Peter Kenyon, TunnelTalk
Many of the largest cities in the United States are continuing to excavate large-diameter deep storage and CSO tunnels of about 5m (16ft) and more as part of long term control plans to comply with the provisions of the US Federal Government Clean Water Act of 1948 and significantly amended in 1972; still more projects are in design. St Louis in Missouri is the latest to opt for a billion dollar 'gray infrastructure' deep tunnel solution to address its problem with combined sewer overflows into the Des Peres River. But with the Environmental Protection Agency trending towards 'green' and sustainable solutions, and with water and sanitation boards across the country coming under increasing pressure from ratepayers to find cheaper solutions, is the tide turning against large-scale large-diameter underground CSO infrastructure? Peter Kenyon investigates how the latest developments impact the US tunneling industry.
- For the best part of two decades, deep storage tunnels and CSO interceptor systems have formed the central spine of projects that many of the largest cities in America and sewer districts have been obliged to adopt as part of a nationwide program to reduce overflows of foul and polluted water into the rivers, creeks and harbors of the nation.
- Since the 1990s, a total of 772 cities and districts have been identified by the Federal Environmental Protection Agency (EPA), as needing urgent action to tackle chronic problems associated with operating outdated combined sewer overflow (CSO) systems incapable of dealing with modern demand requirements. Population expansion since the systems were installed, often decades ago, together with the culverting of natural creeks and the covering over of vast acreages of land with concrete and tarmac, have all contributed to a situation where billions upon billions of gallons of combined stormwater and sewage are being discharged annually into natural watercourses during times of heavy or prolonged rainfall.
772 cities and districts have inadequate CSOs
- Cities and sewer districts are at various stages of delivering EPA-approved Long Term Control Plans (LTCPs) aimed at ensuring that up to 99% of storm water is treated before being discharged into natural watercourses. For many years the method of choice in the larger urban regions has been, almost without exception, deep CSO storage tunnels.
- For the US tunneling industry the program has provided sustainable work with a number of high-profile tunnels designed in the 1990s and 2000s, now under construction in Indianapolis (first TBM launched on Deep Rock Connector Tunnel in 2012), Washington DC (first TBM due for launch next month on 4.5 mile Blue Plains Tunnel, July 2013), North East Ohio (second TBM launched on the 5.5km x 7m diameter (3.4 mile x 24ft) Cleveland Euclid Creek Tunnel in 2012) and Columbus (TBM launched 2011 for the 7km x 6m diameter (4.42 mile x 20ft) OARS Tunnel). With the much-lauded and ongoing TARP deep tunnel system for Chicago as an early blueprint, CSO tunnels have also been completed in Seattle for King County (2005, US$165 million), Portland (2005 to 2010, US$650 million), and a long program of several in Atlanta, among others.
- With Omaha including an estimated US$442 million, 8.5km x 5m (5.4 mile x 17ft) tunnel in its 2009 LTCP, and, more recently, St Louis Sewer District embarking in 2012 on early design of the estimated US$1 billion 21km (13 miles) of deep storage tunnels in its 2004 LTCP (updated and approved by the EPA in 2011), the total estimated value to the US tunnel construction industry of all large-scale deep storage and CSO tunnel projects that are either completed, in construction, or cost estimated since 1998, is in the region of US$4 billion. This figure does not include the (10 miles) of tunnels not yet designed in Indianapolis (in two tunnels) or the outstanding 4.8km (3 mile) North East Boundary Tunnel and 5.6km (3.5 mile) North East Branch Tunnels that comprise the final phases of the Washington DC Clean Rivers Project, or the Chicago TARP tunnels. Together these could be expected to add a further US$2-3 billion in deep tunnel construction contracts.
EPA Consent Decree values
- In addition to these, there is scope for more deep storage tunnel projects. According to 2012 EPA statistics, of the 201 CSO systems serving populations of 50,000 or more, 135 have addressed their obligations (since 1998) by agreeing to comply with a Consent Decree that sets out an enforceable timetable for agreed future delivery of a package of mutually-agreed remedial works. A further 37 are subject to enforcement action where agreement is being negotiated. To date more than US$28 billion of CSO-related works have been agreed since 1998, $17 billion of them in 2010 and 2011 alone. In 2010, St Louis, which has opted for a CSO storage tunnel solution, agreed to one of the largest CSO-related Consent Decree liabilities (US$4.7 billion), while Honolulu has agreed to works costing US$5 billion, Philadelphia to a US$2.4 billion program, and New York City to a $5 billion scheme that it hopes to cut by $1.4 billion.
