WORK PLANS - Laserfiche WebLink

Home Browse Search

ATC Associates Inc. 0% 1117 Lone Palm Avenue,Suite 201 Modesto,California 95351 209-579-2221 ABSOCIAT 98 I N C. Fax:209-579-2225 I In March 1997, WHF, Inc., supervised the advancement of one soil boring to 80 feet below ground surface (bgs). Soil and groundwater samples collected from the soil boring contained detectable concentrations of total petroleum hydrocarbons as gasoline (TPHg) and BTEX. A water sample was also collected from the on-site drinking water and it contained no detectable concentrations of petroleum hydrocarbons. In December 1998, BSK & Associates (BSK) advanced five borings at the site and completed four of the borings as groundwater monitoring wells MWI through MW4. Soil samples collected from borings B2 and MW2 contained detectable concentrations of TPHg and BTF,X. Soil samples collected from soil boring B2 contained detectable concentrations of methyl tertiary butyl ether(MTBE): In June and July 2000, WHF supervised the advancement of ten soil borings at the site and completed five of the borings as groundwater monitoring wells MW5, MW6, MW8, MW9, and MW10, and three of the borings as vapor extraction wells VEl, VE2, and VE3. Groundwater monitoring well MW7 was replaced by vapor extraction well VE3. Soil samples collected fiom borings B101, B103, B104, VE3, and VEl contained detectable concentrations of TPHg and BTEX. On September 18 and 29, 2003, ATC performed a short-term vapor extraction test and a long- term vapor extraction test, respectively. On the first day, the short-term vapor extraction test utilized vapor well VW2 as the vapor extraction point while monitoring vacuum response in VW 1, VW3, MWI, MW2, MW3,MW4,MW5,MW6, MW8,and MW9. The sort-term test was operated for approximately 3 hours and 45 minutes and the long-term test was operated for approximately 5 hours. ATC prepared an Interim Remediation Plan on March 25, 2004, recommending the installation and engineering design of a soil vapor extraction/air sparging system designed to remediate petroleum hydrocarbon impacted soil and groundwater. During the week of August 15, 2005, ATC supervised trenching and plumbing activities for the subsurface remediation piping designed to direct extracted hydrocarbon vapor from the extraction wells to the remediation compound. NRC personnel installed the subsurface piping and wellhead connections between the vapor extraction/air sparging wells and the remediation compound. Each wellhead connection included a gate valve, vacuum gauge, sampling port, and flow rate measurement port. The trenches were backfilled with pea-gravel aggregate base material,followed by native soil to approximately four inches below grade. The backfill was compacted and the trench locations were resurfaced with asphalt and concrete to match the pre-existing site surface conditions. In August 2005, the San Joaquin Valley Air Pollution Control District (SJVAPCD) issued an Authority to Construct for the installation and operation of a catalytic oxidizer that is part of the w:\25291Vepous\wkpCPT.doc 2 '.. i