Sewer infrastructure and CSO Systems

South Bay/South End Sewer infrastructure and CSO Systems

Disclaimer: This is a collection of research notes and images accumulated and published while preparing the Feb. 23 2026 Petition/Notice. At some point I intend to come back and merge, organize, annotate, etc. but until then, I at least wanted to make some of the references and data I found during my investigation publicly available. -AG

SOUTH BAY RESEARCH NOTES & RESOURCES:

GEOLOGY & GEOGRAPHY:

ENGINEERING, SAFETY, & REGULATORY: 

Combined Sewer Overflow Outfalls:

BOS062 under Seaport Blvd Bridge (23LCSO062)
BOS064 at 245 Summer St. (23LCSO064)
BOS065 at 25 Dorchester Ave (22KCSO065)
BOS068 Fort Point Channel North of Broadway (22KCSO068)
BOS070 at West Fourth St (21KCSO070)
BOS073 at Dorchester Avenue (22KCSO072)
BOS073 at 1 Gillette Pk (22LCSO073)

Storm Drain Outfalls:

23LSDO074 Summer St Bridge
23LSDO075 Congress St Bridge
23LSDO164 Congress St Bridge
23LSDO196 New Northern Ave Bridge
22LSDO580 Necco Street Extended
21KSDO069 125' North Of W. Fourth Street

CSO Facilities:

MWR215 Union Park Treatment Facility

Fort Point Channel
Constitution Beach
(2016 Stormwater Management Report, Table 2-1)

BRA - South End Project - Report on Water - Sewer Systems Inspection - Flow Measurements - 1964-3

South end / South Bay Sewerage Maps

1875 Boston Main Drainage

1875, Boston & South Bay, Sewerage Current and Proposed

1877, Boston & South Bay, Proposed Sewer Improvements

1902

1921

1967 Current Sewer Connections

1967 Connections to City Sewers

1967 Existing and Proposed Sewer Infrastructure

1967 Initial Recommendations

Overview

"Many older communities in the United States are served by sewer systems that carry both sewage and stormwater runoff in the same pipe. When rainstorms or malfunctions cause flow volumes to exceed pipeline capacities, untreated sewage overflows to nearby waterbodies. These combined sewer overflows (CSOs) pose a serious problem for the communities they serve. Contaminants in the mix of industrial, commercial, and domestic waste can cause toxic shock to the receiving waterways and can linger in the sediments permanently. As continuing sources of pollution, CSOs complicate and delay river and harbor cleanups by contributing unquantified and unidentified masses of pollutants to the cleanup sites. Under the Clean Water Act, sewer system authorities must obtain CSO permits that impose severe restrictions on the quality and quantity of discharges from combined sewer systems. If hazardous substances were discharged without the benefit of one of these permits, i.e., if they were discharged before a permit was issued, if they violated permit limits, or if they were not contemplated by the permit at all, CERCLA may well be used to impose joint and several liability on sewer system authorities for the costs of investigating, removing, and remediating the hazardous substances and restoring any natural resources that have been damaged or destroyed."

BOHANNON & LIN, Polluters and Protectors: Combined Sewer System Authorities and Urban Waterway Restorations, Natural Resources Journal, Vol. 45, No. 3 (Summer 2005), pp. 539-586.

1850-1851 built egg-shaped sewer on Tremont, intercepting sewers previously discharging to Back Bay and now directing to South Bay. Original plans called for flushing the sewer periodically with water from full basin or new public water system, but never constructed.

Gaining ground: a history of landmaking in Boston, Nancy Seasholes (2003).

"In a report to the Honorable City Council of December 17, 1874, they called the attention of that body to the conditions of the old Roxbury Canal, crossing under Albany Street; to the Stoney Brook Sewer, discharging upon the Back Bay flats; and the Muddy Brook Sewer, between Brookline Avenue and Downer St. The tide in the canal was sluggish they pointed out, and the discharge of three or four sewers into it, leaves shallow water at low tide “through which the foul gases from the putrid bottom can be seen bubbling into the atmosphere. It is so bad, they stated, that in the streets around there, there is a daily average of 230 patients who require found equal pure air. They found nuisances at the other two points of discharge.

The Board of Health had no doubt that summer diseases the prevalent of the City were largely influenced by that poisoned atmosphere. If the sewage could not be retained and used but had to be discharged into the water and lost, would be best, it in the opinion of the Board, that large main sewers should be built to carry the sewage out to sea. As for which came first, the water or sewer pipe, that water pipes they regretted had preceded the laying of sewers, but they thought it fair to say that the supply become a necessity of pure water had and the people would have suffered without it. In 1874, Superintendent Bradley was able to report that his department had laid seven and three—quarter miles of sewer, some of brick, some of pipe (iron, scotch and Arron.) and some still of wood. They ranged in size from nine inches, to 78 by 72 inches."

"The nuisance had not been abated however, but only transferred to some other parts of the City, the drainage going through tide-locked sewers which emptied at some different points along the waterfront, frequently depositing the sewage on the flats at low water, causing an intolerable stench. Pointing out that the drainage was discharged at 100 points along the waterfront, sometimes at low tide where it would settle on the mud and sometimes at flood tide where it often washed back in, the Committee reminded its readers that the sewage had so built up in the Roxbury Canal that it became necessary to dredge there. That the stench and noxious gases emanating from the sewage were a source of ill health, they had no doubt."

SAVEAGE FOR THE BWSC, THE WATER AND SEWER WORKS OF THE CITY OF BOSTON 1630 — 1978.

"The quality of runoff has also been affected by urbanization in the lower Charles River watershed. Runoff from the watershed typically contains a variety of contaminants, including fecal bacteria, phosphorus and other nutrients, and lead and other metals. Fecal bacteria pose risks to the health of swimmers and boaters, phosphorus and other dissolved nutrients promote excessive algal growth, and dissolved metals can be toxic to fish and other aquatic species.
Although some of these contaminants, especially bacteria, may originate from illicit sewage connections to storm drains, the majority of the contaminants derive from the buildup of particulate matter on streets, parking lots, roofs, and other impervious surfaces during dry weather, and from their subsequent removal by rainstorms. Long periods of dry weather before rainstorms tend to result in high contaminant concentrations in runoff.

From 1625 to the late 1700s, water supply and wastewater disposal in the watershed were strictly local. Springs and dug wells were the principal form of water supply in Boston, and privies were the preferred mode of human waste disposal. As in most early American cities, Boston’s privy vaults would be emptied by hand, often at night, and the nightsoil would be disposed of locally or conveyed to farms in the surrounding countryside (Tarr, 1996).
In the 18th century, Boston was one of the first American cities with cobblestone-paved streets drained by an underground storm drain network (Bridenbaugh, 1971; Spirn, 1984). Paved streets with underground drainage systems were major sanitary innovations at the time. Kitchen and household wastewater, but not human wastes, could be legally disposed of in these drains, which discharged to the tidal flats of the Charles River (Back Bay) and Boston Harbor (Seasholes, 2003)."

In both Boston and New York City, the advent of a reliable public-water supply in the 1840s coincided with, and probably spurred, the introduction of water closets to private homes. With a reliable public-water supply, water carriage of human wastes became practical, and sewage-collection systems in the modern sense began in Boston (Tarr, 1996; Melosi, 2000). However, Boston’s first modern sewer system, the Main Drainage Works, would not be completed until 1884, some 36 years after the water supply was introduced (Clarke, 1888). In the interim, sewage was sent directly to the Charles River, Boston Harbor, and their tidal flats through so-called common sewers and street drains—contrary to previously established regulations. In some parts of Boston, specially designed pipes were introduced to facilitate water carriage of human wastes By the 1870s, about 24 common sewers discharged a combination of sewage and stormwater directly to the Charles River (City of Boston, 1878). The replacement of privy vaults by common sewers probably benefited public health, but with adverse consequences for the health and aesthetic quality of the Charles River and nearshore areas of Boston Harbor.

By the late 1870s, the main body of Back Bay east of Gravelly Point had been filled, leaving a relatively small area of tidal water and mudflats in westernmost Back Bay, at the mouth of Stony Brook and Muddy River. Because of rapid population growth in these two watersheds, sewage flows to Stony Brook and Muddy River had greatly increased, and the waters and mudflats of western Back Bay became grossly polluted. Prevailing winds carried sewage odors to the fashionable new Back Bay residential districts to the east, provoking the following observation from the Boston Board of Health: Large areas have been at once, and frequently, enveloped in an atmosphere of stench so strong as to arouse the sleeping, terrify the weak, and nauseate and exasperate nearly everybody… It visits the rich and poor alike. It fills the sick chamber and the office. It travels in a belt halfway across the city, and at that distance seems to have lost none of its potency… (City of Boston, 1878). The germ theory of disease was not yet widely accepted; miasmas and foul odors were considered to be disease agents as well as aesthetic nuisances (Duffy, 1992). Consequently, the sewage odors emanating from western Back Bay and other parts of the city were treated as serious public health threats.

The Main Drainage Works was one of the first large sewer systems built in the United States. It was specifically designed to limit the pollution of tidal flats adjacent to densely populated areas of the Boston Harbor and lower Charles River watersheds by conveying flows to a remote lagoon-and-outfall facility at Moon Island, an uninhabited Boston Harbor island. The system employed a network of interceptor conduits that were generally parallel to the shorelines of the receiving water bodies (the Charles River and Boston Harbor). The interceptors received the combined sewage and stormwater from sewers that had previously discharged directly to the city’s tidal flats and waters (old sewer outlets). At selected points along their routes, often coinciding with the old sewer outlets, the interceptors were designed to overflow into receiving waters under storm conditions. These points would become known as “combined-sewer overflows” or CSOs

N.L. Hatch, The bedrock geology of Massachusetts, Professional Paper 1366-E-J, U.S. Geological Survey (1991).

Environmental assessment statement as required by EPA is presented in Chapter IV. The Environmental Assessment
Form required by the State is not necessary at this time. State approval will be required for sections of conduit routes in and crossing certain highways and for locations in Fort Point Channel, (Appendix I).

The existing Boston Main Drainage system vas constructed between 1877 and 1894. Structural failures have occurred, the most notable being those of the Main Interceptor in Massachusetts Avenue and at Kosciuszko Circle. The system is frequently surcharged from sanitary wastewater, stormwater, and tide water which results in overflows to end pollution of Boston Harbor. An operable system consisting .of the proposed facilities is required to collect and carry dry weather wastewater from the Main Drainage system to the MDC system and for elimination of physical hazards.

The need for immediate initiation of design and construction of the interceptor replacements and the Mt. Vernon Street Sewer is further documented by the implementation schedule issued by the U.S. Environmental Protection Agency and the Commonwealth of Massachusetts, Division of Water Pollution Control, executed and dated by the Director of the DWPC on April 1, 1975 (State designation M-121) and by the Enforcement Division of the EPA, Region 1, Boston, on April 2, 1975. (Federal designation NA 0101192). (Appendix K). The permit is to expire on June 30, 1977.

The Mt. Vernon Street Sewer has been scheduled by the State and Federal NPDES permit as the first order of priority for design. The length of conduit is relatively short (about 3140 ft), there are few special structures, both surveys and subsurface exploration are not complex and design shoulda be straightforward. For this reason, the lt. Vernon Street Sewer could be designed within a short time and could be under construction sooner than the remainder of the program. The Main Interceptor Replacement should be the second item of design and construction so as to complete its construction at least by the time the East Side Interceptor Replacement, South Branch, is completed to make it of use. Surveys and borings for the Main Interceptor Replacement alignment should be initiated as soon as the design phase, Step II, is approved by EPA. Design should follow as soon as sufficient information is available. Surveys and subsurface exploration for the North and South Branches of the East Side Interceptor Replacement should follow as soon as possible after those for the Main Interceptor Replacement, and detail design for these branch interceptor replacements should be started as soon as information becomes available. It should be noted that with the South Branch of the East Side Interceptor and the Main Interceptor Replacements constructed and in use, and with the completion of the several special structures at Massachusetts Avenue, East Concord Street, East Brookline Street, and Union Park Street, sewers in a portion of Massachusetts Avenue south of Harrison Avenue, large areas in the South End could be served through the interceptor replacements, if the existing Main Interceptor should become inoperable, and reduce the flow in the Main Interceptor during emergency repairs.

Construction of the North Branch without undue delay is necessary to avoid the difficulties now experienced with the grit chamber at High Street. The invert of the conduit entering this chamber is at elevation minus 2.9 and the invert of the outlet to the existing East Side Interceptor is at elevation minus 0.9. This two foot rise in the invert at the outlet results in trapping accumulations of grit and putrescent sludges.

To minimize infiltration of groundwater, preformed compression joints are recommended. Tide gates must be provided or rehabilitated to prevent direct connection between tide water and the sewerage system.

It should be noted that the State Department of Public Works is now (1975) resurfacing the section of Old Colony Avenue through which the conduit would be built. The resurfacing operation apparently includes replacing local surface drainage and sewers to provide separate sanitary and storm conduits on each side of the street, and installing a central dividing strip. The proposed Dorchester Brook Dry Weather Connection to join the Main Interceptor Replacement west of the railroad bridge, although recommended in the 1967 and 1972 Reports, and eligible for grant aid in 1972, is not included for construction at present. A temporarily closed stub for future connection would be left in the interceptor replacement conduit. The special structure required to contain a regulator and tide gates would be included with the construction at that time.

The proposed Main Interceptor Replacement must be constructed before any effective use can be made of capacity to be provided in the proposed South and North Branches of the East Side Interceptor Replacement. The Kain Interceptor Replacement thus must be constructed early in the construction program and should be given high priority for surveys, subsurface explorations and design. The proposed South Branch of the East Side Interceptor Replacement, (Fig.. II-2), would receive flows from existing sewers and from sewers to be constructed in the future in Massachusetts Avenue both north and south of Albany Street. The replacement would also receive flows from connections to the existing East Side Interceptor in Albany Street, including sewers built under Site Preparation contracts by the Boston Redevelopment Authority (BRA) for the South End Urban Renewal Area.

Dry weather flow from the Union Park Street area will be connected to the proposed East Side Interceptor Replacement, South Branch. The cost of the dry weather connection from Albany Street at Malden Street to the proposed South Branch is included with the South Branch construction costs. The proposed East Side Interceptor. Replacement, ‘South Branch, would conduct flows from southwest to northeast in a reverse direction to the existing East Side Interceptor segment in Albany Street. A special structure in Massachusetts Avenue would receive flows from proposed connections in Massachusetts Avenue north and south.

Wastewater would be received at the north connection from existing sewers in Massachusetts Avenue including the Roxbury Interceptor and E. Chester Park Sewer, in addition to the recently constructed sewers built by the Public Facilities Department in the vicinity of the outpatient Department of the Poston City Hospital and capacity would be
provided for the discharged from a 36-in sewer in Tremont Street recently constructed by the ERA. Consideration has been given to the effect of future proposed sewers shown on the Site Preparation plans for the South End Project Area proposed by the BRA as discussed below. These sewers would include a replacement for the E. Chester Park sewer known to be in partially collapsed condition.

The connection to the South Branch Replacement from the south would receive flows from existing combined sewers along Massachusetts Avenue south of Albany Street to the vicinity of Shirley Street. A lift station discussed in detail in our 1967 Report and 1972 Update has been recommended for future construction at this location. The selected route is south of the Roxbury Canal Conduit rather than north of the conduit as was proposed in 1967, to obtain greater clearance for construction and to avoid buildings recently built north of the conduit. When the South Branch Replacement is designed, consideration should be given to plans which might then be in effect for highway construction in the Vicinity of the ramp from Massachusetts Avenue to the Southeast Expressway, and for additional building construction.

The South Branch Replacement would extend northeasterly from the junction chamber in Massachusetts Avenue along the southeast side of the Roxbury Canal Conduit to a point adjacent to the Southeast Expressway north of the exit from the Massachusetts Avenue off ramp. At this point the South Branch Replacement would receive flows from Union Park Street at Malden Street. The interceptor replacement would cross in open cut beneath the elevated section of the off ramp and southbound lane of the Expressway, and by jacking beneath the northbound feeder and northbound lanes and the east side service road to near the present Boston and Taunton Express building, thence south of the building to the junction with the proposed fain Interceptor Replacement. The conduit sizes in the proposed South Branch Replacement range from 72 inches to 84 inches and the total length is about 3550 ft. The total length of connecting pipes from dry weather connections at Massachusetts Avenue, E. Concord Street, E. Brookline Street and Union Park Street is about 1530 ft. New or rehabilitated regulators would be required to intercept dry weather flows at each of these connections. New or rehabilitated tide gate structures would be provided where construction of the South Branch Replacement would make them necessary.

The existing storm flow connection from the combined sever regulator at E. Dedham Street to the Roxbury Canal Conduit has been abandoned because of construction of the Flower Mart Building. A substitute connection for storm flows rejected at the E. Dedham Street regulator must be provided for proper operation of the proposed interceptor replacements. The 42-inch Storm drain shown on the BRA South End Project Area site preparation plans to be constructed in E. Brookline Street extended should be restudied and scheduled for early construction to serve this function.

The storm flow connection from the combined sewer regulator at E. Concord Street to the Roxbury Canal Conduit is reported to have been bulkheaded, when tide gates were removed within the last year or so, and to be no longer in service. It would be necessary in the present proposed construction to rehabilitate the E. Concord Street storm flow connection to act as a storm overflow from the regulator at Albany Street. We understand that a request has been made of the MDC in this regard.

The time schedule for construction of the South Branch of the proposed East Side Interceptor Replacement would be based on the consideration that it cannot be put into operation until the proposed Main Interceptor Replacement is in operation. However, completion of the South Branch Replacement must precede the construction of sewers in Massachusetts Avenue proposed for future programs.

The plan titled "Boston Redevelopment Authority, South End Urban Renewal Area, Recommended Sewer and Drain Systems" prepared for the BRA by Charles A. Maguire and Associates, dated October 1971, and revised to December 1974, indicates that restrictions have been introduced into the approved comprehensive plan of 1967 by the continuing program of construction by the BRA of sewers connected directly to the existing Main Interceptor in Massachusetts Avenue.

The BRA plan shows a recently constructed sanitary sewer extending southwesterly in Tremont Street from near the intersection with Union Park Street, aid sanitary sewers proposed to connect to this new Tremont Street sewer from the north and south, to serve the westerly portion of the South End Urban Renewal Area. The Tremont Street sewer has been constructed at a low elevation, lower than that of the existing combined sever at Camden Street to take advantage of the low elevation available in the existing Main Interceptor conduit. The introduction of the Tremont Street sewer requires that the Main Interceptor be retained in service to serve this portion of the urban renewal area with the provision of a pumping station at Albany Street as discussed below, or, alternatively, that a sanitary sewer be constructed generally southeasterly in Camden Street, Washington Street and Mass. Ave. or a parallel street such as Northampton Street to Albany Street to serve this area and to receive connections from the additional sanitary sewers proposed by BRA, as shown on its 1971 plan.

This construction and proposed construction is not compatible with the CDM 1967 Master Plan arrangement because it will reverse the direction of service for sanitary sewerage in the South End District. The 1957 CDM report approved by the State DWPC and the 1972 Update of that report both were based on the continuing passage of sewage generally easterly and southeasterly from the South End District to enter the proposed Fast Side Interceptor Replacement, South Branch. at the several regulators at Union Park Street, E. Dedham Street, E. Concord Street and Massachusetts Avenue. The BRA divergence from the 1967 Report plan places a heavier burden on the southwest end of the South Branch of the East Side Replacement, requiring an increase in capacity in that section, because of rerouting of the sewage flow generally southwesterly and thence back northeasterly to the Main Interceptor Replacement.

