Supplemental Interim Measures Work Plan
E Sciences was selected to design and implement a Supplemental Interim Measures Work Plan for a documented chlorinated solvent contaminated site in Orlando, Florida. The request for proposals described the “ultimate objective of the remedial measures was to remediate the chlorinated solvent groundwater contaminant concentrations in the upper surficial and a small portion of the intermediate surficial aquifers to Natural Attenuation Default Concentrations”. A secondary objective was to meet groundwater clean-up target levels or alternative clean-up target levels.
The remedial strategy consisted of excavation of source area material followed by groundwater polishing using ISCO. Assessments were conducted utilizing direct push technology in order to further define the extent of the impacts and to evaluate the lithology of the area to assist with remedial option selection. The presence of significant volumes of clay within portions the solvent impacted area validated our excavation strategy, as this clay was likely to severely impede the effectiveness of treatment options based on injecting products into the aquifer. Following assessment activities, a treatability study was conducted to evaluate the effectiveness of the selected oxidation agents. A Work Plan documenting the findings of our assessment, and our proposed remedial activities was prepared and submitted to the FDEP for approval.
Remedial implementation activities completed included the following:
- Dewatering of the surficial aquifer to 30 feet bls. Excavation and off-site disposal of low permeability clay rich soils to a depth of 20 to 25 feet bls.
- Disposal of 11,000 tons of solvent contaminated soils
- Application of approximately 12,000 gallons of Sodium Permanganate solution, to the backfill material to reduce surficial aquifer contaminant concentrations
- Injection of sodium persulfate for ISCO in the surficial and upper intermediate aquifers
- Installation of six wells for groundwater monitoring.
Groundwater monitoring subsequent to the source removal and injection activities has indicated that groundwater samples collected from all wells are within NAM guidelines, thus meeting the project objectives.