Diverting Stormwater

As in many urban waterways, Boston Harbor had fallen prey to ongoing environmental problems during the 1980s. “On every tide on nearly every day, we were dumping hundreds of millions of gallons of largely untreated, although sometimes chlorinated, waste into the harbor,” says Bruce Berman, spokesman for Save the Harbor/Save the Bay, a local advocacy organization.As federal and state clean-water acts made legal action possible, Boston, MA, is now in the midst of constructing a large tunnel to address the combined sewer overflow (CSO) situation in that area. In municipalities from Boston to Portland, OR, officials have been addressing the issue of CSOs, which result when storm events overwhelm the systems that carry both storm- and sanitary-sewer flows. Boston, MAAction began in Boston when a state solicitor from Quincy, MA, literally stepped into the problem: He had been jogging on the beach when he stepped in what he assumed was a tar ball, but when he flicked it off his foot, he noticed it had toilet paper in it.“He brought a legal action in state court, which rolled into a federal action under the Clean Water Act, which resulted in 1985 with a judge ordering a cleanup of the harbor and putting it on a schedule–which began in 1986,” Berman says. At that time, millions of dollars were invested in shutting down an old sewer plant and redirecting the sanitary sewer flows to another wastewater treatment plant, Berman says.“We created a 9-mile-long outfall for the relatively clean water that’s coming out of the plant now, and we saw a marked improvement in water quality in both the harbor and the bay,” Berman notes. “The gross pollution events ended. But we have always known that at the end of the day the critical questions are going to be: Can you swim on the beaches? Can you fish for recreation off the piers? Those problems often seem to be related to the closest pipe, not necessarily the biggest pipe. We decided to allow some CSO discharges to continue while we figured out the best strategy to solve them.”It had been observed that on Boston’s beaches, not only were beach closings occurring one out of every five days, but in 85% of the cases, the closings seemed to be associated with lesser, lower flows.“That was a good news/bad news situation,” Berman notes. “It was good news because it made it clear what would work and give us more beach days. It was bad news because the regulatory framework is kept toward CSO. Because no one has ever successfully sued EPA to make them enforce their discretionary powers, we decided that strategy wouldn’t work. Instead, we tried to pull together a consensus on the science.”Thus, the Massachusetts Water Resources Authority (MWRA) at the end of 2003 formulated a plan for a 17-foot-diameter, 2.1-mile-long tunnel that would have enough capacity to hold CSO from a large event and would be used infrequently, Berman explains.“We suggested that it would make sense, when that tunnel was not being used for CSO, to use it for stormwater,” Berman says. “The plumbing, while not cheap, is not terribly expensive if you do it at the same time. In order to build the original pipe, you have to sever the [connecting] pipes anyway. So if you reconnect them to the pipe instead of back to the beach, for all practical purposes you capture any stormwater up to when you start to have a CSO event. Then you just turn the valves and capture only CSO.“What we ended up with was the understanding that although CSO is terrible, the events are infrequent, and that the frequent events often closed the beach–so we targeted both.”Jonathan Yeo, communications director for the MWRA Board, a wholesale supplier of water and sewer services to 60 cities, points out that Carson Beach and Treasure Beach compose a 2-mile-long strip of beach in South Boston. “It’s a very nice urban beach,” he says. “There is daily water-quality testing on the beach, and there are usually a handful of days each summer when it is closed due to high bacteria–nothing that unusual for an urban beach. There are a few different sources of contamination in the region. There are seven CSO discharge locations right off this beach, and the MWRA agreed to eliminate those quite a few years ago and has been working on a plan to do that.