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-WASTE DISCHARGE REQUIREME RIDER NO R5-2012-0106 • 5
<br /> GLENN SPRINGS HOLDING COMPANY,
<br /> FORMER OCCIDENTAL CHEMICAL COMPANY, GROUNDWATER REMEDIATION PROJECT,LATHROP FACILITY
<br /> SAN JOAQUIN COUNTY
<br /> 23. Under MRP Order No. R5-2004-0800, the Site's groundwater is monitored for sulfoiane,
<br /> DBCP, EDB, BHC isomers, nitrate, chloride and sulfate. Subsets of monitoring wells
<br /> are sampled quarterly, semi-annually, and annually; groundwater elevations are
<br /> measured on a quarterly basis.
<br /> 24. MRP No. R5-2012-0105, a- part of this Order, also requires monitoring the injection
<br /> zones above and below the Corcoran Clay. Data collected for Order No.R5-20D6-0800
<br /> can also be used to determine compliance with Order No. R5-2012-0106.
<br /> GROUNDWATER DEGRADATION
<br /> 25. In 2012, the maximum concentrations of sulfolane, DBCP, and EDB in groundwater
<br /> were 180,000 pg/L, 2,400 pg/L and 10 pg/L, respectively. Maximum concentrations of
<br /> sulfate, nitrate and chloride in groundwater were 9,050 mg/L, 320 mg/L, and 2,210
<br /> mg/L, respectively. Concentrations of gamma-BHC, alpha-BHC, beta-BHC, and delta-
<br /> BHC were 0.34 pg/L, 2.2 pg/L, 1.8 pg/L, and 2.9 tag/L, respectively.
<br /> BASIN PLAN, BENEFICIAL USES, AND REGULATORY CONSIDERATIONS
<br /> 26. The Water Quality Control Plan, Fourth Edition, for the Sacramento and San Joaquin
<br /> River Basins, Fourth Edition, (hereafter Basin Plan) designates beneficial uses,
<br /> establishes water quality objectives (WQOs), contains implementation plans and
<br /> policies for protecting water's of the basin, and incorporates by reference plans and
<br /> policies adopted by the State Water Resources Control Board (State Board). Pursuant
<br /> to Section 13263(a) of the California Water Code (CWC), waste discharge requirements
<br /> must implement the Basin Plan.
<br /> 27. The designated beneficial uses of underlying groundwater include,-
<br /> a.
<br /> nclude:a. Municipal and domestic water supply (MUN);
<br /> b. Agricultural water supply (AGR);
<br /> c. Industrial service supply (IND); and
<br /> d. Industrial process supply (PRO).
<br /> 28. The Basin Plan establishes numerical and narrative WQOs for surface and groundwater
<br /> within the basin, and recognizes that WQOs are achieved primarily through the Central
<br /> Valley Water Board's adoption of waste discharge requirements and enforcement
<br /> orders. Where numerical WQOs are listed, these are limits necessary for the
<br /> reasonable protection of beneficial uses of the water. Where compliance with narrative
<br /> WQOs is required, the Central Valley Water Board will, on a case-by-case basis, adopt
<br /> numerical limitations in orders, which will implement the narrative objectives to protect
<br /> beneficial uses of the waters of the state.
<br /> 29. The Basin Plan identifies numerical WQOs for waters designated as municipal supply.
<br /> These are the maximum contaminant levels (MCLs) specified in the following provisions
<br />
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