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- Department ofToxic Substances Control

Maziar Movassaghi Linda S. Adams Arnold Schwarzenegger Acting Director Secretary for Governor 700 HeinzAvenue Environmental Protection Berkeley, California 94710-2721

May 13, 2010

Michael M. Montgomery Assistant Director; Superfund Division U. S. EPA (SFD-8) 75 Hawthorne Street San Francisco, California 94105

Dear Mr. Montgomery:

This letter is in regard to the GBF Dump Site (Site) in Antioch, California. DTSC requests that the U.S. EPA de-propose the site from the National Priorities List (NPL) and remove itfrom consideration as an NPL site. The site was proposed forthe NPL in 1988 and subsequently de-proposed in 1989after itwas re-scored and the score dropped belowthe scoring threshhold. The US EPA prepared another Hazard Ranking Package and re-proposed the site to the NPL in 1992.

Before the second proposed listing, DTSC sent a letterto EPA requesting thatthe GBF site not be listed on the NPL. EPA's policy atthattime was to list sites regardless of other agency involvementwith the cleanup, so EPA proceeded with the proposed listing. This policy changed soon after and now EPAcan defer listing ifit is being cleaned up under State authority.

DTSC hasworked on the site cleanup for many years with the responsible party, GBF Holdings, LLC. In 1988the California Department of Health Services, a predecessorto DTSC, issued Remedial Action Order No. HSA 87/88-012 to the current and historic site operators, owners, and hazardous waste generators in orderto initiate site characterization and remediation efforts. In 1997, following several years ofsoil, groundwater, and landfill gas investigations, DTSC developed a Remedial Action Plan (RAP) forthe site identifying groundwater pump-and-treat remedy atthe landfill source
area and the plume leading edge. The current owners ofthe site (and the liability), GBF Holdings LLC, entered into a consent order (HSC-CO 01/02-007) with DTSC and have been operating underthis consent orderforthe past nine years. At thattime, DTSC and GBF decided to divide the remedial efforts into two phases: landfill source remediation (Phase I) and down-gradient groundwater plume remediation (Phase II).Michael M. Montgomery May 13, 2010 Page 2

In 2001 and 2002, a landfill cap was installed and the landfill was certified closed bythe Sacramento Regional Water Quality Control Board in 2002. The landfill is maintained and a landfill gas collection and treatment system is currently operating. In 2002 and 2003, the Phase I groundwater extraction and treatment system (GWETS) was installed along the northern boundary ofthe landfill (downgradientedge of landfill). The GWETS consists of30 extraction wells and a treatment system (activated carbon). Treated groundwater is currently discharged, under permit, to the Delta Diablo Sanitation District (DDSD).

DTSC is currently in the process ofpreparing the Five Year Reviewforthe Phase I GWETS andworking with GBF Holdings, LLC to identify measures to increase the efficiency ofthe system. DTSC is also currently in the process ofworking with GBF Holdings, LLC to re-evaluate potential remedial alternatives to address the distal portion ofthe groundwater plume. As part ofthe re-evaluation, DTSC has required soil vapor sampling to be conducted in areas of historic high chlorinated solvent concentrations in groundwater. Semi-annual groundwater monitoring and site inspections are currently ongoing.

DTSC believes that Superfund involvement atthis site is notwarranted, asthe cleanup has progressed successfully and GBF Holdings is working cooperativelywith the State. DTSC requests that EPA de-proposethe GBF Dumpfrom the NPL and allowthe State to continuewith the site cleanup.

Ifyou have any questions, please contact Jonathan Largent of my staffat (510) 540­ 3826 orJLargent@dtsc.ca.gov

. Sincerely,

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Barbara 

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Acting Assistant Deputy Director California Department ofToxic Substances Control