In addition, local sanitary sewers and storm drains proposed for construction by the BRA in E. Concord Street, E. Newton Street, E. Brookline Street, E. Canton Street, E. Dedham Street and Plympton Street all are shown to connect directly to the existing East Side Interceptor without regulators and may be at gradients steeper than those of the existing combined sewers in some of those streets. The combined sewers now connect to the East Side Interceptor through regulators and thus are higher than the existing interceptor at the Albany Street junction points.

Construction in the unused waterway of the channel would require no more handling of water than would be required for construction in open trench construction onshore which would be in water-bearing soft material below low tide level adjacent to the channel. several of the connections from existing combined sewers are proposed to be made by abandoning the existing regulators and tidegates (in some cases located at a distance back from Fort Point Channel) and providing new regulator structures with tidegates at the present outlets of the existing combined sewer overflows. In these cases flows would be directed from the former regulators into the storm water overflow conduits and dry weather flow would be diverted to the Interceptor Replacement at the proposed regulator Structures. In other cases this cannot be cone and the existing regulators would be rehabilitated and dry weather connections extended rem the regulator to the proposed North Branch Interceptor Replacement. In some instances the provision of new tidegates would be necessary to avoid salt water entry into the regulator structures and would be provided as required.

The North Branch Replacement would receive dry weather flows at High Street (Melcher Lane) (NPDES Outlet No. 061); at a point opposite Oliver Street (Outlet No. 062); at Summer Street (Outlet No. 064); at Atlantic Avenue, extended (west of Dorchester Avenue and the railroad bridges) (unnumbered;) north of Traveler Street (formerly Troy Street) (Outlet No. 068); and at E. Berkeley Street (Outlet No. 069). The unnumbered connection west of the railroad bridges would serve regulators at Beach Street and Kneeland Street, through the conduit to be constructed by BRA for interim use as a substitute for the section of the existing East Side Interceptor to be removed for the construction of a bus terminal, as discussed hereinafter.

The barrel of certain portions of the Belton North Branch of the East Side Interceptor between Atlantic Avenue and Union Park Street would be abandoned and refilled with suitable material to avoid possible future collapse as discussed elsewhere in this report. However certain selected sections of the existing interceptor will probably be required to be kept in operation, if in suitable physical. condition, to act as combined sewers or in some cases as separate sanitary sewers under changes to the sever system being made by the BRA. The cost of filling would not be eligible for grant aid, and is not included in the estimated cost of the replacement conduits and connections.

The principal factor upon which the need for construction of the recommended system of interceptor replacements is that almost all of the existing Main Interceptor and long sections of the East Side Interception: in particular west of Dover Street, are in poor structural condition. This is evidenced by failure of sections of the Main Interceptor in Masearieeete Avenue north of Clapp Street and in Mt. Vernon Street near the Dorchester Interceptor connection, and by the results of photographic inspection (1967 Report pp. 19-21).

The Main Interceptor would have adequate capacity for estimated year 2020 peak rate dry weather flows if all flows from the West Side Interceptor and Stony Brook Interceptor were completely diverted to the MDC Ward Street Headworks as planned (1967 Report, p. 20). This has not been done, because of the incomplete state of the diversion works at Camden Street serving the West Side Interceptor and at Tremont Street serving the Stony Brook Interceptor. In addition, a recently constructed sanitary sewer in Tremont Street east of Camden Street connects to the Main Interceptor south of the Camden Street diversion structure, although an earlier report by a BRA consultant recommended connection at the diversion chamber.

Because of these connections and because of continuing need for the existing interceptor for emergency relief of the Ward Street Headworks the Main Interceptor cannot as yet be removed from service. The proposed East Side Interceptor Replacement will serve most of the South End area, but cannot be laid at low enough elevation at Massachusetts Avenue to receive dry weather flows there from the Tremont Street sewer via the existing Main 3 Interceptor without recourse to pumping. Some pumping might be required from South End sewers if they are built too low to enter the regulator chambers of the Interceptor Replacement by gravity. The proposed East Side Interceptor Replacement, South Branch, however, would be connected to the existing Main Interceptor in such a way that only emergency overflows from the Ward Street Headworks could be accepted when the Main Interceptor would flow at more than about half depth, and thus the replacement would act as a back-up sewer for the downstream section of the Main Interceptor, if that section were to suffer more structural damage.

The need for the North Branch of the East Side Interceptor Replacement is indicated by the inadequate capacity of the existing interceptor conduit for estimated future peak dry weather flows, its 90-year age and questionable structural condition. The need is made further evident by the relative. elevations of the junction chamber at High Street. The elevation of the upstream conduit recently built under the Downtown Waterfront Urban Renewal Area Site Preparation contracts, is about two fret lower than the connecting downstream conduit, a section of the old existing East Side Interceptor. This situation, although accepted as a temporary measure pending construction of the proposed downstream East Side Interceptor Replacement, should not be continued. Construction, also, of the Replacement should be completed before opportunity is lost for the conduit location in the now open waterway of Fort Point Channel.

The alignment of the South Branch of the East Side Interceptor Replacement was considered in the 1967 Report to extend along and northwest of the Roxbury Canal Conduit from near the Expressway to Massachusetts Avenue. Because
of construction in the Eater ant Area, the recommended alignment was altered in the 1972 Update Report to extend along the southeast side of the Roxbury Canal Conduit. In this way additional clearance was gained for construction along this section of the interceptor replacement but more crossings beneath the conduit would be involved. The proposed alignment of the North Branch Replacement was altered in the 1972 Update Report to be constructed at the edge of the little-used waterway of Fort Point Channel 55 an accessible route and for the added advantage of ease of construction. This route would also require minimal disruption to existing utilities and subaqueous construction methods would ease water handling below that for an onshore route.

The presently proposed improvements, by providing adequate capacity for dry weather flows for many years in the future, and structurally sound conduits, will substantially reduce the possibility of overflow to Fort Point Channel and the Inner Harbor during dry weather periods, and the danger of internal sewerage distress in the South End and portions of Roxbury and North Dorchester sections from collapse of interceptors. The provision of new regulators and rehabilitation of others, and of new tide gates under this program, together with the rehabilitation of tide gates by the MDC for the City of Boston in the last few years, will reduce and almost eliminate the earlier reported discharges in dry weather of mixed flows of sanitary and industrial wastewater with salt water to the Harbor, and to the NDC Deer Island Wastewater Treatment Plant. This would be true only with constant inspection and maintenance of the tide gates, to prevent the entrance of tide water which would surcharge the interceptors and return to the Harbor carrying with it an admixture of wastewater.

1975 Supplement to 1967 Report on Improvements to the Boston Main Drainage System, Camp, Dresser & McKee for City of Boston, Commissioner of Public Works (Nov. 24 1975).

The gauging program demonstrates that there is a massive entrance of tidewater to the systems. This is a direct result of faulty tide gates and is in part due to porosity of the interceptor conduits... Gates along the East Side Interceptor are reported generally to be in poor condition.... the tide gate on the Concord Street overflow was observed during the process of conduit inspection. At this location, the wooden, side hung gates appeared to be on their hinges but were jammed shut. A break in the chamber structure
above the gates, amounting to a 6 to 8 square foot opening, allows tidewater to flow over the gates into the system. During each high tide cycle, extensive surcharging and stagnation of dry weather flow occur in the Boston Main Drainage System as a result of gross amounts of tidewater entering the systems, predominantly through faulty tide gates. The surcharging results in the activation of most overflows, the flushing by tidewater of branch and local sewers, and causes an associated high level of pollution in receiving water. In the Project Area, the Main Interceptor has 2 to 3 feet of sediment which reduces its effective cross sectional area by 25 to 30 percent. Hydraulic interference of the tide with normal sewage flow patterns precludes an effective gauging program.
Flows to the new MDC System will include excessive amounts of tidewater unless its entrance to the Main Drainage System is substantially reduced. Of the 62 tide gate facilities on the Boston Main Drainage System it is estimated that: about 30 percent of the installations require gate replacement, 15 percent need repair, and the remainder are in working order. The frequent surcharging that occurs in the system has resulted in deposits of scum on the crown of the conduits. These scum deposits occur predominantly in the interceptors. A clear view of the crown brickwork is therefore not always possible, in which case the condition of the conduit is evaluated on the basis of those portions that are clear. In most cases, the scum forms a film of 1/8 to l/4 inch thickness, and sometimes builds-up to a six inch thickness as shown in Photo 428-1. Cleansing action is provided when high-velocity storm flows occur at low tide, and then the scum reaches a thickness such that it can no longer support its own weight in adhering to the sewer crown or walls, it falls and is washed away. This latter condition applies in particular to manholes where the scum sometimes reaches a twelve inch thickness and may be solid between consecutive manhole ladder rungs.
BRA - South End Project - Report on Water - Sewer Systems Inspection - Flow Measurements - 1964

4.5.2 East Side Interceptor
The East Side Interceptor, within the Project Area, was constructed of two course brick under a single contract in 1879• At Dover Street the interceptor enlarges from 4'-0" x 5'-0" to 5'-6" x 5*-8" and remains at that size for the 4500 feet to its junction with the Boston Main Interceptor at Massachusetts Avenue. The invert of the interceptor is laid at a gradient of 0. 04^ through the Project Area. The average trench depth was 24 feet. The bottom of the trench being 6.5 feet below low tide caused considerable difficulty in dewatering, especially in places where old sea walls and other such obstructions were encountered, and necessitated the use of that sheeting and heavy bracing. It is not known whether this sheeting was removed after construction. The deep trench drained the ground water from adjacent soils allowing them to be compressed thereby causing considerable settlement requiring the whole of Albany Street to be rebuilt and repaved, in some areas several times. From East Newton Street to East Concord, Street, Run 409, infiltration and joint wear are both excessive.. A direct visual inspection of this conduit was made in the process of operating the camera equipment. The crown is in a very poor condition and it appears to be disintegrating. Mortar chips broken loose
from the joints, could be held in the hand and broken when hit with a hammer. Downstream of Stoughton Street the interceptor is on piles. Figure C-2. The change to piles in the middle of this run had no apparent effect upon condition. The photographer walked through and visually inspected Runs 410 and 411, between East Concord Street and Massachusetts Avenue. Operational difficulties
were encountered in photographing these two runs. The high humidity and haze conditions caused a malfunctioning of the camera such that the location of individual frames on the film strips, for these two runs only, cannot be established with
certainty. The stationing for these two runs has been omitted on the evaluation sheets. For Run 410, haze and scum conditions are very bad for half the run. There are no apparent cracks in the rest of the run but joints have been worn up to a one inch depth and are filled with scum in many areas. Run 411 has badly worn joints, in several areas scum may well be obscuring cracks in wide joints of the crown. Two crown courses, of brick have fallen out for about 40 feet at the downstream end of this run. In summary, the overall condition of the East Side Interceptor is poor to fair at best. The poor condition may well be more extensive than this inspection can indicate due -to obscuring scum especially in -the joints. Replacement or extensive structural reinforcement of the interceptor within the Project Area is necessary for it -to serve as an effective part of the system.
4.5.6 Concord Street Sewer ,
The Concord Street sewer was constructed in I87D, from Tremont Street to Albany Street. The 8'-0" x 5'-0" conduit consists of a three course brick arch with a wood bottom of 3 x 8 inch planks which, for the most part, are still structurally sound, 6ilthOT;igh there are some holes and several spots with boards missing. The wood floor supports 12" high brick walls supporting the 4 foot radius arch. The invert elevation I.5 to 2.5, City of Boston Datum, is about 14 feet below the street surface. Records are not available but it is probable that at least east of Harrison Avenue the sewer is supported on piles. Three runs of the Concord Street conduit were inspected photographically, comprising about half Of the 1240 foot distance between Tremont and Albany Streets.
An additional length, to 140 feet measured eastward from the manhole under the MEA elevated on Washington Street, was visually inspected and found to be in good condition. At l40 feet from the manhole four cubic yards of earth had dropped into the conduit through an abandoned 10" x 12" service, connection seriously undermining the street pavement. Manhole Photos 99^-4, -5 and several Polaroid photographs depict this condition which was immediately rectified by the Sewer Division.
East of Harrison Avenue, Run 439, the Concord Street sewer is in poor condition; a 1/8 inch crack starting at Harrison Avenue becomes progressively worse for the full length of the crown towards Albany Street, and becomes 1^ inches at a deformed crown section, this run contains 6 to I8 inches of sediment. West from the Harrison Avenue manhole a 1/8 inch crown crack extends for twelve feet and stops. The change in observed condition occurring in the vicinity of Harrison Avenue can probably be attributed to adverse subsoil conditions east of Harrison Avenue Sewers in areas underlain by unstable subsoil appear to be in poor condition
more frequently than those in areas of stable soils. C-8. The area east of Harrison Avenue and the area bounded generally by Berkeley, Tremont and Dartmouth Streets and the railroad have mud, soft silt and peat underlying fill material and have a predominance of conduits in poor condition. On the other hand, the area that is underlain by stable original ground has a
predominance of conduits in good condition....
Preservation of the wood requires constant or fairly constant submersion in water or sewage. Provision of an effective system of tide gates and separate sanitary and storm drainage systems as recommended in the sewer improvement program, would result in far less frequent submersion of the wood than now exists, with an attendant, acceleration of wood decay. In addition, sewers with wood components cannot be cleaned with mechanical equipment without danger of damaging the conduit....
Catchbasins...Numerous abandoned connections to the system exist.... Unrecorded modifications: modifications of the system have been made and not recorded at several locations...
Deterioration of mortar joints is attributed to prolonged exposure to the deleterious effects of sewage and/or salt water. Mortar erosion and condition became progressively worse in the interceptors and major conduits towards the South Bay. The poorest mortar was found in the East Side Interceptor where the mortar, when held in the hand, would readily break into pieces when struck. Strength of mortar in the Boston Main and Stony Brook Interceptors is much greater....
Conclusions: There is a high incidence of poor condition for all types of conduits in areas underlain by unstable subsoils
BRA - South End Project - Report on Water - Sewer Systems Inspection - Flow Measurements - 1964

"Also affecting the overall inflow/infiltration problem is the construction material used for the existing combined sewers. Many of these sewers in Boston have been constructed of brick with cement-mortar joints. Considering that the majority of the sewers in the city are over 100 years old, defective joints, cracks, and defective masonry could be present in many sewers. This could allow groundwater to infiltrate the sewer through these leaks depending on the relative elevations of the groundwater table and the sewers.

Utilizing the results of preliminary gaging in conjunction with a variety of written sources, visual inspection tours, recent complaint records and interviews, certain areas have been determined as having probable excessive infiltration not to mention the excessive inflow from combined systems. Quantities of storm water in tide water entering the City's collection system are impossible to measure with any degree of accuracy without an all-out gaging program.

1975 Supplement to 1967 Report on Improvements to the Boston Main Drainage System, Camp, Dresser & McKee for City of Boston, Commissioner of Public Works (Nov. 24 1975).

"Both the U.S. Coast Guard and the Army Corps of Engineers have been contacted regarding the installation of the proposed interceptor replacement in the channel. The Coast Guard is not concerned with the construction since the interceptor does not cross the navigable portion of the channel. The Corps of Engineers representative stated that the project will not interfere with any plans it has regarding the channel. An act of the legislature will be required, however, before construction within the channel can be started, and permits must be obtained from the Massachusetts DPW and the Corps of Engineers."

1975 Supplement to 1967 Report on Improvements to the Boston Main Drainage System, Camp, Dresser & McKee for City of Boston, Commissioner of Public Works (Nov. 24 1975).

The combined sewer overflows have chronic long term impacts due to discharges of dry weather flow from combined sewer overflow outlets. These discharges, called dry weather overflow, are caused generally by malfunctioning regulators, tide gate failures, sewer blockages, and illegal sanitary connections to storm drains.

Boston Inner Harbor (Class SC, except SB near Constitution Beach) the commercial and shipping area, having at present
the poorest water quality in the CSO project area, but also witnessing intensive waterfront renewal and residential and commercial development.

Inner Harbor was designated has having 5,900 Acres that consists of: Boston Proper, South End, South Boston, Somerville/Charlestown, Chelsea/East Boston. The 1979 report noted 78% of Inner Harbor has Combined Sewer Service, 9% has no sewer, and only 13% has separate sewers. Inner Harbor has 52 active CSO outlets, 65 CSO regulators and control structures, and 19 separate storm drain outlets.

Early harbor modeling results showed that dry weather overflow was a significant source of coliform, especially in the
Inner Harbor area. Special effort was made to identify the locations and magnitudes of dry weather overflow discharges. Over all of the four areas, about 24 million gallons per day of dry weather overflow was estimated to be discharging. The Boston Water & Sewer Commission and the city of Somerville were notified of the locations, and some correction of the problems was made. Specific recommendations for dry weather overflow mitigation will be a part of each facilities plan.

COMBINED SEWER OVERFLOW PROJECT, Progress to Date Report, CAMP DRESSER & McKEE INC., Commonwealth of Massachusetts, Metropolitan District Commission, (Sept. 1979)

Roxbury Canal

In passing across the old Roxbury Canal, which had been recently filled by the city, an influx of tide-water along the loose walls of the canal and through the filling occasioned some delay and expense. The water was finally kept out by double rows of tongued and grooved sheetpiling. A side entrance and boat-chamber (Fig. 12), were built on this section, at the corner of Swett Street. The latter structure resembled a very large man-hole, with a rectangular opening from the street, 11 X 4 feet in dimensions. This was built to allow the lowering of boats into the sewer. At Albany Street the east-side intercepting sewer joins the main, and above this point the latter is again reduced in size, to eight feet three inches wide by eight feet five inches high. The extra horizontal course was put in at the spring line because it was supposed to facilitate dropping and moving the centres.

MAIN DRAINAGE WORKS OF THE CITY OF BOSTON, ELIOT C. CLAEKE, (1885).

South End Sewer Infrastructure

"The combined sewerage system in the South End is old, generally in poor to fair condition, has Ineffective tide gates, pollutes the Roxbury conduit and has an obsolete storm water pumping station at Union Park Street. Extensive Improvements are necessary to eliminate the deficiencies in the system. This report proposes construction of a separate sanitary sewerage system, reconstruction of existing conduits In poor condition, revision of the storm overflow and storm conduit system in conjunction with modernization and increased capacity of the Union Park Street Pumping Station, repair and replacement of tide gates on the entire Boston Main Drainage System, reconstruction of the East Side and Roxbury Canal Interceptors, and providing a new lining in the Boston Main Interceptor in the Project Area. Improvements to the tide gates and the Union Park Street Pumping Station and reconstruction and repair of the interceptors should be given the highest priority in the entire Project Improvement Program. It is important to note, that although vital, the Improvements to the intercepting system have not been included in the Project Improvements as the result of a policy decision by the Boston Redevelopment Authority. It is strongly recommended that a source of financing this work be resolved and that this work be started as soon as possible before a serious conduit failure occurs."

The South End, generally along Washington Street, was naturally formed land and was a narrow neck that led from the mainland of Roxbury to the Boston Peninsula. Over the years, the tidal areas on each side of the neck were filled, resulting in a soil profile in the man-made area of generally unstable soils. These conditions require special foundations for major utility structures in extended sections of the area. This is particularly applicable to new large sewerage conduits.

