Remediation of Coal Tar in a Manufactured Gas Plant (MGP) Gasholder: North Adams, Massachusetts
Contract Type and Project Goals: Guaranteed performance contract to achieve a permanent
solution in accordance with the Massachusetts Contingency Plan (MCP), by eliminating Dense Non-Aqueaous Phase Liquid (DNAPL) within the holder and reducing concentrations of Volatile Organic Compounds (VOCs), Semi-Volatile Organic Compounds (SVOCs) and Total Petroleum Hydrocarbons (TPH) below MCP Upper Concentration Limits (UCLs) so that residual risk is minimized.
Contaminants of Concern (COCs) were as follows: Coal tar containing concentrations as high as benzo(a)pyrene [B(a)P] 650 mg/kg; naphthalene 14,000 mg/kg; benzene 6,200 mg/kg; and TPH 230,000 mg/kg.
Soil Characteristics: Mixture of sand, gravel, cobbles, bricks, concrete fragments, ash, and clincker.
Groundwater: Perched water table was encountered within the gasholder at 5.5 ft (1.7 m) below ground surface (bgs). The regional groundwater table is beneath the holder.
TerraTherm mobilized to the site in November 2003, with site construction beginning the same month. Dewatering/tar recovery began in February 2004. Full power heating began in July 2004 and was completed in March 2005, with demobilization completed June 2005.