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Mr. Robert Jackson -2- 1 February 2012
<br /> To restore beneficial uses of the groundwater, the water quality objectives that must be
<br /> achieved for these compounds is shown in Table 1.
<br /> Table 1. Water Quality Objectives and their basis for pollutants in groundwater.
<br /> Ammonium Nitrate 1,2,3-Trichloropropane 1,2-Dichloropropane Diuron
<br /> (as nitrogen)
<br /> Maximum US EPA Health
<br /> Taste and Odor Public Health Goal Public Health Goal
<br /> Contaminant Level Advisory
<br /> 1.5 mg/L 10 mg/L 0.0007' ug/L 0.5 ug/L 2 ug/L
<br /> ' A low-level detection limit of 0.005 may be used.
<br /> Groundwater beneath the tank farm (MW-3) contains the highest ammonium and nitrate
<br /> concentrations when groundwater surface elevations are seasonally high (170 mg/L), whereas
<br /> MW-2 contains the highest ammonium concentration when groundwater surface elevation is
<br /> seasonally low.
<br /> Conclusion
<br /> The data show that the HRC injections resulted in reductions in concentrations of ammonium,
<br /> nitrate, 1,2-DCP and 1,2,3-TCP. The HRC-X is depleted, biological activity is minimal, and
<br /> ATC Associates proposes that bioremediation monitoring of the pilot study be discontinued.
<br /> The bioremediation monitoring, however, is incorporated into Monitoring and Reporting
<br /> Program Order No. R5-2007-0825, which must be revised to remove the bioremediation
<br /> monitoring component. Central Valley Water Board staff will prepare a draft revised Monitoring
<br /> and Reporting Program and transmit it to CPS under separate cover.
<br /> Crop Production Services has made progress in reducing ammonium, 1,2,3-TCP and 1,2-DCP
<br /> from the pre-2002 concentrations of 300 rl 12 ug/L, and 50 ug/L, respectively. CPS needs
<br /> to continue to remove ammonium, 1,2,3-trichloropropane, 1 ,2-dichloropropane and diuron from
<br /> groundwater to restore beneficial uses. If CPS intends to continue with in-situ bioremediation,
<br /> it should evaluate if macro-nutrients are limiting biological degradation, submit an Interim
<br /> Remedial Action Plan, and apply for coverage under the General Orderfor InSitu Groundwater
<br /> Remediation at Sites with Volatile Organic Compounds, Nitrogen Compounds, Perchlorate,
<br /> Pesticides, Semi-Volatile Compounds, Hexavalent Chromium and/or Petroleum Hydrocarbons
<br /> (Order No. R5-2008-0149).
<br /> By 15 January 2012, please provide a work plan to remediate ammonium, nitrate, 1 ,2,3-TCP,
<br /> 1 ,2-DCP and diuron in shallow groundwater. If you have any questions, or wish further
<br /> information on the General Order for InSitu Groundwater Remediation, you may contact me by
<br /> tele one at 916) 46,4-4680 or by email at aterrell@waterboards.ca.gov.
<br /> l
<br /> A Y T rR L L
<br /> Private Sites Cleanup Unit
<br /> cc: Mr. Harlin Knoll, San Joaquin County Environmental Health Department, Stockton
<br /> Mr. Brian Duggan, Crop Production Services, Loveland, CO
<br /> Ms. Barbara Rowling, ATC Associates, Austin, TX
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