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water samples, then perform a mass balance calculation of remaining petroleum <br /> i hydrocarbons in the subsurface and prepare a Closure Summary Report B-1 was <br /> advanced to 50 feet, the remainder were advanced to 25 feet <br /> 1999 May SEMC4 did not pay AGE money for work done, so AGE stopped all work on <br /> Langston Project <br /> 1999 Aug PHS-EHD wants additional well on property <br /> 2000 April AGE submitted an Additional Site Assessment Report indicated that ground water <br /> contamination was detected in four soil borings (B-1 to B-4) from April 1999 and <br />' that further investigation was warranted, TPH-g, BTEX, and MTBE were detected <br /> in grab water samples from on- and off-site push points <br />' 2000 May PHS-EHD issued a letter informing the Langstons that additional work needed to be <br /> done to define vertical and lateral extent of the MTBE plume A sensitive receptor <br /> survey was also required AGE resumed active monitoring of the site <br /> 2000 June PHS-EHD approved AGE's Monitoring Well Installation Work Plan dated 23 June <br />' 2000 <br /> 2000 Sept AGE installed four additional monitoring wells to 30 feet bsg(MW-5 to 35 feet bsg) <br /> at the site (MW-5 to 8) <br /> 2000 Decem First monitoring event that includes the new wells Results of the monitoring event <br />' detected high concentrations of TPH-g and MTBE in sample MW-5 (from the <br /> original UST area) and above-Califorma's MCL for benzene Ground water flow <br /> direction for the last four monitoring events is towards the northwest, AGE has no <br />' ground water monitoring wells down-gradient of MW-5 <br /> 2001 May 24 PHS-EHD approvedAGE's Work Plan Addendum dated 16 May 2001 for additional <br />' soil borings northwest and east and vertical at UST area to define vertical and lateral <br /> extent of contaminated ground water <br /> 1 <br />