Remediation System Operation, Maintenance, and Modification

At various sites under remediation, we have reactivated or improved remedial system performance, provided operation and maintenance services, or brought system operations back into compliance with discharge permits. For example, we assisted the City of San Jose to rehabilitate a groundwater recovery and treatment system that operated at one of their closed landfill sites. The system was used to collect groundwater and leachate from beneath the landfill and treat the extracted liquid before discharge to a nearby stream under a National Pollutant Discharge Elimination System (NPDES) permit. Treatment included liquid/liquid separation, air stripping, and carbon treatment of water and air prior to discharge. We assessed operation of the system and enacted several modifications to streamline operation, simplify compliance with discharge permits, and save money. We eliminated the air stripping system, separated the leachate and groundwater streams, and eliminated liquid/liquid separation. Air stripping was eliminated based on an evaluation of cost for liquid-use carbon versus the cost of air stripping followed by liquid-use carbon; separation of leachate and groundwater allowed partial use of the sanitary sewer system; and liquid/liquid separation was eliminated because separate phase liquid was no longer being extracted with groundwater. The system was modified so that only liquid-use carbon treatment was used prior to discharge. The modification simplified compliance sampling, lowered power costs, and reduced operation and maintenance requirements.