| Wastewater | Deer Island, Boston Harbor - Page 18 |
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First as a seven-volume draft in November of 1987, then in a final eight-volume form in March of 1988, the MWRA released its “Secondary Treatment Facilities Plan.” In some ways it was a bookend to the MDC’s EMMA reports from the mid-1970s. That multi-volume series of reports first opened the discussion of a Boston metropolitan wastewater system. Now ten years later it was the MWRA’s time to explain how they were going to clean up Boston Harbor. Reports detailed the agency’s plans for a new wastewater treatment plant on Deer Island, the removal of the Nut Island treatment plant and its replacement with a tunnel to Deer Island, another tunnel deep into Massachusetts Bay for the new plant’s effluent, and the preparations needed on Deer Island site before the plant could be built. Other volumes covered the myriad of institutional issues the MWRA faced in building the plant. While comprehensive, it was not the complete plan. There were no reports on what facilities would be needed to dispose of the sludge generated by the plant. That split between solutions for the handling of the effluent and the sludge dated back to just after the EMMA reports were published when the EPA asked for solutions for each individually. It would lead to delays in the start of the cleanup, but in the late 1980s it worked to the MWRA’s advantage. The EPA was continuing to resist the MWRA’s sludge-to-fertilizer solution as adequate. To keep the overall project on track the MWRA in their Secondary Treatment Facilities Plan would simply leave a space on the southern end of the peninsula for the “Residuals Handling Area” and then get on with designing and building the rest of the plant. They already had the Fore River Shipyard location in place for a sludge-to-fertilizer solution, the EPA had just not yet accepted it. |
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A curious aspect of the reports is the absence of credit given to an engineering consultant. Dating back to the MDC’s 1939 report where Metcalf & Eddy is credited for its “engineering skill,” through all the EPA reports on the harbor there had always been an acknowledgement that somebody other than the agency requesting the report had provided technical assistance. Even the MWRA credited Black & Veatch for its 1987 Residuals Management report. But no consulting engineering firm is mentioned as contributing to the MWRA’s Secondary Treatment Facilities Plan. Beyond just a lack of acknowledgment, in later references to the reports there is a disagreement on what company did provide technical assistance. Some attributions identify the reports as prepared by Camp, Dresser & McKee, others by Metcalf & Eddy. MWRA is on record in its capital budget reports as having paid CDM $16.5 million for the “Facilities Plan.” And CDM did have considerable experience designing wastewater treatment plant across the United States and the world, but they had not done much work in Boston. There are reports available online of CDM’s work at Sales Creek in Revere, Mass. for the state’s Division of Waterways, and for the MDC on CSO issues. On the other hand, as noted, Metcalf & Eddy had been studying wastewater solutions in Boston since the late 1930s. It was impressive effort by CDM to pull together so quickly all the information needed for the reports. |
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While it is common in multi-volume reports to include at minimum an index of the other reports in the study, and sometimes a short introduction outlining the overall objectives of the project, the MWRA in its Secondary Treatment Facilities Plan went a step further. Each of the reports contains a lengthy explanation on why Deer Island was chosen as the best location for the new sewage treatment plant. Oddly a decision that already had been made two years earlier. The analysis goes back in time and considers all options offered since the 1978 Environmental Impact Statements written after the EMMA reports were published. Twenty-two options with a mix of primary and or secondary on Deer Island, Nut Island, Long Island, Lovell’s Island, and a new man-made island are listed. Different outfall locations are in the mix. Even the idea of satellite treatment plants. Then there are criteria for evaluating the options including cost, effects on natural and cultural resources, effects on neighbors including traffic, noise, odor, visual effects, property values, health, and safety), harbor enhancement, implementability, reliability, and two new ones added by the MWRA, equitable distribution of regional responsibility, and mitigation measures. Based on all the criteria the options are reduced to three, all Deer Island, all Long Island, or split between the two. The later loses out for several reasons reducing the choice to two. After detailed examination the two crucial criteria are harbor vision and implementability. That is, first ruining Deer Island is better than ruining Long Island, and second the rather obvious observation that it would be easier to build on Deer Island because it was connected by land. It seemed like a redundant exercise most likely done to offer the EPA’s its Record of Decision (ROD). |
