For years, the Oakland, Calif., location had multiple industrial uses and was the former location of a major production facility for Fleishmann's Yeast, the leading consumer brand of yeast in the United States. But when the company closed the plant in 2002, the 27-acre site sat idle until a leading Fortune 200 homebuilder, with operations in more than 50 markets and over half of all U.S. states, acquired the land with the intention of redeveloping it for residential use.
The firm proposed an "infill" development, an increasingly popular approach where builders seek out previously developed industrial and commercial "brownfield" properties for residential redevelopment in cooperation with local agencies, which in turn contributes to the enhancement of the environment. The builder has planned to construct 366 single-family homes and attached townhomes on the site in a development to be called "Arcadia Park." But before construction could begin, several environmental issues stemming from historical industrial operations and infrastructure had to be addressed.
The 19-acre land parcel to be developed includes a former shipping container refurbishment facility, a recycling facility, a dairy processing facility, and a truck fuel terminal, in addition to the 8-acre site of the former yeast plant. The various sites once contained several underground storage tanks (USTs), used to store fuel oil and other petroleum distillates.
The tanks had long since been removed, and subsequent environmental sampling resulted in closure of the USTs in 1999. But the Fortune 200 builder, with a strong focus on employing environmentally friendly building practices, conducted additional sampling to ensure the property would qualify for residential use status from local and state regulatory agencies. Using an approach advocated by the California Environmental Protection Agency, the site was assessed to determine whether any chemicals detected in soil, groundwater and soil vapor were present in concentrations of potential concern.
The results of the sampling revealed elevated levels of lead and hydrocarbon contamination, resulting from leaking USTs and the refurbishment of the containers' lead paint, which had leached into the soil when the shipping containers were sandblasted during their refurbishment process.
To ensure the site could obtain a clean bill of health, the builder turned to a prominent consulting firm to develop and carry out an extensive remedial action plan for the site. MARCOR Remediation Inc., one the nation's leading environmental remediation contracting companies, executed the consultant's remedial action plan. The builder had contracted with MARCOR for two other infill remediation projects in the past in the Oakland and Emeryville, Calif., areas.
"MARCOR has extensive experience with the cleanup of contaminated soil and water resulting from inadvertent releases of USTs, such as had occurred on this infill site," said Blaine Frost, MARCOR regional manager. "Having worked with this builder in the past, we know how focused they are on environmental protection. And we were completely confident that we could remediate the problems that had been detected, and ready the property for residential use."
The remedial plan, which addressed four specific areas of the site, was the main focus of the overall site cleanup. MARCOR was contracted to excavate on-site soil containing chemicals of concern (COCs) that exceeded the established residential cleanup criteria within the four specific site areas. The largest, primary remediation area called for the excavation of the lead-affected soils through an area spanning approximately 6 acres. Followon excavation areas of 10 feet by 10 feet square and 30 feet by 30 feet square throughout the 6-acre excavation area were completed to obtain the required regulatory cleanup goal.
The environmental project is being carried out in two phases. Phase I covers the 19-acre site used for shipping containers and other industrial processes. Phase II covers the cleanup of the 8-acre former yeast plant site. Beginning in July 2006, MARCOR technicians started excavation activities. In the first area, where elevated lead and TPH concentrations had been detected, workers removed the top 1.5 feet of soil across the entire area, excavating to as much as 2 feet below grade surface (bgs) in five sections and to 3 feet bgs in two sections. Approximately 14,500 cubic yards of soil were removed in total.
In the second area, workers faced several soil, soil vapor and groundwater issues. First, petroleum hydrocarbon- and PAH-affected soil in the vicinity of the former USTs needed to be excavated. In addition, metals-affected soil in one location and pesticide-affected soil in another section were removed to 2 feet bgs and 3 feet bgs, respectively. To mitigate elevated VOC concentrations in soil vapor near the site of the former USTs, MARCOR technicians also removed TPH-contaminated groundwater from the excavation site, dewatering throughout the removal process to reduce the mass of petroleum present and prevent migration.
In both the third and fourth areas, concentrations of TPHd and TPHmo in the soil exceeded screening criteria in some sections, with some elevated cobalt concentrations also appearing in the third area. Soil in both areas was excavated to a depth of 2 feet bgs in some areas and as much as 3 feet bgs in others.
As the excavation limits were reached in each area, confirmation samples were collected from the sidewalls and bottom of the excavation. While the overall program strategy was to continue excavation if COC concentrations still exceeded the screening criteria, the samples showed the excavated soil met the required standards. Excavated soils were stockpiled for off-site disposal, while native soils were not excavated.
Meanwhile, any excavated soil that required disposal as hazardous waste was classified accordingly and transported to an approved hazardous waste treatment facility. All excavated areas exceeding a depth of 5 feet bgs were then backfilled with imported fill material.
The entire remediation process, which will take several months to complete, is scheduled to be completed by the end of 2006. It has been conducted in accordance with HAZWOPER standards (CCR Title 8, Section 5192), using a site-specific health and safety plan developed by MARCOR Remediation.
With the results achieved from the remediation, the Fortune 200 builder is confident that a "No Further Action" letter will be issued from the California Regional Water Quality Control Board, San Francisco Bay Region (Water Board), indicating the site's suitability for unrestricted use. Construction on Arcadia Park is scheduled to begin in first quarter 2007. n
MARCOR is headquartered in Hunt Valley, Md., with 16 offices nationwide. The company was founded in 1988 as an asbestos abatement contractor.