In most Virginia communities, one set of pipes carries wastewater from homes and businesses to wastewater treatment plants (WWTP's). Wastewater gets processed at WWTP's to remove solids and kill bacteria. In the Chesapeake Bay watershed, additional processing removes most nitrogen and phosphorous as well, minimizing the nutrients in wastewater that over-fertilize the Chesapeake Bay.
Except in three Virginia cities today, a separate set of ditches/pipes, independent of the wastewater infrastructure, carries stormwater runoff to Virginia's streams. Stormwater is not treated - pollutants and nutrients washed off roads and lawns will flow directly into those streams and down to the Chesapeake Bay, Atlantic Ocean, or Gulf of Mexico.
Excessive levels of bacteria impair Virginia streams, in addition to the nitrogen, phosphorous, and sediment that affect Chesapeake Bay water quality. For example, Hunting Creek at Alexandria is impaired and not safe for primary recreation use due to bacteria, and is listed on Virginia's Section 303(d) List of Impaired Waters.
In Alexandria, Ashland, Bristol, Cape Charles, Colonial Heights, Covington, Fredericksburg, Lynchburg, Newport News, Radford, Richmond, Roanoke, and Waynesboro, some pipes for carrying stormwater to the nearest stream were connected to the old wastewater pipes, creating a Combined Sewer Overflow (CSO) infrastructure. When stormwater systems were first developed in those communities, downspouts from gutters on houses in old neighborhoods or from buildings downtown were connected to the sewers. In addition, some inlets from gutters carrying water off streets in urban areas were also connected to pre-existing sewer pipes.1
The combination of wastewater/stormwater systems simplified the construction process. Just one set of pipes was placed underground, saving money and minimizing disruption from digging up streets to install a second set of pipes. Combining waste and stormwater flows also ensured a complete flushing of the sewer system during storms.
In most Virginia communities, the stormwater system has been separated from the sanitary sewer system. Alexandria, Richmond, and Lynchburg are the last three Virginia localities that still have a Combined Sewer Overflow infrastructure. Those cities dump raw sewage into the Potomac River (Alexandria) or James River (Lynchburg and Richmond) during rainstorms, when the volume of stormwater exceeds the capacity of the pipes or of the wastewater treatment plant to process the peak inflow.
Across Virginia, except for those three downtown areas, sanitary sewer systems are separate from stormwater management infrastructure. Where stormwater is steered to the stream channels through a separate set of ditches on the surface and separate underground pipes, underground pipes for wastewater are large enough to handle the volume of water generated by toilets/showers/kitchens but are not sized to handle surges of stormwater generated by rainstorms.
Dumping raw human waste mixed with stormwater into Virginia's waterways is a pollution event. Those events were intended and expected; they are not accidents. The Combined Sewer Overflow infrastructure pipes were designed to have outlets (overflow outfalls) where combined stormwater/sanitary waste would be discharged directly to streams, once capacity of the wastewater treatment plant to store more liquid or process its maximum volume was reached.
In storm events, the additional freshwater from rainfall was expected to dilute the polluted runoff, and the mix of extra runoff/sewage was expected to be an acceptable practice. After all, consolidated systems were built long before most wastewater treatment plants. Even when sanitary and stormwater pipes were separate, the sanitary pipes discharged raw sewage directly to streams.
What changed in the 1950's, after construction of the combined sewer systems, was the public's willingness to accept water pollution. By the 1960's, it was clear that the public would no longer concur with the old adage that "dilution is the solution to pollution." By the 1970's, the Clean Water Act required cities with existing Combined Sewer Overflow (CSO) systems to reduce discharges of untreated waste. Since the 1980's, rates charged to utility customers in Alexandria, Richmond, and Lynchburg have helped fund (along with state/Federal grants) some massive construction projects to divert stormwater and wastewater in order to reduce - but not eliminate - pollution.
Long ago the Environmental Protection Agency (EPA) recognized that substantial funding, over several decades, would be required to reduce pollution from existing Combined Sewer Overflow infrastructure. EPA started by requiring each community with a combined system to make progress and implement pollution reduction through a Long Term Control Plan (LTCP), with nine minimum controls on:2
The environmental impacts of dumping diluted-but-untreated sewage into the Potomac and James rivers must be addressed; Alexandria, Richmond, and Lynchburg have not been grandfathered or exempted from meeting the requirements of the Clean Water Act. The Environmental Protection Agency (EPA) has required each city to develop Long Term Control Plans that described how water quality standards would be met, so all waters in Virginia affected by the Clean Water Act would be "fishable" and "swimmable."
