10-03-1988 Planning Packet - Laserfiche WebLink

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jkSIEMair p'.- frj These opimons are currently accepted lis, no warranty is -fl A a:SM 0 - mk ^ i L. i. . ^ L:. ^-w ■->.■ a» m •v' i -V Pa ' %■:A ■V, ti.i' ••-?l US*'.^-c-atuV^**'1» _ ,...rj,;-A> compounds (VOCs) were klentiTied in monitorinj well MW-4D. The presence of YOO in MW-4 promple 8fi«t«iiatinn of three additional wells proposed in the May 24 work plan. 3.Q ADDITIONAL PROJECT RESULTRS 3tl Cfilli Three additional monitoring wells were installed dmii« June 19M to further define the extent of VOC eoatamination. The locations of the new welb (MW-10, MW-11. and MW-12) are shown in Fif ure 2 aloni with the locations of previoosly instaUed wells. After installation, the new wells were developmt And sampled. 3.2 Sail B oHb « and Monitoring Weill Three additional soil borbgs were advanced at the site and were completed as monitoring wells. The boring well locations are shown in Figure 2. The subsurface geology of the site consisQ of heterogeneous mixture of clay, silt, sand, and gravel. The stratigraphy consists of silty clay with intermittent medium to ccnrse grained sand lenses which are generally less than two feet in width. The lenses do not appear to be laterally extensive. Complete lithologic boring logs for the three soil borings are included in Appendix A. Borings MW-10 and MW-11 were each advanced to a depth of 25 feet below the existing grade. Boring MW-12 was advanced to a depth of 55 feet below the existing grade. Each of the three borings were completed as monitoring wells. The wells are constructed of low carbon steel risers with five foot stainless steel screens. Complete well construction details are given in Appendix B. 3.3. Contaminant Conditions 3.3.1 Soil Contamination Soil contamination was previously identified in the vicinity of MW-4 and MW-4D; therefore, the upper 21 feet of soil was not sampled during the installation of MW-1 2. Low contaminant concentrations, as detected by the hNu photoionization meter, were detected in an interval between 23 and 36 feet below the ground surface during the drilling of MW-12. A summary of hNu results for borings MW-10, MW-1 1 . and MW-12 is included in Table 1. lonizable gases were not detected in any of the samples after opening the split-spoon. Headspace checks revealed some volatiles in borings MW-11 and MW-12. However, the concentrations (Table 1) are at the lowest detection limit for the hNu which is approximately one part per million. At these concentrations, interferences with water vapors are common and the concenuations must be viewed in this context. m- A • .* .* _• •• • !. J•4 • V J ' -:v; Vf-.ila .''V: h ■ ■■M .'5r‘ . , V 4- »■ comment ^.6 SollTm We propose te thinspreading buildings or i westerly acra feet. We anticipam insmllation p excavation. S The soil will will be aerate Aeration tilla Soil samples ' we propose s: year the samt to the MPCi^ 6.1 Soil Sat Soil sampling barrel samph inches, the i penetration cohesionless 6.2 Soil Cli As the sampi in accordanc laboratory fc indicating th pertinent ini