“There also are stormwater discharge locations. Stormwater goes through these outfalls from the parkway that runs along the beach and through some nearby neighborhoods where stormwater from the streets goes out off the beach. That probably happens 100 times a year when it rains. And there are other sources of contamination from birds, dogs, and boats, so there are a variety of sources of contamination.”Yeo says the sewer lines are owned by the Boston Water and Sewer Commission, the retail water and wastewater utility in Boston, adding that MWRA has been working on its plans in conjunction with that group. He confirms the plan is to store the CSO discharges, wait until the sewer system has capacity, then slowly pump the overflow back into the system and get it out to the new Deer Island Sewage Treatment Plant for treatment. “Given the size of the tunnel–17 feet in diameter–it would only be used maybe 20 times a year for CSO issues. It then made sense to tie in the stormwater discharges to this tunnel, even though it’s not MWRA’s mission or our mandate, because there are many times a year when this tunnel is going to be empty,” he says.Yeo notes that it had seemed sensible to take stormwater up to a one-year storm. “In addition, there is a separate area where there’s the largest flow of stormwater through one of the outfall locations on the very southern end of the beach,” he says. “EPA and other groups have asked us to look at rerouting that stormwater off the beach into a cove just a little to the south that’s a distance from any swimming beaches.” Yeo says if both projects are done, it will provide a five-year level of stormwater control for the beach region.“Many of our biggest storms happen during the winter and spring, not during the swimming season,” says Yeo. “Our swimming season isn’t that long here–three to three and a half months. This will provide a very, very high level of control.”The price tag for the Boston tunnel work is $300 million. “Based on EPA’s analysis and our analysis, every 100 million dollars’ worth of capital investment will cost the ratepayers between $8 and $10, so this $300 million project will cost between $24 and $30,” says Berman. Combined water and sewer rates for larger MWRA customers will go from $835 this year to $1,407 in 10 years but will encompass all MWRA projects, not just the tunnel, Berman points out.The tunnel will be constructed along the shoreline in Dorchester in South Boston to collect a mix of stormwater and sewerage to be held for processing. A small odor control station near Carson Beach and a 10 million gal/day pumping station at Conley Terminal in South Boston will also be built.Other alternatives considered in the Boston project included a transport tunnel, which would have offered the capacity to move all of the flow from the largest storms away from the beach into another part of the harbor, but residents objected to the 600 million gal/day pumping facility, so the plans were downsized.“It was extremely expensive,” Berman says. “Figure the cost of this project plus another $150 or $200 million, and it would hardly ever be used because it would only be used in those big flow events. Another proposal was a sewer separation, which would increase the number of stormwater events while decreasing the number of CSO events. That was quickly withdrawn.“We said to the authorities that it was becoming increasingly clear that our interpretation of their mission was that they were here to clean the harbor, and if theirs was that they were here to separate sewage from CSO and then dump the stormwater, then we were going to have some big political fights. I anticipate that this drama here is going to be replicated around the country.”Yeo says there are 84 CSO locations in the area of Boston, Cambridge, Somerville, and Chelsea. “It was decided by our board of directors that the MWRA should take the lead on the CSO program, as we were building a new wastewater treatment plant at Deer Island and it made sense to do the program together,” Yeo explains. “We have 25 ongoing CSO projects, and that involves a great amount of sewer separation, which is the main staple of CSO control across the country. Then we have some projects involving storage and treatment and other projects involving hydraulic relief and different ways to control CSOs.”MWRA has been under a federal court order for more than 18 years. Says Yeo, “The Boston Harbor Project [an encompassing approach to harbor environmental issues], the Deer Island plant, and the outfall tunnel were all done as part of compliance with the federal court order. The entire CSO program is under federal court order. The stormwater issue is not part of any kind of court order but is a site-specific, common-sense solution. The judge has played a very positive role in encouraging all sides to reach agreement on this project.”Berman says it was key that MWRA had flexibility on the issue. “That means we have achieved virtual elimination and not actual elimination,” Berman says. “I’m assuming that on a 25-year storm–figure Hurricane Gloria–that we’ll have CSO on the beach. That said, every sewer and every basement in Boston will flood in that kind of a storm. The harbor will be a mess anyway for a few days. So, we’re willing to live with it, and what we expect is instead of one CSO closure in every five days, we’ll see one in every five years from stormwater. That’s a big improvement.”The entire city had been served by a combined system, Berman says, with some of it having since been separated. The impact of the CSO events was mostly recreational, he notes. “In order to get the people who live here and are paying for this cleanup to get value, they have to be able to use the beaches with confidence,” he says. “Because there is a 24-hour delay in the testing, they can’t use them with confidence now because they won’t know until tomorrow whether it was safe to swim today. In other words, you are swimming in yesterday’s results.