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MARYLAND SAND, GRAVEL & STONE SITE
Clean Sites Environmental Services, Inc.
This U.S. Environmental Protection Agency Region 3 National Priorities List site is a Potentially Responsible Party-led site, under the overall management of Clean Sites Environmental Services, Inc. (Clean Sites). EA is assisting the Potentially Responsible Party group and Clean Sites with execution of the Record of Decision requirements. Major contaminants of concern with this site, a former sand and gravel quarry, include volatile organic compounds, semivolatile organic compounds, chlorinated solvents, and 1,4-dioxane. Surface soil and sediment, subsurface soil, and groundwater have been impacted. The Record of Decision-mandated remedies include onsite low-temperature thermal desorption (LTTD) of impacted soils and enhanced bioremediation of groundwater.
EA developed a Remedial Design Work Plan describing pre-design field activities, treatability studies, and remedial design methodologies. As part of Remedial Design Work Plan, EA produced a Field Sampling Plan (Sampling and Analysis Plan and Quality Assurance Project Plan), treatability study plans, and Health and Safety Plan. EA performed pre-design field activities conducted to further delineate the extent of impacts to site soil and groundwater. Field activities included collection of:
- Approximately 1,000 soil samples
- 15 soil vapor samples
- Fugitive volatile organic compound emissions study
- Installation of 8 new monitoring wells
- Installation of 200 direct-push soil borings for soil characterization and chemical analysis
- Identification of non-aqueous phase liquid, slug testing of shallow groundwater
- Monitoring of a local stream to assess the impact of treated discharge sourced from an existing onsite groundwater treatment plant.
Several field activities were performed in Level B personal protective equipment. EA also performed perimeter volatile organic compound air monitoring conducted during pre-design field activities to monitor air conditions and work stoppage triggers for protection of workers and adjacent residents. A fugitive volatile organic compound emissions study was conducted to estimate conditions during open excavation and to calibrate an air model for permit requirements related to full-scale soil excavation for LTTD treatment. As part of pre-design field activities, EA assessed viability of groundwater enhanced bioremediation in laboratory microcosm studies. Soil microcosms were conducted to evaluate biostimulation and sequential bioaugmentation (trichloroethane and trichloroethene/tetrachloroethylene degraders) for accelerating groundwater cleanup. EA designed and oversaw the laboratory LTTD treatability study, which included laboratory treatment of impacted soil and product for optimization of projected operating parameters and costing of LTTD treatment. Reports for the pre-design field activities and treatability studies were prepared as appendixes to the preliminary (30 percent) design. EA supported Clean Sites during negotiations, meetings, and correspondences with federal and state regulators. Report documents were reviewed by over 10 assigned reviewers; all documents submitted to date have been approved.
Subsequent to the pre-design field activities, EA prepared the remedial design, which included bid-ready plans and specifications for implementing site dewatering and LTTD by a remediation contractor. EA is performing remedial construction oversight during the remedial action.