The project area Is now served almost entirely by a combined sewerage system which is more than 80 years old and Is in fair to poor physical condition. Most tide gates are in poor condition which results in surcharging of the system by tide water. This reduces the system's effective capacity and causes sewage discharges into the tidal estuaries. The effluents discharged into the Roxbury Canal pollute the water and are a health menace. Extensive improvements and modifications to the system are needed to eliminate deficiencies, and health hazards and to provide capacity for future demands. Wherever possible, to maintain a program of maximum economy, these improvements have been coordinated with the street improvements. Existing systems generally will be converted to act as storm drains. This will minimize construction costs and add flexibility in the conversion to separated sanitary and storm drainage systems. Drawings entitled Sanitary Sewers and Storm Drains and numbered SE 13-1 through SE 13-8 accompany this report.

Storm flows of the combined system outlet at low tide to the Roxbury Canal and at high tide are pumped to the Roxbury Canal by the Union Park Street Pumping Station. Connections from the combined sewers to the Boston East Side Interceptor and the Boston Main Interceptor, which pass through the area, dispose of dry weather (sanitary) flows. The majority of the combined system within the South End is in fair to poor condition as determined by visual, photographic, and closed circuit television inspection program conducted and reported upon previously. The Union Park Street Pumping Station has adequate design capacity; however the pumps are obsolete, inefficient and irreparable. The tide gates on storm overflows from the area to the Roxbury Canal are mostly inoperable and result in surcharging of the system by entrance of tide waters during high tide, thus reducing the capacity of the entire sewerage system.

There are four major trunk sewers in the Project Area, They are the Boston Main Interceptor in Camden Street and Massachusetts Avenue; the East Side Interceptor in Albany Street; the Roxbury Canal Interceptor in Albany Street, south of Massachusetts Avenue; the Stony Brook Interceptor in Tremont Street, south of Camden Street. The Boston Main Drainage Relief Sewer recently constructed by the Metropolitan District Commission Sewerage Division will intercept the Stony Brook and Boston Main Interceptors at Camden and Tremont Streets and will provide relief to Boston's intercepting system when the new M«D.C. system goes into operation late this year. The Boston Main and East Side Interceptors are of major importance to the South End Area; but are of prime importance to the major part of the City, They are the main outlets for the existing sewerage systems. Conduit inspections in the South End showed that both interceptors are in poor condition and are in need of replacement and major repair. The Roxbury Canal Interceptor, is inadequate in capacity and only in fair condition at its outfall at Massachusetts Avenue and in Albany Street. The Stony Brook Interceptor is in good condition and has adequate capacity.

Inspection of the conduits indicated that many need replacement or repairs. Specific conduits were reported upon in the inspection program report of April, 1964. Most of the conduits in poor condition are scheduled for replacement under the Urban Renewal Program. Most of the existing buildings in the South End have combined sanitary and storm water (roof drains) connections to the combined sewerage system. An inventory of these buildings Is not available and existing records do not indicate this distinction in most cases. Furthermore, many buildings have plumbing systems arranged in a manner that prohibits separating sanitary from storm flows short of a major revision of the plumbing in the building. It is therefore considered to be impractical to expect that broad scale separation of drainage from existing buildings can be effected during the Urban Renewal Program. For this reason, existing combined sewers must continue to function as such for years to come. However, installation of sanitary sewers will be accomplished now to receive sanitary flow from new buildings and from those that now have separate sanitary connections. Over a period of years other buildings will be rehabilitated or demolished and as a matter of course the combined sewerage system will carry less and less sanitary flow and will ultimately be converted to a storm drainage system.

A Master Plan for the improvement of the sewerage system has been developed for the entire South End Project Area, Budget limits require that only those parts of the system to be included as Urban Renewal Project Improvements are where (1) major street improvements are required; (2) sewer construction is necessary to adequately serve the Urban Renewal Developments; and (3) major components must be built to provide a basic workable systems The remainder of the system can be built by the City of Boston over a period of many years as the need arises and funds permit. Working design drawings of the entire system are submitted with this report to supplement the Urban Renewal plans. The sewer construction included as a project improvement will provide effective separate systems for about 60% of the area of the South End that is now served by combined sewers, and provides trunk systems to facilitate further separation in the future.

The elevations of both the storm and sanitary sewers will permit eventual separation of storm and sanitary flows from house connections. There may, however, be individual existing buildings where pumping units would be required for draining the sanitary or storm flows to the street mains with the option of leaving the building with a combined outlet. This condition occurs where construction of a storm drain and/or sanitary sewer at a greater depth than generally necessary for an area would be economically unfeasible for a single connection.

The existing tide gates on the major overflows from this area will be replaced as necessary to insure proper functioning of the system and prevent flooding of the pumping station,, A major problem during construction could be the frequent flooding of the sewerage systems by tide water backing up Into the system through the many faulty and inoperative tide gates on the Boston Main Drainage System. To prevent this, thereby reducing construction costs in this Project Area as well as others adjacent to the waterfront, all the tidegates and overflow conduits that are faulty should be repaired or replaced. A review by Sewer Division Maintenance personnel of this need on individual tidegates provided the basis for estimating the cost for this work at $100,000.

The sanitary system will be primarily new construction since conversion of the existing combined sewers to sanitary sewers is not practical. All combined sewers will be provided with dry weather connections to the sanitary system and overflow weirs will be installed at several points to prevent flooding of the sanitary system. Two major trunk sanitary sewers will be constructed and will discharge flows into the East Side and Boston Main Interceptors."

BOSTON REDEVELOPMENT AUTHORITY ENGINEERING REPORT ON THE PRELIMINARY DESIGN OF PROJECT IMPROVEMENTS, SOUTH END PROJECT, Project No. Mass. R-56, MAGUIRE AND ASSOCIATES, ENGINEERS (JULY 1965)

The entrance of this surface, ground and tidewater, often overtaxes the capacity of the systems and causes
overflow conditions in inland streams, resulting in stream pollution.

Pollution of Boston Harbor. Boston Harbor provides a natural recreational area for Metropolitan Boston. It
is polluted. The seriousness of existing conditions demands immediate attention. Present conditions are so serious that organized public protest has been made to secure correction. This was graphically demonstrated to this Commission at our hearings. Hundreds of men and women charged there is a health menace, declared recreational facilities were lost to them, and decried destruction of the esthetic beauties of the district because of existing conditions. Our personal examinations of waters in Boston Harbor and complaints registered by residents of the Metropolitan area, all substantiate previous reports of investigating bodies that pollution exists. We unequivocally state that conditions now existent in Boston Harbor and along the shores of the bay are sufficiently grave to make it mandatory that we recommend a definite program for alleviation of the objectionable conditions. As a result of our studies into conditions in the harbor, we find that experts and laymen recognize there is a serious pollution there. Municipal officials and taxpayers, who must eventually pay for any improvements, all insist upon abatement of this nuisance, before it seriously threatens the public health or becomes increasingly objectionable.

Actually, however, a large part of the North Metropolitan District 1 is served by combined sewers, intended
to carry both storm water and sewage. The rest of the area is served by separate sewers, which have been
abused by the admission of storm water which they were not intended to carry. These systems are so designed
that the storm flows are discharged directly into the nearest water course, but intercepting sewers collect
the dry-weather flow and deliver it to the outlets in the harbor. In times of storm, since the capacity of the
intercepting sewers is insufficient for much storm water, mingled sewage and storm water are discharged directly into the streams through numerous overflow channels provided for this purpose.

In some cases in the North Metropolitan and Boston Main Drainage systems salt water has been found to
enter the sewers to such an extent as to take up a substantial portion of their capacity, and such misuse of
sewer capacity should be avoided as pointed out in House, No. 1600. We believe it can be much reduced by (a)
replacing tide gates or parts thereof which are worn out; ( b) rebuilding with improved design any gates which may not be suited to the conditions under which they operate; and (c) prompt attention and effective maintenance. Since all the sewage discharged into the harbor at the main outlets from these systems must be pumped at least once, and in the future will be treated also, it is advisable to keep tide gates in good condition and thus to reduce the cost of pumping and treatment.

Leakage of river water into sewers, through manhole covers which may be submerged during high water in
the rivers, as pointed out in House, No. 1600, should be stopped, either by raising the manholes above high
water level, or, where this is not feasible, by sealing them.

If, in the future, it becomes advisable to fill the South Bay, the construction of conduits to deliver the drainage
from the Roxbury Canal and Dorchester Brook into Fort Point Channel will be necessary.

HOUSE No. 2465, REPORT OF THE SPECIAL COMMISSION INVESTIGATING SYSTEMS OF SEWERAGE
AND SEWAGE DISPOSAL IN THE NORTH AND SOUTH METROPOLITAN SEWERAGE DISTRICTS AND THE CITY OF BOSTON. (June 15, 1939)

Boston's Victorian Sewers

"The city of Boston has made very extensive use of underground space since colonial days when wooden water pipes were laid underground for water supply and drainage. In the nineteenth century, pipes for illuminating gas were laid and at the close of the 1800s the first subway in the United States was constructed. Water supply and drainage tunnels have been constructed at various times across metropolitan Boston since the late 1800s."

Barosh & Woodhouse, A City Upon a Hill: Geology of the City of Boston & Surrounding Area, Boston Area Water Supply & Wastewater Tunnels, Civil Engineering Practice, Vol. 26-27 (2011/2012).

"The first sewer was constructed in Boston prior to the year 1700, some 70 years after Boston was first settled. By 1701, the population had increased to about 8,000, and problems were being created by frequent digging of streets to lay or repair sewers. In 1/709, the Massachusetts General Court passed an act regulating the construction of drains and common sewers in Boston and determining the method and distribution of charges for making and repairing the same. For 114 years thereafter (until 1823), the sewers in Boston were constructed, repaired, and owned by private individuals under authority of this 1709 act. The purpose for which the sewers were constructed under this act was for the draining of cellars and lands. Toilet and privy vault wastes were specifically excluded.

One of the first acts of the City Government in 1823, when Boston was granted its City Charter, was to assume control of all existing sewers and the construction and maintenance of new ones. Thereafter, new sewers were constructed by the City. The City ordinances regulated sewers and required that, when practicable, sewers should be of sufficient size to be entered by work crews for cleaning. Fecal matter was excluded from the sewers until 1833, when it was provided that the Mayor and Aldermen, at their discretion, might permit connections which would admit such matter to the sewers. To assist in flushing out deposits in the sewers, it was provided, in 1834, that any person might discharge rainwater from his roof into the sewers "without permit or fee."

During the nineteenth century, extensive operations for reclaiming and filling tidal areas bordering the old shorelines of Boston were undertaken. To meet these changing conditions, sewers were extended long distances at slight or no gradient to reach points of discharge into the harbor or its estuaries. As a consequence, sewers were prevented by tidal action from discharging for long periods each day, resulting in the deposit of sludge and debris within the sewers and upon the tidal flats about the City, with attendant health and odor problems. In 1870, the consulting physicians of the City declared the urgent necessity of a better system of sewerage and in December, 1874, the City Board of Health pointed out clearly the evils of the existing system and strongly urged that a radical change be made.
On March 1, 1875, an order was passed by the City Council authorizing the Mayor to appoint a commission, "consisting of two civil engineers of experience and one competent person skilled in the subject of sanitary science, to report on the present sewerage of the city... . and to present a plan for outlets and main lines of sewers for the future
wants of the city." This report was submitted in December, 1875.

It listed the following three ways in which the City, at that time, failed to dispose of its sewage before it became an extreme nuisance from putrefaction: Sewage could not always be discharged from house drains to the sewers because the sewers themselves were not only full at high tide, but sewage was even forced backward up the drains into the houses; Sludge deposits formed in the sewers because the tide or tide gates prevented outflow. These deposits remained in some places for many months because not enough velocity was produced, even with a falling tide, to induce scour; Sewage discharged from the outlets was held in the harbor by tidal currents permitting the sewage to ''decompose and contaminate the air.

The City of Boston, from 1877 to 1884, constructed what is known as the Boston Main Drainage System. This system consisted of 25 miles of main and branch intercepting sewers, a pumping station at Calf Pasture, and an outfall sewer in tunnel extending to holding tanks on Moon Island from which the sewage was discharged to the harbor on outgoing tides. Sewers constructed were the Boston Main Interceptor (including a portion of the Stony Brook Sewer), East Side Interceptor, West Side Interceptor (including the Brimmer Street Sewer), and the South Boston Interceptor (south branch). The system was designed to have sufficient capacity to intercept the estimated dry weather flow of sanitary sewage, plus a small allowance a for storm water, from combined sewers which formerly had discharged continuously into the harbor and its estuaries."

City of Boston, Massachusetts Report On Improvements to the Boston Main Drainage System Volume 2, HUD Project No. P-Mass-—3306, (Sept., 1967).

East Side Interceptor, from E Chester Park (Mass Ave) to Dover St, on Albany St , 4,524 ft, nearly circular, vertical diameter of five feet eight inches x five foot six inches, 1 in 2k inclination at average depth of 24ft
March mud and peat extended from near surface of the ground to a depth always considerably below the botton of the sewer, piles were required to furnish a secure foundation. Timer platform was fastend to the tops o the pipes and on the platform the sewer, with its rubble masonry abutment wall was built. The bottom of the excavation was about 6.5 ft below the elevation of the die, and considerable trouble was experienced from sea water making tis way into the trench especially in places where the old sea walls and other such obstructions were encountered. The mud on the sides of the trench exerted much lateral pressure and close sheet piling and heavy bracing were necessary. Opening so deep a trench in such material drained the water out of the adjacent soil, redning it spongy and somewhat compressible so that the whole street settle dand had to be resurfaced and repaved. The first common sewer taken in by the receptor is the on concord st . the sewer drains a district in which the cellars are not subject to flooding from rain water during high tides. It was not necessary therefore to let this sewer discharge into the interceptor an amount of sewage in excess of its ordinary maximum dry weather flow, and temporarily during rainstorms, the whole dilute contents of the sewer could without injury be permitted to discharge into the bay at the outlet. An agreement to effect this was desirable because during very heavy rainstorms the while capacity of the intercepting sewer might be needed to afford relief to sewers draining low districts beyond Concord Street. Accordingly the connection between this sewer and the intercepting sewer made through a chamber containing a small regulating apparatus designed to control or cut off the flow automatically. (Fig. 1 and 2, PVIII). Eight similar appliances with slight modifications in the methods of arrangement were used in connection with the same number of common sewers. Under normal conditions the sewage falls into a sump and then passes to the regulator chamber… this apparatus acna be adjusted so that the value will begin to close and cut off the flow of sewage went eh water in the intercepting sewer reaches desired depth. When not cut off, the sewage flows around the tank and passes on through an opening at its further end.
1885 Main Drainage Works.pdf

“At Tremont Street the Stony-Brook intercepting sewer is taken in.
“On each intercepting sewer, just before it reaches the main sewer, is built a penstock chamber, containing a cast-iron penstock gate, by which the flow can be cut off", so that the main sewer can be entirely emptied, should it ever be desirable to do so. At such times the city sewage would be discharged at the old outlets, which are all retained and protected by tide-gates.” (Main Drainage Works, 1885).

City of Boston, Massachusetts Report On Improvements to the Boston Main Drainage System Volume 2, HUD Project No. P-Mass-—3306, (Sept., 1967).

"The first large work of the Superintendent was a system of drainage, executed at great expense, for the southwest part of the City bordering on the Back Bay. Because of the building of the Mill Dam, a portion of the territory had not been graded to a proper height to admit of a natural drainage to the sea and to abate this nuisance it had been necessary to direct the sewage into the tide water. The Main Sewer was laid in Dover Street and Tremont from Castle Street to near the Roxbury line, which intercepted all the drains which then had termination in the Back Bay. To protect the low land and cellars from inundation, it was necessary to build the sewer with self acting tide gates. These gates were worked to stem the tide twice each day. The rest of the time the sewer was used as a cesspool or reservoir where the drainage was retained until the falling of the tide.
The increased use of the rapidly expanding sewer system, however, poised a problem. The drainage from the high of the City was being run through the mains in the lower section, thus it was ending up in the Dover Street Main which was not large enough to hold it when the tide gate was shut. As a consequence, the sewer frequently filled up and flooded basements and cellars. To alleviate the problem, several weirs were built to cause the water to drain into the empty basin (Back Bay) during high tide.

The solution, unfortunately for the Superintendent at least, proved to be only temporary. As the Back Bay was being filled in to re—claim land for the City’s expansion, the weirs had to be continually extended and eventually all were closed save one. The City Engineer’s solution was to recommend the immediate construction of a large main sewer to commence at the Channel in the South Bay, and to extend to Dedham Street to connect to the main sewer now laid in Tremont, thereby diverting all the drainage south of Dedham Street from passing through to Dover Street Main. The proposed sewer would be about 2,600 feet long in the last section across South Bay lands) about 1,000 feet to be built of lumber six feet square and placed on stilts to support it. That section would be available for the drainage of South Bay lands were they to be built on. A second section from Tremont Street to Harrison Avenue, being in original land, could be built of brick laid in cement of a circular shape six feet in diameter or an internal area of about twenty-eight feet. The third and last section would include the building of a gate chamber with its tidal gates, and the required alteration of the sewer at Harrison Avenue at its junction with Tremont Street. The Superintendent further suggested that the continuing complaints of nuisances in vacant lots and abandoned buildings would not be cured until the City required owners to build their houses at sufficient height to allow for proper drainage.

In subsequent reports, the Superintendent observed that the triparize (triparte) agreement among the City, the Commonwealth and the Water Power Company called for the sewers of each street in the filled-in Bay to drain into one main which would discharge sewage directly into the Charles. He very much objected to this, feeling that such a volume could not be absorbed by the River at one location. Better, he said, to have a sewer at every other street discharge into the River, so that the reduced amount could be carried to the middle of the stream and then out to sea on the falling tides.

The remaining years of the 1860’s were taken up with the acquisition of drainage rights in the new sections of the City, the constant replacing of old wooden pipes, and of man hole covers (some were still made of oak). The City could hardly keep up with the demand for new sewers and the growth of the City often depended on how much time it took it to satisfy the appetite for more and more of them. Buildings were continuing to be constructed at too low a grade and consequently cellars flooded at severe high tide. The problem was particularly acute in the area running from Copley Square to Shawmut Avenue. The Superintendent insisted that he license those mechanics who were going to build the sewers, since once built, they became the responsibilty of the City and poor construction caused many a headache.

The City’s death rate, theretofore exemplary, began to climb and the physicians attributed it to the horrid effluent being dumped into the harbor and rivers, or not being disposed of at all. Yet the flow of raw sewage continued, indeed increased. When Atlantic Avenue was constructed, contradicting his previous insistence that several and not one sewer discharge into the less fragile Charles, Smith built one large one to take all the drainage from the area on the theory that it was better to make but one area of the harbor putrid instead of many.

In 1850-51, a large sewer was built running the whole length of Tremont Street to intercept the outlets of the cross sewers in the South End and run the drainage down Dover Street to the South Bay. This sewer was intentionally built very low so that it might discharge into the Bay during low water. A tide gate prevented the water from flowing back into cellars. But when the tide was abnormally high during storms, the system was designed to take the water the sewer could not hold and discharge it into the Back Bay. The filling of the Bay, however, eliminated all of these overflows and even a waste weir built to the Bay did not help since it, in consequence of the building, was now too lengthy to be effective. There were 1,142 cellars between five and ten feet above the low water mark which would be flooded in the event of a very high tide.

