Integrated Remediation Restores Coastal Ecosystem at Power Generation Facility
Comprehensive recovery and treatment systems removed 380,000 gallons of fuel and safeguarded a sensitive estuary from long-term impact.
Client: Coal-fired Electrical Generating Station, Millsboro, DE
Integral staff were retained to manage and implement remedial activities associated with a 500,000 gallon subsurface diesel fuel (LNAPL) spill at an operating electrical generating facility. The fuel spill adversely impacted on-site soil and groundwater and the sediments of an adjacent navigable marine estuary.
Within five months of spill discovery, our team had the first phases of a recovery system installed and operating. The main components of the strategy were four large-diameter groundwater pumping wells, high-volume LNAPL recovery skimming pumps and a central control center. The use of variable frequency drive groundwater pumps allowed for precise and consistent water table control in the tidally-influenced aquifer. Further, custom biocides and anti-fouling agents were used in each recovery well to the great benefit of system operation and up-time.
The ecological sensitivity of the adjacent marine estuary necessitated a supplemental and aggressive remedial approach. Integral staff designed and installed a 54 point dual-phase extraction system along the banks of the estuary. Additional measures along the waterfront included in-situ oxidation treatments, excavation and vegetative restoration.
System-wide LNAPL recovery rates within the first year averaged 18,000 gallons per month. To eliminate off-site disposal, we designed and installed a filtration and conditioning system to provide for the on-site reuse of recovered LNAPL.
Integral staff provided operations and maintenance for all systems. Over the 14-year operational time span, the combined remediation systems averaged 95% up-time. Total LNAPL recovery is estimated to be 380,000 gallons.
In 2015, with the added support of our generated fate and transport model, remedial and regulatory objectives were met and all systems were removed.