comes necessary or desirable in the future. 
 
46 
 
 The design of the works has been carried far enough to furnish a 
 safe basis for an estimate of cost. It is possible that further and more 
 thorough studies than it has been practicable to make within the time 
 available might show that a steam plant would have advantages in 
 economy over the works herein suggested, and while this is very 
 doubtful further consideration of this question may be desirable in the 
 final design of the works. 
 
 Estimate of Cost. 
 
 In preparing the estimates of cost for the work we have considered 
 the cost of laying such outlets as have thus far been constructed for 
 cities and towns in Massachusetts. These costs, where the sizes of 
 pipe have been the same as proposed for the city of Lynn, have shown 
 very little difference, the maximum differences amounting to not 
 more than 13 per cent. The conditions at these outlets have been 
 compared with those at Lynn, the results indicating that a large part 
 of the Lynn outlet will probably be constructed under more favorable 
 conditions for doing such work than is the case at most of the outlets 
 thus far constructed. Near the outer end the work will be more ex- 
 posed but no more so than some portions of the outlets at other places. 
 
 Estimate of Cost. 
 
 Laj'ing 9,000 feet at $20, . . $180,000 
 
 Laying 6,000 feet at $25, 150,000 
 
 Construction of outlet, .... 7,000 
 
 Cost of pipe, $16 per foot, . . 240,000 
 
 Total,. . . $577,000 
 
 Pumping station, pumps, machinery and appurte- 
 nances. 
 Reconstruction of present sewer to outfall. 
 Force main to connect with outfall sewer, 
 OutfaU from shore to gate on force main, 
 Venturi meter, .... 
 
 Total ... 
 
 Add 15 per cent, for engineering and contingencies, 
 
 Total, 
 
 Estimated annual cost of maintenance, 
 
 $96,200 
 4,200 
 6^00 
 2,700 
 3,300 
 
 
 
 112,700 
 
 
 $689,700 
 103,455 
 
 
 $793,155 
 $9,000 
 
Missing Page 
 
Missing Page 
 
47 
 
 Conclusions and Recommendations. 
 
 As a result of the investigations of various methods of sewage dis- 
 posal and their applicability to the problem under consideration, we 
 have no hesitation in reaching the conclusion that the sewage of the 
 city of Lynn can be disposed of more effectively and satisfactorily by 
 discharging it at the bottom of the sea m 30 feet or more of water off 
 the mouth of Lynn Harbor continuously as it flows from the sewers 
 and without preliminary treatment than by any other available 
 method. 
 
 Other methods might be used, and the applicability of each to the 
 conditions found at Lynn has been given careful consideration. The 
 first cost of works for chemical precipitation might be less than the 
 cost of an outlet into the sea if a suitable location for such works 
 could be found, but the effluent from such works is not suitable for 
 discharge into the harbor unless it were stored and discharged on the 
 outgoing tide or /conveyed to a point of discharge located at a con- 
 siderable distance beyond the present outlet. The cost of maintenance 
 of such works, however, would be several times as great as the cost of 
 a sea outlet, and the net annual cost to the city of this method of dis- 
 posal would be much greater than by the plan herein recommended. 
 
 The disposal of the sewage by any of the various filtration methods 
 would require an outlay for the initial works as great as that for a 
 proper sea outlet, and the cost of maintenance would be several times 
 as great as the cost of pumping all of the sewage to sea. 
 
 None of the other partial treatments such as screening or sedimenta- 
 tion would improve the character of the sewage sufficiently to admit 
 of its discharge into any water in the immediate neighborhood of 
 the city without the probability of creating a nuisance. 
 
 Finally, in our opinion, there is no area within the limits of the 
 city of Lynn or in its immediate neighborhood where it is practicable 
 to dispose of the sewage by any of these plans without causing offence 
 to the inhabitants living in the neighborhood of the works. 
 