The Committee of Aldermen who considered the problem in 1868 dismissed the idea of building a large new sewer to take this overflow and hold it until the tide was low as too expensive. They also ruled out the idea of pumping the excess water to a level of above the high tide, being weary, as were the planners of the Water Works, of the dependency on such a method. They finally concluded that the cellars could be kept dry by removing any connection in them to the sewer system and by boxing them. The also recommended that the territory between Dover Street and the Albany Railroad should be raised to a sufficiently high level to drain independently to South Bay by a separate system of sewers, and leave the rest of the area the full use of the large sewer in Tremont Street and the other in Dover."

he Great Stoney Brook which ran through a large part of the City was being used by some as an open sewer and the City was forced to proceed to cover parts of it over creating a conduit."

The Water & Sewer Works of the City of Boston 1630 — 1978

This sewer drains a district in which the cellars are not subject to flooding from rain-water during high tides. It was not necessary, therefore, to let this sewer discharge into the interceptor an amount of sewage in excess of its ordinary maximum dry-weather flow, and temporarily, during rain-storms, the whole dilute contents of the sewer could, without injury, be permitted to discharge into the bay at the old outlet. An arrangement to effect this was desirable, because, during very heavy rain-storms, the whole capacity of the intercepting sewer might be needed to afford relief to sewers draining low districts beyond Concord Street. Accordingly the connection between this sewer and the intercepting sewer was made through a chamber containing a small regulating apparatus, designed to control or cut off the flow automatically. Under ordinary circumstances the sewage falls into a sump, and thence passes to the regulating chamber, which it enters through a cast-iron nozzle. This nozzle is circular, 12 inches in diameter at its upper end, and rectangular 20 X 6 inches at its orifice. In front of the orifice plays a cast-iron valve, moved by afloat in a tank set in the floor of the chamber. The water in the tank stands at the same elevation as that in the intercepting sewer, a 4-inch iron pipe connecting one with the other. The apparatus can be adjusted so that the valve will begin to close and cut off the flow of sewage when the water in the intercepting sewer reaches any desired depth. When not cut off, the sewage flows around the tank and passes on through an opening at its further end.
(Main Drainage Works, 1885).

“In general terms it may be said that none of the old sewer outlets were in unobjectionable locations.” (Main Drainage Works, 1885). “The position of the principal sewer outlets and of the areas on which the sewage which caused most offence used to accumulate, is indicated on Plate V. From these places foulsmelling gases and vapors emanated, which were diffused to a greater or less distance, according to the state of the temperature or of the atmosphere. Under certain conditions of the atmosphere, especially on summer evenings, a well-defined sewage odor would extend over the whole South and West Ends of the city proper.”

In 1967, a report on the conditions of Boston’s sewer infrastructure described this E. Concord regulator as part of the Roxbury Canal Conduit infrastructure and explained it is a 81-in x 93- horseshoe-shaped reinforced cone conduit using Outlet No. 77. The report also notes the regulator has a “tidegate chamber with two 81-in x 87-in rect. wooden tide gates in series at Albany St.” and that the “dry weather connection working satisfactorily” with “moderate sludge,” but the “upstream gate has fallen off and is laying in invert” and the “downstream gate works but leaks at high tide.” Report On Improvements to the Boston Main Drainage System Volume 1 HUD Project No, P-Mass-—3306, Camp, Dresser & Mckee (Sept., 1967).

The storm flow connection from the combined sewer regulator at E. Concord Street to the Roxbury Canal Conduit is reported to have been bulkheaded, when tide gates were removed within the last year or so, and to be no longer in service. It would be necessary in the present proposed construction to rehabilitate the E. Concord Street storm flow connection to act as a storm overflow from the regulator at Albany Street. 1975 Supplement to 1967 Report on Improvements to the Boston Main Drainage System, Camp, Dresser & McKee for City of Boston, Commissioner of Public Works (Nov. 24 1975).

“This construction and proposed construction is not compatible with the CDM 1967 Master Plan arrangement because it will reverse the direction of service for sanitary sewerage in the South End District. The 1957 CDM report approved by the State DWPC and the 1972 Update of that report both were based on the continuing passage of sewage generally easterly and southeasterly from the South End District to enter the proposed Fast Side Interceptor Replacement, South Branch. at the several regulators at Union Park Street, E. Dedham Street, E. Concord Street and Massachusetts Avenue. The BRA divergence from the 1967 Report plan places a heavier burden on the southwest end of the South Branch of the East Side Replacement, requiring an increase in capacity in that section, because of rerouting of the sewage flow generally southwesterly and thence back northeasterly to the Main Interceptor Replacement. In addition, local sanitary sewers and storm drains proposed for construction by the BRA in E. Concord Street, E. Newton Street, E. Brookline Street, E. Canton Street, E. Dedham Street and Plympton Street all are shown to connect directly to the existing East Side Interceptor without regulators and may be at gradients steeper than those of the existing combined sewers in some of those streets. The combined sewers now connect to the East Side Interceptor through regulators and thus are higher than the existing interceptor at the Albany Street junction points.” 1975 Supplement to 1967 Report on Improvements to the Boston Main Drainage System, Camp, Dresser & McKee for City of Boston, Commissioner of Public Works (Nov. 24 1975).

"In 1823, when the city of Boston was granted its charter, it assumed control of all existing sewers and of the construction and maintenance of new ones, but not until 1833 was it determined that the mayor and aldermen at their discretion might permit fecal matter to be discharged to the sewers. Thus was born the combined sewer system in Boston. Between 1834 and 1870 the city conducted extensive operations for reclaiming and filling tidal areas bordering the old shorelines of Boston.

To meet these changing conditions, sewers were extended long distances at practically no grade to reach new points of discharge into the harbor. As a result, the deposit of sludge and debris within the sewers and on the tidal flats around the city occurred. In 1870 the city declared that a better system of sewerage was urgent, but it was not until the period between 1877 and 1884 that the city of Boston con structed what is known as the Boston Main Drainage System. This system consisted of 25 miles (39.5 km) of main and branch intercepting sewers and a pumping station and outfall sewer to Moon Island where waste water was discharged raw on the out-going tide. The wastewater collected by the Boston Main Drainage System now is discharged to the new Metropolitan District Commission sewerage system where it receives primary treatment and chlorination. Still the combined sewer overflows exist.

At the present time, there are about 1,360 miles (2,150 km) of sewers in the city of Boston, many of which were built over 100 yr ago. Most of these sewers, particularly in the older sections of the city, are combined and their condition is questionable. Much of the Boston Main Drainage System is surcharged and several sections have collapsed."

Charles A. Parthum, Building for the Future: The Boston Deep-Tunnel Plan, Journal (Water Pollution Control Federation) , Apr., 1970, Vol. 42, No. 4 (Apr., 1970), pp. 500-510

"Much of the South End district, an area of about 190 acres, being almost all filled land, is too low to provide adequate drainage to the Fort Point Channel and the recently construction drain through the former South Bay. The original point of disposal for surface drainage to the former Receiving Basin at El. +3.0 in a portion of the estuary of the Charles River was lost when the Receiving Basin was filled in about 1860. Drains built when the South End district was developed were of relatively large size to provide storage for storm water between the periods when the tide level in the former South Bay was below the drain outlet levels. To assist surface drainage, about 50 acres of the district, including streets and buildings, were raised in about 1870. The Union Park Street Pumping Station was constructed in 1913-15 to serve about 82 acres of this district. Other portions of the district, including an area at East Concord Street were not included. The pumping station is reported to be in poor condition and necessary measures for its rehabilitation are in progress."

"The sewers in the streets leading to the South Bay were made extra large to provide storage capacity for sanitary sewage and storm runoff between the periods when the tide level would be low enough in South Bay to allow the conduits to drain. When the East Side Interceptor was constructed in 1879, open connections at East Dedham Street and at Dover Street were provided for unobstructed access to the intercepting sewer without the control of regulating devices. Even with the diversion to Fort Point Channel, however, of all sewage from the East Side Interceptor north of Dover Street through an overflow controlled by a district regulator at Dover Street, the capacity of the interceptor was not sufficient to provide relief for the low areas between Massachusetts Avenue and Camden Street.

REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM, VOLUME 1, HUD Project No, P-Mass-—3306 Camp, Dresser, McKee (SEPTEMBER, 1967).

"It was not until the 19th Century, like in most America cities, following the path of the hygienization of urban environments, that Boston engaged in the construction of a modern sewage system. Prior to that, both Boston and its neighbouring communities used the geographical advantage of their lay-out. The “natural drainage” flow towards the beds of the watersheds of the Neponset River to the south, the Charles River to the west, and the Mystic River to the north, and both the southern and northern areas allowed the landowners to channel their waste out of their towns and city by building lanes to the shortest distance, which ultimately resulted in an anarchic grid of combined sewers.

The backed-up pressure created by high tides prevented the flow of the sewage to the sea, thus creating constantly a stagnant cesspool-like mass of water that continuously deposited sewage material in the harbor and nearby wetlands and beaches. Typhus (documented as early as 1796) and constant cholera outbreaks during the mid 1860s became common. No swimming warnings (risk of getting skin boils) were also common during the mid 1800s.

It was during the late 1800s that the city consolidated, through a set of tunnels, interceptors and pumping stations, the combined sewer grid into three main systems: 1) the Boston Main Drainage System, completed in 1884 which discharged wastewater via Moon Island; 2) the North Metropolitan Sewage System, completed in 1894, discharging from Deer Island (with its world-famous steam driven pump station built in 1899; and 3) the South Metropolitan Sewage System, completed in 1904, which discharged from Nut Island.

The Sewage, though, did not have any treatment, being discharged during the out-going tides. The establishment of the Metropolitan District Commission (MDC hereinafter) in 1919 consolidated the institutional base for the management of the system. Ironically, the result was mismanagement, the system being neglected during the following 60 years, well into the 20th Century. In 1939 the Massachusetts legislature concluded that the conditions of the harbour were “revolting".

Alonso & Recarte, The Boston Harbor Project, Friends of Thoreau Environmental Program, Research Institute of North American Studies, University of Alcalá, Spain.

"The recently constructed MDC Boston Main Drainage Relief Sewer extends about 4,800 ft westerly from its Camden Street junction with the Main Interceptor and the Stony Brook Interceptor in Tremont Street, rightof- way, Columbus Avenue, Ruggles Street, Huntington Avenue and Vancouver Street to a junction chamber where it joins the Charles River Valley Sewer and the South Charles Reldef Sewer and near the Ward Street Headworks. The conduit is a 6 ft 6-in cast-in-place concrete tunnel for most of its length. The invert slope is 0.001 and the estimated capacity flowing full is about 105 med. The purpose of this relief sewer is to divert peak dry weather flows from the West Side and Stony Brook Interceptors of the Boston Main Drainage System to the Ward Street Headworks and thence to Deer Island. Under certain hydraulic conditions, flows from the East Side Interceptor also may be diverted westerly through the Main Interceptor to the conduit and thence to Ward Street. The Boston Main Drainage Relief Sewer was placed in partial operation in May 1967. The Boston Main Drainage Tunnel extends generally easterly from Shaft A at Ward Street, Roxbury, about 13,800 ft at 10 ft in diameter to Shaft Bdiameter to Shaft C at the Deer Island Pumping Station. This tunnel is also about 300 ft below mean sea level. The maximum capacity of the Boston Main Drainage Tunnel is estimated to be about 440 million gallons per day operating surcharged. at Columbus Park, South Boston, thence about 23,800 ft at 11-1/2 ft in."
REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

"New sewers and conduits have been designed wherever existing principal sewers and conduits are inadequate to carry estimated design flows or wherever there is evidence of structural deterioration. We consider that much of the existing Boston Main Drainage System, including tributary sewers, will complete its useful life and require relief or replacement by the year 2020 either for hydraulic or structural reasons. Rehabilitation of existing interceptors and conduits is, in our opinion, justified only for maintaining service until adequate replacement facilities can be constructed or, in specific cases, where inspection indicates that the sewer or conduit is worthy of repair."
REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

Fort Point Channel Storage Feasibility: BWSC is evaluating the feasibility of having a flood control gate structure installed at the harbor end of the Fort Point Channel to mitigate the impacts of tidal surge and increased wet weather discharges from outfalls located within the channel. When a large storm event is anticipated the gate would be closed, and waters in the channel pumped out, thus providing storage capacity for the stormwater discharges from outfalls located within the Channel. After storms have passed stormwater detained in the storage basin would be pumped out and the gates reopened to allow for normal discharges and tidal flow. Preliminary analysis indicates that installation of a gate structure will prevent flooding in almost 10 percent of the City of Boston, including significant portions of the critical downtown, South End and seaport districts during a 10 year design event. To handle storms larger than this design storm, pumps within the dam4structure would maintain levels within the channel until the higher tides recede.
BOSTON WATER AND SEWER COMMISSION CAPITAL IMPROVEMENT PROGRAM 2022-2024
https://www.bwsc.org/sites/default/files/2022-01/2022-2024%20CIP%20FINAL.pdf

"Storm Water. Proposed control structures and dry weather flow interceptors have been designed such that all flows in excess of interceptor capacities will pass to nearby water bodies. When the proposed Deep Tunnel Plan is constructed, as discussed in Chapter VII and in detail in Appendix F, such overftows will be received by deep rock storage tunnels. Therefore, no allowance has been made for storm water in the design of principal dry weather interceptors. For roof, areaway and foundation drains and catch basins connected to a sanitary sewer, contributions of storm water are excessive. Regulations should be rigidly enforced to prevent the entrance of storm water into Sanitary sewers from all sources. Since full compliance with such regulations may result in increased building construction costs, and in added expense to owners of many existing buildings, it must be anticipated that there will not be full compliance to such enforcement. Furthermore,
separation of building plumbing will in many cases be impossible to accomplish as a practical matter as discussed in Chapter VII.
REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

Tide Water. In the lower reaches of the existing Boston sewerage system, the entrance of tide water into sewers is a major source of extraneous flow. This has been true for many years. In Senate Document No. 56, January 1931, it was stated, "The main sewers of the Boston Main Drainage System and those in the low territory in the North Metropolitan District adjacent to salt water have been found to receive in some cases considerable leakage through tide gates at regulated overflows to the harbor or tributary waters.'' Tide gates were originally installed at points of discharge from the sewerage system into Boston Harbor and its estuaries in order to prevent the entrance of tide water into the sewerage system during high tide levels and permit excess sewage flows to be discharged through regulating structures during sufficiently low tide levels. However, from observations made during the course of this study as well as the reports of previous investigators, it is evident that during incoming tides there is considerable leakage of tide water back into the sewerage system due to broken, inoperative, or blocked tide gates. On outgoing tides, raw sewage is discharged through the tide gates into the harbor each day, regardless of weather conditions. In many of the sewers affected by tide water, the sewers are surcharged above their crowns for extended periods during each tidal cycle, thus greatly reducing the sewer capacities available for storm and sewage flows. Our design estimates of required capacity for proposed new sanitary sewers and dry weather interceptors, as well as our determination of the adequacy of existing sewers, contemplate the exclusion of all tide water from the sewerage system. Therefore, no design allowances for the entrance of tide water have been made.
REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

Boston Main Drainage System. The principal components of the Boston Main Drainage System serving the Boston Main Drainage District are the Boston Main Interceptor, five branch interceptors, and outlet works. The five branch interceptors are the East 3 Side Interceptor, West Side Interceptor, South Boston Interceptor, Dorchester Interceptor and Stony Brook Interceptor. In addition to these principal components, two major district trunk sewers join the Boston Main Interceptor directly through dry weather connections. The two sewers are known as the Dorchester Brook Sewer and the Roxbury Canal Sewer. Outlet conduits from these two districts are known as the Dorchester Brook Conduit and the Roxbury Canal Conduit respectively. All of the above components of the Boston Main Drainage System are described below. A description of the entire Stony Brook System is also included inasmuch as it serves a large portion of the Boston Main Drainage District.

At Tremont Street the main interceptor is connected to the MDC Boston Main Drainage Relief Sewer, a relief conduit discharging to the Ward Street Headworks which was placed into operation in May 1967. The main interceptor at the Columbus Park Connection is 126-in diameter circular brick conduit, and its estimated capacity flowing full is about 185 mgd. Upstream of Tremont Street it is a 90-in x 92-in modified circle brick conduit, and its estimated capacity flowing full is about 80 mgd. The interceptor passes through the Dorchester Improvement Area, borders the Roxbury-North Dorchester General Neighborhood Renewal Plan (GNRP), extends across the South End Urban Renewal Area, and into the Parker Hill- Fenway GNRP. The estimated capacities of the interceptor flowing full are inadequate for the estimated year 2020 peak dry-weather flows, but if all flows from the West Side Interceptor and Stony Brook Interceptor are diverted to the MDC Ward Street Headworks as planned, the capacities would be adequate for the estimated peak dry weather flows from the areas then remaining tributary. The poor structural condition of the sewer is evidenced by failure of the sewer in two places, in Mt. Vernon Street east of the Southeast Expressway in 1961 costing over $120,000 to repair, and in Massachusetts Avenue near Clapp Street in 1962 costing over $180,000 to repair. In addition, both repairs involved other large expenditures caused by the loss of use of the sewer, traffic rerouting and delays and damages from emergency overflows of sanitary sewage. Traffic is now barred from passing over the interceptor in the portion of Massachusetts Avenue east of the New Haven Railroad bridge. The structural condition of other portions of the Boston Main Interceptor, particularly in Massachusetts Avenue is considered to be poor.
REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

Photographic inspection to determine the structural conditions of conduits in the Boston Main Drainage System could not be accomplished due to high water levels. Gagings of water levels were made at several selected points in August 1966 before the MDC diversion at Camden Street took place, and it was found that there was not sufficient time during low tide periods nor was there sufficient clearance below the crowns of the conduits, to permit photography even with all available
pumps at the Calf Pasture Pumping Station operating. After the MDC diversion took place in May 1967, gagings and observations were again made with results similar to those obtained earlier. We have, therefore, utilized photographic and other evidence previously obtained in evaluating the conditions of conduits. Extensive photographic inspection was accomplished in 1963 of portions of the Boston Main Interceptor and East Side Interceptor and a small portion of the Stony Brook Interceptor in conjunction with preliminary investigation of the sewerage system in the South End Urban Renewal Project area. Additional photography has been done by the city on portions of the Boston Main Interceptor and Dorchester Brook Sewer.

The East Side Interceptor and its associated principal sewers and conduits serve the South End, downtown Boston and North End sections ‘of the city, a total tributary area of about 1,030 acres. Most of the sewers in this district are on the combined plan. Some streets, however, contain two or more structures carrying sanitary sewage and/or storm water. Most
conduits connect to combined sewers, with a few storm drains discharging directly to the Inner Harbor. The principal subdistricts in order upstream from Massachusetts Avenue where the interceptor connects to the Boston Main Interceptor are those connected at East Concord Street, East Dedham Street, Union Park Street, East Berkeley (Dover) Street, a point south of Broadway (formerly Troy Street), Kneeland Street, Oliver Street-Purchase Street (which includes much of the downtown shopping district), Central Street including the Canal Street Relief Sewer district, Clinton Street, and the area north of Richmond Street along Commercial Street to north of Hanover Street.

