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l� <br /> LATHROP PROPERTY <br /> WKA No. 1184.02 <br /> January 30, 1992 <br /> Pegg 12 <br /> also had non-detectable lead concentrations. The ground water analytical results are <br /> summarized in Table 3 and laboratory reports are included in their entirety in Appendix E. <br /> The ground water flow direction beneath the property is northeasterly, ranging from N350E <br /> j to N470E, based on the ground water elevations during the four consecutive months that <br /> ' measurements were obtained. The average hydraulic gradient over the four month period is <br /> Tx� 0.0006. Table 4 is a summary of the ground water level measurements, flow directions and <br /> hydraulic gradients. <br /> r,z <br /> Ground Water Migration <br /> The ground water flow direction data indicate that W2 is a downgradient well with respect <br /> to the suspected former petroleum hydrocarbon-related site features,located approximately <br /> 40 feet northeasterly of the northeastern-most extent of the excavation resulting from the <br /> removal of contaminated soils (Plate 2). Althoughahis Well is greater than"the required.ten <br /> feat from former petroleum infrastructure,we believe.that;this is;in the.case of,tlie subjapt. <br /> [(` , . <br /> property, inconsequential, given the time elapsed since the infrastructure was reportedly <br /> a <br /> removed tat least 15 years), the consistency of the calculated ground water flow direction <br /> based on our water level measurements, and the relatively high permeability of site soils in <br /> which contamination was present. <br /> CONCLUSIONS <br /> Our historical research pertaining to the subject property indicated that the vicinity of its <br /> southwesterly corner contained an automobile service station. We therefore initially <br /> investigated the property for potential subsurface petroleum hydrocarbon contamination <br /> resulting from former UST(s) leakage. <br /> r <br /> When subsurface soils contamination by petroleum hydrocarbons was confirmed, we <br /> performed a site characterization, followed by regulatory agency-approved soils remediation. <br /> 3 We also performed a preliminary evaluation of.ground water quality directly beneath the <br /> contaminated area of the property,given the vertical extent of subsurface soils contamination <br /> with respect to the depth at which ground water exists beneath the property. <br /> Li <br /> WALLACE-KUM <br /> f GA5SOCiATLS INC. <br /> .t <br />