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MEMORANDUM <br /> CAUFORNIA REGIONAL WATER QUALMY CONTROL BOARD 9CENTRAL VALLEY REGION ` <br /> 3"3 RovWr Road,lune A MOW: (916)W-56W <br /> onmertto.Caorr3ls X5827-308 Cauv : 8� Oo <br /> M <br /> To: Regional Board FM Gordon Lee Boggs <br /> Underground Tank Underground Tank <br /> Program Managers Program Manager <br /> WE; 8 January 1996 310"WRE. /J . <br /> SUBJEC=: UNDERGROUND TANK"NO FURTHER ACTION" EQUIREMENTS IN <br /> THE CENTRAL VALLEY REGION <br /> Central Valley Board staff have reviewed the 8 December memo from Walt Pewtr <br /> j Executive Director of the State Board which references the Lawrence Uvermore National <br /> Laboratory Report and provides guidance for closing"low risk soil only cases"and saes <br /> with"low rLsk"ground water. Although the definition of"low risk ground water"is <br /> subject to debate,we agree that with proper site characterization,any site can be <br /> considered for closure with no further action requited if impacts to ground water and <br /> beneficial uses are insigni€icant. Indeed,Region 5 has always used this procedure to <br /> 1 close cases. We believe it Is also consistent with the federal EPA Office of Sohd Waste <br /> jand Emergency Response Directive No.9510.17 for use of the Risk Based Cleanup Action <br /> (RSCA)process for underground tanks. <br /> We believe it is Important to understand that the sites used to develop the <br /> recommendations in the Lawrence Livermore report were single source,rtort. <br /> commingled,plumes in alluvial soils Therefore,the report's conclusions n_nd <br /> f recammendations do not apply to co-mingled plumes or sites in fractured rock or <br /> cobble/sand areas. State Board and Lawrence Livermore staff have repeatedly stated <br /> this qualification in training sessions and at the S81764 committee meetings. The <br /> distinction between alluvial soils and fractured rock or cobble and sand lithology was <br /> omitted frau:the LLNL Report <br /> 1� . <br /> On a statewide bans,closure8 by Region 5 and local agency staffs account for 399' of the <br /> Regional Board and 171/16 of LTA total closures,respectively. In our experience,almost all <br /> sites are Closed with some petroleum hydrocarbons left in soil and/or ground water. <br /> This procedure is consistent entitle,and predates,the guidance provided by the State <br /> Board. Region 5 has 4,150 open cases and over 900 sites that have not been Investigated <br /> (i.e.no site characterization).When characterized,some will likely have ground water <br /> problems. <br /> 1 <br />