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Kennedy/Jenks Consultants <br /> . Ms Diane M Hinson, REHS <br /> 7 January 1994 <br /> Page 2 <br /> LABORATORY ANALYSES RESULTS <br /> TPH-G was detected in the original and duplicate samples collected from MW-1 at <br /> concentrations of 1 6 mg/1 and 1 9 mgll, respectively TPH-D was not detected at <br /> concentrations above the method detection limit (5 0 mg/1) in ether the original or duplicate <br /> groundwater samples collected The TPH-G concentration detected in MW-1 during the 9 <br /> December 1993 sampling event is lower, and in the same order of magnitude, as the TPH-G <br /> concentrations detected in MW-1 during previous sampling events The TPH-D detection limit <br /> is at least one order of magnitude lower than the TPH-D concentrations detected in samples <br /> collected from MW-1 during previous sampling events Table 2 provides current and historical <br /> analytical data for MW-1 and other site monitoring wells The laboratory data sheets and <br /> Chain-of-Custody form for the 9 December 1993 sampling event are attached <br /> FUTURE SAMPLING EVENTS <br /> We are requesting a revision to our sampling plan approved by you in your undated letter <br /> received in our office on 15 November 1993 This sampling plan consisted of the collection of <br /> groundwater samples from the Site for a total of four consecutive quarters In light of the <br /> results of the 9 December 1993 sampling event, we are proposing that groundwater samples <br /> be collected from the site for a total of three consecutive quarters The 9 December 1993 <br /> sampling event comprises the second of three consecutive quarterly sampling events to be <br /> conducted One additional sampling event will be conducted in March 1994 Due to <br /> fluctuating groundwater flow directions, groundwater flow direction will be calculated in the <br /> field to determine which onsite well is located downgradient from MW-1 If MW-5 is <br /> downgradient, it will not be sampled because chemicals of concern have not been detected in <br /> this well since its installation in May 1990 If another onsite well is downgradient, a <br /> groundwater sample will be collected from that well and analyzed for the presence of TPH If <br /> chemicals of concern are only present in MW-1, groundwater sampling will be discontinued <br /> after the March 1994 sampling event If TPH concentrations in MW-1 are relatively constant <br /> (within the same order of magnitude) or decrease during this sampling event, we will request <br /> closure of all facility monitoring wells (wells MW-1 through MW-5) <br /> If you have any questions regarding the results of our latest sampling event, or if you would <br /> Ike to discuss our future work at the site, please contact me at (916) 362-3251 <br /> Sincerely, <br /> KENNEDY/JENKS CONSULTANTS <br /> Kelye A cKinney, P E <br /> Project anager <br /> 01110/94 9 48am <br /> attachments <br /> cc Catherine Whitworth, Trustee <br />