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Additional Vapor and�roundwater Monitoring Well Work Plan
<br /> Raymond Investment Corporation
<br /> August 4,2009
<br /> Page 3
<br /> gradient hydropunch borings located in the sidewalk or street on the other side of the above-mentioned
<br /> building. The rationale for installing only one additional monitoring well at that time was the uncertainty
<br /> of the distribution of contamination in the down-gradient area. Results of the samples collected from the
<br /> proposed well and other proposed borings would assist in effectively locating additional wells, if
<br /> necessary. If other additional wells were installed during the previous work phase, prior to evaluating the
<br /> results from the new borings,they might have been ineffectively located.
<br /> MW4 was installed on August 29, 2006. Soil borings were installed on September 7, 8, and 28, 2006.
<br /> The installation and investigation activities were documented in the report titled Additional Soil and
<br /> Groundwater Investigation Report and Third Quarter 2006 Monitoring Report, dated January 2, 2007.
<br /> Groundwater monitoring continued with some modifications. The report titled Site Conceptual Model
<br /> 2008, dated October 31, 2008,summarized data that had been collected regarding the Site to date and
<br /> clarified existing data gaps". The letter from the SJCEHD dated May 12, 2009, authorized the reduction of
<br /> sampling frequency and analyte list for the existing monitoring wells. The May 12, 2009 letter indicated
<br /> that the SJCEHD "believes that additional investigation is needed to delineate the vertical and lateral
<br /> extent of groundwater contamination at the identified source of the contamination and down-gradient
<br /> northeast of the source area. This includes investigating soil and groundwater beneath the building
<br /> located northeast of the source and may possibly warrant collecting soil gas samples near the building."
<br /> A Condor representative met with Ms. Victoria McCartney and Mr. Nuel Henderson of the SJCEHD at
<br /> the Site on May 28, 2009. The SJCEHD observed,the,conditions.and,placement:of,the building.and .+
<br /> basement of the building and agreed;that the interior of the_building.was.practically�inaccessible,and_
<br /> down-'gradient ells would need to be placed along the exterior of the building.
<br /> 3.0 PROPOSED MONITORING WELL LOCATIONS AND SAMPLE INTERVALS
<br /> A total,of,seven:additional groundwater. monitoring wells and three.soil-vapor monitoring wells are .
<br /> proposed.,,The wells,will,be-installedin two phases. The first phase will include the installation of one F
<br /> well for vertical,definition, three monitoring wells for horizontal definition, and three soil vapor wells. If
<br /> laboratory..analytic 1 re ults indicate that hydrocarbons are present in�the o itoring wells installed.
<br /> during the.first phase, then three additional monitoring wells will be installed'northeast of the building
<br /> along Grant Street and in line with the average groundwater gradient direction from MW-4.
<br /> One monitoring well, MW-41), will be placed ad* cent to MW-4. The purpose of MW-4D will be to
<br /> provide data on the vertical distribution of aqueo s phase hydrocarbons. There will be a 20-foot vertical
<br /> separation between the screen interval of MW-4 and;.MW-4D.,Specifically, the data will support or
<br /> discount the analytical data from the groundwater grab sample collected in September 2006 from SB-7 at
<br /> 72 feet bgs. Monitoring well MW-4D will be advanced to a depth of approximately 75 feet bgs and
<br /> constructed with a 10-foot screen interval The monitoring well will be constructed with 2-inch-diameter $`7
<br /> casing. No soil samples will.be collected.from the soil boring-made for the installation of monitoring well s ilt
<br /> MW-4D due its proximity,to sail sample analytical data collected from SB-7.
<br /> Monitoring well MW-5 will be placed northeast of MW-4 and installed with a 25 to 40 degre?an le fir[
<br /> toward the northeast and under the building. MW;5 will be constructed with a screen length of�5 to.50.
<br /> feet from the surface. The purpose of MW-S will be to provide data on the horizontal distribution 0
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<br /> sorbed and aqueous phase hydrocarbons beneath the building and northwest of MW-4. Soil samples will G�
<br /> { be collected from.the soil;boringmade for.the installation of MW-5 at 5-foot intervals. The samples will ,,
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<br /> be analyzed by the laboratory, as described below, from the depths of 5 feet, 15 feet, 25 feet, 35 feet, and
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<br /> i1� CONDOR
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