Third Party Review: Residential Redevelopment
Former Dry Cleaner
Partners reviewed various environmental documentation associated with redeveloping a former dry-cleaning site to residential development. Dry cleaning operations were conducted from 1970 through the early 1980s using Tetrachloroethene (PCE). The Phase I ESA report indicated the potential for dry cleaning operations to have adversely impacted the site. Phase II activities were subsequently conducted and included the collection and analysis of soil, groundwater and soil vapor samples. Soil and groundwater analytical results indicated chemicals of concern, including PCE, were below the comparison standards. Soil vapor analytical results detected several chlorinated compounds, including PCE above the comparison standard. The environmental consultant opined a Vapor Encroachment Condition (VEC) existed but concluded vapor mitigation measures were not warranted based on subsequent soil vapor testing.
After reviewing the environmental documentation, Partners concluded vapor mitigation measures were necessary to prevent vapor intrusion. Based on our recommendation, the Client required the developer to install a sub-slab depressurization (SSD) system in conjunction with a vapor barrier and to collect post-construction indoor air samples to confirm the effectiveness of the SSD system. Post-construction air indoor results indicated the SSD systems would require conversion to active SSD systems to prevent vapor intrusion. The additional engineering controls will ensure the future residents are not exposed to chlorinated vapors.