REMEDIATION SERVICES - Manufactured Gas Plant

Location: Midcoast Maine

Historical/Current Use: Former manufactured gas plant

Contaminants of Concern: Coal tar

Summary of Impact/Sensitive Receptors: Coal tar impact to beach sediments, groundwater and subsurface soils.

Phase II Subsurface Investigation Using a Geoprobe in a Tidal Area

Campbell Environmental Group was contracted to investigate and remove coal tar-impacted material from a former manufactured gas plant  site located in Maine's midcoast region.  The gas plant was in operation from approximately 1850 to 1950.  The site currently serves as a parking lot for trucks and other vehicles and is located adjacent to a beach and an inter tidal zone.  CEG has performed several environmental investigations that have been conducted under the Maine DEP's Voluntary Response Action Program.  During the investigations, a tar-like material was identified on the beach, adjacent to the site, and was also discovered leaching from an embankment that borders the site. The presence of this material has resulted in the completion of a remedial feasibility study and the design of a remedial system by CEG.

Cross section of the beach area at a former manufactured gas plant

The purpose of the investigations were to evaluate the potential sources and extent of coal tar observed on the beach, characterize the soil, and document groundwater quality and flow.  Field investigation techniques included the installation of monitoring wells across the site and the beach, excavation of several test pits on the Beach and the collection groundwater, soil, pore water, and sediment samples.  Select samples were analyzed for priority pollutant metals, cyanide speciation, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), using total compound analysis methods and toxicity characteristic leaching procedure (TCLP).  TCLP analysis was performed to determine the leaching potential of the metals, VOCs, and SVOCs from the soil. 

Low metals, VOCs, and SVOCs concentrations were detected in the soil and groundwater.  The constituents detected were considered to be at concentrations that would not adversely impact human health or the environment.  Coal tar was also observed in select borings. 

The coal tar impacted material exposed on the beach and the embankment was manually recovered and excavated.  The recovered material was transported offsite to a licensed disposal facility.  Coal tar, however continued to migrate onto the beach and through the embankment. 

Based on the results of the subsurface investigation, CEG performed a limited feasibility study. Several alternatives were considered to minimize the migration of tar-like material to the beach.  The alternatives ranged from no further action to soil excavation.  The selected method of installing a barrier wall and erosion control system was determined to be the most effective approach.  The purpose of this system is to minimize the potential for direct human contact to tar-like substances and abate the flow of the material to the beach and inter-tidal sediments.

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Campbell Environmental Group

173 Gray Road

Falmouth, ME 04105

(207) 253-1990 f(207) 253-1988