Laserfiche WebLink
ARCADIS Mr. Roberto Cervantes <br /> October 21, 2011 <br /> groundwater in the southwestern portion of the property. Based on the analytical <br /> data from the 2001 investigation and the recent CPT-UVOST screening data, the <br /> hydrocarbon impacts were not detected in the northwestern and western portion of <br /> the site. <br /> In 2001, Geological Technics advanced three soil borings (GP-1, GP-2, and GP-3) to <br /> 16 feet below ground surface (bgs) in the western portion of the property. A soil and <br /> grab groundwater sample was collected from each borehole and analyzed for total <br /> petroleum hydrocarbons (TPH) as gasoline range organics (TPH-GRO); TPH as <br /> diesel range organics (TPH-DRO); TPH as motor oil (TPH-mo); and benzene, <br /> toluene, ethylbenzene, and total xylenes (BTEX). Soil samples were collected from <br /> GP-1, GP-2 and GP-3 at 7 feet bgs, 12 feet bgs, and 8 feet bgs, respectively. TPH- <br /> GRO, TPH-DRO, TPH-mo, and BTEX were not detected in soil and grab <br /> groundwater samples collected from GP-1 and GP-2; soil samples were collected at <br /> 7 feet bgs and 12 feet bgs, respectively. TPH-DRO and TPH-MO were the only <br /> constituents detected in soil (0.0497 milligrams per kilogram [mg/kg] and 0.261 <br /> mg/kg, at 8 feet bgs) and groundwater(1.42 milligrams per liter[mg/L] and 4.40 <br /> mg/L) samples collected from GP-3 (Geological Technics, 2002). <br /> In 2010, ARCADIS advanced one CPT-UVOST soil boring (CPT-4-UVOST) to <br /> screen for potential petroleum hydrocarbon impacts on the western portion of the <br /> property. Soil samples were collected from CPT-4-UVOST at 1.5 bgs and 2.5 bgs <br /> and TPH-DRO and TPH-mo were detected (100 mg/kg and 140 mg/kg maximum <br /> concentrations, respectively). Laser induced fluorescence (LIF) screening was <br /> conducted to the final borehole depth and the maximum fluorescence was observed <br /> within the asphalt cover; i.e., no indication of light non-aqueous phase liquids <br /> (LNAPL)to the final borehole depth of 32 feet bgs (ARCADIS, 2011). <br /> Based on these results, soil and groundwater impacts are limited to the southwest <br /> portion of the property. Access to the western portion of the property is limited due to <br /> boat storage. ARCADIS recommends collecting a grab groundwater sample in the <br /> northwest portion of the property to further assess groundwater in the anticipated <br /> sand zones (20 feet bgs and 35 feet bgs, respectively) in the vicinity of the former <br /> ASTs. <br /> Comment#2 <br /> "Four monitoring wells were installed in the shallow groundwater bearing zone (from <br /> 7 to 25 feet bgs) in November 2010 as part of the initial site investigation. All four <br /> Page: <br /> 2/7 <br /> G!Pro-WCHEVROW01 N San Jou SnTECHNICAURWQCBRTCWesponse to RWQCB Comments doo <br />