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Explaining the choice of Deer Island for the location of the new treatment plant was a look to the past, in a look to the future the MWRA included in each report their analysis that removing the prison from the site would have serious consequences. In June 1987, before the draft of MWRA’s Secondary Treatment Facilities Plan was published, the city of Boston had officially turned over the title to the agency for the land occupied by the Suffolk County House of Correction but then did nothing to indicate when the prison would actually be closed. In each of the reports the MWRA made it very clear their frustration with the lack of action by the legislature by reprinting the signed 1986 legislation that instructed the state to build a new Suffolk County Prison in South Bay area of Boston. Unfortunately, the closing of the old prison and building of a new one had been caught up in the battle over incinerators between Boston Mayor Ray Flynn, governor and presidential candidate Michael Dukakis, and the powerful Speaker of the House, South Boston’s William Bulger. Nothing had been decided when the MRWA published its Final Early Site Preparation report in April 1988. Upping the pressure, the agency stated in the report that attempting to build the sewage plant around an operating prison would require extraordinary and costly mitigation measures, delay the plant’s completion, and potentially degrade its final functionality. Judge Mazzone was well aware what was happening and made it known that he would step in to make sure the prison was moved. Though later than the MWRA would have liked, the Deer Island prison was abandoned at the end of 1991. Today’s Boston’s trash, what is not recycled, goes to incinerators in Saugus and Haverhill, Massachusetts, and to out-of-state landfills. The site of the former South Bay incinerator is now the home of the 117,000-square-foot Yawkey Distribution Center of The Greater Boston Food Bank. |
| Secondary Treatment Facilities Plan, MWRA, 1988 - |
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Fortunately for the MWRA, acquiring ownership and access to the 40 acres of the former Fort Dawes in June of 1989 went off without a hitch. The General Services Administration declared the land last used in the 1960s surplus. The Department of Health and Human Services took the title and turned it over to the EPA, who handed it over the MWRA. For the first time since colonial days Deer Island was under common ownership. Unfortunately for the MWRA removing Fort Dawes was not as easy. Construction during World War II included a bunker fortified with 17 feet of reinforced concrete designed to survive a direct hit from a battleship. The contractor tasked with removing the fort reported using over 10,000 pounds of dynamite to remove the bunkers. |
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One of the biggest problems facing the MWRA was how to shoehorn a massive new sewage treatment plant on to the 185 acres of Deer Island. While not a small amount on land, by comparison the Boston Common and Garden combined cover 75 acres, the 1.27 billion gallons of wastewater a day it was designed to treat would make it at the time the second largest in the country. The sewage plant with the highest capacity was the Stickney Water Reclamation Plant outside of Chicago. It is designed to treat 1.66 billion of wastewater a day. The Stickney plant covers 413 acres of predominantly flat mid-western land. The MWRA had two 100-foot drumlins to deal with. To build the massive sewage treatment plant the MWRA would need to flatten them. |
| They idea of flattening the drumlins had not been considered in the original 1975 EMMA proposal for a metropolitan sewage system. It had recommended a partial enlargement of the existing treatment plants and two new satellite treatment plants inland. For Deer Island the Metcalf & Eddy plan recommended using a landfill on the northeast side of the island for the 48 settling tanks and similar number of aeration tanks. There would be little separation from the homes on Point Shirley. Needless to say, this was not a solution favored by the residents of Winthrop, especially because at the point in time incineration was the preferred solution for eliminating the sludge produced. In the plan the prison would be moved to the center drumlin with the southern end of island used for recreation, though with no direct access from the mainland. The EMMA reports on a metropolitan sewage system had been written almost concurrently with state’s Department of Natural Resources release of a major report on Boston Harbor Island. Prepared by the Metropolitan Area Planning Council it recommended the Boston Harbor islands be organized as a unique and special park where the focus would be on recreation and preserving the natural resources. It’s plan for Deer Island had the prison eliminated and only a slightly expanded footprint for the sewage treatment plant. Like the Metcalf & Eddy plan, the southern portion of the island would be used for recreation. |
| By the mid-1980s it was becoming clear to engineering firms developing a new metropolitan wastewater system that the all-Deer Island treatment plant solution would be the likely scenario. A clever solution to both what to do with the drumlins and how to shield the residents of Winthrop from the noise of the construction and then operation of the plant first appears in the 1985 final Thibault/Bubly report on siting the wastewater facilities. As an idea only to mitigate the problem of noise during construction of the new plant, it suggested relocating the drumlins to the northern side of island shielding the residents of Point Shirley. The MWRA in their 1987 report expanded on the idea examining different arrangements of man-made hills to reduce the visual impact of the plant, reduce any noise it would produce during operations, and provide a solution for what to do with most of the material excavated from the existing drumlins. The final solution selected and built was a combination of the Necklace and the Ring concepts. |
