A dry cleaning facility was discharging cleaning solution containing perchloroethylene (PCE) contaminant, which infiltrated the soil and aquifer through a leak in a storm drain. The EPA was called in to evaluate the site and determined that a major excavation of a city block, 28 feet down to the bedrock, would be necessary. The project required bypassing both an 18-inch sewer main and a 30-inch storm drain for the duration of the excavation and rebuild of the site. The agency also required treatment of the groundwater that would be extricated during the excavation.

Controlling the groundwater

Rain for Rent was able to provide the pumps needed for the bypass project. The company also provided needed support for the pumping operation.

The facility contacted an equipment rental agency that was able to supply a turnkey system to handle both the sanitary and stormwater discharges, including monitoring the systems from 7 p.m. to 7 a.m. The sanitary bypass system consisted of two DV-150i 6-inch pumps. The storm system was designed with three pumps (one DV-300 12-inch, one DV-200c 12x8-inch, and one DV-100 4-inch for backup in case of major weather events) manifold into a 12-inch HDPE pipe for discharge.

The sanitary system would continuously operate 24/7; the stormwater system ran during rain and storm events as needed. Both systems, installed side by side, were piped through a 12-foot road crossing to allow dump trucks access to the dig site, back to the disposal area, and 300-feet down the street to the discharge points.

Treatment

All of the groundwater that was removed was circulated through tanks and filters. The water had to meet permit limits before discharge.

To meet EPA requirements, the groundwater had to be tested and filtered to applicable permit requirements of less than 5 ppb PCE before discharge. The groundwater was pumped into two 21,000-gallon frac tanks to allow settling of the solids, and testing before and after filtration. A 4-inch pump was used to circulate the groundwater from the frac tanks through a sand media filter, a 200-gpm bag filter, and two 5,000 lb. activated carbon units. The clean water was batched again into a 21,000-gallon frac tank to be tested prior to discharge into the city's sanitary sewer system.

For three and a half months both the stormwater and sanitary systems were successfully bypassed to allow excavation and reconstruction of the contaminated site. During that time, over 120,000 gallons of contaminated groundwater were treated and discharged into the city's sanitary sewer system with a non-detect reading for contaminant. PE