McAlister GeoScience, Inc.

Scope Of Work

Background

As a result of a Phase II Environmental Site Assessment conducted in August 2016, McAlister GeoScience recommended Sub-slab depressurization in areas of shallow soil vapor impacts within the existing dry cleaning unit and in the area immediately outside the rear entry to the lease unit.  In October 2016, McAlister GeoScience performed pre-field preparation, coordinated construction and installation of the system, and performed system startup tasks.

Results

The system was operated for a period of one year.  At that time, vapor samples were collected for laboratory analysis.  Concentrations of Tetrachloroethylene (PCE) in vapor showed a steady reduction in the surrounding soil by the system.

Analytical results for the sub-slab depressurization and soil-vapor extraction system indicated that the system was successful in decreasing the concentration of PCE in soil vapor from beneath the Subject Property.  The results of the two indoor air surveys demonstrate that concentration of PCE in ambient air decreased in adjacent lease units as a result of the sub-slab depressurization and soil-vapor extraction system operation.

Agency Interaction

The work was reviewed and a final soil vapor  and indoor air assessment performed under the supervision of the Riverside County Department of Environmental Health.  The County representatives determined McAlister GeoScience had indeed performed sufficient remediation and granted a No Further Action (NFA) letter for the site.