MGP Site Assessment & Remediation

MGP Assessment, Remediation and Reporting Regarding Potential MGP Waste

Weston & Sampson provided site assessment services, remediation cost estimates, and an expert report regarding potential Manufactured Gas Plant (MGP) waste dumped in a residential neighborhood. The suspected source of this waste was a former MGP facility located approximately one mile north of the neighborhood. Weston & Sampson’s geologists and engineers conducted the following tasks as part of the project:

  • Review of environmental assessment data for over 90 individual properties in the neighborhood
  • Development of a conceptual site model and data gap analysis
  • Creation of an Access database to store, query, and evaluate analytical data, physical evidence,
    and site stratigraphy
  • Completion of limited site assessments on 13 neighborhood properties including soil borings, test pits,
    sample collection, field screening, and photo documentation
  • Completion of a limited site assessment of the former MGP
  • Oversight of assessment activities conducted by the town
  • Preparation of an expert report describing our observations and the results of our site assessments in the neighborhood and on the former MGP site
  • Preparation of remedial cost estimates for over 90 properties

As part of the assessment of the neighborhood and former MGP, Weston & Sampson reviewed historical information, including aerials, Sanborn Fire Insurance Maps, USGS topographic maps, and facility drawings to evaluate the location of potential contamination/contaminant sources. Our assessment of the former MGP site was conducted with oversight by five legal firms, an environmental forensic firm, and an analytical laboratory. Weston & Sampson also collected soil samples for environmental forensic analyses to assess if soil from the neighborhood contained a coal tar signature on the lab chromatograms and, if so, was there a link to soil on the former MGP site. The results of these analyses indicated coal tar signatures in the neighborhood and a possible source linkage to the former MGP.

Remediation cost estimates were prepared to excavate and appropriately dispose of the MGP waste and associated impacted soil. These cost estimates also evaluated if additional assessment was required on the property to delineate the nature and extent of MGP waste impacts as well as costs for other property specific features such as:

  • Resident relocation
  • Septic tank protection or removal/replacement
  • Support of excavation
  • Dewatering
  • Site preparation
  • Odor/noise control
  • Soil/waste excavation and off-site disposal
  • Confirmatory sampling
  • Backfill, restoration, and landscaping


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