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Page 1 of 1 <br /> ti.►' <br /> Vicki McCartney [EH] <br /> From: Vicki McCartney [EH] <br /> Sent: Monday, January 05, 2009 4:06 PM <br /> To: 'Jim Barton' <br /> Cc: Nuel Henderson [EH] <br /> Subject: JIMCO Truck Plaza <br /> Jim: <br /> On January 2, 2009, you requested that I send to you current data concerning the contamination of diesel-range <br /> hydrocarbons (TPHd)at JIMCO Truck Plaza, 1022 Frontage Road, Ripon, California. This is in response <br /> to concern by the EHD that recent groundwater data support the view that the source for a significant portion of <br /> the TPHd plume is related to the above-ground storage tanks (ASTs). The information presented below is from <br /> Site Assessment Report dated September 5, 2008, submitted by Conestoga-Rovers and Associates (CRA). <br /> Between May 27 -29, 2008, thirteen soil borings were advanced to approximately thirty feet below surface grade <br /> (bsg). Sixty soil and thirteen grab groundwater samples were collected from soil borings B-29 through B-41. <br /> The highest soil concentrations of TPHd and TPH-motor oil (TPHmo)were 8,600 mg/kg and 2,500 mg/kg, <br /> respectively, detected in boring B-31 at sixteen feet bsg. This boring was advanced directly east of <br /> the ASTs. The highest soil concentration of gasoline-range hydrocarbons (TPHg)was detected at 350 mg/kg <br /> in boring B-32 at twenty-four feet bsg. B-32 was advanced approximately seventy feet northeast of the ASTs. <br /> TPHd and TPHmo were detected in grab groundwater samples collected from all 13 borings. The highest <br /> groundwater concentrations of TPHd and TPHmo were 1,400,000 ug/L and 510,000 ug/L, respectively, detected <br /> in boring B-32 advanced approximately seventy feet northeast of the ASTs. <br /> There appears to be two TPHd plumes which may be comingled. One is near the former diesel UST and the <br /> other plume is near the diesel pump station located near the ASTs. CRA stated that the low concentrations of <br /> TPHd in soil and groundwater detected in borings B-39 and B-40 are an indication that there exists "a non- <br /> impacted area between the former diesel UST and the diesel pump station", although low concentrations are an <br /> impact. <br /> The vertical extent of TPHd in soil is defined. Soil is impacted near the ASTs from approximately 2.5 feet bsg to <br /> approximately 25 feet bsg. The lateral extent of impacted soil appears to be defined both in the area near the <br /> former diesel UST and near the ASTs. <br /> The vertical extent of TPHd in groundwater may or may not be defined. CPT-2 was advanced near the former <br /> diesel UST. At 90 to 93 feet bsg, TPHd was reported less than 50 ug/L with silica gel cleanup and 75 ug/L <br /> without silica gel cleanup. CPT-3 was advanced approximately 75 feet northeast of the ASTs. At 72 -75 feet bsg, <br /> TPHd was reported less than 50 ug/L with silica gel cleanup and 81 ug/L without silica gel cleanup. The lateral <br /> extent of TPHd impacted groundwater is defined in all directions except toward the south (Ripon Farm Services <br /> property). <br /> Groundwater was collected from MW-2 and MW-3 located at the Ripon Farm Services site during the fourth <br /> quarter 2008 sampling event. I do not have the groundwater results yet. <br /> I believe this gives you a very brief oversight of the TPHd contamination at the JIMCO Truck Plaza. Please let me <br /> know if you have any questions. <br /> Vicki McCartney, Senior REHS <br /> San Joaquin County <br /> Environmental Health Department <br /> 600 East Main Street <br /> Stockton, California 95202 <br /> Phone: (209)468-9852 <br /> Fax: (209)468-3433 <br /> Email: vniccartney��i%sjcehd.com. <br /> 1/5/2009 <br />