This time two years ago, officials from the historic city of Alexandria, VA, were jockeying with state legislators for more time to curb the sewage overflows that wash 140 million gallons of untreated sewage into the Potomac River and its tributaries each year. But since then, in an effort to meet the General Assembly’s 2025 deadline to complete the work, the city has found a way.
Like many centuries-old wastewater treatment systems in the country, Alexandria’s captures both sewage and stormwater in its pipes. To prevent sewage backups, the system was designed to divert wet-weather overflows to the nearest water body, sending untreated sewage directly into the stream or river. This has come to be known as a combined sewer overflow system.
Now, under pressure to reduce nutrient pollution in waterways, many cities are chipping away at combined sewer overflow problems through costly long-term programs to comply with federal requirements. But when river advocates rang the alarm that Alexandria wasn’t doing the work quickly enough, the General Assembly voted to speed up the time line.
Their 2017 law requires Alexandria to reduce the number of overflows into the Potomac from 60 per year to less than four — and to remove nearly all of the E. coli bacteria flowing from the other three outfalls into impaired waterbodies.
Overall, the planned project is expected to keep pollution from overflowing 96 percent of the time. As an added benefit, it should remove several thousand pounds of the trash that flows into the river via the sewer system.
This summer, the Northern Virginia city transferred ownership of its four outfalls — and the permits requiring expedited treatment — to the local wastewater treatment facility, Alexandria Renew Enterprises, or
AlexRenew. Staff at the facility brought not only expertise but also a new outlook to what had been an intractable problem for a city council unaccustomed to such projects.
Can the city funnel a few million more gallons per day to the plant for treatment by 2025? Yes, said Alex-Renew and its contractors. During a tour of the utility’s LEED Platinum-certified environmental education center — the first of its kind in Fairfax County, located just southwest of the city’s Old Town corridor — staff seemed more than able to tackle the project. They were excited about the challenge.
“When you say, ‘You got combined sewer overflows,’ that’s not the most exciting thing,” said Caitlin Feehan, program manager for the utility’s RiverRenew project. “But we see it as serving our ultimate goal of helping the community improve water quality. We do that by treating wastewater — but also with this project.”
If the plans come to fruition, Alexandria will join dozens of other cities that have curbed polluted overflows with costly projects to increase capacity at wastewater treatment facilities.
Like the District of Columbia and the Virginia cities of Richmond and Lynchburg — where projects are all well under way — Alexandria plans to build concrete tunnels deep underground to divert tainted water from the overflow points away from the river and toward the treatment facility.
Alexandria’s RiverRenew project entails building more than two miles of tunnels, two pumping stations and increasing treatment capacity at the plant, costing an estimated $370 million to $555 million. Across the Potomac River, DC Water’s Clean Rivers Project includes 18 miles of tunnels and an estimated cost of $2.7 billion.
But, if Alexandria is able to complete its project by the 2025 deadline, it may be one of the fastest timeframes in which a city has addressed its overflow problems.
Adam Krantz, CEO of the National Association of Clean Water Agencies, which represents water utilities, said many such projects take 15–20 years to complete. But if anyone can get it across the finish line, he said, it’s AlexRenew’s CEO Karen Pallansch, who also sits on the NACWA board and previously served as its president.
“She embodies an innovative, problem-solving mentality. She’s very good at completing projects,” Krantz said. “AlexRenew did a remarkable thing stepping forward to do this [project] for the city.”
Potomac Riverkeeper Dean Naujoks was among those pushing the city to clean up its sewer overflows much sooner than originally planned. With the state’s blessing, the city had planned to leave the largest of the four outfalls — which spews tens of millions of gallons of polluted stormwater annually into the Potomac River’s Oronoco Bay — untouched for the next 20 years while addressing other outfalls.
“The idea that they were still flushing their toilets into the Potomac was unacceptable to not only us but to a lot of communities downriver,” said Naujoks, who has continued to participate in the plan’s process to ensure overflows are reduced as much as possible. “AlexRenew, to their credit, kept picking up the capacity. Their consultants all seemed to suggest they could do this.”
The project could increase residents’ utility bills by $20 to $40 a month in the coming years, but the exact amount depends on whether the city gets grants from the state to defray the cost.
Richmond and Lynchburg each have received millions of dollars from the state for their combined sewer outflow reduction projects. Alexandria officials plan to ask the General Assembly for $25 million this year and for more in future years to equal about 20 percent of the project’s cost, according to AlexRenew staff.
The city initially planned to reduce overflows over time by building storage tanks in various places and redeveloping areas with modern stormwater controls, but the General Assembly’s decision sent officials back to the drawing board and led to a more holistic project.
“We already have the treatment plant and, by doing some tweaks here, we can take on additional flow and do work that’s already in our wheelhouse,” said AlexRenew’s Feehan.
The plant already provides wastewater treatment services for 300,000 residents in a tan-bricked portion of the facility that blends into its surroundings near Cameron Run, cleaning more than 13 billion gallons of wastewater each year before it is discharged into tributaries of the Potomac.
Diverting the outfalls — out of which about 140 million gallons of sewage-tainted water currently flow each year — to the plant for treatment entails a marginal increase in capacity.
The project will use a tunnel boring machine, which chews away at the earth and builds a concrete tunnel in its wake, to complete a pair of 12-foot-wide tunnels more than 100 feet underground. A federal environmental assessment is under way to help determine the path of the tunnels.
The National Park Service is the owner of much of the land under which tunnel construction would occur — including Jones Point Park, the George Washington Memorial Parkway and the Potomac River waterfront. The service required both the assessment and public listening sessions, which took place this fall.
“We’ve heard from the public consistently that there’s a desire to stay as far away from Old Town as possible,” Feehan said, summarizing many of the public comments about tunnel construction.
To quell concerns about a machine boring a tunnel deep under historic homes — or under the edge of the Potomac River, as one plan would entail — Feehan points to the other cities that have successfully built tunnels with little to no interruption on the surface. An added benefit of AlexRenew taking over the project, she said, is that the utility can pull all of the earth that the boring machine removes out at its plant, leaving fewer disruptions in the Old Town corridor where the Oronoco Bay outfall is located.
As part of the process, AlexRenew has already begun collecting soil samples along the proposed tunnel routes. The plan calls for the work to take place in a deep layer of prehistoric clay where — even in a centuries-old city such as Alexandria — it would be unlikely to disturb historical artifacts. (But better safe than sorry in a town that was built in some places atop buried wooden ships. [See Experience Alexandria’s maritime past, March 2017]).
During a boat trip with elected officials on the Potomac River earlier this year, AlexRenew’s CEO Karen Pallansch thanked the state legislators among them for the funding her facility received to complete wastewater treatment upgrades in recent years. And she reminded them that more would be needed to complete a project that AlexRenew had only recently acquired.
“We’re very excited, with a little trepidation around the program,” Pallansch said, “because we have to do it by 2025.”