- But are the days of deep storage tunnels, and their associated power-hungry pumping infrastructure, coming to an end? A new trend in favor of 'green' and 'sustainable' solutions is developing, one that is leading to the shelving of a number of planned storage tunnels and one that is being encouraged, at least for the moment, by a once-skeptical EPA. It seems that the EPA is intent on giving CSO storage tunnels a temporary time-out while assessment is afforded to 'sustainable' alternatives.
Green policy shift memo
- In a memo to all EPA Regional Administrators in October 2011, Nancy Stoner, Acting Assistant Administrator of the Office of Water, wrote: "One of the most basic objectives of the Clean Water Act is to keep raw sewage and pollutants carried by stormwater out of our nation's waters. As we move forward with our work we must be mindful that many of our state and local government partners find themselves facing difficult financial conditions. Their ability to finance improvements by raising revenues or issuing bonds has been significantly impacted during the ongoing economic recovery."
- She goes on to suggest that "integrated planning" of the "sometimes overlapping and competing requirements that arise from separate waste and stormwater solutions" is needed so as to "identify sustainable and comprehensive solutions such as green infrastructure that can improve water quality and enhance the vitality of communities." The memo implies that, in the past, emphasis has been placed on cities and districts demonstrating an ability in their LTCPs to deliver a CSO solution as quickly as possible; whereas henceforth EPA discretion should be exercised to "flexibly evaluate a municipality's financial capability in tough economic times" to "set appropriate compliance schedules" that will "allow for implementing innovative solutions."
- Stoner then specifically mentions the case of Cincinatti and the Hamilton County Sewage District, which earlier this month was given the green light by the EPA to change direction radically and away from its once-preferred deep storage tunnel solution to pursue instead a number of demonstration projects that tackle the problem from a separation angle - that of restoring natural watercourses and creeks long-since concreted over to harness capacity so as to prevent 1.8 billion gallons a year of storm water from ever entering the existing CSO system and thereby allowing the CSO system to cope with polluted stormwater and sewage only.
- At the heart of the revised Cincinatti plan, called Project Groundwork, is the daylighting of creeks, starting with Mill Creek, that have been long since concreted over, to provide a natural channel for capturing stormwater for dispersal directly into the Ohio River. The City plans to restore brownfield sites along the Mill Creek corridor and regenerate the local community by creating a 3.2km (2 mile) linear park.
- This latest solution is very different to the plan proposed to the EPA in 2002. In a settlement order, the EPA reported that Cincinatti was evaluating a 25.5km (16 mile) network of deep storage tunnels that were estimated in 2002 to cost US$450 million and would "end the area's chronic flooding problems" caused almost entirely to a single SSO (storm sewer overflow) (SSO 700). But by 2010 Cincinatti had reached a new agreement with the EPA to defer its earlier tunnel plan and instead conduct further analyses and propose an alternative plan. In December 2012, after three years of design, evaluation and consultation, Cincinatti proposed its radical solution to the problem of Mill Creek. Earlier this month the EPA agreed to drop the tunnel requirement for Phase 1, retaining a 2km x 9m diameter (1.2-mile x 30ft) storage as "the Regulator's default solution. This saves the district an estimated $150 million. A deep tunnel option is still possible in Phase 2, but, if evaluation of Phase 1 is positive, that too, is likely to be shelved. This is a clear demonstration of a new shift in policy at the EPA towards evaluating early phase green proposals with a view to repeating them in later phases.
- Cincinatti is not alone. Philadelphia has finally won its fight for a green-based $2 billion Consent Decree after three years of negotiations with the EPA. The project will involve green roofs, rain gardens, porous streets, and an increased number of parks and open spaces, in conjunction with existing gray infrastructure, to keep rainwater out of its CSOs. If these measures prove successful in delivering targets, the city could serve as a blueprint for other cities to bypass the need for deep storage CSO tunnels. These, critics argue, are expensive, lie redundant for long periods of time during the year, and cost millions in annual pumping costs.
- Project Groundwork
Cincinnati has shelved deep level CSO tunnel in favour of daylighting a natural creek
- In its 2009 LTCP Update, the Philadelphia Water Department modeled a system that incorporated three deep storage CSO tunnels of a total 45km (5.9 miles for the South East District, 10 miles for the North East District, and 13.7 miles for the South West District), with diameters ranging between 4.5m to 10.5m (15ft-35ft). By 2011 the City had changed tack away from the tunnel solution, and in its Amended CSO Control Program declared: "Philadelphia Water District has become a national leader in its quest to demonstrate how to protect and restore stream water quality without the expenditure of billions of dollars on new pipes, tunnels and treatment systems."
