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... ... WEISS ASSOCIATES M4 <br /> 3 SAMPLING PLAN <br /> To meet the objective stated in Section 1.1, soil samples will be collected from <br /> borings drilled beneath the five vaults. Chemicals released from the vaults would migrate <br /> downward into the soil underlying the vaults; therefore, there is a high probability that <br /> chemical analysis of samples collected from beneath the vaults will indicate whether <br /> chemicals stored in the vaults have leaked. The sampling and analytic methods, sampling <br /> points, and potential obstacles are discussed below, <br /> 3.1 SOIL BORING AND SAMPLE COLLECTION <br /> Soil samples will be collected from soil borings drilled beneath each end of the <br /> vaults. Two samples will be analyzed from each boring. Samples adjacent to the bottom <br /> of the vaults and three to four ft beneath the vaults will be analyzed as discussed in <br /> Section 3.4. Analyzing samples from several ft beneath the vaults increases the <br /> probability of detecting chemicals that may not have leaked directly above the location of <br /> the samples collected adjacent to the bottom of the vaults. <br /> The borings will be drilled at an angle of about 30 degrees from horizontal using a <br /> hollow stem auger drilling rig. We understand from DWG that many underground utilities <br /> occur in the subsurface in the vicinity of the vaults. Therefore, as stated in our contract <br /> with DWG, DWG assumes all responsibility to accurately locate and mark all underground <br /> utilities and structures within 30 ft. of the drilling sites, and will hold WA harmless for <br /> any damages or ensuing environmental consequences resulting from damage to buried <br /> structures that are not marked or shown on plans furnished to WA. To minimize the <br /> possibility of damaging any unmarked utilities, extreme care will be taken in positioning <br /> the borings and the upper three to four feet of soil will be hand-dug before drilling. If <br /> buried obstacles are encountered the borehole orientations and drilling angle will be <br /> adjusted. <br /> WP1F:\ALL\331D WG\331R1APS.D OC:74-331-00:V1.038 Page 14 <br />