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/ o i <br /> Mr Chuck Carmel <br /> .Tune 21 L994 <br /> Page <br /> The concentration of TPH-G in well E-12 is the lowest since 1991 The concentration of <br /> benzene in well BHD-1 is the lowest since 1992 The samples from off-site wells PR-1, <br /> PR-2, and BHD-2 did not contam detectable concentrations of hydrocarbons, indicating that <br /> off-site migration is being contained by the GWES ARCO well MW-1 also did not contain <br /> detectable concentrations of hydrocarbons <br /> Status of Site Remediation <br /> This section provides a description of the remediation system and discusses the operation of <br /> the remediation system for the fust quarter 1994 <br /> Description The remediation system at ARCO Station 2133 consists of a GIVES The <br /> GIVES consists of one groundwater extraction well with a designed pumping capacity of <br /> 15 gallons per minute The extracted groundwater does not require treatment prior to <br /> discharge to meet the requirements of the City of Stockton wastewater discharge permit issued <br /> for this site The system is sampled monthly to ensure the discharge is within. permitted <br /> limits The analytical results are included in Exhibit C Groundwater is extracted from the <br /> well via a submersible pump Installation and start-up of a free product recovery system <br /> occurred in 1984 After the free product was recovered, the system was modified for use as <br /> a GIVES and operated periodically from 1986 to 1991 Additional modifications were made <br /> to improve the system in 1991, and it has been operated nearly continuously since June 1991 <br /> Operating Conditions This Quarter During the first quarter of 1994, the system operated <br /> 100 percent of the tune During operation of the GIVES in the first quarter of 1994, <br /> approximately 105 million gallons were extracted and discharged In the second quarter of <br /> 1994, the pumpmg rate of the extraction well will be reduced from nearly 10 gpm to <br /> approximately 8 gpin to reduce the area of influence of the GWES The reduction is needed <br /> to optimize the effectivness of the GIVES The total amount of BTEX and TPH in the <br /> extracted groundwater is shown in Table 4 in Exhibit B The quantity of BTEX and TPH <br /> discharged to the sewer is well within the omits stated in the permit <br /> A soil vapor extraction./air sparge system has been designed for this site to enhance the site <br /> remediation The system will incorporate the newly installed vapor extraction and air sparging <br /> wells ARCO has awarded a construction contract for the installation of the soil vapor <br /> extraction/air sparge system, and construction should begin in the third quarter of 1994 <br /> Use or disclosure of data contained on this sheet is subject to the restriction specified at the beginning of this <br /> document <br /> 12734ZEP0RTS\I M4QTR1tFr <br />