Design and Implementation of a Subslab Depressurization System (SSDS) in San Diego, CA

Background of the Subslab Depressurization System (SSDS)

65,000 square feet of Subslab Depressurization System (SSDS) in a concrete tilt up building
Historical use: manufacturing filter membranes
Chemicals of Concern (COC’s): TCE and chloroform
TRG worked coordinated its Subslab Depressurization System work with two Fortune 500 consulting firms who did not have SSDS construction capabilities.

Prior to SSDS construction, Due to the manufacturing operation that was in the building, several trenches and swales needed to be filled in.
Due to borings from previous environmental investigations, hundreds of “holes” from 1” to 18” in diameter needed to be plugged
The slab was severely impacted with cracks, holes and trenches.
The slab was sealed which ultimately significantly increased the effectiveness of the SSDS

Subslab Depressurization System extraction points were installed along interior walls and roof support beams to minimize impact on future building uses
SSDS Extraction points were connected to collection pipes hung from the roof beams and trusses
SSDS extraction blower and carbon filters were installed outside of the building to keep floor space open and available
11 SSDS performance observation ports were installed in the floor of the building with flush mounted stainless steel covers

The California Department of Toxic Substances Control (DTSC) accepted the SSDS design and construction
Subslab Depressurization System start-up parameters exceeded design specifications.
More than sufficient vacuum influence was observed at all 11 observation points
Current owner has requested we reevaluate the SSDS to accommodate tenants request to remove/relocate some extraction pits to accommodate a clean room operation
Current owner has entered into a contract with TRG to perform routine minimal maintenance and sampling of the Subslab Depressurization System