“In many ways, a harbor cleanup is a great value, but it’s a recessive tax. Rich people and poor people both will go to the bathroom and use the same amount of water. To make it fair, the people who pay for this have to have some value, and the value–we hope–will be recreational access. We expect that promise to be kept here.”Berman points out that the appetite for using the harbor is increasing dramatically. “It turns out that one part of the harbor we thought no one would ever want to use, Fort Point Channel, is going to be totally redeveloped, and the guys who are investing hundreds of millions of dollars in the dozens of properties along it want water quality,” he says. Berman says the public is receiving the action favorably. “The goal of the Boston Harbor project and the cleanup has always been clear to the public,” he says. “It is to have a harbor safe for swimming, fishing, and boating. For too long, we have had to put up with this problem on the beach. We are all delighted to see that we are going to get a shovel in the ground soon.“They think it will take six years to do after they get the design, final environmental, and construction permits done,” Berman continues. “We are hoping they can do better than that. We’ve known about the problem since 1985. It would be good if the kids in South Boston and Dorchester could swim on clean beaches. It’s been too long, and although we understand the technology is pretty sophisticated and takes some time, we still want to see this thing done quickly.”Yeo says the construction phase will be from 2006 to 2010. “The first shaft has to be built, the tunnel boring machine then needs to bore the tunnel, and then piping needs to be placed on the inside of the tunnel and connections made to the surface piping. It’s an urban residential area so it’s going to take several years to build, but I think in the end it will have an enormous impact on water quality in the area.” The Conservation Law Foundation was a plaintiff in the original federal Boston Harbor suit. That organization, along with State Senator Jack Hart, who represents the First Suffolk district, is concerned not only with the time frame but also with the diversion of dirty water to Patten’s Cove in Dorchester, an area used for boating but not swimming.“The MWRA will discover that the more stormwater you put in that pipe, the less room there is for CSOs,” Berman says. “Since it is a pipe you can control–a Å’smart’ pipe–the question is if there are circumstances under which you would want to shut off stormwater and put in more CSO. In order to anticipate that circumstance, at the end of the day they proposed a small piece of this project which would allow them to shed stormwater around the corner and not actually on the beach. Our position on it is that off the beach is off the beach. However, we do know that in the future some people might want to use that part of the harbor for recreational use, and we would prefer to see improvement on that stormwater pipe, not just increased flow.”Berman says MWRA has agreed to take into consideration information obtained about CSOs and come up with an inexpensive way to improve the quality of water coming out of the pipe.“Some of the problems you see in an older city like ours involve materials coming out in dry weather,” says Berman. “There’s no reason they couldn’t build a little lip on that pipe so it wouldn’t come out in an unpredictable fashion.” Another option, he notes, is to construct it in such a way that very small rains wouldn’t cause discharge. “They are looking into those optimization strategies.”Berman says what he has learned from the experience is that if Boston wants to increase the number of days people can use the water, CSOs should not be the first point of concentration.“Some strategies for dealing with combined sewer overflows–and here I am talking about stormwater separation–can actually make the matters worse on the beach in terms of the frequency of discharges and the frequency of polluting events that close the beach,” he says. “We have to be really careful that we don’t make things worse while we are trying to technically comply with the law. I would urge people who are thinking that separation is going to solve their problems to remember that under current regulations, the stormwater, at the end of the day, turns out to be the municipalities’ responsibility. They ought to be very careful about spending a lot of money now and then spending a lot of money again, when they could probably get by with spending a lot of money once.”Yeo says other alternatives were considered. “We had another project which we were slated to pursue in 1999, which involved a smaller tunnel and then a larger pump station, so you would have