Lynchburg was one of the first cities in Virginia to build a drinking water system. Once fresh water arrived in volume at houses, the city needed a sewer system to dispose of wastewater. Lynchburg constructed an underground set of pipes carrying wastewater and stormwater, together, directly to the James River. Those pipes dumped raw sewage directly into the river every day and, after a rainstorm, the pipes carried stormwater to the James River as well.
In 1955, Lynchburg built its first wastewater treatment plant to treat the sewage and reduce pollution impacts on the river. To move sewage to that new facility, the city built an interceptor pipe parallel to the James River. The interceptor connected the pre-existing sewer pipes in 21 watersheds (8,300 acres) to the new treatment plant. As described by the city:3
Lynchburg ended up with 132 overflow outfalls that could relieve pressure on the pipes by releasing combined wastewater/stormwater into the James River, or tributaries flowing into the James. However, to meet the requirements of the Clean Water Act, the city needed to stop intermittent dumping of raw sewage into the river.4
Lynchburg committed to spend $350 million over 20 years to gradually separate its stormwater and sanitary sewer systems, including disconnecting downspouts on 4,000 houses/businesses that contributed 20% of the flow in the city's sewer system. One major item was a $60 million investment to install seven miles of new interceptor pipe (some as wide as seven feet) along the James River. People who use the city's sewer system (ratepayers to the utility) were obliged to fund the construction required to separate the now-combined systems, but the city was successful in obtaining state and Federal grants to reduce substantially the costs imposed on local ratepayers. The city negotiated an agreement with the State Water Control Board and EPA that rates increases would be based on a defined percentage (roughly 1.25%) of median household income in the city. That limit on revenue stretched out the completion date, but ensured that current ratepayers in Lynchburg would not be hit with exorbitant increases in their sewer fees.5
By 2012, Lynchburg had eliminated all but 20 of its 132 overflow outfalls, reduced the volume of Combined Sewer Overflow discharges by 80%, and completed 60% of 59 priority projects. The city saved the most expensive projects for last, and then examined "lessons learned" in other communities to change its plans. Lynchburg revised its strategy in 2012, when faced with the impacts of massive disruption and very high costs to tear up streets and install separate pipes in the 4-square mile historic downtown core.
Lynchburg chose to send the remaining combined sanitary waste/stormwater from the downtown district to an expanded wastewater treatment plant, upgraded to process the occasional high volumes of flow, rather than completely separate the underground pipe infrastructure. Costs to expand the wastewater plant to process combined flows and close two more overflow outfalls were estimated to be $60 million, compared to an estimate of $280 million to close all of the remaining 20 overflow outfalls. One tradeoff: the State Water Control Board and EPA had to accept that some overflows with some untreated sewage would occur in the future from the 18 remaining overflow outfalls.6
Eliminating the combined sewers did not completely eliminate the potential for sewage spills into the James River. After a massive storm known as a "derecho" in July, 2012, the Lynchburg wastewater treatment plant lost electricity and released 2.6 million gallons of partially-treated sewage. The facility lacked backup generators, and Lynchburg had not planned for a region-wide event where multiple sources of electricity would fail.7
Like Lynchburg, Richmond was one of the first cities in Virginia to create a system to carry sewage directly to the James River. The city covered Shockoe Creek and converting the natural drainage in Shockoe Bottom into two underground systems, a 17-foot by 12-foot concrete sewer known as the Shockoe Box and a pressure conduit known as the Shockoe Arch.
Richmond ended up with 12,000 acres draining into a combined sanitary/stormwater pipe system, the largest Combined Sewer Overflow (CSO) area in Virginia. There are 29 overflow outfalls along the James River or its tributaries (especially Shockoe Creek and Gillies Creek), and 2/3 of the city's total CSO Area is in the Shockoe Basin drainage.
