DORCAS — It’s a hole with thick concrete walls, and it smells bad.
It does its job, though, and the creatures that inhabit the nearby creek live easier because of it.
It’s a clarifier, installed at West Virginia’s Spring Run Trout Hatchery in Grant County to keep fish waste from polluting the facility’s namesake stream. Completed in 2007 at a cost of $2.9 million, it has cut the amount of solid waste entering Spring Run to a tiny fraction of what entered there before.
“Before the waste-treatment system was put in, the total suspended solids going into the stream were running around 110 to 120 [milligrams per liter],” said Eric Hevener, the hatchery’s superintendent. “The maximum limit allowed by the state was 60. Something had to be done.”
Space for a treatment facility was limited on the cramped hatchery grounds, so Division of Natural Resources officials had to do some rearranging.
“We used to have 10 ponds on the lower end of the property,” Hevener explained. “We took the ponds out and put raceways in.”
Raceways are long, concrete-lined rectangular troughs. They’re easier to clean, they require less water, and they take up less room than circular ponds.
The clarifier sits on the extreme downhill end of the hatchery grounds. Gravity carries the cold spring water that enters at the upper end of the facility downhill through the raceways and on to the clarifier.
The raceways are constructed so that suspended wastes pass through screens and accumulate in designated low-current areas. Workers clean half the raceways each week. They scrub the troughs’ sides and bottoms, pushing the sludgy waste into the low-current areas where it drains via underground pipes to the clarifier.
The clarifier holds a lot of waste.
“It’s 21 feet deep,” Hevener said, gesturing toward the sunken concrete-lined cylinder. “We let the solids settle out for at least 24 hours. Then we pump the sludge to a sludge-holding tank located next to the clarifier, and then we pump the ‘gray water’ to the stream.”
Once a month, hatchery workers are required to test the clarified water as it’s being pumped. An automatic sampler does most of the work.
“The clarifier does a good job. Right now, the [level of total suspended solids] is non-detectable,” Hevener said, holding up a printout of the sampler’s most recent readings.
Every six weeks, workers empty the accumulated sludge from the holding tank and have it trucked off to agricultural areas, where it is used as fertilizer.
“Between the sludge hauling and the water sampling, the clarifier costs about $25,000 a year to operate,” Hevener added.
To casual onlookers, spending so much money and manpower to get rid of fish waste might seem a bit extreme. Jim Hedrick, the DNR’s supervisor of hatcheries, said that simply isn’t the case.
“Fish waste is considered to be just like any other industrial waste,” he explained. “Our hatchery is a state entity, but we’re as responsible for treating its wastewater as any other industry would be.”
Hedrick said wastewater-treatment requirements are even more critical for Spring Run, because the facility is located within the Chesapeake Bay watershed. Pollution problems in the Chesapeake have led to stricter government-mandated discharge limits along the river systems that feed into the bay.
“Having to monitor the water going out of our hatcheries adds complexity to our trout-rearing system, but it has to be done,” Hedrick said. “We have a number of hatcheries for which the next step is to ensure that we get samplers to monitor our discharges, and flow meters so we can accurately estimate the contaminants going into the ecosystem.”
Down the road, Hedrick added, the DNR has plans to install clarifiers into facilities that don’t currently have them.
“The cost is going to be extensive,” he said, “but it’s something we’re going to have to factor into our long-term budgets.”
Reach John McCoy at email@example.com, 304-348-1231 or follow @GazMailOutdoors on Twitter.