Until 1952, the land in Union City, CA, was used for agriculture. Then Pacific Gas & Electric (PG&E) used the Decoto Pipeyard for blasting, wrapping, and welding metal pipe. In the early 1980s, the company refurbished oil-filled electrical equipment there. Finally, it became a storage area for PG&E’s natural gas pipe and telecommunications equipment. Today, the utility company is negotiating to sell the land to Union City, whose officials have included the land in a planned regional transit center. The dramatic shift in usage for this industrial site has been made possible by a major soil remediation and reclamation project funded by PG&E and carried out by MARCOR Remediation Inc.

Creating a Crossroads
Situated about 30 miles southeast of San Francisco, Union City is perfectly suited to offer an alternative to living in some of the more congested and expensive suburbs of San Francisco. Because it boasts its own Bay Area Rapid Transit (BART) stop, Union City is also an easy commute to San Francisco. In fact, the existing BART station is one of the major reasons the city is considering developing the former pipeyard. The 30-acre PG&E site is adjacent to 20 acres owned by BART. Current plans call for developing a 16-bay bus station for AC Transit at BART and creating a stop for the Capitol Corridor rail line, which runs northeast through Union City from San Jose to Sacramento. These improvements will provide easy access to the approximately 1.12 million square feet of office space, 630 residential units, up to 100,000 square feet of retail, and approximately 2.85 acres of open space that are also planned for the area.

Photos: Marcor Remediation Inc.

For 50 years, Pacific Gas & Electric maintained and stored electrical and natural gas pipe on the Decoto Pipeyard. To reclaim it, the utility contracted with MARCOR Remediation to clean up the site.

In addition, the San Francisco Business Times reported in September 2002 that “the city hopes to create stops for the Altamont Commuter Express or ACE train, which runs from Stockton to San Jose, and the newly planned Dumbarton Commuter Rail line, which will connect Redwood City to Union City. Eventually, [Union City] also hopes to become a stop on California’s high-speed rail line and tie into the hub as well.”

Assessing the Risk
Before beginning the reclamation project, PG&E contracted with SECOR International, an engineering and consulting company, to evaluate soil conditions and develop a work plan. More than 800 soil samples were used to assess the extent of the contamination. The samples indicated that surface and near-surface soil in portions of the site were contaminated with varying levels of metals; polychlorinated byphenals (PCBs); the pesticide dieldrin; and petroleum byproducts, mainly diesel and motor oil. Fortunately, samples indicated that the groundwater in the area had not been affected. Based on these data, PG&E determined that the Decoto Pipeyard could be cleaned up well enough to meet the national EPA standard as safe for long-term residential use.

Remediation of the Decoto Pipeyard in Union City, CA required extensive planning. The major work included the excavation, stockpiling, loading, and landfilling of contaminated soil.

MARCOR Remediation also removed 900 feet of rail spur, which had been treated with crosote, and the soil underneath.

The remedial action work plan developed by SECOR included excavating, stockpiling, loading, and landfilling the contaminated soil. In addition, MARCOR Remediation--one of the nation’s leading environmental contracting companies--was tapped to remove storm drain lines, a rail spur, concrete, and asphalt paving. MARCOR, which is headquartered in Hunt Valley, MD, maintains an office in San Leandro, CA.

Cleanup
The main focus of the remediation effort was a 15-acre area where previous site activities had caused soil contamination. Using large excavators and heavy equipment, MARCOR excavated and stockpiled the contaminated soil into 15-foot-high windrows, some of which were 200 yards long. Samples from the windrows were constantly evaluated to ensure that the soil met the criteria for California non-hazardous, Class 2 waste, which can be used as cover in landfills. Once the level and types of contaminants were verified, the soil was loaded onto trucks and transported to a local landfill.

Safety Precautions
The closest residential area is about 200 feet from the northern edge of PG&E’s site. Elevated BART tracks run along the southern edge. Because some of the contaminants in the soil are suspected carcinogens, MARCOR developed a plan to minimize the amount of airborne particulate matter at the pipeyard and control the amount of dust migrating to the surrounding area. To control the dust, the site was kept wet. Also, the excavated soil was covered while it was stacked in the windrows and during transport.

Based on the specific contaminants, MARCOR developed a real time COPC exposure assessment in accordance with the State of California’s Preliminary Endangerment Assessment Guidance Manual. The assessment established a maximum relationship value for particulate-in-air and contaminant-in-particulate exposure. To reach this goal, the work was conducted under appropriate dust suppression measures. Initially, all the remediation was performed under OSHA Level C PPE, which requires respirators. But direct mini-RAM dust monitor instrumentation and mercury badges worn by workers indicated that the dust level during soil mitigation activity was well below the OSHA-permissible level of 10 milligrams per square meter and the established COPC particulate exposure value. In consultation with PG&E and SECOR, MARCOR downgraded the area to Level D, allowing workers to continue their soil mitigation activities without respirators.

Some areas were excavated up to 10 feet deep. "We just kept digging until the soil samples came back clean," a manager said.

Pollution Control
A drainage canal borders the western edge of the Decoto Pipeyard. To prevent contaminated runoff from draining into the canal, MARCOR personnel established a stormwater pollution prevention plan according to criteria established by the California Water Resources Control Board. Basically, the drainage was controlled through a series of dikes, hay bales, and bags filled with gravel.

MARCOR project manager Scott Williams estimates that in December 2002, 2 to 3 inches of rain fell during a four-day period, during which the pollution prevention system was monitored and maintained continuously.

Part of MARCOR’s project was the full demolition of a 42,000-square-foot warehouse building, building foundation, and other site infrastructure. All concrete and asphaltic concrete rubble was crushed and incorporated into the site as engineered backfill. The company also removed 900 feet of rail spur, which had been treated with creosote, and the soil underneath.

22,000 Yards of Soil
In all, Williams estimates that 22,000 cubic yards of soil were removed from the Decoto Pipeyard. Williams explains, “In this 30-acre site, there were approximately 15 acres that received what we call a ‘shallow scrape.’ We removed the top 1 foot of soil. Then in other areas, called “hot spots,” the depth of the contaminated soil varied. Some of the hot spots were 20 by 20 by 10 feet deep. One was approximately 200 by 100 by 8 feet deep. Then, within those excavations we sometimes dug another 10- by 10- by 10-foot pit. Put simply, we just kept digging until the soil samples came back clean—less than 1 part per million of PCBs.”

In the end, the remediation, which was estimated to cost approximately $956,000, took approximately five months to complete. But when it was finished, PG&E could turn over the land to Union City knowing that it is safe for everyone who uses the planned transit hub.

GEC - January/February 2005