For over 20 years, Weston has successfully partnered with the ReSolve site potentially responsible party (PRP) group to restore a former waste disposal site and nearby sensitive wetlands. Inaccessible dense nonaqueous phase liquid in bedrock continues to contaminate groundwater. Therefore, long-term groundwater extraction and treatment are required to prevent risk to downgradient drinking water wells.
Weston constructed the original 50-gallons per minute (gpm) groundwater extraction and treatment system in 1997. The design of the original system was based on technologies in widespread use at that time, including metals precipitation and air stripping. Weston designed and implemented several enhancements during construction of the original system that reduced capital costs by approximately $100,000.
After 13 years of operation, Weston designed and constructed new groundwater treatment processes that significantly reduced energy use, chemical use, and waste generation by the treatment system. The key process in this “green remediation” system is a highly innovative anaerobic bioreactor that stimulates the growth of naturally occurring bacteria to break down the organic contaminants in the groundwater. The modified system has provided highly effective and efficient operational use since the startup period.
To further improve the sustainability of the remedial program, Weston installed a 150-kilowatt (kW) solar photovoltaic (PV) system at the ReSolve site. The solar PV system provides approximately 107% of the electricity required for operation of the groundwater treatment system. In addition to providing renewable energy to power the remediation systems, the solar PV system has reduced electricity costs (per kW hour) for the ReSolve PRP group by approximately 12%.
The green remediation enhancements designed and implemented by Weston include the following benefits:
- Generate 191,000 kilowatt hours per year from solar energy, which is sufficient to fully power the groundwater treatment system on an annual, net-metered basis.
- Reduced electricity use at the site by 25% (saving $13,000/year).
- Reduced process chemical use from 59,000 lb/year to 9,000 lb/year (saving $23,000/year).
- Reduced waste (sludge and carbon) generation and disposal from 75,000 lb/year to 14,000 lb/year (saving $24,000/year).
- Realized an overall reduction of 80% in the “carbon footprint” of the groundwater treatment plant.
Weston continues to operate, monitor, and maintain the groundwater extraction and treatment system and the solar facility at the ReSolve site.