| Even with a solution for what to do with the drumlins the MWRA still would have to come up with wastewater treatment solutions that used less room. A distinctive feature of the Stickney plant, and many other treatment plants, are large circular basins known as clarifiers or settling tanks. A boom slowly moves around the tanks skimming off any scum that rises to the surface. At the bottom of the tanks another boom collects the sludge. The remaining liquid is the effluent and, after disinfection, is what gets discharged. Stickney has 96 clarifiers. The plan presented in the 1975 EMMA reports had 48 tanks on Deer Island and 16 more on Nut Island. Greeley and Hansen in 1978 saved some space by recommending rectangular tanks, but in their Deer Island-only option it showed much of the island covered by the tanks. In the mid-1980s the MWRA had a new space saving solution, stacked clarifiers. Developed in Japan in the mid-1960s, Deer Island would be their first major use in the United States. Forty-eight primary and 54 secondary clarifiers, each holding over a million gallons, would be needed. |
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| Secondary Treatment Facilities Plan, MWRA, 1988 - |
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| Alternative buffer and recreational zones for Deer Island |
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While it was primarily the use of stacked clarifiers that made it possible for the MWRA to squeeze a new treatment plant on Dear Island, they are not the most recognizable feature of the facility. That would be the twelve 150-foot-tall egg-shaped anaerobic digester tanks located near the end of the island. The technology is not new. The fact that decomposing organic material in the absence of oxygen produces a flammable gas has been known for millennial, and in cases used for heat or light. What has generally been identified as the first wastewater treatment plant where anaerobic digestion was used and a "combustible gas" captured is the Acworth Leprosy Hospital in Mumbai, India.
Established in 1890 the hospital had a problem. The surrounding villages did not want any human waste from the facility flowing through their sewers. The solution was devised by the Cornish Quaker civil engineer Charles Carkeet-James. First, in 1901 he devised a closed system where the output from a septic tank and effluent filters made what been an area of infertile clay soil productive for farming. Then in 1902, after a visit to England where he observed how the coal gasification process was producing a gas usable for heating and lighting, he returned to India and had constructed an air-tight cover for the septic tank. After development over several years the system was producing enough gas for cooking and lighting at the hospital, and in addition provide lighting for nearby neighborhoods. The hospital was also able to make a profit from selling food grown on their farm. Carkeet-James, after his work in India, went to Egypt where he designed and supervised a wastewater drainage system for Cairo and Alexandria. |
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The adoption of an egg shape for anaerobic digester tanks solved several problems that were experienced compared to those with cylindrical design, such as the ones at the Nut Island and the first Deer Island treatment plants. Cleaning a conventional anaerobic digester tank is a difficult, time consuming, and smelly task. An egg shape for anaerobic digester tanks produces more efficient mixing of the sludge, eliminate dead zones where partially digested sludge accumulates, minimize the surface of the tank where a scum blanket forms, and are self-cleaning. They also take up half the space of a conventional digester tank, a very important consideration for the limited space available on Deer Island. |
| The concept of an egg shape for anaerobic digester tanks was first patented in Germany then in the United States in the late 1920s. They became widely used in Germany and Japan in the 1960s. In the United States their first use was at the Terminal Island treatment plant in Los Angles in the late 1970s. Four 1.4 million-gallon digesters were constructed out of concrete. Each of the digesters at Deer Island holds 3 million gallon of sludge and are built of welded steel, insulated, and covered with aluminum. Two additional tanks of similar size hold the methane generated by the digesters. The initial plan was for 16 digesters while only 12 would be needed. The space on the island where the other four tanks would have been located now is covered by solar banks centered around two 190-foot wind turbines. The MWRA estimated that egg-shaped digesters cost thirty percent more than conventional tanks. |
| Deer Island's egg-shaped anaerobic digesters |
| The Deer Island sewage treatment plant the MWRA took over in 1985 received wastewater from three sources. The North Metropolitan Trunk Sewer was the portion of the original circa-1900 brick-lined tunnel running through East Boston and Winthrop. To service a growing population in the rest of the North Metropolitan service area the MDC had constructed a relief tunnel along the northern side of the Charles River finally connecting it to Deer Island in the 1960s with a deep rock tunnel that ran from Chelsea to the then new sewage treatment plant. The third source for wastewater was a second deep rock tunnel dug at the same time from South Boston to Deer Island. It eliminated the Boston Main Drainage System’s discharge of raw sewage into the harbor from Moon Island diverting the wastewater to the then new treatment plant. Consolidating all metropolitan wastewater streams meant eliminating the Nut Island treatment plant and routing the South Metropolitan System’s wastewater flow to Deer Island. That meant another tunnel. The MWRA described their solution in Volume 4 of its 1988 eight-volume Deer Island Secondary Treatment Plan calling it an Inter-Island Conveyance System implying that it was more than a simple tunnel. But there is no other mention of use other than a relief tunnel for communities the MWRA served on Boston’s south shore. Its more expanded uses would become evident later. |
