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1 <br /> LATHROP PROPERTY <br /> WKA No. 1184.02 ^ <br /> January 30, 1992 171 <br /> Page 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 N35°E <br /> 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 /> 0.0006. Table 4 is a summary of the ground water level measurements, flow directions and <br /> hydraulic gradients. <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). Although this well is greater than the required ten <br /> feet from former petroleum infrastructure, we believe that this is, in the case of the subject <br /> - property, inconsequential, given the time elapsed since the infrastructure was reportedly <br /> removed (at 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 /> When subsurface soils contamination by petroleum hydrocarbons was confirmed, we <br /> performed a site characterization, followed by regulatory agency-approved soils remediation. <br /> 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 /> r' <br /> 'NALi-AC2-K U H L <br /> r ASSGC:ATES INC. <br />