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<br /> ATC Associates Inc
<br /> M%TC
<br /> 1117 Lone Palm Avenge, Suite B
<br /> Modesto, California 95351
<br /> 209-579-2221
<br /> ASSOCIATE s iN c Fax 209-579-2225
<br /> In November 1998, ATC personnel supervised the advancement of two soil borings to 78 5 feet
<br /> bgs and one soil boring to 86 5 feet bgs The soil borings were converted into groundwater
<br /> monitoring wells (MW1, MW2, and MW3), respectively Analytical results of soil samples and
<br /> groundwater samples indicated that soil and groundwater are impacted by petroleum
<br /> hydrocarbons Site activities were summarized in ATC's Summary Report of Subsurface
<br /> Investigation, dated January 15, 1999
<br /> In December 2000, ATC personnel supervised the advancement of one cone penetrometer test
<br /> (CPT) boring to 140 feet bgs, four soil borings to 80 feet bgs, and one soil boring to 100 feet bgs
<br /> The soil borings were converted into groundwater monitoring wells MW4, MWS, MW6, MW7,
<br /> and MW8 Analytical results of soil and groundwater samples indicated that soil and
<br /> groundwater are impacted by petroleum hydrocarbons Site activities were summarized in
<br /> ATC's Summary Report of Additional Subsurface Investigation, dated March 6, 2001
<br /> In September 2001, ATC supervised the advancement of four geoprobe soil borings, SBI
<br /> through S134, and eight hollow stem auger borings SB 1 through SB4 were advanced to first
<br /> encountered groundwater, at approximately 61 feet bgs, ASI was advanced to approximately 85
<br /> feet bgs, PZ 1 a and PZ 1 b were advanced to approximately 80 feet bgs, V W 1, V W2, and V W3
<br /> were advanced to approximately 65 5 feet bgs, and MW9 and MW10 were advanced to
<br /> • approximately 81 feet bgs AS 1 was completed as a 4-mch diameter air sparge well with two 2-
<br /> inch diameter piezometers located in the same borehole PZla and PZlb were completed as 2-
<br /> inch diameter piezometer pairs V W 1, V W2, and V W3 were completed as 2-inch diameter
<br /> vapor extraction wells and MW9 and MW 10 were completed as 2-inch diameter groundwater
<br /> monitoring wells
<br /> On October 31 and November 1, 2001, ATC performed a short-term vapor extraction test and a
<br /> long-term vapor extraction test On the first day, the short-term vapor extraction test was
<br /> approximately 2 hours in length and on the second day, the long-term vapor extraction test was
<br /> approximately 4 hours in length
<br /> In December 2001 and January 2002, ATC conducted an air sparge pilot test at the site for
<br /> approximately 31 days AS 1 was used to evaluate the site-specific radius of influence created by
<br /> air sparging at the site The details and results of the air sparge pilot test, vapor extraction tests,
<br /> and the installation of the air sparge wells, vapor extraction wells, and MW9 and MW 10 are
<br /> described in ATC's Remedial Investigation/Feasibility Study, Pacific Coast Recreation, 3755
<br /> Munford Avenue, Stockton, California, August 13, 2002
<br /> On June 16 through 19, 2003, ATC supervised four CPT borings, which were advanced to
<br /> approximately 160 feet bgs Soil and groundwater samples were collected from the four cone
<br /> CPT borings and submitted for analyses
<br /> S U63931REPORTSI3stgtr-2005 doe 2
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