- At the signing of the so-called Green City, Clean Waters plan in December 2012, EPA administrator Lisa Jackson said: "We want to see the benefits of green infrastructure taking hold in other large metropolitan areas, not just Philadelphia." Mayor Michael Nutter explained: "Our plan uses green technologies on top of Philadelphia's gray infrastructure to capture rainwater before it enters the city's 3,000-mile sewer network. We will transform a third of our paved surfaces like streets, parking lots and sidewalks with green areas."
- Mayor Nutter is not alone in his preference for a green solution. Others are keen to follow the blueprint. In April this year (2013), six City Mayors representing 773 cities and jurisdictions impacted by the CSO clean-up mandate, met with EPA officials in Washington DC to push the case for green solutions over gray ones. The meeting was attended also by representatives of the National League of Cities, the National Association of Counties, and the Mayors' Water Council established by the US Conference of Mayors to address CSO and other water issues.
- Omaha Mayor Jim Shuttle, whose city includes a $442 million deep CSO tunnel in its current LTCP, was among the delegation as part of the Mayors' Water Council delegation. He urged regulators to "focus on cost-effective and flexible approaches to achieve clean water standards." The deep tunnel plan in Omaha represents 40% of the total cost of the Omaha CSO clean-up project, and Mayor Shuttle is leading a request for EPA regulators to ease enforcement timescales to allow alternative, cheaper, strategies to be explored before committing to tunnel construction.
- "While moving the Federal Government is never easy, I will continue to push regulators toward innovative and cost-effective methods of achieving a safe and clean environment that is economically sustainable," said Shuttle. "The taxpayers of Omaha are my top priority and I will do all I can to protect them from onerous expense."
Green streets will divert runoff to planters
- New York City is also hoping to demonstrate to the EPA that $187 million of new green solutions implemented between now and 2015 will enable it to cancel earlier plans in a 2005 agreement with the EPA for two CSO tunnel projects at Newtown Creek and Flushing Bay, that were set to cost an estimated $1.3 billion and $800 million respectively.
- In an innovative November 2011 modified draft agreement with the EPA, the City pledged to continue with $1.6 billion of smaller gray infrastructure CSO projects, but was allowed to defer until 2017 previous plans for the two CSO tunnels "to allow time to determine if green infrastructure projects can serve as efficient alternatives to large-scale gray infrastructure facilities." The City believes that not having to build the large diameter CSO tunnels that it once planned, will save $1.4 billion net. The new plan involves rebuilding stormwater collection infrastructure at the roadside, and other places such as car parks and malls, to prevent water, that hits 10% of the City's impervious surface area as rain, from entering the CSO system. For each inch of rainfall collected across just 10% of such surfaces, the City calculates it will save 1.5 billion gallons/ year from entering the overstretched current CSO system. The first target it must demonstrate is a diversion of 1.5% of that volumn by 2015. After this period the City will be subjected to careful scrutiny between five - year incremental milestones.
- Washington DC is another city trying to opt out of the gray CSO control systems and into the green one. DC Water has started construction of the $1.6 billion Blue Plains tunnel, together with associated treatment and pumping infrastructure, with the TBM due for launch next month (July 2013), and last month awarded a $254 million contract to the Impregilo/Healy JV for TBM construction of the second Anacostia tunnel that will connect with it. In the meantime, however, DC Water has begun a formal process, in conjunction with the Mayor's Office, of trying to convince the EPA that it should be granted more time to demonstrate if green initiatives can defray the need for about 11km (7 miles) of planned CSO storage tunnel infrastructure known as the North East Boundary Tunnel and the North East Branch Tunnels (also known as the Potomac Tunnel and Piney Branch Tunnels).
Washington DC wants to drop Northeast tunnels from its Clean Rivers Project
- In a letter to EPA Administrator Lisa Jackson, DC Mayor Vincent Gray wrote: "I am hopeful that the EPA continues to work in collaboration with DC Water to extend the current Consent Decree to explore alternatives to large and expensive underground storage and conveyance tunnels."
- In December (2012) DC Water and the District of Colombia approached the EPA to extend the deadline imposed by its 2004 Consent Decree for moving into the design and construction phase of the Potomac and Piney Branch tunnels. Instead DC Water wants to focus on a series of multi-million dollar green demonstration projects in the affected area, with a view to abandoning the need for the remaining tunnels, which it estimates will cost $1 billion.
- Under the terms of the informal Green Infrastructure Partnership Agreement, agreed between DC Water, the District of Colombia and the EPA in December last year (2012), DC Water is to implement green initiatives while it files a formal Consent Decree Modification request to extend the deadline imposed on it for undertaking design and construction of the northern tunnels. The new deadline, if agreed, would be subject to a number of key decision points to assess whether the green initiatives have a chance of working on a large scale.
