SCH Number 2013102001

Project Info

Title

South San Francisco Downtown Station Area Plan

Description

In preparation for the construction of a multi-family residential project located in the City of South SF, the DTSC approves a Response Plan in order to remove approx. 140 cubic yards fo lead contaminated soil from a proposed at-grade parking lot, and to transport the impacted soil to an approved off-Site landfill facility. In addition, approx. 600 cubic yards of soil with elevated volatile organic compounds (VOCs) in soil gas from the area proposed for six at-grade residential units will be excavated and reused under the area proposed for use as a parking garage. The excavated lead impacted soils will be placed into trucks and hauled to an approved disposal facility. However, excavated soils may be stored in temporary stockpiles on-Site prior to off-Site disposal (in the case of lead impacted soil) or on-Site reuse (in the case of soil containing VOCs in soil gas). Stockpiles will be covered with tarps and all excavation areas will be sprayed with water as necessary to ensure adequate dust suppression during fieldwork. In addition, air quality will be monitored, a storm water management program will be implemented, and a Health and Safety Plan utilized. Following excavation confirmation sampling, the VOC impacted soil will be characterized for reuse and palced under the parking garage. To address potential vapor intrusion, the Response Plan requires soil gas sampling throughout the area where future at-grade residential units will be located. As a contingency measure, if the post-backfill soil gas samples reveal the presence of PCE above residential screening levels in the area proposed for the six at-grade residential units, then a vapor intrusion mitigation system will be installed to control subsurface migration of vapors. The contingent VIMS would be installed between the backfill and the floor slab of the six at-grade residential units The VIMS would be adaptable for active ventilation, if monitoring results warrant such modification. The excavation and off-Site disposal of the lead impacted soil is expected to be completed over approx. one week and result in a total of approx.. 10 truckloads (roughly 140 cubic yards) of contaminated soils for off-Site disposal. The relocation of soil impacted with elevated VOCs in soil gas is expected to be completed in approx. one week and will not result in any off-Site truck trips. If required, installation of the contingent vapor mitigation system is expected to be completed as part of normal construction activities and would not result in additional excavation, off haul, or truck trips.

3 documents in project