discharged more of the water out into the reserve channel,” says Yeo. “It’s a channel a little north of this beach area, and larger amounts of the flows would have been discharged into this channel. Unfortunately, the neighborhood didn’t want that giant pump station near them, so we were not able to get legislation to get the land.”Milwaukee, WIOther cities are successfully using the tunnel concept to handle similar problems. The Milwaukee Deep Tunnel System is 19.4 miles long and can hold 405 million gallons of water. Since the deep tunnel has gone on-line in the early 1990s, Milwaukee has cut overflows dramatically. Milwaukee Metropolitan Sewerage District (MMSD) officials were pleased when the area went for an entire year without having an overflow caused by heavy rain. The district had not had a CSO in 17 months, the last one having occurred in August 2002.  The tunnel is part of a larger effort. “We put together the Water Pollution Abatement Program [WPAP], which included expanding and improving the sewer system, improving capacity at the treatment plants, and [creating] a deep tunnel system,” explains Bill Graffin, public information manager for MMSD. Several alternatives were considered, explains Dennis Grzezinski, chairman of the MMSD commission, including separate treatment facilities in the various communities MMSD serves; complete separation of storm and sanitary sewers; and a combination of treatment plant expansions and upgrades, metropolitan interceptor sewer upgrades, and a deep tunnel storage system. MMSD serves 28 communities and covers 420 square miles. Combined sewer systems–which are located in the older portion of Milwaukee and in neighboring Shorewood–compose just 5% of the total system. However, before construction of the deep tunnel system, the region averaged 50 to 60 overflows a year, totaling 8 billion to 9 billion gallons of sewer overflows. “I think our average right now is 2.7 combined sewer overflows,” Graffin says. “Overall, combined and separate overflows were at about five to five and a half a year, but the volumes are down significantly.”The public has quickly gotten used to the water-quality improvements and other benefits, Grzezinski notes. “When the combined sewers used to overflow every time it rained a quarter-inch or more, on average 50 times per year, and the Å’separated’ sewers used to overflow an average of 25 times per year, the general public was relatively indifferent,” he says. “People were disgusted with our rivers being essentially open, stinking sewers, but they were used to it. Since 1993, when the WPAP improvements were completed and became operational, there have been an average of about two CSOs per year. Now, any sewer overflow gets a newspaper article, usually on the front page, and much of the public believes that since overflows have not been entirely eliminated, the program was a failure.” He notes, however, that during the same period, hundreds of millions of dollars have gone into condominiums, apartments, restaurants, and other commercial buildings along the waterfronts. “Because their condition has dramatically improved, they are now attractive assets rather than detriments to the community. Fishing has become very popular along portions of the river that no one would have thought of for fishing before 1993.”The project cost $2.3 billion and is still being paid off, Graffin notes, through property tax and user fees. “Of the $2.3 billion price tag, the deep tunnel was about a billion dollars,” he says. “The rest of the money went toward improving and expanding capacity for the sewers and the treatment plant. Also, we are lucky that things happened when they did because federal grants were available. We received about $1.1 billion in federal grants.“Communities out there now are having to pay for this all on their own. All the federal grant money has dried up, and those that are having to put on the programs that we did years ago are facing massive tax increases. Our tax rate at the highest went up to about $3.50 per $1,000. We were at $1.70 for about six or seven years, and last year we lowered it to $1.59.”Milwaukee is presently working on a $900 million overflow-reduction plan stemming from a Wisconsin Department of Natural Resources court-approved stipulation. “These are projects and programs we have to have in place by 2010,” Graffin says. “We also are building another deep tunnel that will drain into the original one. This new one is 7.1 miles long, and by the time it is lined, it will be 20 feet in diameter and hold 88 million gallons. That is a 21% increase in storage capacity.” Richmond, VAIn Richmond, VA, CSO discharges had resulted in undesirable aesthetic impacts and had been a significant concern, particularly in the James River Park areas. Robert Stone, an engineer with the City of Richmond Department of Public Utilities, says the city began addressing CSO issues in the 1980s with a study of the city’s entire combined sewer system. Approximately 32% of Richmond is served by combined sewers.