 On the other hand, the experience at each and all of the sewer 
 outlets in Massachusetts where the sewage is discharged at the bottom 
 of the sea in a depth of 30 feet or more of water at low tide, and where 
 the volume of water passing the outlet is ample for its proper dilution, 
 shows that the sewage is in all cases diluted before reaching the sur- 
 face of the sea to an extent comparable with the purification effected 
 by the best methods of treatment that have thus far been developed 
 for the disposal of sewage. The studies of the tidal currents and 
 volumes off the mouth of Lynn Harbor show that favorable conditions 
 
48 
 
 for such an outlet can be reached at a point about 3 miles south of the 
 shore line near the present outlet and about 3,500 feet southwest of 
 the southerly end of Bass Point. Tests of the direction of, the currents 
 in this region by means of floats show that on the incoming tide the 
 current sets toward the harbor entrance and on the outgoing tide 
 directly to sea. Experience at other sewer outlets shows that, under 
 the conditions found in this neighborhood, the sewage would become 
 quickly diffused in the water and under ordinary conditions would be 
 unrecognizable beyond a limit of less than one-third of a mile from the 
 outlet, that is, long before it could reach any inhabited shore or any 
 flat exposed at low tide. 
 
 While a large section of the city of Lynn is situated at a sufiicient 
 elevation to admit of the discharge of the sewage at the proposed sea 
 outlet by gravity, it will be necessary to pump the sewage of the lower 
 areas, which probably supply more than half the entire quantity of 
 sewage at the present time. In order to convey the sewage of the 
 higher portions of the city to the proposed outlet by gravity, it would 
 be necessary to. lay a line of main sewer with branches which would 
 be operated under pressure beneath the streets of the city, and the 
 investigations indicate that the cost of these works would probably be 
 greater than the cost of pumping the sewage of the higher areas in 
 connection with that from the lower areas. In view of the probably 
 greater cost of delivering the sewage of the higher areas to the outlet 
 by gravity, and the undesirability of carrying sewage in conduits under 
 pressure beneath the city streets, this plan appears to have no ad- 
 vantages which make its adoption desirable. 
 
 We recommend that the sewage be diverted from the present outfall 
 sewer to a pumping station, to be constructed on land owned by the 
 city near the shore of the harbor through which this sewer passes, 
 and that it be pumped to the proposed outlet continuously at all 
 stages of the tide. 
 
 Since the present sewers of the city of Lynn receive both sewage and 
 storm water, the cost of the proposed outfall system would be greatly 
 increased if works were provided for disposing of all of the flow of the 
 sewers delivered at the present outlet, including the quantity flowing 
 in periods of heavy rain. Such a provision is unnecessary, however, 
 since no harm will be done by allowing a portion of the dilute sewage 
 flowing in the sewers at times of heavy rain to discharge at the present 
 outlet, providing only for pumping such a quantity as will prevent 
 frequent overflows and the discharge of sewage at times of small storms 
 when the dilution would be slight. Provision for the removal of storm 
 water equivalent to a rainfall of one-quarter of an inch in twenty-four 
 
49 
 
 hours over the area drained by the sewers has been found to be a 
 satisfactory allowance in such cases, but in this case we have made 
 allowance for the removal of twice that quantity, and under these 
 conditions the overflow of sewage will be of infrequent occurrence, 
 provided that, in the construction of sewers in areas to which sewers 
 have not been extended, storm water is excluded, as is now being done 
 generally by cities and towns in Massachusetts, especially in cases 
 where the sewage requires pumping or treatment. 
 
 We therefore recommend a pumping statio^ with an equipment of 
 adequate capacity for the removal of a maximum of 50,000,000 gallons 
 per day flowing from the sewers, and an outfall sewer 60 inches in 
 diameter, which will be capable of conveying the sewage without diffi- 
 culty to the outlet proposed. 
 
 The general outlines of the proposed works are shown on the plans 
 appended hereto, which show a practicable method of conveying the 
 sewage of the city to the proposed place of disposal. We estimate the 
 cost of construction of these works at $793,000 and the cost of main- 
 tenance and operation in the earlier years of the works at $9,000 per 
 year. 
 
 In these investigations we have had the assistance of Mr. R. M. 
 Whittet, assistant engineer of the State Department of Health, who 
 has had charge of the investigations of the various tidal currents and 
 the studies of conditions about the various sewer outlets and who has 
 been assisted in this work by Mr. A. D. Weston of the State Depart- 
 ment of Health and Mr. J. W. Raymond, Jr., of the engineering de- 
 partment of the city of Lynn. In the design of the pumping station 
 and»works appurtenant thereto we have had the assistance of Mr. 
 Charles H. Dodd, M.E., who has had extended experience in the design 
 of similar drainage works. 
 
 Respectfully submitted, 
 
 X. H. GOODNOUGH, 
 
 Chief Engineer, State Department of Health. 
 
 W. L. VENNARD, 
 
 City Engineer of the City of Lynn. 
 
W§^^^3 "% '^ ''-■>■■'