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e • • Page 2 of 3 <br /> In accordance wit i your 07/26/12 letter, we would like to offer the following <br /> additional information for your consideration: <br /> The core of hydrocarbon soil impact is located directly beneath the <br /> former UST area to depths of 45 feet bsg (see attached figure); the <br /> core of hydrocarbon dissolved impact appears to be located within the <br /> first hydro eologic unit (i.e. between 17' and 50'). <br /> Remediat n wells EW-1, EW-2 and DPE-1 are proposed solely to <br /> address the core of hydrocarbon-impact at depths between 10' and <br /> 30'. Initial y, a DPE-stinger will be slowly lowered to within a few feet <br /> of the bottom of each well casing with the intent of completely de- <br /> watering Each well and exposing a greater area to soil-vapor <br /> extraction <br /> Remediat on well DPE-2 is proposed solely to address the significant <br /> hydrocarb n-impact at depths between 25-45'. Because it is <br /> anticipate that EW-1, EW-2 and DPE-1 will eventually dewater the <br /> UST area to depths of 30 feet bsg, then at a minimum, it is <br /> reasonable to expect that the screened portion in DPE-2 at depths <br /> between 5-30 feet bsg can be dewatered and exposed. <br /> Based on an aquifer pump test conducted at the site in March 2008 <br /> (see attac iel the ground water level at EW-1 was induced to a <br /> depth of 3D feet after 7 hours and at extraction rates between 2-3 <br /> GPM. Bi use the ground water level was induced below the bottom <br /> of the punip, the aquifer pump test was terminated. It is therefore <br /> reasonable to assume that the ground water level will be induced to <br /> depths grE ater than 30 feet bsg. <br /> Because a DPE stinger can be set to a desired depth, high vacuum <br /> extraction is an effective remediation tool in isolating specific <br /> hydrocarbon impact at select depths. High vacuum extraction (even <br /> w/o a dewatering effect) is still a mechanism for extracting the <br /> dissolved and the adsorbed portions of hydrocarbon impact at isolated <br /> depths. <br /> Please let us kno if you have any further questions. <br /> Thanks - Tim <br /> Timothy J. Cuellar <br /> Senior Project Gec logist <br /> Advanced GeolEnvironmental, Inc. <br /> Stockton • Santa Rosa • Monterey • Brea • Spokane • Reno • Dallas <br /> 1-800-511-9300 <br /> tcuellar@advgeoenl(.com <br /> www.advgeoenv.co <br /> This email/fax message is for the sole use of the intended recipients)and may contain confidential and privileged information.Any <br /> unauthorized review, use,dis losure or distribution of this email/fax is prohibited. If you are not the intended recipient,please contact <br /> 8/30/2012 <br />