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-eg% Californialtegional Water Quality Cor_ A Board io
<br /> Central Valley Region
<br /> Karl E. Longley,ScD,P.E.,Chair
<br /> Linda S.Adams Sacramento Main Office Arnold
<br /> Secretary,for Schwarzenegger
<br /> 11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114
<br /> Environmental Governor
<br /> Protection Phone(916)464-3291 •PAX(916)464-4645 ; /�
<br /> httpJAv),N-wwaterboards.ca.gov/centralvalley (/� lI�'//
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<br /> September 2007 ENVIROVtIrl..
<br /> 25 Se007
<br /> p PERwIIT/�ERVIvrj� CT y
<br /> Ms. Nancy Bishop S
<br /> Western Farm Service
<br /> P.O. Box 6969
<br /> Moraga, CA 94570-6969
<br /> PILOT STUDY WORK PLAN, DRAFT MONITORING AND REPORTIIvv PROGRAM,
<br /> WESTERN FARM SERVICE, VERNALIS, 35100 SOUTH HIGHWAY 33, SAN JOAQUIN
<br /> COUNTY
<br /> Site investigations conducted at the Western Farm Service facility in Vernalis have identified
<br /> two source areas of contaminants in groundwater: chlorinated volatile organic compounds,
<br /> such as 1,2-dichloropropane (1,2-DCP), 1,2,3-trichloropropane (1,2,3-TCP), and diuron, as
<br /> well as nitrate and ammonium in the northwestern corner of the property; and nitrate and
<br /> ammonium near the northeastern portion of the property. The groundwater flow direction is
<br /> northeasterly and the terminus of the diffiuse plume of 1,2-DCP and ammonium is off-site.
<br /> Western Farm Service (WFS) reports on the distribution of pollutants, the status of a
<br /> remediation pilot study, and proposes a modification of the pilot study in the following
<br /> documents, which were prepared by its consultant, GeoSyntec Consultants, Inc.:
<br /> • 1 November 2006 Results of 2006 Semi-Annual (August) Groundwater Monitoring, 2006
<br /> Annual Report, and Remediation Pilot Study Monitoring
<br /> • 20 April 2007 Pilot Study Assessment Report, Vernalis
<br /> • 20 August 2007 Work Plan for Modifying Existing In-Situ Pilot Test, Western Farm Service,
<br /> Vernalis
<br /> In 2002, WFS implemented a pilot study injecting Hydrogen Releasing Compound° (HRC) into
<br /> a 600 square-foot area in the northwest corner of the site. HRC slowly releases lactate
<br /> molecules that stimulate indigenous micro-organisms. These microbes anaerobically degrade
<br /> nitrate, ammonium, and chlorinated constituents. As documented in the Pilot Study
<br /> Assessment Report, a monitoring well (MW-2) located about eight feet downgradient of the
<br /> injection area showed evidence of reducing conditions developing about 18 months after
<br /> injection. After four years, this well showed a decline of 1,2-DCP from a high of 37 ug/I to
<br /> 5 ug/I, a decline of 1,2,3-TCP from 9 ug/I to less than 1 ug/l, and a decline of ammonium from
<br /> 400 mg/I to 60 mg/l. However, the monitoring well that was positioned within the injection
<br /> area, MW-6, did not show similar declines, even though indicators of biological activity were
<br /> present, such as increases in alkalinity and in methane.
<br /> California Environmental Protection Agency
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