Richmond built its wastewater treatment plant in 1958, and located it on the southern bank of the river near the Port of Richmond. The city built a 96-inch Shockoe Creek Interceptor pipe to gather waste/stormwater from the north bank and twin 66-inch pipes to carry that polluted water underneath the river from the downstream edge of Chapel Island (near Great Shiplock Park) to the wastewater treatment plant on the opposite side of the river.
To address pollution from its consolidated sanitary/stormwater system, Richmond used the same approach as Lynchburg and separated some pipes. However, Richmond's primary solution was to build a massive storage system to capture the surge of stormwater mixed with raw sewage after a rainstorm, then treat the captured water after the storm subsided and flows dropped to normal dry weather conditions.
In 1983, the city built the 50-million gallon Shockoe Retention Basin on Chapel Island (just downstream from the former mouth of Shockoe Creek) to capture the initial surge or "first flush" of stormwater runoff from a rainstorm.8
The underground retention basin included an aeration system intended to keep solids in suspension until the storage was emptied. By 2008, however, a 10-foot thick layer of sewage had settled on the bottom, similar to the solids that accumulate on the bottom of a septic tank. Contractors used backhoes to remove the solidified sewage from the floor of the retention basin.9
Storing that initial runoff helped the city avoid overwhelming the wastewater treatment plant with too much inflow. To stop discharges from two CSO outlets upstream from the river rapids that attract a great deal of recreational use, in 2003 the city built a $50 million, 600-foot long, 14-feet wide underground tunnel between Hampton and McCloy streets (the Hampton McCloy Tunnel). The city located the underground storage for 7 million gallons in Petersburg granite, to minimize the amount of infiltration, and designed the tunnel so water from the James River and Kanawha Canal could be used to flush out the solids.10
Some Richmond CSO outfalls discharge sewage less than once/year on average, but others regularly pour a mixture of water and untreated waste into the James River.
Richmond chose to start at the upstream side of its Combined Sewer Overflow, eliminating discharges from overflow outfalls on the western side of the city first. That resulted in cleaner water for recreational use downstream in James City Park, especially for popular rafting/kayaking activity at the Fall Line. Because the city's population on its western side is wealthier and includes less minorities, that decision also exposed city officials to charges of environmental prejudice.
EPA conducted a "knee-of-the-curve" economic analysis to define a point where increased clean-up expenses in a Long Term Control Plan would no longer be matched by a reasonable set of increased environmental benefits. For its Combined Sewer Overflow project, Richmond has proposed to reach compliance with Clean Water Act standards for 92% of the James River.
Using EPA's willingness to consider costs as well as benefits, Richmond has proposed to the State Water Control Board and EPA that the costs to implement 100% of the possible clean-up actions would fully exceed the benefits.
economic analysis indicates a point ("knee of curve") where incremental costs to reduce pollution increase dramatically after 92% of the James River miles comply with water quality standards
Source: State Water Control Board, City of Richmond Reasonable Grounds documentation
Richmond's proposed solution for avoiding the costs of the remaining 8% includes reclassifying Gillies Creek through a Use Attainability Analysis, so the city is not expected to reduce pollution enough to permit recreational use. Reclassifying the creek would eliminate recreational use as an objective would lower the threshold for clean-up.
