Industrial Complex | Litigation Support, Site Assessment, Complex Remediation and Chemical Oxidation of DNAPL
GeoInsight completed a source area evaluation and Remedial Action Plan (RAP) in a multi-party litigation case involving a former mill building in Manchester, New Hampshire. Through our initial assessments, we determined that a tetrachloroethylene (PCE) release originated from aboveground storage tanks impacting unsaturated and saturated overburden and bedrock. We were then retained to evaluate and remediate the source and extent of dissolved and dense non‑aqueous phase liquid (DNAPL) and to provide expert testimony and litigation support.
REMOVAL AND TREATMENT/DISPOSAL OF APPROXIMATELY 2,000 TONS OF PCE- AND FUEL OIL-IMPACTED SOIL – Through implementation of a
multi-phase treatment plan, we were able to provide considerable cost savings to our client by treating impacted soil and groundwater at various stages with different methods, including soil excavation and chemical oxidation using powdered potassium permanganate.
SOIL CHARACTERIZATION SAVES MONEY ON DISPOSAL – Careful characterization of the PCE-impacted soil allowed the use of soil disposal options that did not require hazardous was landfilling, incineration, or other disposal options typically required for chlorinated volatile organic
EXPERT TESTIMONY – Our expert testimony involved time lapse animation presentations and resulted in a favorable settlement for our client.
SALE OF PROPERTY – Successful remediation allowed the sale and redevelopment of the property.
LITIGATION SUPPORT – Our staff provided expert testimony and litigation support that resulted in favorable mediation opinion and award. We prepared technical arguments, coordinated with other experts, and developed/used animated presentations during mediation proceedings.
Scope of Services
- Site Assessment and Remedial Action Planning
- Management of ±2,000 Tons of PCE- and Fuel Oil-Impacted Soil
- In-Situ Chemical Oxidation (ISCO)
- Remediated DNAPL
- Evaluated Indoor Air Impacts
- Reporting and Ongoing Monitoring Activities
- Litigation Support
- Site Redevelopment Support
SITE ASSESSMENT AND REMEDIAL ACTION PLANNING – Through source area evaluation, it was determined that a PCE release resulted from aboveground storage tank releases, comingled with #6 fuel oil, and impacted unsaturated and saturated overburden and bedrock. An evaluation of potential preferential migration pathways was completed using passive and active soil gas surveys, overburden monitoring wells (some installed in active utility corridors), and multi-level bedrock wells. Following the evaluation of multiple remedial technologies (including multiphase extraction and air sparging), a Remedial Action Plan (RAP) was prepared that focused on source area removal and treatment with potassium permanganate with natural attenuation of the downgradient
REMOVAL AND TREATMENT PCE- AND FUEL OIL-IMPACTED SOIL – GeoInsight coordinated and implemented the removal and treatment/disposal of approximately 2,000 tons of PCE- and fuel oil-impacted soil and in situ chemical oxidation of residual PCE using potassium permanganate. After excavating source strength soils to the bedrock surface, solid form potassium permanganate and a mixture of silica sand was added to the excavation for release over time into groundwater. Three-fold reductions in PCE concentrations were observed.
INDOOR AIR IMPACTS EVALUATION AND INVESTIGATION – Indoor air impacts were evaluated using sub-slab soil gas and indoor air sampling with eight-hour time weighted samples. Using the results from this sampling, a soil vapor extraction/sub-slab depressurization system was designed and implemented to abate residual PCE vapors in indoor air.
GeoInsight designed and implemented investigation and remedial strategies that included the following activities:
- Vertical soil profiling using direct-push technology to rapidly assess the extent of impacts;
- Passive and active soil gas surveys;
- Telescope drilling in DNAPL source area;
- Overburden and bedrock well couplets and rock coring;
- Fracture lineament analysis;
- Indoor air quality evaluation and risk assessment;
- Hand-cored riverbank wells;
- Large diameter caissons next to mill building; and
- “Contained-out” determinations for PCE soil and water.
REPORTING AND ONGOING MONITORING ACTIVITIES – This information was described in three separate investigation reports: a RAP report, a RAP Addendum report, and a Design report, all submitted to the NHDES.
In addition, a Groundwater Management Permit (GMP) Application was applied for and a GMP was issued, under which monitoring activities continue to occur.