| Another of the many challenges the MWRA faced was to find a new location where it could discharge would be the secondary treated effluent from the yet-to-be-built consolidated treatment plant. Just off the end of Deer Island was not acceptable to EPA. The MWRA tackled in Volume 5 of its 1987 report, Effluent Outfall. Since the first sewerage system was proposed in the late 1890s the further out into harbor the then raw sewage could be discharged the better. At the time off Deer Island was as far as practically possible, but by the 1930s it was becoming clear that it was not far enough. A 1936 proposal had a deep rock tunnel from a pumping station on Lovell Island leading to an outfall located just under four miles out to near The Graves in the outer harbor. No treatment, just the discharge of raw sewage. Ambitious, very expensive, and after float showed a significant portion of the wastewater coming back into the harbor on an incoming tide, the plan was dropped. |
| In 1960s it was Camp, Dresser & McKee’s Deep-Tunnel Plan. A series of deep rock storage tunnels under the city and harbor to capture stormwater overflow. Then a pumping station under Deer Island where the overflow would be chlorinated and then discharged 9 miles out into Massachusetts Bay from a pipe made of reinforced concrete laid in a trench. It would only have offered a solution to Boston’s CSO problem not the whole metropolitan area and not for regular wastewater treatment making it a very expensive partial solution that would not have met EPA demands. |
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| The next proposal for an outfall in the bay came in the late 1970s and early 1980s with the MDC’s 301(h) waiver requests. The plan from Metcalf & Eddy was for a deep rock tunnel starting at Deer Island extending 9 miles out into the bay. First filed in 1979, and then refiled in 1984, it was the Dukakis administration’s attempt to avoid paying for secondary treatment at the new plant. It was rejected twice the last time in 1985 because it was only to provide primary treatment of the effluent. In 1987 it was the MWRA looking for approval of secondary effluent at about the location 9 miles out into the bay. There would be some modifications on the final outfall location, but the EPA’s final decision was really never in doubt. They had denied the MDC a waiver twice on the grounds that the effluent discharge was to receive only primary treatment, now the MWRA was providing the secondary treatment they had asked for. |
| While what would ultimately be constructed would be two deep rock tunnels, both the MWRA and EPA reports looked at the cut-and-cover option with a sunken tube or pipe. Howard Carson had used the technique in the late 1800’s to cross Shirley Gut. The process involves digging a trench under water, adding a bedding layer, lowering in pre-manufactured pipe or tube segments, then covering up the trench with a protective cover layer. Carson had used wood-wrapped steel pipes with a brick lining for the segments. Modern options were precast concrete pipes in 16-ft. to 24-ft segments or pre-made 40 feet fabricated steel and concrete tube sections. The later allows for complicated structures than just a simple pipe to be incorporated such as the twelve preconstructed twin tube 325-foot sections that were partially finished then sunk into a trench in Boston Harbor to create the Ted Williams Tunnel. |
| For the Inter-Island Conveyance System the MWRA considered an option where a sunken pipe/tube would be placed in a trench extending from Nut Island to Long Island with the remaining portion extending to Deer Island a deep-rock tunnel. The sunken pipe/tube technique would not work for spanning the much deeper ship channel into the harbor. Though even the Nut Island to Long Island stretch was problematic. The proposed route extended due north from Nut Island, then made a a curve to avoid a sunken ledge and the Quarantine Rocks blocking a direct path. The MWRA also had no desire to explain why stirring up the polluted bottom off Nut Island sewage treatment with blasting and dredging was a good idea. Then there was the problem of establishing a major construction site on Long Island. The Inter-Island Conveyance System would be a deep-rock tunnel from Nut Island to Deer Island though it is interesting that it would not be a straight shot. A slight dogleg was introduced to avoid an area of poor-quality bedrock discovered during the drilling of core samples. |
| In their Effluent Outfall draft report, the EPA examined the cut-and-cover option for the conduit portion where the diffusers were located on the outfall tunnel. In the plan there would be a single riser from the main deep rock tunnel feeding a pipe in an excavated trench with multiple diffuser ports. The MWRA plan for the Effluent Outfall called for a deep rock tunnel with 80 individual risers spaced at an equal distance in the last 6,600 feet that would disperse the effluent out of multi-port heads. The system would be gravity fed with no pumping station needed. |
