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Page 1 of 2 <br /> Vicki McCartney [EH] <br /> From: William Little [wlittle@advgeoenv.com] <br /> Sent: Friday, October 29, 2010 3:02 PM <br /> To: Vicki McCartney [EH] <br /> Cc: Nuel Henderson [EH] <br /> Subject: 308 North Grant Street- Larrys Auto <br /> Ms. Vicki McCartney, <br /> AGE reviewed your directive dated 16 April and 11 October 2010 containing a directive for a <br /> soil vapor sampling work plan for the 308 North Grant Street, in Stockton. The 16 April 2010 <br /> letter referenced the potential threat from ground water at 30 feet below surface grade as an <br /> elevated risk to the detection of petroleum hydrocarbons. <br /> A review of historical soil data from wells drilled in the UST area on the northern portion of the <br /> parking area and the UST area under the southern sidewalk of the site, revealed limited soil <br /> impact above the historic water table level. Shallow soil contamination above 15 feet bsg is <br /> very limited. No significant impacted was noted in any soil samples collected above 15 feet bsg <br /> with the exception of approximately 400 mg/kg of TPH-d in a ten-foot soil samples. Volatile <br /> hydrocarbons are not detected in the shallow soil and active soil vapor extraction is mitigating <br /> soil impact, therefore soil vapor sampling within shallow soil is not warranted at the site. The <br /> entire site is covered with a hardscape roadway surface. <br /> The threat of volatilization of petroleum from impact ground water does not appear reasonable <br /> based on the site conditions; including a non permeable floor and 30-foot section of soil above <br /> ground water in the area of highest dissolved contamination. <br /> The main building on the site which would be the target of investigation include an auto repair <br /> shop with stores very minor volumes of gasoline, yet Larry the tenant stated that the shop only <br /> services vehicle when operating with one third of building open to the atmosphere (Shop doors <br /> open). The second building is a parts warehouse that utilizes a liquid fuel (diesel) powered, 10- <br /> ton forklift on a daily basis when operating. Today, I was performing a site mspecfio'n and t <br /> melt with Jeff the shop foreman for electric motor company which occupies the warehouse to <br /> discuss the threat and locations of the potential threats, however, as we talked about your <br /> directive the smoke from his cigarette was filling the warehouse faster than we could decide <br /> how access would be granted. <br /> AGE would like to evaluate the soil vapor with an approach which minimizes the threat, yet <br /> does not waste effort and funds to sample for a non-threat problem. AGE recommends <br /> continues active remediation of the soil and ground water. <br /> Thank you in advance for your help in this matter. <br /> Please call me if you have any questions. <br /> Sincerely, <br /> William R. Little <br /> California Professional Geologist 7473 <br /> 10/29/2010 <br />