- There is also a financial dimension. With such large capital investments required to meet compliance standards, the Clean Water State Revolving Fund (CWSRF) has been established to finance up to 100% of the cost of cleaning up CSOs. To date CWSRFs have funded more than $89 billion for clean water related programs, including CSO management, but, crucially, the funding is in the form of repayable loans. Whereas in the 1990s Federal grants were given towards the completion of CSO projects, the nation's cities and sewer districts now have to repay all money borrowed at a rate of 2.2% per annum over a maximum 20 years. In the meantime water rates are having to increase faster than ever in affected areas, and pressure is mounting on local authorities and enforcement agencies to pursue the most cost-effective remedies.
- The surge of green and sustainable alternative solutions, however, are very much in the demonstration stage. It will be up to the cities concerned to prove that their ideas can translate into tangible and target-driven results. The tunnel industry, which has itself been working hard to incorporate green and sustainable techniques and practices, especially those related to the disposal of muck, will be watching with interest.
|Table 1. Major large diameter CSO and storage tunnel project progress since 2005|
|Location||Project/tunnel||Cost ($million)||Contractor||Length x i.d.|
|DC Water (Washington DC)||Blue Plains Tunnel||330.5||Traylor/Skanska/Jay Dee (TBM launch expected July 2013)||4.5 miles x 23ft|
|Anacostia Tunnel||253.9||Impregilo/SA Healy (construction not yet started)||2.4 miles x 23ft|
|North East Boundary Tunnel||-||Planned for construction 2018-21||2.8 miles|
|North East Boundary Branch Tunnels||-||Planned for construction 2018-21||3.1 miles|
|Portland, Oregon||West Side CSO||269||Impregilo/SA Healy (completed 2005)||3.5 mile x 14.5ft|
|East Side CSO||381||Kiewit/Bilfiger Berger (completed 2010)||1.6 miles x 25ft|
|North East Ohio SD (Cleveland)||Mill Creek Tunnel (MCT3)||90||Kassouf Co/Mole Constructors/Murray Hill/Kenny (completed 2008 after significant project delays due to methane gas infiltration)||3 miles x 20ft|
|Euclid Creek Storage Tunnel||198||McNally/Kiewit (TBM launched 2012, due for completion 2015)||3.4 miles x 24ft|
|Dugway Storage Tunnel||145||Design contract pending, bid year 2016||2.7 miles x 24ft|
|Doan Valley Storage Tunnel||101||Design start 2015, bid year 2017||1.8 miles x 17ft|
|Shoreline Storage Tunnel||180||Design Start 2018, bid year 2021||3 miles x 21ft|
|Westerly Tunnel||202||Bid year 2020||2.3 miles x 24ft|
|Big Creek Tunnel||221||Bid year 2028||3.7 miles x 20ft|
|Chicago TARP||Phase 1 (1975-2006)||Approx 3,000||-||109 miles x 9-33ft|
|Indianapolis||Deep Rock Connector||180.2||Shea/Kiewit (TBM launched 2012)||7.5-mile x 18ft|
|Fall Creek/White River Tunnel||Approx 389.2||In design (Black & Veatch) Estimated construction start 2016||8.6 miles x 18ft|
|Pleasant Run Tunnel||-||-||Estimate 7 miles|
|Pogues Run Tunnel||-||-||Estimate 3 miles|
|St Louis Sewer District||Upper River Des Peres Storage Tunnel||-||-||1.7 miles x 24ft|
|River Des Peres Tributaries Storage Tunnel||-||-||2.3 miles x 20ft|
|Lower and Middle River Des Peres Storage Tunnel||-||Engineering Services Contract awarded to Jacobs (March 2012)||9 miles x 28ft|
|Columbus||OARS Project||260.5||Kenny/Obayashi||4.4 miles x 20ft|
|Omaha||Deep Level Tunnel||442 (2009)||Not yet in design Included in 2009 LTCP||5.4 miles x 17ft|
DC Water scales back CSO tunnel plans - TunnelTalk, January 2014
New York City Green Infrastructure Plan (2010, Executive Summary)
Philadelphia Green City Green Waters (2012)
Mobilizing for a Deep Rock Tunnel Connector start in Indianapolis - TunnelTalk, December 2012
Columbus mobilizes the OARS project - TunnelTalk, January 2011
Cincinnati plans deep CSO program - TunnelTalk, November 2010
Portland West Side CSO - TunnelCast, September 2009
Portland CSO closing in on major breakthrough - TunnelTalk, September 2009
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