Corrective Action Plan Featuring SCADA Swiftly Returns Excess Landfill Leachate to Compliance

When the Southeastern Public Service Authority discovered the leachate elevations in two of its landfill cells significantly exceeded regulatory depths, swift action was taken to remedy the situation. SPSA partnered with HDR to develop a corrective action plan including emergency pump and hauling, pre-treatment assessment, permitting, design and construction administration for a permanent leachate loadout station, and a site-wide Supervisory Control and Data Acquisition system for leachate management. SPSA was able to return the landfill leachate management system to compliance within seven months. 

At the time the elevated leachate levels were discovered, an estimated 8 million gallons of excess leachate had accumulated on two cells covering 80 acres of the landfill liner system. We worked with SPSA to begin repairing the existing system immediately, and to procure a contractor to pump and haul leachate for discharge to additional treatment plants. Up to 200,000 gallons of leachate per day were safely removed and delivered to four treatment plants through the existing forcemain connection, and via pump and hauling. The leachate discharge rate was limited to 50,000 gallons per day at each facility due to concentration of contaminants in the leachate.

The SCADA system provides real-time pump station operation data, alarm and warning conditions, auto shutdown, flowrates and totals, leachate elevations, and pump performance trending data. Unlike the previous manually operated leachate collection and management system, data from the SCADA system is accessible for review and input at each pump station, terminal stations at the administration offices, or via secured wireless communication to a tablet. 

To assess the continuation of discharging to the existing treatment plant, pre-treatment alternatives were considered. SPSA and Hampton Roads Sanitation District determined these alternatives were cost prohibitive and not desired. As a long-term solution, we’re working with SPSA and HRSD to design a new, 17-mile forcemain that would discharge to an alternative HRSD wastewater facility. This alternative would offer flexibility on the daily volume and the concentration of some of the specific parameters in the leachate, without additional pre-treatment.