Laserfiche WebLink
iC\LYA <br /> o r <br /> 1 <br /> A S S O C I A T E S I N C <br /> November 24, 1997 MJ Kloberdanz and Associates concluded that additional investigation <br /> activities would be required <br /> In November 1998, ATC supervised the advancement of two soil borings to 78 feet bgs and one <br /> soil boring to 86 feet bgs Soil samples were collected at five-foot intervals and analytical data <br />' indicated that the soil was impacted with petroleum hydrocarbons mainly between 20 feet and 60 <br /> feet bgs The three soil borings were completed as groundwater monitoring wells and the wells <br /> were developed Groundwater samples from the wells contained elevated concentrations of <br />' petroleum hydrocarbon constituents The on-site domestic well was also sampled and benzene, <br /> toluene, ethyl benzene, and xylenes (BTEX) constituents were detected Benzene concentrations <br />' in the three monitoring wells and the on-site supply well exceeded the State of California <br /> Maximum Contaminant Level (MCL) Site activities were summarized in ATC's Summary <br /> Report of Subsurface Investigation, January 15, 1999 <br />' In December 2000, ATC personnel supervised the advancement of one cone penetrometer (CPT) <br /> boring to 140 feet bgs ATC personnel also supervised the advancement of four soil borings to <br /> 80 feet bgs and one soil boring to 100 feet bgs The soil borings were converted into <br /> groundwater monitoring wells Analytical results of soil samples and groundwater samples <br /> indicated that soil and groundwater are impacted by petroleum hydrocarbons Site activities were <br /> summarized in ATC's Summary Report of Additional Subsurface Investigation, dated March 6, <br /> 2001 <br /> In September 2001, ATC supervised the advancement of four Geoprobe soil borings, SBI <br /> through S134, and eight hollow stem auger borings Soil borings SBI through S134 were <br /> advanced to first encountered groundwater, approximately 61 feet bgs, boring AS 1 was advanced <br /> to approximately 85 feet bgs, borings PZla and PZlb were advanced to approximately 80 feet <br /> bgs, borings V W 1, V W2, and V W3 were advanced to approximately 65 5 feet bgs, and borings <br /> MW9 and MW 10 were advanced to approximately 81 feet bgs Soil boring ASI was completed <br />' as a 4-inch diameter air sparge well with two 2-inch diameter piezometers located in the same <br /> borehole Soil borings PZla and PZlb were completed as 2-inch diameter piezometer pairs <br /> Soil borings VW I, VW2, and VW3 were completed as a 2-inch diameter vapor extraction wells <br /> 1 and borings MW9 and MW 10 was completed as a 2-inch diameter groundwater monitoring well <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, a short-term vapor extraction test was <br /> approximately 2 hours in length and on the second day, a long-term vapor extraction test was <br /> approximately 4 hours in length The soil vapor extraction pilot test yielded a radius of influence <br /> of approximately 50 feet Approximately 13 7 pounds of total petroleum hydrocarbons as <br /> gasoline (TPHg) and benzene were removed during the 6-hour combined vapor extraction pilot <br />' tests <br /> In December 2001 and January 2002, ATC conducted an air sparge pilot test at the site, running <br /> for approximately 31 days Well AS 1 was used to evaluate the site-specific radius of influence <br /> created by a density driven convection (DDC) well at the site The air sparge test yielded a <br /> S 1EnvjromentaRl6393aEPORTSIcptpumpreport doc 2 <br />