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subsurface investigation activities are presented in ATC's Subsurface Investigation Report, dated
<br /> April 23, 2008.
<br /> On March 31, 2008, an ATC geologist supervised the destruction of MW17 and installation of its
<br /> replacement, also identified as MW17 to a depth of approximately 59.75 feet using 2-inch
<br /> diameter Schedule 40 PVC casing. Refer to ATC's Second Quarter 2008 Monitoring Report,
<br /> dated July 31, 2008, for additional information.
<br /> On August 25 and 26, 2008, an ATC geologist supervised the installation of vapor extraction wells
<br /> VE1, VE2, VE3, and VE4 to depths of approximately 40 feet bgs. One long term and four short
<br /> term vapor extraction tests were performed at the site in October of 2008 in an effort to evaluate
<br /> the feasibility of soil vapor extraction as a remedial option. Refer to ATC's Vapor Extraction Well
<br /> Installation and Pilot Test Report, dated April 30, 2009, for additional information.
<br /> On August 28, 2008, ATC staff collected soil and groundwater samples for bench scale testing to
<br /> evaluate the potential effectiveness of ozone sparging as a remedial option under laboratory
<br /> conditions prior to implementation in the field. The bench scale study results indicate ozone
<br /> sparging at the site would be effective in remediating the impacted groundwater. Refer to ATC's
<br /> Ozone Bench-Scale Treatability Study, dated February 26, 2009, for additional information.
<br /> On September 9, 10, and 11, 2009, an ATC geologist supervised the installation of two dual
<br /> nested ozone sparge wells identified as OS1 and OS2. Each sparge well consisted of a shallow
<br /> well and a deep well extending to depths of approximately 65 and 90 feet bgs, respectively. A
<br /> four week long pilot test was conducted at the site from November 11 to December 9, 2009, in an
<br /> effort to evaluate the feasibility of ozone sparging as a remedial option under field conditions.
<br /> Refer to ATC's Ozone Sparge Well Installation and Pilot Test Report, dated March 10, 2010, for
<br /> additional information.
<br /> In late June of 2011, an ATC geologist supervised the installation of three dual nested ozone
<br /> sparge wells identified as OS3, OS4, and OS5. Each sparge well consisted of a shallow sparge
<br /> point and a deep sparge point extending to depths of approximately 65 and 90 feet bgs,
<br /> respectively.
<br /> On January 14, 2013, electrical service was supplied to the remediation system compound. The
<br /> concrete slab for the remediation system compound was poured on February 14, 2013, and an
<br /> electric catalytic thermal oxidizer was placed in the remediation compound on March 5, 2013.
<br /> On August 1, 2013, soil vapor extraction was initiated utilizing VE1 through VE4. The soil vapor
<br /> extraction system operated until February 22, 2019, and removed approximately 14,933 pounds
<br /> of petroleum hydrocarbon vapors.
<br /> From August 4-31, 2015, approximately 80.75 pounds of ozone were injected into groundwater
<br /> at the site.
<br /> In April of 2020, ATC conducted a sensitive receptor survey in the vicinity of the site to identify
<br /> potential groundwater wells, surface water bodies, and schools located within 2,000 feet of the
<br /> site. Refer to ATC's Sensitive Receptor Survey Report, dated May 15, 2020, for additional
<br /> information.
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