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BC&D Property <br /> phase II-Ground Water Assessment Proposal <br /> Page: 2 <br /> indicating that these tanks were probably the source. Analytical data indicates that there is <br /> only low levels soil of contamination. It is possible that natural microbial degradation has <br /> already significantly reduced the levels contamination in the sedimented surrounding the tank <br /> location.Soil analytical data is summarized in Table]. <br /> Ground water contamination also exists only in a local plume around the previous tank locau,�n. <br /> Water samples were collected from the 3 monitoring wells and by grab samples from the soil <br /> boring. The grab samples will tend to maximize contamination to the influence of <br /> levels due <br /> dr'iling. If contamination was not detected in these samples,then the ground water in that <br /> area has not been impacted. However,if contamination is detected,the data probably does not <br /> s in the ground water. Levels of contamination are fairly low, <br /> accurately represent levelwith <br /> xylene having the highest concentration and the widest distribution. Even though the levels of <br /> cmitamination are not high,they are above state allowable limits for drinking water. Ground <br /> mater analytical data is summarized in Table 2. <br /> t.. <br /> J 3.0 PROPOSED WORK PLAN <br /> It has been approArnately one year since the property assessment study was conducte l <br /> Therefore,Geological Technics proposes to first redevelop and sample MW#1 through#3 to <br /> aier at these locations. After the samples have been <br /> evaluate the condition of the ground w <br /> reviewed,the final decision on the location of the new set of monitoring <br /> analyzed and the data <br /> wells will be made. If the current information correlates with that of last year,then the new <br /> wells will be placed in their proposed locations. If the data does not correlate with the <br /> previous data,then their Iocations may have to be moved. <br /> Geological Technics proposes to install four monitoring wells. Proposed location of each <br /> _ monitoring well is shown in the Site Man. The placement of these monitoring wells were chosen <br /> to best define the plumes'dimensions and to cause as little disruption to business as possible. As <br /> discussed above,the water contamination plume was tentatively defined during the property <br /> assessment by using both monitoring well and grab samples from soil borings. The purpose of <br /> these new monitoring wells are to verify the Iateral limits of the plume,to determine if deeper <br /> ed by these hydrocarbons,and for future monitoring of <br /> water bearing strata have been impact <br /> ground water. <br /> The three monitoring wells installed into the first aquifer will be constructed as follows. Each <br /> well will extend to the bottom of the first aquifer and will be seated into the lower bounding <br /> well casing will be of 2-inch threaded joint PVC casing, <br /> clay layer at about 17 feet deep. The <br /> factory perforated with_0.04=inch slots. Perforations will extend no higher then 5 feet below <br /> composed of medium aquarium sand and will extend from <br /> ground surface. The filter pack will be <br /> the bvu'n*n of the well through the perforated zone to about I foot above the perforations. An <br /> T annular seal compose of bentonite will-be placed above-the filter_pack._A_surface seal of - <br /> concrete will be placed above the annular seal and the well will be secured with a locking well <br /> capnd water tight well cover. Figure <br /> a 5 illustrates the general construction plan of these <br /> �` shallow monitoring wells. A hollow stem auger drill rig will be used for installation. During <br />