“The initial CSO Special Order was issued in 1992 and was amended or reissued several times as the program progressed,” he says. “Phases I and II of Richmond’s CSO control plan began in 1992 and were completed with the startup of the tunnel in mid-2003.”The tunnel was designed to minimize CSO discharges from the westernmost CSO discharge points along the north bank of the James River, reducing overflows from about 50 down to only four for an average year, Stone explains. He says the main challenge of the tunnel project was the nature of its location and limited space.“The two CSO outfalls are in close proximity to the James River, city parks, the historic Kanawha Canal, residential neighborhoods, railroad tracks, and a major highway bridge,” he says. “As construction progressed, the contractor encountered two small areas of unstable rock geology that delayed tunneling progress.”The concrete-lined CSO retention tunnel is 6,000 feet long with an interior 14 feet in diameter and a 7.2 million-gallon storage capacity. It is located 40 to 150 feet below the surface.At the western end of the tunnel is the new McCloy Pump Station, which is designed to dewater the tunnel within 48 hours. The contents of the tunnel are pumped to the city’s wastewater treatment plant for full treatment before being released into the James River.“The overall cost of the tunnel project was roughly $50 million, including design, construction, project management, city overhead, and capitalized interest. The construction contract was roughly $31 million,” Stone says.“The public–including environmental groups–has participated in the project’s design and development and has been supportive of Richmond’s CSO control program,” he notes. “The project was required under the terms of a Special Order by Consent between the City and the Virginia Department of Environmental Quality.”Stone says the tunnel alternative was chosen to minimize the impact to neighborhoods, parks, and sensitive environmental areas along the river. The cost was comparable to other more disruptive alternatives, he says.The tunnel includes several innovative features. “In order to clean the tunnel after CSO events, a flushing structure was built at the eastern end of the tunnel, which utilizes water from the Kanawha Canal to flush the tunnel in a computer-controlled set of sequences,” Stone explains. “The tunnel is also designed such that on those few storms each year that exceed the storage capacity of the tunnel, it will passively discharge excess flow at the downstream Hampton Street CSO outfall.”Portland, ORIn Portland, OR, CSOs occur nearly every time it rains. The overflows carry bacteria from untreated sewage and other stormwater pollutants into the Willamette River.The city is in the midst of a project that includes constructing a pipeline on the west side of the river using a tunnel boring process, establishing a large pump station on Swan Island, and designing an east-side pipeline to reduce CSO volume to the Willamette River by 94%. The pipe will be 3.5 miles long and 14 feet in diameter and will be located 120 feet underground. The project is expected to be completed in 2006. Government officials are already noting progress in CSOs as the west-side project, which includes the West Side Big Pipe and the Swan Island Pump Station, continues. The amount of bacteria and stormwater pollution into the river is decreasing. When Portland’s Environmental Services launched a CSO control program in 1991, some 6 billion gallons of sewage had been overflowing to the Columbia Slough and Willamette River annually; the program has since reduced CSO volumes by 3.2 billion gallons each year. Bacteria levels are dropping in the river, declining between 18 and 49% at specific locations on the river. Environmental Services completed work on the Columbia Slough Big Pipe in 2000, construction commenced on the West Side Big Pipe in 2002, and the design for the east side of the river is in the final phase. That will be the largest of Portland’s CSO projects, providing a 20-foot-diameter, 6-mile-long pipe to prevent CSOs from reaching the Willamette River. Construction is slated to begin in 2006, with project completion targeted for 2011. Dan Vizzini, a principal financial analyst and project manager with Portland’s Bureau of Environmental Services, says the city is operating under a stipulated federal court agreement in conjunction with the Oregon Environmental Quality Commission to eliminate overflows by 2011: “Hence the unprecedented construction going on at this point.” He says overall project costs, estimated to exceed $1 billion, are being borne by the ratepayers.“The bureau has been borrowing large sums of revenue bonds to cover the capital costs,” Vizzini says. “The debt service on the bonds is paid from sanitary-sewer user fees and stormwater management charges. Ratepayers are quickly reaching a tipping point with respect to utility rates, particularly stormwater rates.”