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Monitoring wells MW5, MW6, MW8, MW9, MW10, and MW12 were developed on December 22
<br /> and 23, 2004. An obstruction encountered in MW7 at approximately 64 to 65 feet bgs prevented
<br /> development of this well. MW11 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
<br /> of the well was measured to be approximately 58 feet.
<br /> On December 22 and 23, 2004, monitoring wells MW1 through MW12 were surveyed relative to
<br /> NAD 83 and NGVD29 for position and elevation and groundwater samples were collected from
<br /> MW1 through MW6, MW8, MW9, MW10, and MW12. Petroleum hydrocarbon constituents were
<br /> detected in soil samples collected from the boreholes of MW5 through MW9 and MW12.
<br /> Groundwater samples were not collected from MW7 and MW11 due to an obstruction in MW7
<br /> and grout infiltration in MW11. Petroleum hydrocarbons were detected in the groundwater
<br /> samples collected from MW1 through MW6, MW8 through MW10, and MW12. The results of the
<br /> subsurface investigation activities are presented in ATC's Subsurface Investigation Report, dated
<br /> July 25, 2005.
<br /> On April 7, 2005, an ATC geologist supervised the destruction of MW11 and the installation of
<br /> replacement monitoring well MW11 R to a depth of approximately 65 feet bgs using 2-inch
<br /> diameter schedule 40 PVC casing. Refer to ATC's First and Second Quarter 2005 Monitoring
<br /> Report, dated October 10, 2005, for additional information.
<br /> From September 25 to 30, 2006, an ATC geologist supervised the installation of monitoring wells
<br /> MW1 3, MW14, and MW1 5. MW13 and MW14 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
<br /> shallow zone. Monitoring well MW15 was installed on-site downgradient from the source area to
<br /> evaluate the vertical extent of impacted groundwater. Each well was constructed with 2-inch
<br /> diameter PVC casing, with MW13 and MW14 extending to a depth of approximately 60 feet bgs
<br /> in the shallow groundwater bearing zone, and MW15 extending to a depth of approximately 151
<br /> feet bgs in the deep groundwater bearing zone. Monitoring wells MW13, MW14, and MW15 were
<br /> developed and sampled on November 9 and December 7, 2006, respectively. The results of the
<br /> subsurface investigation activities are presented in ATC's Subsurface Investigation Report, dated
<br /> December 20, 2006.
<br /> From January 8 to 11, 2008, an ATC geologist supervised the installation of MW16 and MW17 to
<br /> approximately 60 feet bgs, and MW18 and MW19 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
<br /> the lateral extent of impacted groundwater in the shallow zone. Monitoring wells MW18 and MW19
<br /> were installed off-site to the southeast at 2080 East Fremont Street to evaluate the lateral extent
<br /> of impacted groundwater in the intermediate zone.
<br /> Monitoring wells MW1 6, MW1 8, and MW1 9 were developed on February 28, 2008. MW1 7 was
<br /> purged dry after removing one gallon of water. The odor of grout in the purged groundwater
<br /> coupled with high pH measurements (9.5- 11.6) indicated the potential presence of grout inside
<br /> the well. The total depth of the well was measured to be approximately 50.6 feet. Monitoring wells
<br /> MW16 through MW19 were surveyed relative to NAD 83 and NGVD29 for position and elevation.
<br /> On March 6, 2008, groundwater samples were collected from MW1 through MW6, MW8, MW9,
<br /> MW12, MW16, MW18, and MW19. Petroleum hydrocarbons were detected in all the groundwater
<br /> samples, with the exception of the groundwater sample collected from MW16. The results of the
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