The interceptor extends northeasterly in Albany Street from Massachusetts Avenue to near Herald (Castle) Street, thence easterly and northerly in the New Haven Railroad yards to Atlantic Avenue near Beach Street and in Atlantic Avenue and Commercial Street to Hanover Street, a total length of about 2.9 miles. Sections have been replaced in the railroad yards and along the Central Artery (Fitzgerald Expressway), and relocations will be required by work in the Downtown Waterfront Urban Renewal project areas. The interceptor is a 66-in x 68-in modified-circular brick conduit at its junction with the Boston Main Interceptor at Albany Street, with an estimated capacity flowing full of 33.4 mgd. Wet weather flows of mixed sewage and storm water in excess of pipe capacity overflow directly to the Roxbury Canal Conduit, Fort Point Channel and the Inner Harbor.

The physical condition of long sections of the sewer is poor as revealed by a photographic inspection of portions downstream of Dover Street in 1963. Substantial deposits of material have been found by soundings at manholes.

The subdistrict between Camden and Berkeley Streets, on the west and east, and between the Providence Division of the New Haven Railroad and Tremont Street on north and south, and along Union Park Street to Albany Street is an area of about 82 acres of fairly low flat land served by drainage pumps at the Union Park Street Pumping Station. The need for such a drainage pumping station became apparent with the filling of the former "Receiving Basin'' in which water was to be held permanently, in the early 1800's, at Elev. 3.0 as part of a tidal power development. With the loss of the advantage of the low water level of the basin, and subsequent filling of the Back Bay in the period starting about 1858, drainage conduits in the Union Park Street and adjacent areas were constructed to discharge to the former South Bay east of Albany Street. The sewers in the streets leading to the South Bay were made extra large to provide storage capacity for sanitary sewage and storm runoff between the periods when the tide level would be low enough in South Bay to allow the conduits to drain.

When the East Side Interceptor was constructed in 1879, open connections at East Dedham Street and at Dover Street were provided for unobstructed access to the intercepting sewer without the control of regulating devices. Even with the diversion to Fort Point Channel, however, of all sewage from the East Side Interceptor north of Dover Street through an overflow controlled by a district regulator at Dover Street, the capacity of the interceptor was not sufficient to provide relief for the low areas between Massachusetts Avenue and Camden Street. As a result of need indicated by frequent flooding, the Union Park Street Pumping Station was constructed and put into operation in 1915, to pump mixed sewage and storm water from the low level storm drainage system serving the Union Park Street district to the Roxbury Canal through a short force main. The station is now in process of rehabilitation, with the provision of new pumping equipment and piping.

REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

The Dorchester Brook Conduit extends for about 4,400 ft north of Massachusetts Avenue, parallel to the Midland Division of the New Haven Railroad, passing beneath Southampton Street and the Southeast Expressway, thence northwesterly crossing beneath the Midland Division and passing for about 1,900 ft to a junction with the Roxbury Canal Conduit. From this junction the Roxbury Canal Conduit extends about 900 ft to the Fort Point Channel outlet (Outlet No. 219) north of the Dover Street - West Fourth Street Bridge embankment.

In March and April, 1966, photographic inspection was made by the City of 484 feet of the trunk section extending southwest from Massachusetts Avenue. This inspection showed that this section was in poor condition with a large crown crack evident for much of its length. The condition of the remainder of the sewer is not known.

The Dorchester Brook Conduit at Massachusetts Avenue is a 142-in by 104-in horseshoe-shaped concrete conduit with an estimated capacity flowing full of about 120 mgd. At its junction with the Roxbury Canal Conduit it is a double 204-in by 162-in reinforced concrete box culvert and has an estimated capacity flowing full of about 1,420 mgd if tidal effects are not considered. Its condition upstream of the railroad crossing is not known, and the downstream section is currently under construction.

The Roxbury Canal Sewer, a principal tributary to the Boston Main Interceptor at Massachusetts Avenue and Albany Street, serves an area in the Roxbury district of Boston of about 250 acres. The sewer extends southwesterly in Albany and Dearborn Streets to Dudley Street. At this point, it divides into two branches, one extending west in Dudley Street to Warren Street, and the second east in Dudley Street and south in Blue Hill Avenue to near Stafford Street. A principal submain sewer extends from the main sewer in Albany Street south in Hampden Street to near Dudley Street.

Roxbury Canal Sewer. The tributary area is generally served by combined sewers with a few separate Sanitary sewers and storm drains near the south edge. Mixed sewage and storm water from this tributary area discharges through a regulator into the recently constructed Roxbury Canal Conduit and thence to Fort Point Channel. The drainage area generally south of Eustis Street is high, steeply sloping ground, and the portion generally north and northeast of Eustis Street is former marsh land and therefore generally flat. At Massachusetts Avenue, the sewer is a 54-in x 57-in modified-circular brick conduit with an estimated capacity flowing full of about 57 mgd. The estimated capacity is inadequate for storm flows for the 15-year frequency design storm, in the reaches of the sewer in Blue Hill Avenue, in Dudley Street, in Dearborn Street and in Albany Street to Massachusetts Avenue. The structural condition of this brick sewer is not known. At Massachusetts Avenue, the Roxbury Canal Sewer joins a common sewer in Massachusetts Avenue which in turn joins the main interceptor through the above described regulator south of Albany Street.

The Roxbury Canal Conduit, constructed by the State Department of Public Works in 1965 and 1966, extends generally northeasterly from Massachusetts Avenue to the south end of the existing culvert beneath the West Fourth Street Bridge viaduct through which it discharges to the Fort Point Channel. The major branch of this conduit is the Dorchester Brook Conduit, the lower reaches of which are now under construction. The Roxbury Canal Conduit receives the discharges and overflows of mixed sewage and storm water from the Roxbury Canal Sewer at Massachusetts Avenue, from common sewers in Massachusetts Avenue north and south of the conduit, from outlets at East Concord Street, East Dedham Street, Union Park Street, and Dover Street and from the Dorchester Brook Conduit. The drainage area tributary to the conduit is the area which drains naturally to what was formerly South Bay.

REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

"The outlet from a combined sewer comprises the diversion structure at the sewer with its regulating device, a back flow prevention gate if necessary, a connecting pipe, an outlet sewer serving one or more diversion Structures, and a point of discharge to the Charles River Basin or to Boston Harbor or its tidal estuaries. The diversion of the flow of mixed sewage and storm water in excess of the capacity of the interceptor or in excess of the rate of flow it is desired to discharge to the interceptor is made by regulator devices. The three types commonly installed in the Boston Main Drainage System and the Boston combined sewers connected to MDC branch sewers in East Boston, Charlestown, Brighton and Back Bay, are designated as weir, sump and high-outlet regulators. None of the originally installed mechanical regulators consisting of float-actuated shutter gates or sector shear gates were found still in use during our examination.' The weir-type regulator consists of a low, broad crested weir or dam in the combined sewer and a short connecting pipe to the interceptor. The connection acts essentially as an orifice or short tube to divert all flow to the interceptors below the rate corresponding to the hydraulic head between the sewage level at the dam crest and the level of the hydraulic grade line in the interceptor. At higher rates of flow the amount of mixed sewage and storm water conveyed to the interceptor may increase or decrease, as the net head changes with increasing depths in the combined sewer and in the interceptor. The excess flow is discharged over the dam to the outlet conduit. In some instances, because of the relative elevations of the interceptor and a combined sewer constructed earlier, the intercepting sewer masonry itself has become in effect the dam in the combined sewer. The sump-type regulator consists of a sump or depression in the invert of the combined sewer and a short connecting pipe from it to the interceptor. The connection, as for the weir-type regulator, acts essentially as an orifice or short tube to divert all flow to the interceptor at all rates less than the rate corresponding to the level in the sump at which flows pass downstream. At higher rates, the amount of mixed sewage and storm water conveyed to the interceptor may increase or decrease as the net hydraulic head between the level in the combined sewer and the level of the hydraulic grade line in the interceptor changes. The balance of mixed sewage and storm water flow continues across the flooded sump in the diversion chamber into the outlet conduit. The third type, the high-outlet orifice type regulator consists of the open end of a pipe connected to the outlet sewer extended through the wall of the diversion chamber of the combined sewer above the invert. In this case, the dry weather flow normally continues through the diversion chamber
to the interceptor. Under storm conditions as the level in the combined sewer rises with increasing rates of flow and rising hydraulic gradient in the interceptor, the water level in the combined sewer becomes higher than the invert of the connecting sewer entrance, resulting in the discharge of a portion of the mixed sewage and storm water to the outlet conduit. The balance of the flow passes to the interceptor. The rate of flow diverted depends upon the relative hydraulic grade line elevations in the outlet conduit and the interceptor, and the dimensions of the connecting pipe. Regulating devices also include stop-logs and sluice gates for closure of the diversion connections.
The outlet conduit receives the mixed sewage and storm water from one or several combined sewers and possibly one or more storm drains, and conveys the flow to the point of discharge at the shore line or a short distance offshore. Waters which receive such discharges include the Inner Harbor and Dorchester Bay or their estuaries, the lower Charles, Chelsea and Neponset Rivers. The outlets from the combined sewers in the Stony Brook system and the West Side Interceptor districts are connected to the MDC Boston Marginal Conduit, and may discharge to the Charles River Basin or to the Charles River estuary as determined by tide height and available conduit capacity.
REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM VOLUME 1 HUD Project No, P-Mass-—3306, Camp, Dresser & McKee (SEPTEMBER, 1967).

"It was allowed to run out into the water from numerous outlets. This was found objectionable. The water became contaminated, and the dock frontage was injured by the deposits of sludge. As the sewers were all constructed and in place, only the radical method of dealing with the problem seemed practicable. It was determined to surround the city with an intercepting sewer, which should receive the delivery from all the lines formerly discharging into the h arbor and adjacent water.

From this intercepting sewer, that was to encircle the city like a girdle, the sewage was to be taken to a distant point and, after proper clarifying, was to be discharged into the harbor. Referring again to the map, the course of the new works, constructed in accordance with these ideas, may be traced. The old system, though still in place and in use, is not shown. The heavy black line encircling the city, and with branches running out into South Boston, indicates the intercepting sewer.

While it was constructed so as to cut off the discharge into the waters of the bay of all ordinary drainage, the old outlets were not completely closed. They are preserved, and, by means of dams or gates, are arranged to discharge all over a certain amount. This amount is made great enough to allow for all ordinary flow and for the lighter rain storms. In case of heavy falls of rain, the overflows come into action, and permit part of the water to run directly away into the bay."

THE BOSTON SEWER SYSTEM AND MAIN DRAINAGE WORKS, Scientific American, Vol. 57, No. 23 (DECEMBER 3, 1887), pp. 351, 358-359.

The City of Boston sewerage system was constructed in the late 1800's. From past experiences in large cities, it is likely that some local sewers, for which there are no records, have never been intercepted and are presently discharging sewage directly to the harbor and tributaries. These sewer outfalls would be in addition to the 102 sewer outfalls listed previously.

Joint Report on Pollution of Navigable Waters of Boston Harbor, US DOI and MA Water Resources Commission, April 1969

As presented in Chapter 1, Massachusetts House Document No. 1600 of 1936 evaluated pollution problems In Boston Harbor and its tributary streams. This study inventoried in detail pollution problems and sewerage systems in the
Boston Harbor area identifying 217 external overflow locations, 165 internal overflow locations to relief conduits, and 1514 regulators . Major factors relating to pollution conditions were Identified as: Bacterial pollution, floating solids, slick, and sludge deposits. Dissolved oxygen content in the waters was not found to be a nuisance anywhere. However, the oxygen content in the Port Po int Channel was found to be lowest of the readings taken.

Sewer Separation. In the past sewer separation was considered as the ultimate answer However to overflow problems. , more recently it has been considered as a poor alternative In many cases. Not only is it expensive , it could cost up to $1.7 billion’ to completely separate Sewers in this metropolitan area, but it is physically not feasible in many cases such as downtown Boston. In addition, as shown in Table 2—2, the pollution content of stormwater itself makes the quality improvements achieved by separation not comparable to the investment necessary to accomplish separation. To overcome some of the physical constraints and reduce costs, partial separation is carried out in selected cases . This involves separating the street runoff from the combined sewer system but leaving the roof runoff, cellar drainage and other building sources to drain to the combined system. Although this Is considerably less expensive, about $525 million’ for the Metropolitan Boston area and the runoff component is separated from the combined system, roof runoff is left in thereby failing to provide marked Improvements to water quality .

Proposal: No. 7 — Fort Point Channel | Facility No. 7 would be located in the vicinity of the outfall of Dorchester Brook Conduit and treat the overflows 57, 45, 143, 19, 9 and 27 from the East Side Interceptor and Dorchester Brook overflow 33. Final design of this facility must consider the effects of planned urban renewal projects namely, Government Center, Waterfront, South Cove and South End on the combined sewer system For combined sewer overflows not tributary to a proposed regulation system, special localized solutions may be required . In some cases, these are already planned to be implemented and , although they may not comply with the design criteria selected for this study , are assumed to be part of the plan.

WASTE WATER ENGINEERING MANAGEMENT PLAN FOR BOSTON HARROR, METCALF AND EDDY INC (1975)

mAIN dRAINAGE & THE combined sewer system

"The Boston Main Drainage System, was designed as a combined sewerage system and intercepts the dry-weather flow and part of the storm run-off from areas not tributary to the Metropolitan systems. Combined flows in excess of the interceptor capacities are discharged through local overflows. District regulators are installed at some of the connections and tide gates are provided on all overflow conduits. This system serves an area of 11,500 acres, a resident population of 450,000, and a transient population of over 800,000, or an equivalent population of approximately 500,000. The Main Drainage was constructed during the period from 1877 to 1888 and consists of over 27 mi. of intercepting sewers, chiefly of brick masonry, which flow by gravity to the Calf Pasture works.

The main interceptor, 3.25 mi. long, and varying in size from 7 ft. 7 in. to 10 ft. 6 in. in diameter, carries the/ flow from five principal branch interceptors; namely, the South Boston interceptor, 5.25 mi. long, varying in size from 15 in. to 6 ft., which follows the shore line; the Dorchester interceptor, 6.6 mi. long, varying in size from 3 ft. to 5 ft., which follows the shore line and the north bank of the Neponset River; the East Side interceptor, 2.9 mi. long, sized from 15 in. to 5 ft. 8 in., which follows the north side of the Roxbury Canal and Fort Point Channel, thence along the waterfront; the West Side interceptor, 3.35 mi. long, varying in size from 15 in. to 5 ft. 6 in., which extends from the upper end of the main interceptor through the Back Bay section and along the south side of the Charles River Basin; and the Stony Brook interceptor, 4.0 mi. long, varying in size from 3 ft. to 4 ft. 8 in., which lies in the Stony Brook Valley.

At present the sewage, after passing through elevator-cage type screens, is lifted by motor-driven pumps about 35 ft. into twin 8 ft. by 16 ft. deposit sewers, 1,300 ft. long, and, after passing through these sewers for the purpose of grit removal, the sewage is carried under Dorchester Bay through a tunnel, which is an inverted siphon, brick lined, 7 ft. 6 in. in diameter and 7,160 ft. long. The lower portion of this siphon lies more than 140 ft. below mean low water for a distance of 6,090 ft. The tunnel discharges at Squantum, into an 11 ft. by 12 ft. outfall sewer 5,400 ft. long, built in embankment to Moon Island."

John F. Flaherty, Sewage Treatment and Disposal for Boston, Sewage and Industrial Wastes, Vol. 22, No. 3 (Mar., 1950), pp. 277-288.

"Pollution of the Harbor and its tributaries extends back over more than a century. The first drains constructed prior to the year 1700 and until 1823 were all privately owned and used for draining cellars and land only. These drains and later the common sewer discharged into the nearest water course. Fecal matter was excluded until 1833. By the 1870's conditions in the sewerage system and at the outlets resulted in odor and health problems. Between 1877 to 1884 the City of Boston pioneered in constructing major sewerage works known as the Boston Main Drainage System; consisting of 25 miles of main and branch intercepting sewers, a pumping station at Calf Pasture and storage tanks at Moon Island for discharge on the ebb tides. This system was designed to carry the dry-weather sewage flow with an allowance for a small quantity of storm water from combined sewers which formerly discharged into the Harbor and its tributaries."

STATUS AND PROPOSED CONTROL OF POLLUTION IN BOSTON HARBOR AND ITS TRIBUTARIES, JOHN F. FLAHERTY, JOURNAL OF THE BOSTON SOCIETY OF CIVIL ENGINEERS Volume 55, Number 4, (OCTOBER 1968).

Such changes have taken place in the contours of the city, through operations for reclaiming and filling tidal areas bordering
the old limits, that, from being a site easy to sewer, Boston became one presenting many obstacles to the construction of an
efficient sewerage system. This will be understood from an examination of the plan of the city proper, Plate V. On this plan the shaded portion represents the original area of the city, and very nearly its limits in 1823. The unshaded portion of the plan, indicating present limits, consists entirely of reclaimed land filled to level planes little above mean high water, the streets traversing such districts being seldom more than seven feet above that elevation. A large proportion of the house basements and cellars in these regions are lower than high water, and many of them are but from five to seven feet above low-water mark, the mean rise and fall of the tide being ten feet. This lowness of land surface and of house cellars necessitates the placing of housedrains and sewers at still lower elevations. Most house-drains are under the cellar floors, and fall in reaching the street sewers ; the latter must be still lower, and in their turn fall towards their outlets, which were rarely much, if at all, above low water. Moreover, as filling progressed on the borders of the city, it became necessary to extend the old sewers whose outlets would have been cut off. The old outlets being generally at a low elevation, even where the sewers themselves were sufficiently high, the extensions had to be built still lower, and when of considerable length could have but little fall towards the new mouths. As a consequence, the contents of the sewers were damned back by the tide during the greater part of each twelve hours. To prevent the salt water flowing into them many of them were provided with tide-gates, which closed as the sea rose, and excluded it. These tide-gates also shut in the sewage, which accumulated behind them along the whole length of the sewer, as in a cesspool ; and, there being no current, deposits occurred. The sewers were, in general, inadequately ventilated, and the rise of sewage in them compressed the foul air which they contained and tended to force it into the house connections. To afford storage room for the accumulated sewage, many of the sewers were built very much larger than would otherwise have been necessary, or than was conducive to a proper flow of the sewage ; and, as there would have been little advantage in curved inverts where there was to be no current, flat-bottomed and rectangular shapes were frequently adopted. Although at about the time of low water the tide-gates opened and the sewage escaped, the latter almost immediately met the incoming tide, and was brought back by it, to form deposits upon the flats and shores about the city. Of the large amount of sewage which flowed into Stony Brook and the Back Bay, and especially that which went into South Bay, between Boston proper and South Boston, hardly any was carried away from the vicinity of a dense population.

The position of the principal sewer outlets and of the areas on which the sewage which caused most offence used to accumulate, is indicated on Plate V. From these places foulsmelling gases and vapors emanated, which were diffused to a greater or less distance, according to the state of the temperature or of the atmosphere. Under certain conditions of theatmosphere, especially on summer evenings, a well-defined sewage odor would extend over the whole South and West Ends of the city proper.

