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ATC Associates Inc.
<br /> YVATC 1117 Lone Palm Avenue, Suite 201
<br /> Modesto, California 95351
<br /> 209-579-2221
<br /> ASS O C I ATE S INC , fax: 209-579-2225
<br /> California report both USTs contained gasoline , but the 4 , 000-gallon UST previously
<br /> contained diesel . Four soil samples were collected beneath the former USTs , which
<br /> contained low concentrations of TPHd and MTBE . Fuel pipelines connected the USTs
<br /> to dispensers located adjacent to Honker Cut and near the boat dock . Three soil
<br /> samples were collected from the former product line trench located on the levee that
<br /> separates the store from the river. MTBE , TPHg , toluene, ethyl benzene , and total
<br /> xylenes were detected in the two soil samples located on the eastern portion of the
<br /> levee . In June 1999 , Pile Construction installed one duel chamber AST for diesel and
<br /> gasoline and double-walled product lines that serviced the AST and fuel dispensers
<br /> located on the dock. According to Westrec Properties , the fuel lines have an electronic
<br /> monitoring system .
<br /> In July and August 1999 , ATC advanced ten soil borings , SB28 through SB37, to
<br /> evaluate the extent of petroleum hydrocarbons and trace amounts of free product
<br /> detected by SECOR . Soil borings advanced along the levee , southwest of the location
<br /> of the former USTs and the current AST location contained elevated concentrations of
<br /> TPHg , TPHd , and MTBE . The extent of impacted soil was defined and generally
<br /> extended along the landward side of the levee, west of the store. The extent was
<br /> approximately 200 feet in length and 65 feet in width limited to depths between 5 and 15
<br /> feet bgs , with the highest MTBE concentrations detected within the upper 10 feet.
<br /> Additionally, MTBE impacted soil extended eastward , between the store and office
<br /> building .
<br /> In April 2001 , ATC drilled one soil boring to 30 feet bgs , which was converted into
<br /> groundwater monitoring well MW-7 . MW-7 is located between the levee road and the
<br /> on-site store where elevated petroleum hydrocarbons were detected during previous
<br /> investigations . TPHg , benzene , ethyl benzene , and total xylenes were detected at
<br /> concentrations of 60 mg/kg , 0 .46 mg/kg , 1 . 0 mg/kg , and 2 . 9 mg/kg , respectively, in a
<br /> soil sample collected at five feet bgs . MTBE was detected at concentrations of 56
<br /> mg/kg and 41 mg/kg in soil samples collected at five and ten feet bgs , respectively.
<br /> In August 2004, cone penetration testing (CPT) activities were completed in general
<br /> accordance with ATC's Workplan for Subsurface Investigation and Preparation of a
<br /> Problem Assessment Report, dated October 8 , 2003 . Three CPT borings, CPT1 , CPT2 ,
<br /> and CPT3 , were advanced to investigate the subsurface lithology and to evaluate the
<br /> vertical extent of dissolved-phase hydrocarbons at the Site. CPT1 was advanced in the
<br /> vicinity of monitoring well MW-6 , down gradient with respect to the petroleum
<br /> hydrocarbon release and source area . CPT2 was advanced in the vicinity of the on-Site
<br /> domestic well . CPT3 was advanced in the vicinity of monitoring well MW-7 , up gradient
<br /> with respect to the petroleum hydrocarbon release and source area . The borings ,
<br /> CPT1 , CPT2 , and CPT3 , were advanced to depths of 89 feet, 104 feet, and 97 feet bgs,
<br /> respectively.
<br /> KIR 2009 WP for Pilot Testing.doc ATC Associates Inc.
<br /> S :\Environmental\62514 — KIR ATC Project No. 54.62514.0001
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