From where the creek enters the city to its confluence with the James River near the old Fulton Gas Works, the natural channel of Gillies Creek was replaced with concrete in 1974. Paving the creek reduced flooding and sediment erosion, but did not reduce the excessive levels of bacteria that contaminate the water. The city claims it would have to spend $300 million to construct a 30-million gallon storage tunnel to capture stormwater and divert it to the wastewater treatment plant. The city also notes that Gillies Creek:11
Richmond's proposal for a Use Attainability Analysis notes that Gillies Creek has a normal flow of water only 2" deep except in rainstorms, offering little opportunity for swimming or wading, so Primary Contact Recreation is not currently an existing use
Source: State Water Control Board, City of Richmond Reasonable Grounds documentation
Alexandria's first wastewater treatment plant started operations in 1956, processing a maximum of 18 million gallons per day (MGD). Today, the facility is knwn as Alexandria Renew Enterprises (AlexRenew), and has a 54 mgd design capacity.12
In 1972, 730 acres in Alexandria were served by combined sewers. By 1990, 80% of the original 31 miles of combined sewers had been separated. Eliminating the remaining six miles in Old Town was projected to cost over five times the amount required to eliminate the total previous 25 miles. Today, 540 acres (6% of the city's area) drains into the combined sanitary/stormwater sewers.13
Alexandria has four outfalls that spill waste during storms. One (CSO-001) drains into the Potomac River at Oronoco Bay, near the intersection of Pendleton and Royal streets. One (CSO-002) sends sanitary waste mixed with stormwater directly into Hunting Creek. Two (CSO-003 and CSO-004) drain into Hooffs Run at Duke Street. The last three affect water quality of Hunting Creek, which is on Virginia's Section 303(d) List of Impaired Waters due to excessively high levels of bacteria. Between the four, discharges of 90% stormwater/10% sanitary waste occur 30 to 60 times/year.14
Alexandria initially committed to meet Clean Water Act requirements by implementing the Nine Minimum Controls in its Long Term Control Plan (LTCP). The Virginia Department of Environmental Quality (DEQ) has raised the bar in its latest Virginia Pollution Discharge Elimination Permit (VPDES), which must be renewed every five years.
The 2013 permit prohibits any discharge from the four CSO outfalls in dry weather, and required an update of the city's 1999 Long Term Control Plan to comply with the Hunting Creek Total Maximum Daily Load (TMDL) maximum for bacteria by 2035. To reduce bacteria from the three outfalls that drain into Hunting Creek, the city will require separation of sanitary and stormwater pipes as parcels are redeveloped. By 2018, Alexandria will also remove 60-92 sanitary sewer connections on Payne and Fayette streets, connecting instead to the Potomac Yard Trunk Sewer. The city will consider green infrastructure techniques, including green roos and bioretention (rain gardens), to reduce flows at Outfall 003 and Outfall 004.15
combined pipes (in purple) near Pendleton Street outfall
Source: Alexandria Sewer Viewer
References1. "Combined Sewer Overflows in the Commonwealth," General Assembly, Senate Document 40, 1990, p.3, http://leg2.state.va.us/dls/h&sdocs.nsf/By+Year/SD401990/$file/SD40_1990.pdf (last checked October 4, 2013)
2. "Combined Sewer Overflows - Nine Minimum Controls," Environmental Protection Agency, http://cfpub.epa.gov/npdes/cso/ninecontrols.cfm?program_id=5 (last checked October 4, 2013)
3. "Combined Sewer Overflows in the Commonwealth," General Assembly, Senate Document 40, 1990, p.4, http://leg2.state.va.us/dls/h&sdocs.nsf/By+Year/SD401990/$file/SD40_1990.pdf; "Why do we have a CSO problem?," City of Lynchburg, http://www.lynchburgva.gov/history-0 (last checked October 4, 2013)
4. City of Lynchburg’s Consent Order, Commonwealth of Virginia State Water Control Board, August 19, 1994, http://www.lynchburgva.gov/sites/default/files/COLFILES/Water-Resources/Documents/CSO_special_order.pdf (last checked October 4, 2013)