There are no plans in detail of the sewers of Boston. Many of the older ones have no man-holes. In some streets several sewers exist side by side. Occasionally a sewer is found built directly above an older one. Probably one-half of the larger main sewers are wholly or partly built of wood and have flat bottoms. An unwise provision was inserted in the charters of some of the private corporations organized for the purpose of reclaiming and filling areas of flats, by which it was stipulated that the corporations should themselves extend all sewers whose discharge would be obstructed by the filling. Such extensions were made without system, by building flat-bottomed wooden scow sewers, which were laid upon the soft surface of the flats before the filling was done. Cross-sections of various common forms of existing city sewers are shown on Plate II., Figs. 1 to 22. Fig. 22 shows Stony-Brook culvert, which constitutes the lower mile of Stony Brook, and is that part of it which is covered and used as a sewer.

One fact which increased the danger arising from the damming up of the sewers, and the consequent compression of their gaseous contents, was that the house-drains connecting with these sewers were ill adapted to resisting this pressure. Most of them were built of brick or of wood, before the rise of modern ideas in regard to sanitary drainage ; and, as they were usually leaky, the gases forced into them found ready egress into the houses. Figs. 23 to 29 on Plate II. show common forms of these house-drains.

Fears were expressed that the intercepting system (by doing away with the semi-daily damming up by the tide of the contents of the sewers) might lower considerably the soil-water in such regions, and, by reducing it below the tops of the piles cause them to decay and endanger the stability of the buildings supported by them.

MAIN DRAINAGE WORKS OF THE CITY OF BOSTON, ELIOT C. CLAEKE, (1885).

As elsewhere stated, the Main Drainage Works were designed and built to correct two principal evils inherent in the old system of sewerage. These were : — First. The damming up of the common sewers by the tide, by which, for much of the time, they were converted into stagnant cesspools, and the air in them was compressed, and to find outlets was driven into house-drains and other openings. Second. The discharge of the sewage on the shores of the city in the immediate vicinity of population, thereby causing nuisances at many points. The first of these evils has been entirely corrected by the new
system. The old sewers now have a continual flow in them, independent of the stage of the tide, as has been ascertained by
frequent observations, and also from the testimony of drain-layers, who formerly were only able to enter house-pipes into the the sewers when the latter were empty at low tide, but now can make such connections at any time.

The new system has also substantially remedied the second evil. From the moment that any of the city sewers was connected
with an intercepting sewer, the sewage which had before discharged on the shore of the city was diverted, and has since
been conveyed to Moon Island and emptied into the Outer Harbor at that point.

Building the intercepting sewers has also dried cellars in other parts of the city in a way which was not at first anticipated.
When land on the shores of the city was reclaimed for building purposes, most of the old walls and wharves were covered up
by the new filling. Tide-water followed along any such structures through the ground, and entered cellars lower than high-tide level. The new sewers were generally built along the present margins of the city, and in digging deep trenches for them the old structures found were cut off and removed. The backfilled earth in the trenches forms an impervious dam surrounding the city, beyond which tide-water cannot pass. The sewers have been examined frequently since they went into operation. The average depth of dry-weather flow in the intercepting sewers is from ten to twenty inches, so that they can be entered on foot. So, also, can the main sewer above Tremont Street, and, sometimes, above Albany Street. Below that point the dry-weather flow is from two to three feet deep, necessitating the use of a boat.

Most of the city sewers, when first intercepted, were found to contain deposits of sludge varying from a few inches to several feet in depth. All these deposits were carried into the intercepting sewers, and the sludge reached the pumping-station and was pumped up into the deposit-sewers. Gravel, stones, and brickbats also were swept along and taken out at the filth-hoist.
Fine sand, however, did not move so freely, but settled in ridges here and there, and had to be removed by hand.

In some portions of the sewers earthy accretions form on the arch. Where the sewer is surrounded by marsh mud these are turned black by sulphuretted hydrogen, sometimes they are colored yellow by iron, often they appear as white stalactites. In clayey soil the arch seems to be about as clean as when laid.

MAIN DRAINAGE WORKS OF THE CITY OF BOSTON, ELIOT C. CLAEKE, (1885).

"In this report, a Deep Tunnel Plan was proposed for the Boston Area to prevent the continued pollution of Boston Harbor and adjacent waters. This plan developed as a logical consequence of investigations into existing conditions and sewerage facilities in Boston, and the need for a genuine solution of the total water pollution problem. About 100 years ago, the records tell us, health and odor problems became so bad in the Boston Area that a special commission was created to find a solution to the problems resulting from the discharge of sewage to open water at innumerable points along the streams and shoreline. Now, 100 years later, in an age of rocketry and atomic power, this problem persists.

There is no question that the waters of Boston Harbor and vicinity are in violation of the established water quality standards. Of particular importance in considering pollution due to overflows of mixed sewage and storm water, are the requirements of the water quality standards for solids and coliform bacteria. No sludge deposits or floating solids are allowable except for those amounts that may result from the discharge from waste treatment facilities providing appropriate treatment."

THE DEEP TUNNEL PLAN FOR THE BOSTON AREA, DAVID R. HORSEFIELD, JOURNAL OF THE BOSTON SOCIETY OF CIVIL ENGINEERS Volume 55, Number 4, (OCTOBER 1968).

Roxbury Canal Sewer
The Roxbury Canal Sewer, a principal tributary to the Boston Main Interceptor at Massachusetts Avenue and Albany Street, serves an area in the Roxbury district of Boston of about 250 acres. The sewer extends southwesterly in Albany and Dearborn Streets to Dudley Street. At this point, it divides into two branches, one extending west in Dudley Street to Warren Street, and the second east in Dudley Street and south in Blue Hill Avenue to near Stafford Street. A principal submain sewer extends from the main sewer in Albany Street south in Hampden Street to near Dudley Street. The tributary area is generally served by combined sewers with a few separate Sanitary sewers and storm drains near the south edge. Mixed sewage and storm water from this tributary area discharges through a regulator into the recently constructed Roxbury Canal Conduit and thence to Fort Point Channel. The drainage area generally south of Eustis Street is high, steeply sloping ground, and the portion generally north and northeast of Eustis Street is former marsh land and therefore generally flat. At Massachusetts Avenue, the sewer is a 54-in x 57-in modified-circular brick conduit with an estimated capacity flowing full of about 57 mgd. The estimated capacity is inadequate for storm flows for the 15-year frequency design storm, in the reaches of the sewer in Blue Hill Avenue, in Dudley Street, in Dearborn Street and in Albany Street to Massachusetts Avenue. The structural condition of this brick sewer is not known. At Massachusetts Avenue, the Roxbury Canal Sewer joins a common sewer in Massachusetts Avenue which in turn joins the main interceptor through the above described regulator south of Albany Street.

REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM, VOLUME 1, HUD Project No, P-Mass-—3306 Camp, Dresser, McKee (SEPTEMBER, 1967).

"As a result of need indicated by frequent flooding, the Union Park Street Pumping Station was constructed and put into operation in 1915, to pump mixed sewage and storm water from the low level storm drainage system serving the Union Park Street district to the Roxbury Canal through a short force main. The station is now in process of rehabilitation, with the provision of new pumping equipment and piping."

REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM, VOLUME 1, HUD Project No, P-Mass-—3306 Camp, Dresser, McKee (SEPTEMBER, 1967).

Offensive Odors

1887

Main Drainage Sewage Outfall

Conditions

TABLE 1 CONDITION AND CAPACITY OF EXISTING OUTLETS (1967)
Report on Improvements to the Boston Main Drainage System, Vol. 1, Camp, Dresser & McKee for City of Boston, HUD Project No, P-Mass-—3306 (Sept., 1967).

Outlet No. | Location | Description of Outlet | Observed Condition | Estimated Capacity

68 | Fort Point Channel at Congress Street | Regulator (high point in outlet) and tidegate chamber near Gilbert Place, followed by 36-in x 36-in rect. wooden conduit. 36-in double-leaf, wooden tide gate upstream. 36-in metal tide gate downstream. | Dry weather flow discharging through out let at low tide. Outrect. wooden conduit. 36-in let surcharged at high double-leaf, wooden tide gate tide. upstream. 36-in metal tide gate downstream. | 10.3

69 | Fort Point Channel at Summer Street | Regulator (high point in outlet) and tidegate chamber near Dorchester Avenue, followed by 60-in brick conduit. Two 60-in double-leaf wooden tide gates. | Some dry weather flow discharging through outlet at low tide. Outlet surcharged at high tide. | 36

70 | Fort Point Channel at Kneeland Street extended | Sump-type regulator and tidegate chamber at Atlantic Avenue, followed by 81-in x 81-in horseshoe-shaped, brick conduit. Two pairs of tide gates in series near upstream end. | Dry weather connection working satisfactorily. No sludge. Some backflow
through upstream pair of 36-in metal tide gates at high tide. Downstream pair of tide gate openings
are planked up. | 77

259 | Fort Point Channel north of Congress Street Bridge (west bank) | 24-in circ. vit. clay storm
drain. | Not inspected | -

71 | Fort Point Channel at Castle Street extended | 8-in cast iron stormwater pumping station force main. | Not inspected | -

72 | Fort Point Channel near Troy Street extended | Sump-type regulator in Albany Street, extended as 72-in circ. reinf. cone. sec~ion. Two original 60-in rect. wooden tide gates in series. | Sump surcharged. Some backflow at high tide. | 62

73 | Fort Point Channel at Dover Street extended | Regulator at Harrison Avenue, followed by 40-in x 49-in ovoid-shaped, brick conduit, extended as 48-in circ. reinf. cone . conduit. Tidegate chamber with two 48-in doubleleaf wooden tide gates at upstream end of 48-in conduit. | Outlet blocked. Overflow line surcharged. Tide gates not visible. | 32

219 | Fort Point Channel, Roxbury Canal Conduit outlet (Dorchester Brook Conduit tributary)& Outlets tributary to Roxbury Canal Conduit and Dorchester Brook Conduit | Roxbury Canal Conduit extends north easterly as 204-in x 120-in rect. rein£ . cone. conduit; 216-in x 120-in rect. reinf. cone. conduit, double 180-in x 120-in rect. rein£. cone. conduit; double 204-in x 120-in rect. reinf. cone. conduit; double 204-in x 150-in rect. rein£. cone. conduit double 240-in x 186-in rect. reinf cone. conduit, discharging to fort Point Channel. Sump-type regulator and tidegate chamber, followed by 72-in x 78-in horseshoe-shaped, brick conduit in Massachusetts Avenue, from northwest (Outlet No. 79) Two 60-in rect. wooden tide gates. | Regulator surcharged but dry weather connection working satisfactorily. Moderate sludge in tidegate chamber. Upstream gate working Downstream gate missing. | 2240

219 | continued | Sump-type regulator and tidegate chamber in Massachusetts Avenue from southeast (Outlet No. 80), followed by 48-in circ. brick conduit. Two 48-in x 48-in rect. wooden tide gates in series. | Regulator and tidegate chamber surcharged at low tide.

219 | continued | Not found (Outlet No. 78).

219 | continued | Regulator, followed by 81-in x 93-in horseshoe-shaped reinf. cone. conduit in E. Concord Street (Outlet No. 77). Tidegate chamber with two 81-in x 87-in rect. wooden tide gates in series at Albany Street. | Dry weather connection working satisfactorily. Moderate sludge. Upstream gate has fallen off and is laying in invert. Downstream gate works but leaks at high tide.

219 | continued | Sump-type regulator and tidegate chamber at E. Dedham Street, extended (Outlet No. 76), followed by 60-in x 72-in arch and scow bottom shaped brick conduit, extended as 60-in x 72-in rect. cone. conduit. 78-in x 92-in rect. wooden tide gate followed by 60-in metal tide gate. | Regulator manhole surcharged but dry weather connection appears to be working satisfactorily. Light sludge. Downstream tide gate timbered shut.

219 | continued | Union Park Street Pumping Station at Union Park Street extended (Outlet No. 75 , "low level") connected by 69-in x 63-in cone. force main to tidegate chamber at Albany Street, followed by 33-in x 126-in con. conduit extended in 91-in x 126-in rect. reinf. cone. conduit (shared with Outlet No. 74). One 69-in x 54-in rect. wooden tide gate. | Station under repair. Tidegate chamber surcharged.

219 | continued | Sump-type regulator and tidegate chamber at Union Park Street extended (Outlet No. 74, "high level")at Albany Street, followed by 58-in x 126-in rect. reinf. cone. conduit, followed by 91-in x 126-in rect. reinf. cone. conduit. Two 88-in rect. wooden tide gates. | Regulator and tidegate chamber surcharged.

219 | continued | Sump-type regulator and tidegate chambers on Dorchester Brook Sewer at Massachusetts Avenue (Outlet No. 81), followed by Dorchester :lrrook Conduit as 142-in x 104-in, 142-in x 124-in and 144-in x 120~in horseshoe-shaped reinf. cone. conduit discharging to open channel at railroad crossing to double 204-in x 150-in rect. reinf. cone. conduit and double 204-in x 162-in rect. reinf. cone. conduit to Roxbury Canal Conduit. Two sets in series of four parallel 48-in x 72-in rect. wooden tide gates. | Dry weather connection partially blocked or too small, and constant flow being discharged to outlet. Some sludge. Tide gates missing or not working.

219 | continued | Sump-type regulators and tidegate chambers in Damrell Street, and D Street near Dorchester Avenue, (Outlet No. 82), followed by 9O-in x 1O1-in horseshoe-shaped, reinf. cone. onduit to Dorchester Brook Conduit, except for short section of open channel at railroad crossing. Additional tidegate chamber on this outlet at upstream end of open channel. Damrell Street chamber has one 36-in rect. wooden tide gate; D Street chamber one 48-in rect. wooden tide gate; downstream outlet chambers have two 51.5-in x 1O1-in rect. wooden tide gates in parallel. | Dry weather connection working satisfactorily. Light sludge at regulators. Tidegate chamber in Damrell Street always surcharged at high tide. Tide gates in remaining chamber stuck open. Slight backflow at high tide

219 | continued | Sump-type regulator in B Street and tidegate chamber west of Dorchester Avenue, (Outlet No. 83), followed by 72-in circ. brick conduit extended as 78-in x 94-in rect. cone. conduit, 72-in circ. brick conduit and 92-in x 78-in rect. cone. conduit to Dorchester Brook Conduit. Two 72-in x 72-in rect. wooden tide gates in series. Second tidegate chamber near end of outlet, with one 78-in x 92-in rect. wooden tide gate. | Dry weather connection working satisfactorily. Sludge condition not known. Tide gates in upstream chamber badly deteriorated and not working. Gate in downstream chamber missing.

84 | Fort Point Channel at West Fourth Street Bridge | Sump-type regulator and tidegate chamber at Foundry Street, followed by 24-in x 24-in rect. wooden section. Two 24-in circ. wooden tide gates in series | Sump not visible but no dry weather flow discharging through tidegate chamber Condition of gates not determined, but appear tight | 8

85 | Fort Point Channel At Dorchester Avenue Bridge | High outlet-type regulator near Foundry Street, followed by 60-in circ. brick section. Tidegate chamber near end of outlet. Two60-in double-leaf, wooden tide gates in series | Dry weather connection working satisfactorily No sludge build-up. Both gates not working. Substantial backflow at high tide. | 28

86 Fort Point Channel at Mt. Washington Avenue | High outlet-type regulator and tidegate chamber, followed by 72-in circ. brick conduit. Two 36-in double-leaf, wooden tidegates in series. Tributary sewers converted to separate sanitary system | Dry weather connection working satisfactorily.No sludge build-up. Downstream tide gates blocked open by heavy debris in chamber.Regulator surcharged and substantial backflow at high tide. | 1.2

86A | Fort Point Channel at Sumner Street Bridge (southeast end) | Stormdrain outlet | dry

87 | Fort Point Channel at Congress Street Bridge (southeast end) | Storm drain outlet | Slight discharge -no odor

RECENT EVALUATION NOTES (FROM CITY OF BOSTON DOCUMENTS):

Receiving Water | Facility ID| Location Type | Inspection Date | Weather | Odor | Color | Floatables | Turbidity | Deposits or Stains | pH | Conductivity | Bacteria | Result CFU | BWSC Comments

FORT POINT 21KCSO070 CSO 11/27/2013 Enterococci 36,000
FORT POINT 21KCSO070 CSO 11/6/2014 Enterococci 5800
FORT POINT 21KCSO070 CSO 7/22/2015 Enterococci 1200
FORT POINT 21KCSO070 CSO 7/22/2016 Oily Sheen Marine life Enterococci 550
FORT POINT 21KCSO070 CSO 10/10/2024 Sunny Cloudy 7.24 Enterococci 900
FORT POINT 21KSDO069 SDO 3/15/2016 Rain Enterococci 1,800 "North inlet looks to be a new service for the bridge drainage. Cracked cover for upstream manhole 21K487. Unable to open manhole 21K486 rusted cover."
FORT POINT 21KSDO069 SDO 4/4/2024 Raining Grey Garbage Unknown "see conditions sheet - confusing data"
FORT POINT 21KSDO069 SDO 5/29/2024 Sunny Cloudy 8.24 757 Enterococci 910 Outfall submerged, went upstream.
FORT POINT 22KCSO065 CSO 9/24/2012 Enterococci 120
FORT POINT 22KCSO065 CSO 7/22/2016 Rotten Eggs Other "Platform midway down blocking view of pipe. Water was swirling in channel."
FORT POINT 22KCSO065 CSO 5/2/2024 7.61 Enterococci 50 "CNL"
FORT POINT 22KCSO068 CSO 11/27/2013 Enterococci 2,800
FORT POINT 22KCSO068 CSO 11/6/2014 Enterococci 2300
FORT POINT 22KCSO068 CSO 7/22/2016 Musty Marine life
FORT POINT 22KCSO068 CSO 5/2/2024 Sunny 7.63 1294 Enterococci 11,000
FORT POINT 22KCSO072 CSO 9/24/2012 Enterococci 60
FORT POINT 22KCSO072 CSO 7/20/2016 Salt Water
FORT POINT 22KCSO072 CSO 1/26/2024 Raining Grey Cloudy 7.37 3480 Enterococci 2,100 "Could not access due to area closed at the hour"
FORT POINT 22KCSO072 CSO 5/2/2024 Sunny "CNL"
FORT POINT 22KCSO072 CSO 8/6/2024 Raining Yellow Clear 7.57 358 Enterococci 5,500 Submerged; Sample warm
FORT POINT 22LCSO073 CSO 7/20/2016 Salt Water Foam Sampled from upstream manhole 22LMH447 where significant flow was observed. Did not attempt to isolate flow at outfall. Sump of manhole was lined with sudsy water. A faint ring of suds surrounded outfall as well.
FORT POINT 23LCSO062 CSO 2/4/2016 Cloudy Enterococci 160
FORT POINT 23LCSO062 CSO 7/21/2016 Salt Water Walked up outfall to isolate flow from tidegate.
FORT POINT 23LCSO062 CSO 10/24/2024 Sunny 7.75 Enterococci 510 Easier access to outf…
FORT POINT 23LCSO064 CSO 9/24/2012 Enterococci 54000
FORT POINT 23LCSO064 CSO 5/16/2013 Enterococci 80000
FORT POINT 23LCSO064 CSO 7/3/2014 Enterococci 180
FORT POINT 23LCSO064 CSO 3/1/2016 17450 Enterococci 90 "Outfall under Summer Street bridge. Outfall diameter and material taken from list."
FORT POINT 23LCSO064 CSO 10/10/2024 Sunny Enterococci 40 "Outfall completely submerged, cannot locate."
FORT POINT 23LSDO074 SDO 10/29/2015 Enterococci 3700
FORT POINT 23LSDO074 SDO 3/15/2016 Rain Enterococci 1,900
FORT POINT 23LSDO074 SDO 3/15/2016 Enterococci 1900
FORT POINT 23LSDO074 SDO 4/12/2024 Raining Grey Sediments 0.5 546 Enterococci 1,700 Outfall under bridge and/or submerged
FORT POINT 23LSDO074 SDO 9/26/2024 Cloudy Uknown "Could not locate"
FORT POINT 23LSDO074 SDO 12/9/2024 Outfall under bridge, metal pipe. Outfall observed dry. Located under the bridge.
FORT POINT 23LSDO075 SDO 8/22/2012 Enterococci 1600
FORT POINT 23LSDO075 SDO 9/26/2024 Cloudy "Could not locate"
FORT POINT 23LSDO164 SDO 9/11/2012 Enterococci 400
FORT POINT 23LSDO164 SDO 9/26/2024 Cloudy Brown Cloudy Enterococci 210 "coud not locate" - but they tested it and observed it?
FORT POINT 23LSDO196 SDO 8/22/2012 Enterococci 140
FORT POINT 23LSDO196 SDO 4/4/2024 Raining Sediments 9.02 406 Enterococci 900 Submerged
FORT POINT 23LSDO196 SDO 7/25/2024 Cloudy 12790 Enterococci 630

COMMENTS:
- unclear methodology, protocols, or QA
- does not post photographs, lab reports, or field notes
- claims it cannot find infra that is in prior reports or is in later reports -- do they not have maps?
- unclear where alternative sample locations are actually located
- uses sample results from undisclosed alternative locations to determine risk of actual location without assessing actual location
- lots of "-999" error codes, including for conductivity, so no published results

Tide Gates & Tidal Intrusion

"In the metropolitan Boston area there are in excess of 100 stormwater drainage outlets to tidewaters while in the Boston main drainage system there are approximately 72 outlet structures with about 200 individual tidegates appurtenant to these outlets. The second session of the conference pointed out that a large number of tidegates appurtenant to the stormwater drainage outlets within the Boston main drainage system were inoperative allowing the intrusion of salt water into the sewerage system. This salt water intrusion increases the flow to the Deer Island wastewater treatment plant and reduces the overall efficiency of this primary waste treatment facility.