| Examining both tunnels, the EPA moved quickly to publish its two volume Boston Harbor Wastewater Conveyance System Draft Supplemental Environmental Impact Statement in April of 1988, following it up with a one volume final version in July of 1988. Ultimately it would be two deep rock tunnels, the Inter-Island Conveyance System 11.5 feet in diameter, the Effluent Outfall 24 feet in diameter. Both dug by TBMs (tunnel boring machines). The two tunnels would be lined differently. The Inter-Island tunnel would use a cast-in-place technique, the Effluent Outfall would use over 60,000 precast tunnel segments with each ring requiring six segments. The final design for the Effluent Outfall would incorporate 55 risers. |
| The EPA in its final approval suggested only minor changes, along with an insistence that the MWRA regularly conduct surveys of the ocean near the risers. Technical assistance for the EPA was provided by Metcalf & Eddy, a firm well versed in producing reports on effluent outfalls in Massachusetts Bay. |
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Secondary Treatment Facilities Plan, Vol. 4 |
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Secondary Treatment Facilities Plan, Vol. 5 |
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| A TBM would be used to construct two 12-foot tunnels just under a portion of the Deer Island Treatment Plant itself. They were needed to take the wastewater flow from both the North Main Pump Station (Boston Main Drainage and North Metropolitan Relief) and the Winthrop Terminal Facility and bring it to a new grit removal facility to be built at southern portion of the site. Screening earlier in the flow would have removed large objects such as bottles, rags, plastics, metals. That still left small objects such as sand, seeds, coffee grounds, eggshells, etc. that if not removed could damage pumps and other equipment. The wastewater flow through the new South Sewerage System tunnel had grit removal performed at a new facility on Nut Island. |
| On Deer Island itself, the two tunnels could have been constructed using a typical dry-land open cut and cover method. However, that would delay the construction of that portion of the plant until the tunnels were finished. A cost analysis showed that using despite being a most costly technique, the use if TBMs saved money. Over 100 years earlier digging through the compacted glacial clay that made up Deer Island had proven difficult for Howard Carson’s work crews. For modern-day TBMs the conditions were ideal, easier than digging through bedrock. |
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| One could describe the MWRA as being in the tunneling business. Their systems of many tunnels bring fresh water into the metropolitan areas and then take wastewater out for treatment. For the Deer Island Treatment Project, the eventual completion of Inter-Island Conveyance System tunnel from Nut Island would complete the system of tunnels bringing all the Boston metropolitan area’s wastewater to the new plant. The completion of the Effluent Outfall tunnel would take the treated wastewater 9.5 miles out into Boston Harbor. The project would be called compete when the plant and the new tunnels were functioning. Technically true, but only if you overlook the use of barges required to bring sludge from Deer Island to Fore River sludge-to-fertilizer plant. It would be in 2006 that connection would be made completing project as designed. |
| The Department of Geosciences of the College of Natural Sciences at the University of Massachusetts Amherst have on their website the contract document for the Inter-Island Tunnel portion of the Boston Harbor Project. The October 1990 report by the civil engineering firm Sverdrup primarily details with the anticipated subsurface conditions and their impact on the design and construction of the tunnel. Mentioned in the description of the tunnel are two 14-inch internal diameter pipes “for future connection” to the Fore River sludge drying and pelletizing plant in Quincy. There had been no mention of this feature in 1988 plans from the MRWA or EPA. In those reports the Inter-Island Tunnel was simply the required solution to meet a court ordered deadline to eliminate all discharge from the Nut Island treatment. |
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| However, from the perspective of building a complete sewerage system for the Boston metropolitan area the most efficient and reliable method to transport sludge from the new treatment plant to the drying plant was a pipeline. Even though that final link from the Inter-Island Tunnel to Fore River plant would not be completed until 2006, including the pipes in the design ensured the system would be ready when that time came. Barges would be used at first, but effectively the pipeline was the answer to the question of what to do with the sludge and should have quieted any concerns over a problem that had confounded the MDC for years. The agency did not hide that the final sludge solution would be a pipeline line. The MWRA in a spring 1991 pamphlet on the Fore River Staging Area stated that the final sludge solution would be a pipeline. But that wasn’t good enough for the EPA. Their insistence that that the MWRA purchase a local backup disposal site led to the multi-year controversy over the Walpole site. An issue that never really had to be faced. It made little sense, the fact the Fore River location, as a former shipyard, had a ready rail link that would make it easy for dried sludge in any form to be shipped almost anywhere in the country at low cost. |
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