Los Angeles County Department of Public Works:
Los Angeles, CA
Leighton has completed nearly 200 task orders under many multi-year on-call contracts with LADPW for geotechnical and environmental services.
The Leighton Solution.
Leighton was contracted to provide assessment and remedial excavation of impacted soil. The primary concerns at the site were lead-impacted fill soils, burn ash, and polynuclear aromatic hydrocarbon (PAHs) impacted soils that have been a known concern in the fill soils in downtown San Diego. Leighton performed a preliminary assessment of the site that included soil borings and profiling of lead-impacted artificial fill soils that were to be removed prior to site excavation for construction of a subterranean parking structure. Based on the results of the investigation, Leighton prepared a site-specific Property Mitigation Plan (PMP), which was reviewed and approved by the SD-DEH.
Leighton observed the removal of the lead-impacted soil, three abandoned cisterns, and two abandoned wells from the site during the remedial excavation program. Approximately 7,000 cubic yards of impacted soil were removed from the site and transported to approved landfills in California and Arizona. Confirmation samples were collected to confirm the effective removal of impacted soil to a site cleanup level established in the PMP. Groundwater dewatering activities at the site were discharged to the City’s storm drain under a NPDES permit.
Based on the excavation and results of analytical testing, a closure report was issued by Leighton to the SD-DEH requesting that the site was approved for general construction activities. The SD-DEH concurred and recommended monitoring of clean native soils exported during excavation of the parking garage for any potential contamination. Leighton monitored the excavation of clean soils and prepared a final closure report resulting in no further action for the site issued by SD-DEH.