5. "The History of Combined Sewer Overflow in Lynchburg, Virginia," Blair Marketing, video posted on YouTube, http://www.youtube.com/watch?v=4BimS2RM1MU; "Project Updates - James River Interceptor," City of Lynchburg, http://www.lynchburgva.gov/project-updates; Appendix A, City of Lynchburg’s Consent Order, Commonwealth of Virginia State Water Control Board, August 19, 1994, http://www.lynchburgva.gov/sites/default/files/COLFILES/Water-Resources/Documents/CSO_special_order.pdf; "Combined Sewer Overflows in the Commonwealth," General Assembly, Senate Document 40, 1990, p.7, http://leg2.state.va.us/dls/h&sdocs.nsf/By+Year/SD401990/$file/SD40_1990.pdf (last checked October 4, 2013)
(last checked October 4, 2013)
6. "Holistic Approach," Municipal Sewer and Water, July 2013, http://www.mswmag.com/editorial/2013/07/holistic_approach; "Lynchburg to hold open house on CSO project," News and Advance (Lynchburg), April 22, 2013, http://www.newsadvance.com/news/local/article_1f43ddd2-abb2-11e2-be4f-0019bb30f31a.html (last checked October 4, 2013)
7. "Partially treated sewage released in the James River at Lynchburg," Richmond Times-Dispatch, July 4, 2012, http://www2.timesdispatch.com/news/state-news/2012/jul/04/tdmet03-partially-treated-sewage-released-in-the-j-ar-2033073/ (last checked July 4, 2012)
8. Robert C. Steidel, Robert Stone, Lin Liang, Edward J. Cronin, Federico E. Maisch, "Downtown Shall Not Flood Again," Proceedings of the Water Environment Federation, WEFTEC 2006, pp.3770-3772, http://dx.doi.org/10.2175/193864706783751401; "McDonnell proposes $40 million to help clean up RVA’s wastewater system," RVANews, December 26, 2012, http://rvanews.com/news/mcdonnell-proposes-40-million-to-help-clean-up-rvas-wastewater-system/78637 (last checked October 4, 2013)
9. "At First Flush," Richmond Style Weekly, January 13, 2010, http://www.styleweekly.com/richmond/at-first-flush/Content?oid=1369472 (last checked October 4, 2013)
10. Rob Baker, "Management of Combined Sewer Overflows," http://home.eng.iastate.edu/~tge/ce421-521/Baker.pdf; "Diverting Stormwater," Stormwater, April 13, 2004, http://www.stormwater.org/SW/Editorial/Diverting_Stormwater_16949.aspx (last checked October 4, 2013)
11. "Reasonable Grounds Documentation to Conduct a Recreational Use Attainability Analysis for Gillies Creek, City of Richmond, Virginia under VAC 62.1-44.19:7," City of Richmond, August 24, 2010, http://www.deq.virginia.gov/Portals/0/DEQ/Water/WaterQualityStandards/Gillies_Creek_UAA_Reasonable_Grounds_8-26-2010.pdf (last checked October 4, 2013)
12. "Sanitary Sewer Master Plan," City of Alexandria, April 2013, http://alexandriava.gov/tes/info/default.aspx?id=51410 (last checked October 4, 2013)
13. "Combined Sewer Overflows in the Commonwealth," General Assembly, Senate Document 40, 1990, p.4, http://leg2.state.va.us/dls/h&sdocs.nsf/By+Year/SD401990/$file/SD40_1990.pdf; "Combined Sewer System," City of Alexandria, http://alexandriava.gov/Sewers (last checked October 4, 2013)
14. Proposed Combined Sewer System Permit Information Meeting & Public Hearing, City of Alexandria, August 5, 2013, p.19, http://alexandriava.gov/uploadedFiles/tes/oeq/CSSPermitInfoMeetingandPublicHearingPresentation08052013.pdf; "Decision Rationale - Total Maximum Daily Loads for Recreation Use (Bacteria) Impairments in Hunting Creek, Cameron Run and Holmes Run Watersheds City of Alexandria and Fairfax County, Virginia," Environmental Protection Agency, November 10, 2010, http://www.epa.gov/waters/tmdldocs/Hunting%20Creek%20Bacteria_combo.pdf; "Even Small Amounts of Precipitation Dump Raw Sewage into Potomac River," Connection newspapers, August 19, 2013, http://www.connectionnewspapers.com/news/2013/aug/19/even-small-amount-precipitation-dumps-raw-sewage/ (last checked October 4, 2013)
15. Proposed Combined Sewer System Permit Information Meeting & Public Hearing, City of Alexandria, August 5, 2013, pp.35-39, http://alexandriava.gov/uploadedFiles/tes/oeq/CSSPermitInfoMeetingandPublicHearingPresentation08052013.pdf; "Reissuance of VPDES Permit No. VA0087068 Alexandria Combined Sewer System, City of Alexandria," Virginia Department of Environmental Quality, August 22, 2013, http://alexandriava.gov/uploadedFiles/tes/oeq/info/VA0087068%20Permit%20Aug%202013_44828757.pdf (last checked October 4, 2013)
redirecting 60-92 connections to the Potomac Yard Trunk Sewer involves just a tiny portion (colored in blue) of Old Town Alexandria
Source: City of Alexandria, Proposed Combined Sewer System Permit Information Meeting & Public Hearing (August 5, 2013)