As of July 19, 1971, there were 22 combined sewer outlets in the Boston main drainage system which were operational, 6 under construction, 2 proposed for construction, and 42 under investigation. This information was supplied by the Metropolitan District Commission In 1967 a consultant for the city of Boston recommended that Boston rehabilitate and expand their existing sewer system, which included repairs to tidegates and regulators. Many of Boston's sewers are overloaded and in need of repair. The city has not implemented these recommendations."

JOINT STATUS REPORT FOR THIRD SESSION OF CONFERENCE ON POLLUTION OF THE NAVIGABIE WATERS OF BOSTON HARBOR AND ITS TRIBUTARIES, Environmental Protection Agency, Region I & Massachusetts Division of Water Pollution Control (September 1971).

"The discharge to Fort Point Channel is now from the recently completed Roxbury Canal Conduit which eliminated 12 outlets. At its downstream end this conduit is a double 240-in by 186-in rectangular reinforced concrete box culvert with an estimated capacity of 2,240 mgd or just slightly less than for the Fens outlet. These estimated capacities do not reflect the restricting effect of high tide on discharge capacity, but are considered to represent capacities which may be realized under free discharge conditions with the installation of remedial measures such as the proposed Deep Tunnel Plan. It is, of course, evident that surcharging and backing up occurs during periods of high tide at the present time. Because of the extremely poor conditions of the tide gates, regulators, and outlets, lower reaches of the principal sewerage system throughout the city are surcharged by tidewater on flood tides, and purged through outlets on ebb tides."

HORSEFIELD, THE DEEP TUNNEL PLAN FOR THE BOSTON AREA, JOURNAL of the BOSTON SOCIETY OF CIVIL ENGINEERS VOLUME 55 120 YEARS 1848-1968 (OCTOBER - 1968).

During the nineteenth century, extensive operations for reclaiming and filling tidal areas bordering the old shorelines of Boston were undertaken. To meet these changing conditions, sewers were extended long distances at slight or no gradient to reach points of discharge into the harbor or its estuaries. As a consequence, sewers were prevented by tidal action from discharging for long periods each day, resulting in the deposit of sludge and debris within the sewers and upon the tidal flats about the City, with attendant health and odor problems. In 1870, the consulting physicians of the City declared the urgent necessity of a better system of sewerage and in December, 1874, the City Board of Health pointed out clearly the evils of the existing system and strongly urged that a radical change be made. On March 1, 1875, an order was passed by the City Council authorizing the Mayor to appoint a commission, "consisting of two civil engineers of experience and one competent person skilled in the subject of sanitary science, to report on the present sewerage of the city... . and to present a plan for outlets and main lines of sewers for the future wants of the city." This report was submitted in December, 1875. It listed the following three ways in which the City, at that time, failed to dispose of its sewage before it became an extreme nuisance @ from putrefaction: \ is Sewage could not always be discharged from house drains to the sewers because the sewers themselves were not only full at high tide, but sewage was even forced backward up the drains into the houses. $e Sludge deposits formed in the sewers because the tide or tide gates prevented outflow. These deposits remained in some places for many months because not enough velocity was produced, even with a falling tide, to induce scour. oe Sewage discharged from the outlets was held in the harbor by tidal currents permitting the sewage to ''decompose and contaminate the air." Their report presented three possible methods of disposing of sewage as follows: ai Precipitation or sedimentation of the solid portions of the sewage. eis Irrigation. 3. Deep water discharge. It was the recommendation of the Commission that discharge of the sewage to deep water be adopted. The Commission specifically proposed two main drainage systems, one for each side of the Charles River. The system on the south side would have its outlet at Moon Island, and on the north side discharge would be at Shirley Gut near Deer Island. Because of opposition to the Commission's recommendations, the City Council adopted the recommendations only insofar as they referred to the territory south of the Charles River. Based on these recommendations, Chapter 136, Acts of 1876, entitled "An Act to Empower the City of Boston to lay, finance, and maintain a main sewer discharging at Moon Island in Boston Harbor and for other purposeg, " was passed by the Massachusetts Legislature. In the period from about 1867 to 1918, the sewer conduits and channels serving Stony Brook, Muddy River, and the Back Bay Fens were constructed, extended from time to time upstream to further enclose Stony Brook. Upper reaches of Stony Brook have only recently been enclosed. Subsequent to construction of most of the Boston Main Drainage System described herein, the North Branch of ‘the South Boston Interceptor was built during the period 1882 to 1890, and the Dorchester Brook Sewer and Dorchester Interceptor were constructed during the periods from 1897 to about 1926 and 1887 to 1895, respectively. In the period 1912 to 1915, the pumping station at Union Park Street, together with high and low level sewers, were built to reduce flooding in low-lying areas of the South End. And in 1916 the Canal Street Relief Sewer was constructed to divert sewage from portions of downtown Boston, from the West Side Interceptor to the East Side Interceptor. Following the completion of the Boston Main Drainage System, few changes in the system, except those of a local nature, have occurred up to the present time.

"Tide Water. In the lower reaches of the existing Boston sewerage system, the entrance of tide water into sewers is a major source of extraneous flow. This has been true for many years. In Senate Document No. 56, January 1931, it was stated, "The main sewers of the Boston Main Drainage System and those in the low territory in the North Metropolitan District adjacent to salt water have been found to receive in some cases considerable leakage through tide gates at regulated overflows to the harbor or tributary waters.'' Tide gates were originally installed at points of discharge from the sewerage system into Boston Harbor and its estuaries in order to prevent the entrance of tide water into the sewerage system during high tide levels and permit excess sewage flows to be discharged
through regulating structures during sufficiently low tide levels. However, from observations made during the course of this study as well as the reports of previous investigators, it is evident that during incoming tides there is considerable leakage of tide water back into the sewerage system due to broken, inoperative, or blocked tide gates. On outgoing tides, raw sewage is discharged through the tide gates into the harbor each day, regardless of weather conditions. In many of the sewers affected by tide water, the sewers are surcharged above their crowns for extended periods during each tidal cycle, thus greatly reducing the sewer capacities available for storm and sewage flows. Our design estimates of required capacity for proposed new sanitary sewers and dry weather interceptors, as well as our determination of the adequacy of existing sewers, contemplate the exclusion of all tide water from the sewerage system. Therefore, no design allowances for the entrance of tide water have been made."

REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM, VOLUME 1, HUD Project No, P-Mass-—3306 Camp, Dresser, McKee (SEPTEMBER, 1967).

Around 1870 there was an “aggregation of old sewers discharged by about seventy outlets into tidewater chiefly along the harbor front. The fluctuations of the tide waters, particularly in the inner harbor, serve to aggravate conditions which were, even without this factor, manifestly inimical to public health and comfort.” 25 miles of main intercepting sewers, located generally along the tidal margins of the city and lying mainly below the level of low tide.”
1899 Report on Boston Main Drainage Works.pdf

We compromise the matter by closing all the vents that we can with the certainly of poisoning the air of our homes
1885 Main Drainage Works.pdf

“An hour at high-tide in summer on the Roxbury canal, or in the midst of the foul gases bubbling up back of Beacon St… the mud banks are the chief but not the only sources of offense.” “comparatively little help in removing the causes of disease.” “no prevention of the deposit of fifth in our sewers.” “no diminution in the foul character of the gases now generated in our sewers” “ no constant low drainage point (like what formally furnished by the “closed basin”) by which our sewage and most of our rainfall can be always discharged without delay” “no remedy for the force pump section of the rising tide which drives foul gases forcibly into every crack where they can find vent.” Boston Post Wed, May 10, 1876 ·Page 3

The Present Evils – in the existing system the sewage is discharged through seventy different outlets along the shore line of the city and a number of these outlets may be said to be in the very heart of the city; such as those which empty into the Roxbury Canal, South Bay, and Fort Point Channel. Because the “borders of the severed portions of Boston consist largely of broad strips of made land filed to level plants only six or eight feet above mean high tide, the sewers are necessarily built with slight grades, and are so situated as to be tide-locked a large portion of the time. They discharge during the latter part of the ebb and the first part of the flood tides so that the sewage instead of being swept out into the harbor and there diffused is carried inland and such portion as will deposit in still water is thrown down as the turn of the tide upon the broad acres fo the flats that exist with and around the city. This intermittent discharge produces other serious evils. During the time the sewage is accumulating in the sewers there is very little current in them, and in consequence deposits are formed which are not readily removed, and when putrefaction begins are the source of dangerous gases. Again as the sewage accumulates and risaes in the sewers the gases are compressed and since adequate ventilation is not provided, are liable to be forced through the house drains into the houses.
Boston Evening Transcript, Fri, Jul 13, 1877 ·Page 8

Had the commission of 1886 duly considered the importance of protecting the paramount public interest in the Fens by securing the purity of the water in in the park pond, a sufficient channel of discharge into Charles River would have been provided for Stony Brook at any cost. Or, diversion of the brook from Roxbury Crossing into Roxbury Canal and South Bay might easily have been accomplished.
Boston Evening Transcript, Sat, Feb 08, 1902 ·Page 19

While laying main drainage excavating occurrence of quicksand esp along water fronts
1899 Report on Boston Main Drainage Works.pdf

Area is level but slightly above high water mark “without adequate drainage” and in places “loads the air with miasma that breathes deadly poisons wherever the wind takes it – a foul, pestilential cesspool that has carried death into many a family. Upon this territory we have erected numberless dwellings and place many of our finest buildings… as sure as neglect brings ruin, just as certain it is that unless we provide proper sewerage and air spaces for it our glory will soon have departed and the immense revenue the city derives from it will be lost.
Boston Post, Mon, Feb 01, 1875 ·Page 3

Tributary to the Main Drainage System bounded by Charles River and Boston Harbor etc
Lower portion, not more than 40ft above mean low water , 46 sq miles
Expected to be intercepted by a low level intercepting sewers so always need pumped
1899 Report on Boston Main Drainage Works.pdf

Report of the Special Commission Investigating Systems of Sewerage and Sewage Disposal in the North and South Metropolitan Sewerage Districts and the City of Boston, Report, No. 2465 (June 15, 1939).

considerable trouble was experienced from sea-water making its way into the trench, especially in places where old sea-walls and other such obstructions were encountered. The mud on the sides of the trench exerted much lateral pressure, and close sheet-piling and heavy bracing were necessary. Opening so deep a trench in such material drained the water out of the adjacent soil, rendering it spongy and somewhat compressible, so that the whole street settled and had to be resurfaced and repaved. This section was built by contract. One firm of contractors gave up the job, and the work was re-let under provisions of the contract.
1885 Main Drainage Works.pdf

A considerable item in the total cost of building the intercepting system was the expense incurred in repairs to street surfaces and paving, over the sewers. The trenches were so large and deep that the backfilling, often of a peaty consistency, could not be sufficiently compacted by ramming or puddling, but continued to settle for a year or more after the sewer was built. As it was necessary to keep the surface in a safe and reasonal>ly smooth condition the portion over the trench was sometimes repaved three, or even more, times before it would remain permanently in place. Where the earth miderlying the street was of a peaty nature, it would be rendered spongy and compressible by its water draining out into the open trench during construction. Then the whole street surface, including sidewalks and sometimes even adjacent yards, would settle out of shape and need repairing. Another source of expense and trouble was the breaking of house-drains where they passed across the sewer trench, due to the settlement of the backfilling.
The intercepting sewers were frequently, indeed generally, built in streets which already contained a common sewer. The house-drains from one side of the street crossed the trench of the intercepting sewer. These drains were maintained, or replaced, as securely as possible, but many of them were afterwards broken. These were generally found to be sheared off on the line of the sides of the excavation, and the portion within the trench sunk bodily, half a foot or so, below the rest.
The Main Drainage System is so arranged that any principal portion of it can be isolated and emptied for inspection and repair. Any intercepting sewer can be thus isolated by closing the penstock gate at its lower end, and also the inlet valves connecting it with the common sewers, the latter then discharging at their old outlets. By closing the gates at the ends of all intercepting sewers the main sewer can be emptied. The connections between the common sewers and the interception-sewers were usually made during the construction of the latter. The valves of the inlet-pipes, built into the common sewers, were closed and made tight by a little cement around their edges. By raising these valves the connection between the old and new system could at any time be established.
Second. The discharge of the sewage on the shores of the city in the immediate vicinity of population, thereby causing nuisances at many points.
Building the intercepting sewers has also dried cellars in other parts of the city in a way which was not at first anticipated. When land on the shores of the city was reclaimed for building purposes, most of the old walls and wharves were covered up by the new filling. Tide-water followed along any such structures through the ground, and entered cellars lower than high-tide level. The new sewers were generally built along the present marghis of the city, and in digging deep trenches for them the old structures found were cut off and removed. The backfilled earth in the trenches forms an impervious dam surrounding the city, beyond which tide-water cannot pass
The sewers have been examined frequently since they went into operation. The average depth of dry-weather flow in the intercepting sewers is from ten to twenty inches, so that they can be entered on foot. So, also, can the main sewer above Tremont Street, and, sometimes, above Albany Street. Below that point the dry-weather flow is from two to three feet deep, necessitating the use of a boat
Most of the city sewers, when first intercepted, were found to contain deposits of sludge varying from a few inches to several feet in depth. All these deposits were carried into the intercepting sewers, and the sludge reached the pumping-station and was pumped up into the deposit-sewers. Gravel, stones, and brickbats also were swept along and taken out at the filth-hoist. Fine sand, however, did not move so freely, but settled in ridges here and there, and had to be removed by hand.
1885 Main Drainage Works.pdf

Infiltration & Inflow

"All studies to date of the cause of groundwater drawdown attribute a significant influence to the local sewer system. A discussion of the influence of the sewer system on the groundwater table by Snow (7) in 1936 follows: "With the filling of the basin came the construction of drains and sewers emptying into either the South Bay or the Charles River. Plans in 1863 show that by that time an extensive system had been constructed, but definite records as to location have been since either lost or destroyed. This, together with the fact that they have settled several feet in places, makes the present location of these drains entirely a matter of conjecture, except where they have been uncovered by recent construction. These sewers and drains were the beginning of the present maze of underground channels of which little or nothing is known, but which form channels by or along which the groundwater can escape to sewers in which the gradient is at a sufficiently low elevation to help drain the area." In the opinion of Mr. Snow, the city was underlain by a maze of subterranean channels leading groundwater off to the Harbor. All of the early sewers were constructed on top of an 8 to 12 inch underdrain which was designed to collect and control groundwater during construction. These remain in place to this day and are capable of transporting significant quantities of groundwater.

Both the West Side Interceptor and the Boston Marginal Conduit impeded the flow of groundwater into the Back Bay from the Charles River. They also have the ability to transport water rapidly along their length via their underdrain system. The St. James Avenue sewer has been the source of groundwater table drawdown since it was investigated as a result of concern for the foundations of the Trinity Church during the 30's. The installation of a dam in the sewer caused nearby groundwater to return to acceptable levels, but the dam requires periodic • maintenance and when it does not function the local groundwater falls.

Recharge from the local rivers - The largest local body of water is the Charles River. The West Side Interceptor, the Boston Marginal Conduit and the Mill Dam effectively isolate the Boston Peninsula from significant recharge from the Charles River. The Muddy River is a groundwater source in the Fenway. 3. Recharge from leaking water mains - This has proved in the past to be a significant source of localized recharge. Currently the BW&S is aggressively finding and repairing leaking pipes to minimize losses."

Final Report, Report on Groundwater, Observatories Wells, Stone & Webster Civil & Transportation Services, Inc~ (April 1990).

“In the spring, when the ground is full of water, much of it leaks into the common sewers, and is by them carried to the interceptors. Sea-water also, at high tide, finds its way along some of the old box-sewers, and leaks into them back of the tide-gates. Many defective house-drains and common sewers still exist, and must in time be replaced ; but the new system provides an outlet for the rest, without which other reforms would be comparatively useless.” (Main Drainage Works, 1885).

Roxbury canal conduit & fILLING

Roxbury Canal Conduit
The Roxbury Canal Conduit, constructed by the State Department of Public Works in 1965 and 1966, extends generally northeasterly from Massachusetts Avenue to the south end of the existing culvert beneath the West Fourth Street Bridge viaduct through which it discharges to the Fort Point Channel. The major branch of this conduit is the Dorchester Brook Conduit, the lower reaches of which are now under construction. The Roxbury Canal Conduit receives the discharges and overflows of mixed sewage and storm water from the Roxbury Canal Sewer at Massachusetts Avenue, from common sewers in Massachusetts Avenue north and south of the conduit, from outlets at East Concord Street, East Dedham Street, Union Park Street, and Dover Street and from the Dorchester Brook Conduit. The drainage area tributary to the conduit is the area which drains naturally to what was formerly South Bay.

