Former UST Site 2
Location
Santa Cruz, CA
Project Cost
$50,000
Services Provided
- Permitting
- UST Fund reimbursement
- Remedial design and work plan
- In-situ soil profiling
- Shoring design and placement
- Soil over-excavation
- Resurfacing
- Post-remedial monitoring
- Reporting
Project Background
RRM was hired to design and implement a soil over-excavation and Oxygen Releasing Compound® (ORC®) interim remedial program at a commercial property where a leaking gasoline underground storage tank (UST) had been located. The UST had been situated immediately adjacent to a building, at the end of a narrow alleyway that led to a parking area. The parking area is small and almost entirely enclosed by buildings. The UST was removed by another contractor in 1989. At that time, some soil excavation was performed and a soil vapor extraction system (SVE) was installed and operated for several years.
When RRM took over the project, we reviewed historical soil and quarterly groundwater monitoring analytical data, concluding that: one, a significant source of petroleum hydrocarbon-effected soil and groundwater remained around the former UST location; two, past remedial efforts had not effectively cleaned up the site; and three, timely site closure would only be realized if an aggressive remedial program was implemented.
Solutions Provided
RRM developed an active interim remediation program with three main components:
- Remove residual petroleum hydrocarbons trapped in soil below the groundwater table.
- Remove free product or heavily impacted groundwater via vacuum extraction.
- Promote the proliferation of aerobic organisms to degrade any post-remediation petroleum hydro-carbons remaining in the saturated zone by applying ORC® (magnesium peroxide) to the excavation before backfilling.
RRM worked with the client to obtain UST Fund pre-approval of all remediation costs before initiating work, obtained regulatory approvals at the local and state level, and worked closely and smoothly with multiple on-site tenants and off-site property owners. Several of the major work elements completed by RRM on this project are:
- Placement of 100 feet of shoring.
- Excavation of 500 cubic yards of soil in a confined work area.
- Dewatering of the excavation via vacuum extraction.
- Placement of 100 pounds of ORC® to promote aerobic degradation of any remaining petroleum hydrocarbons.
- Backfill, compaction and testing, and site restoration.
- Post-remediation well installation, replacement and monitoring.
Benefits to Client
- 100% reimbursement of interim remedial cleanup costs from the UST Cleanup Fund.
- Complete tenant and neighboring property owner satisfaction with RRM's work and professionalism.
- Successful implementation of the remediation program.
- Complete satisfaction with resurfaced asphalt and concrete surfaces, and reconstructed fences.
- Future site closure within a reasonable timeframe, based on the promising, order-of-magnitude decreases observed in quarterly monitoring of wells.