|
1117 Lone Palm Avenue, Suite 201
<br /> HAkT W Modesto, California 95351 C
<br /> 209-579-2221
<br /> Aff
<br /> ENVIRONMENTAL - GEOTECHNICAL Fax: 209-579-2225
<br /> BUILDING SCIENCES • MATERIALS TESTING
<br /> and MW12 and selected soil samples were submitted for laboratory analyses. Each well was constructed
<br /> with 2-inch diameter PVC casing, with MW8, MW9, MW 10, and MW 11 extending to a depth of 65 feet
<br /> bgs in the shallow groundwater bearing zone, MW5, MW6, and MW12 extending to a depth of 90 feet
<br /> bgs in the intermediate groundwater bearing zone, and MW7 extending to a depth of 121 feet bgs in the
<br /> deep groundwater bearing zone.
<br /> Monitoring wells MW5, MW6, MW8, MW9, MW 10, and MW12 were developed on December 22 and
<br /> 23, 2004. An obstruction encountered in MW7 at approximately 64 to 65 feet bgs prevented
<br /> development of this well. MW 11 was purged dry after removing 0.5 gallons of water. Efforts to
<br /> develop this well using a bailer revealed the presence of grout inside the well and the total depth of the
<br /> well was measured to be approximately 58 feet.
<br /> On December 22 and 23, 2004, monitoring wells MW 1 through MW12 were surveyed relative to NAD
<br /> 83 and NGVD29 for position and elevation and groundwater samples were collected from MW 1
<br /> through MW6, MW8, MW9, MW 10, and MW12. Petroleum hydrocarbon constituents were detected in
<br /> soil samples collected from the boreholes of MW5 through MW9 and MW12. Groundwater samples
<br /> were not collected from MW7 and MW 11 due to an obstruction in MW7 and grout infiltration in
<br /> MW 11. Petroleum hydrocarbons were detected in the groundwater- samples collected from MW 1
<br /> through MW6, MW8 through MW10, and MW12. The results of the subsurface investigation activities
<br /> are presented in ATC's Sztbsurface Investigation Report, dated July 25, 2005.
<br /> On April 7, 2005, an ATC geologist supervised the destruction of MW 11 and the installation of
<br /> replacement monitoring well MW11R to a depth of approximately 65 feet bgs using 2-inch diameter
<br /> schedule 40 PVC casing. Refer to ATC's First and Second Quarter 2005 Monitoring Report, dated
<br /> October 10, 2005, for additional information.
<br /> From September 25 to 30, 2006, an ATC geologist supervised the installation of monitoring wells
<br /> MW 13, MW 14, and MW 15. MW 13 and MW 14 were installed off-site to the east and in the northern
<br /> portion of the site, respectively, to evaluate the lateral extent of impacted groundwater in the shallow
<br /> zone. Monitoring well MW 15 was installed on-site downgradient from the source area to evaluate the
<br /> vertical extent of impacted groundwater. Each well was constructed with 2-inch diameter PVC casing,
<br /> with MW 13 and MW 14 extending to a depth of approximately 60 feet bgs in the shallow groundwater
<br /> bearing zone, and MW15 extending to a depth of approximately 151 feet bgs in the deep groundwater
<br /> bearing zone. Monitoring wells MW 13, MW 14, and MW 15 were developed and sampled on November
<br /> 9 and December 7, 2006, respectively. The results of the subsurface investigation activities are
<br /> presented in ATC's Subsurface Investigation Report, dated December 20, 2006.
<br /> From January 8 to 11, 2008, an ATC geologist supervised the installation of MW 16 and MW 17 to
<br /> approximately 60 feet bgs, and MW 18 and MW 19 to approximately 90 feet bgs. Monitoring wells
<br /> MW16 and MW17 were installed off-site to the southeast at 2080 East Fremont Street to evaluate the
<br /> lateral extent of impacted groundwater in the shallow zone. Monitoring wells MW 18 and MW 19 were
<br /> installed off-site to the southeast at 2080 East Fremont Street to evaluate the lateral extent of impacted
<br /> groundwater in the intermediate zone.
<br /> s:\enviromental\28349\reports\2020 Offsite WP CPT.doe 2 ATC
<br />
|