REPORT ON IMPROVEMENTS TO THE BOSTON MAIN DRAINAGE SYSTEM, VOLUME 1, HUD Project No, P-Mass-—3306 Camp, Dresser, McKee (SEPTEMBER, 1967).

modern Conditions in Roxbury Canal Conduit

Roxbury Canal, 2019 Drone Inspections

State report noting over three feet of sediment and debris build-up throughout the conduit.

Roxbury Canal, 2019 Drone Inspections

Dorchester Brook Canal, 2019 Drone Inspections

"A 2014 study of Boston’s Fort Point Channel (FPC) found the channel to be degraded by contamination from sewage, bacteria, oils, grease, and floatables. Because of these contaminants, the FPC did not meet the water quality objectives of a Class SB combined sewer overflow (CSO) receiving water as defined by the Massachusetts Surface Water Quality Standards. The study found that during dry-weather conditions, sampling site SW1 at the upstream (southern) end of the FPC exceeded the water quality standard for Enterococcus (104 MPN/100mL) 65 percent of the time over the 143 samples taken. The remaining downstream sample locations in the FPC (SW3-SW8) complied with the standards between 92 percent and 100 percent of the time. The study found the CSO 070 outfall to be the primary contributor to the FPC’s dry weather water quality issues. Furthermore, the study recommended that the Boston Water and Sewer Commission (BWSC) investigate the CSO 070 combined sewer system for illicit sources of bacterial contamination.

Two large outfall pipelines—the Roxbury Canal conduit (RCC) and the Dorchester Brook conduit (DBC) in the BWSC CSO 070 combined sewer system that drains into the FPC—were constructed in the 1960s. These pipelines are reinforced-concrete box culverts that convey a combination of groundwater base flow, storm flow from the local drainage catchment, and combined sewer flow during large storm events to the FPC through the CSO 070 outfall as illustrated in Figure 2. The RCC/DBC pipeline dimensions vary from a 15 ft (4.2 m) wide by 10 ft (3 m) high, single-barrel culvert at the upstream end of the RCC to twin-barrel culverts, each 20 ft (6.1 m) wide by 15.5 ft (4.7 m) high at the CSO 070 outlet to the FPC. Water levels within the conduits are greatly influenced by tide fluctuation, as the FPC is hydraulically connected to Boston Harbor. The FPC project area is divided by Interstate 93 (I-93), an elevated, congested highway, and numerous railroad tracks that shepherd daily commuters to Boston’s South Station. The area includes various municipal, commercial, industrial, and institutional. Fort Point Channel sampling sites sites that require access for inspection to be coordinated. This highly developed, urban environment within about 1 mi (1.6 km) of the FPC overshadows the relatively flat nature of the local topography. Grades rest at an elevation of approximately 17 ft (5 m) on the Boston City Base (BCB) datum, and the RCC and DBC pipeline crowns are buried roughly 7 ft (2 m) below grade. Between their single- and double-barrel configurations, the RCC and DBC pipelines extend more than 12,000 lf (3,658 m).

An illicit discharge detection and elimination (IDDE) program, known as the FPC CSO 070 project, was developed in 2017 to investigate these water quality issues and their sources of contamination within the CSO 070 combined sewer system. The project’s objectives are as follows:

Improve the BWSC’s understanding of the CSO 070 collection system configuration, connectivity, and functionality
Identify specific source(s) of illicit connections, direct cross-connections, or indirect connections between the sanitary and storm-drainage networks contributing to water quality issues
Develop recommendations for eliminating confirmed illicit connections and, if needed, identify areas for additional study

The CSO 070 system investigation included pipeline inspections, building inspections and dye testing, and manhole water quality grab sampling for laboratory analysis. Central to the pipeline inspections were obtaining internal digital video information of the RCC and DBC pipelines and confirming their connectivity to the rest of the drainage system. Although the BWSC’s mapping was relatively accurate, these inspections were to identify and inspect any undocumented, existing connections. Early on, the BWSC understood that conventional inspection would be difficult given the limited access into the conduits, the conduit configurations, and the complex behavior of the tidally influenced water levels. Records of the conduits show that concrete access panel slabs were constructed every 1,000 ft (300 m) or so along each pipeline’s alignment. Field reconnaissance found these slabs to be deteriorated and unusable for inspection. Furthermore, access manholes were constructed every 300 ft (91 m) along the pipeline alignments, flanking the conduits at either side, and the non-centered location of the manholes limited access into the center of the pipelines.

The outfall pipelines are hydraulically connected to Boston Harbor and have no tide gates. Confined space entry (CSE) investigations of the conduits identified the complex behavior of the tidally influenced water levels. The water levels within the outfall pipelines change constantly with the daily tide cycle, varying up to approximately 13 ft (4 m) vertically from a BCB elevation of roughly 11.5 ft (3.5 m) to -1.5 ft (-0.5 m). During high tide, both outfall conduits are effectively submerged and inaccessible. The CSE investigation found that crews had roughly 4 to 5 hours for insertion and extraction before the workspace within the conduits was submerged by tidal waters. In addition to the challenge posed by the tidal waters, the outfall pipelines also contain several feet of sediment, consisting of sand and gravel washed down from the drainage and organic backwash from the Boston Harbor, that has built up over more than 50 years of operation. The sediment changes from loose sludge to hard-packed deposits over the length of the two outfall pipelines. Given the challenges to inspection described above, an innovative approach was needed.

Implementing any of the conventional approaches to inspect the RCC and DBC conduits would have been difficult given the conditions; hence, drones were piloted as one potentially viable and cost-competitive alternative to conventional CCTV pipeline assessment. Three approaches, using a combination of technologies, were devised:

1. The project team attempted to pilot a drone through the conduits with just the bare necessities for accessories: a camera and a lighting system. An onsite crew provided additional lighting.
2. The project team constructed a remote controlled boat, affixed with its own camera and lighting system, to supplement the drone inspection approach. The lighting crew was not used during this inspection attempt.
3. The project team strung a wire rope through the conduits that would be tethered to a pontoon-mounted camera and lighting system and pulled throughout the conduits.

The drone used for the inspections was provided by the operator. When using these technologies, it is important to provide for safe
access through a limited number of locations, to work around sediment levels, and to accommodate a shortened work window due to tidal conditions. Each approach used to inspect these conduits had benefits and opportunities for improvement, and the successes identified in one approach could be used to alleviate the challenges of another approach. In turn, this sharing of information improved the technical feasibility and cost-effectiveness of all approaches used. The objectives of the drone/remote-controlled inspection approaches included the following:

Gain access and make a safe entry into RCC and DBC conduit manholes
Understand the tidal influence on the conduits
Photograph the inside of the conduits, including piped connections
Test multiple approaches to lighting the interior of the conduits
Demonstrate that a quadcopter drone can fly within the conduit
Develop a 3D model of the conduit, if conditions permit

Through these drone inspection demonstrations, the project team anticipated using the drone’s versatility to meet other IDDE objectives. If active flow was detected coming through a lateral during dry weather, the drone could perform a close-up inspection of the lateral piping for illicit indicators. The drone would also allow for the visual inspection and documentation of conditions from various angles. In the event of debris or obstructions, the drone could maneuver in and around areas of interest to obtain point-specific data. Drones also can be outfitted with any combination of advanced pipeline inspection tools, including laser scanning, sonar, thermal imaging, and 3D rendering. Software would compile the digital photography and video data from the drone inspection to generate a 3D model of the inspected pipeline. The FPC project team intended to use the model of the RCC and DBC conduits to determine the locations of any detected laterals. If necessary, the project team could perform follow-up IDDE investigations upstream of these identified laterals to determine dry-weather, illicit sources.

Through these drone demonstrations, both the UAV and remote-controlled boat methodologies showed they could successfully inspect large outfall pipelines when other traditional methods are unavailable. Photo 2 illustrates a lateral inspected by the UAV. The first and second drone demonstrations inspected 300 ft (91 m) and 250 ft (76 m) of conduit, respectively. The limited production from these approaches was due to unforeseen circumstances with available equipment and the tides. Proper planning was critical to maximize the work windows between high-tide cycles. Other findings from the drone demonstrations included the following:
The video quality output depended on adequate lighting while maintaining a centered and stable camera position within the conduits. Powerful lighting systems affixed to the drone are needed to capture quality video and photo data.
The drone could easily eclipse inspection speeds of 30 ft/min (9 m/min) and greater.

The slight air flow within the conduits caused the drone to rotate horizontally on its own. The changing air flow conditions were related to the tidally fluctuating water levels.
The sediment within the conduit was a fine, loose material that prevented stable footing, and the debris build-up throughout the conduit was apparently from leftover construction. Inspections using conventional crawler equipment would not have been feasible.
During the beginning and end of the 5-hour tidal work window, the water levels were found to rise and fall at a rate of roughly 1 ft (30 cm) every 30 minutes.
Owing to the uniform concrete conduits and lack of distinguishing marker points, the 3D rendering software could not develop a model of the conduit pipelines.

Ultimately, the decision to implement the drone inspection approach would be driven by cost, regardless of the drone’s capabilities. The costs to perform the two drone demonstrations are compared to the unit cost to perform the inspections using a pontoon camera system. As depicted, the unit price to perform the drone inspections decreased between the first and second demonstrations following some adjustments. However, the drone inspection unit costs were still an order of magnitude greater than those of the pontoon camera. Thus, further attempts to refine the drone inspection approach were dismissed in lieu of the quoted pontoon inspection method. Nonetheless, an increase in the daily production rates of the drone approaches is feasible with proper planning and refinement and, therefore, a drone inspection can be cost-competitive with conventional inspection methods. The drone demonstrations accomplished the IDDE objective of pipeline inspection, and, with advancements to the technology, more opportunities will arise to incorporate drones in other water resource assessments. The drone approach demonstrated a cost-competitive alternative to conventional inspection methods, and, with enough initial investment, water utility providers may add drone technology to their system-management tools.

To foster continuous learning and innovation, recommendations for consideration in drone inspection include the following:

Site Inspections. Crews should perform field reconnaissance to confirm the condition of pipelines planned for inspection. Drone inspection should address the challenges of each pipeline. Also, access into the pipelines should be evaluated as it may require additional scaffolding and staging equipment to establish a safe work area.
Pipeline Conditions. Stormwater and combined sewer outfall pipelines hydraulically connected to tidally influenced waterbodies will experience fluctuating water levels. Similarly, the flow conditions within these pipelines should be evaluated so that the proper controls may be in place to safely perform drone inspections.
Drone Accessories. Various advanced inspection tools that may be necessary for successful pipeline inspection projects, and the drone itself should have the necessary features to gather the intended data. The drone demonstrations found lighting critical to successful data capture during inspections. For large pipelines and conduits, drones should have a heavy-duty lighting system for proper illumination (greater than 1,000 lumens is recommended).
Data Collection/Telemetry. The underground environment is not always conducive to relaying signals for GPS/video telemetry. Accessories for repeating signal data or boosting signal strength may be required given the pipeline configuration. When possible, the data collected should be relayed and stored on the drone pilot’s controller. Data stored directly within the drone risks being lost due to a drone failure or crash.
3D Modeling. Developing a 3D model is difficult when only photogrammetry is used. The uniform appearance of underground pipelines hinders the 3D software’s capability to stitch video and photographic data together in order to render a complete model of the pipeline. Instead, laser scanning and/or defined marker points along the pipeline in tandem with digital photo capturing may improve 3D model development.

As the feasibility of using drone technology for pipeline inspections progresses, applications exist today that may be considered. For water utility providers, these include CSO storage tunnels, stormwater outfalls, and water transmission aqueducts. Although suitable for inspections in less complex pipeline systems, drone inspections show the most apparent benefits in larger systems with more-complex pipe networks. Drone inspection technology may alleviate the risks in performing maintenance on these large, critical infrastructure elements of our water resource systems. In general, the conditions in which implementing a drone inspection should be considered include pipelines 60 in (150 cm) in diameter or greater that have the following attributes: stagnant flows, no flow, or flows difficult to bypass; tidal influences; sediment build-up; odd cross-sections; limited access points.

In summary, proper planning and preparation are key to successful drone inspections. These inspections can be cost-competitive with conventional pipeline inspection technologies when high production rates are met. Drones used in underground pipeline inspections should be outfitted according to the environment where the inspection occurs. Advancements in pipeline inspections are driven by the challenges faced when investigating the unique pipeline infrastructure of the modern world. With that in mind, the future holds many opportunities for the use of drone inspection technology to become more widespread."

Jacques, Schofield, & Peterson, Piloting innovation in the waters of Boston NEWEA Journal (Winter 2018).

roxbury_canal_journal-winter-2018.pdf
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CSO #70 Outfall & Union park Pump Station

2019

outfall maps

4.2.1.3 Outfalls BOS062 and BOS065 (Fort Point Channel) Figure 4-14 presents a schematic of the upstream end of the New East Side Interceptor (NESI) system. Semiannual Report No. 6 presented a description of minor adjustments made to the physical configuration of the regulators tributary to outfalls BOS060, BOS062, BOS064, and BOS065. MWRA used the updated model to identify and evaluate system modifications that could further lower CSO discharges toward attainment of the LTCP activation and volume goals at outfalls BOS062 and BOS065.
These system modifications included raising the overflow weirs and upgrading interceptor connection capacities at the BOS62 and BOS65 regulators, and the results of these evaluations were presented in Semiannual Report No. 6. Following that report MWRA updated the model to include Contracts 1 and 2 of the South Boston Sewer Separation project as described above and continued evaluating alternatives. Table 4-7 presents the Interim Q3Q4-2020 results as presented in Semiannual Report No. 6, Interim Q3Q4-2020 Conditions with South Boston sewer separation Contracts 1 and 2, and the LTCP goals for outfalls BOS062 to BOS068. As indicated in Table 4-7, sewer separation Contracts 1 and 2 were predicted to provide a nominal benefit on Typical Year CSO volume at Fort Point Channel regulators along the NESI due to a reduction in the downstream HGL.
With the updated model, MWRA, in coordination with BWSC, continued to analyze the alternatives to bring regulators RE062-4 and RE065-2 into attainment with LTCP goals. The evaluations identified an alternative referred to as the “BOS062/BOS065 Alternative” with the following components: • Constructing a second interceptor connection at regulator RE062-4 • Raising the weir at regulator RE064-5 by 3 inches from El. 104.32 to El.104.57 • Raising the weir at regulator RE065-2 by 2.8 feet from El. 102.83 to El.105.60 Table 4-8 presents a comparison of the Typical Year model results for the Interim Q3Q4-2020 conditions, Interim Q3Q4-2020 conditions with sewer separation contracts 1 and 2, Interim Q3Q4-2020 conditions with sewer separation contracts 1 and 2 plus the “BOS062/BOS065 Alternative”, and the LTCP goals.
The model results show that adding a second interceptor connection at RE062-4 would bring CSO discharges at BOS062 into attainment with the LTCP goals and result in no activation in the Typical Year. The increased flow to the NESI required that the weir at RE065-2 be raised as described above. The model results showed, however, that allowing more flow to enter the NESI at RE062-4 would not affect overflows at other hydraulically related regulators except at regulator RE064-5, where one very smallvolume activation is predicted to reappear. While this one activation would theoretically put outfall BOS064 slightly over the LTCP goal, the one predicted small-volume activation is still considered to be immaterial. MWRA and BWSC are evaluating this group of alternatives for constructability and cost.

Among the multiple regulators tributary to outfall MWR023, the following differences were found: o Regulator RE046-54 was originally believed to be closed, but was found to be open; o Regulators RE046-80 and RE046-110 were originally believed to be open, but were found to be closed; • At two outfalls, two regulators were found to be tributary to the outfall, where the LTCP had only one regulator: o Regulator BOS078 was revised to include two regulators, RE078-1 and RE078-2; o Regulator RE101 at outfall MWR010 was revised to include two regulators, RE037 and RE036-9.
Final CSO Post Construction Monitoring Program and Performance Assessment Report 2021

In 2021 listed as open: BOS062, 64, 65, 68, 70, 73
Closed: 72 (but thought it was open)
70 separated into RCC and DBC
RCC is RE70 5-1 and 6-1 but 6-1 is noted as closed
MWR215 is Union Park CSO
DBC lists 11-2 closed, but all others open 8-3 , 6, 7, 8, 13, 15; 9-4, 10-5, 7-2

Chalk was applied in the upstream invert of the overflow pipe or weir structure. Figure 8-3 shows an example of chalking at regulator RE070/8-8. Following a storm event, the regulator structure was revisited to identify if the chalk in the overflow pipe had been washed away by an overflow. However, in many locations where chalking was applied, results were inconclusive. Chalk may have been washed away by non-CSO activity, such as groundwater or tidal water leaking into the regulator structure.

The initial list of regulators identified as closed in the MWRA and CSO community systems was generated from the list of regulators provided in the 1992 sampling program conducted in support of MWRA’s LTCP (Metcalf and Eddy, 1993). This list was compared to a list of open regulators provided by MWRA prior to the start of the inspections. Regulators listed in the 1992 sampling program that were not identified as open in the list provided by MWRA were initially assumed to be closed and were targeted for surface inspections. An example of an inspection form for a closed regulator location is presented in Figure 6-3. Regulators that were identified as being open from the surface inspections received internal inspections as described below. Regulators that were identified as closed but in need of repair were referred to MWRA so repairs could be made. Table 6-1 presents a summary of the regulator inspections and whether the open/closed status changed from the LTCP based on the inspection work. The main differences between the LTCP and the inspection findings as indicated in Table 6-1 were as follows: • One regulator originally believed to be closed was found to be open (RE046-54); • Two regulators originally believed to be open were found to be closed (RE046-80, RE046-110); • At two outfalls, two regulators were found to be tributary to the outfall, where the LTCP had only one regulator: o Regulator BOS078 was revised to include two regulators, RE078-1 and RE078-2, and o Regulator RE101 at MWR010 was revised to include two regulators, RE037 and RE036- 9

Final CSO Post Construction Monitoring Program and Performance Assessment Report 2021

MassDEP: Sewage Outfalls

1967 Separation by Ward

Construction

1908, Otter St. Sewer Overflow

1860, Documents of the City of Boston, Annual Report of the Superintendent of Sewers.

The Commission owns and operates a system for the collection and transport of wastewater in the City of Boston. The original backbone of the sewer system was the Boston Main Drainage System (“BMDS”). The BMDS was constructed from 1877 to 1884 under the direction of a special committee established by the City of Boston for that specific purpose. The original system consisted of five combined interceptors, the Calf Pasture pumping station and the Dorchester Bay Tunnel. Neither the pumping station, nor the tunnel is in use today. The BMDS interceptors were initially designed to carry a peak dry weather sanitary flow together with an allowance for stormwater.
In 1988, construction of the New Boston Main Interceptor and the New East Side Interceptor were completed, replacing portions of the original system. The interceptors serve the sewer needs of downtown Boston, the South End, Roxbury, Dorchester, and South Boston. These improvements have increased capacity, eliminated dry weather overflows, and decreased the occurrences and volume of wet weather overflows. The backbone of the Commission’s sewer is several major interceptors, which convey flows from the Commission’s system to the MWRA’s interceptors. The New East Side Interceptor, the Boston Main Interceptor completed in 1988 and the New Albany St. Interceptor completed in 1990, serve Downtown, South Boston, the South End and Dorchester.
BOSTON WATER AND SEWER COMMISSION CAPITAL IMPROVEMENT PROGRAM 2022-2024
https://www.bwsc.org/sites/default/files/2022-01/2022-2024%20CIP%20FINAL.pdf