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RUSS CHAPIN 209-464-6947 11-17-95 07:48 P.04 <br /> Mr, Russell F.Cita in,Sr. <br /> November 15, 1995 <br /> Page 3 <br /> Operation and maintenance. <br /> Not listed,but importlAnt ap a separate task,uc final design of the recommended system <br /> for mitigating contamination at the site,to include permitting as necessary,quarterly <br /> monitoring of four groundwater monitoring wells,verification sampling at the close of <br /> the remediation process,and reporting. <br /> MUly1Ti2]1311G_WELLfDN6TRUC1M <br /> Agency comments have included it requirement for one additional groundwater <br /> monit(yrlt)g well (see Site Plan,attached). We will drill one soil boring, collect and analyze two <br /> soil samples from the boring,and construct,develop,and sample one groundwater monitoring <br /> well using?-in inner diantetct PVC casing. No chemical cements,glues, or solvents will be used <br /> ill well construction. 'The base of the well will be fitted with a threaded PVC plug, The screened <br /> panion of the well will consist of factory-perforated casing with 0.020-in-wide tdots. The well <br /> ccreen will be set through the augers and will extend from the total depth of the horing to <br /> alTroximately 15 ft below the ground surface. <br /> The annular space of the well will be packed with sorted sand to a point appmxin3ately <br /> 0.5 ft above. the top of the perforated ca.5ing. A 2-ft thick plug consisting of bentonite pellets or <br /> chips will be placed above the sand in the wells to prevent cement frortt entering the sand pack. <br /> The mmaining annulus will he backfilled with a mixture of neat,cement And powdered kwntonitc <br /> fits%)to grade. <br /> Soil samples will be collected at maximum 5-ft intervals and at lithologic contacts in the <br /> boring using a California-modified split-spoon sampler fitted with clean brass sleeves. Soil <br /> samples designated for possible laboratory analysis will he sealed and placed in iced stark, A <br /> photo ionizing organic vapor meter(()VM)will be used during sampling to detect potential <br /> hydrocarbon concentrations in the foil samples, Two soil samples from each boring will be <br /> analyzed for TPHg using FPA Method 8015(modified)and.for BTEX using EPA Method 8020. <br /> PROPOSE <br /> The FRP called for construction of a 40•fi deep,2-in air sparging well new the northeast <br /> corner of the site with a 5-11 slotted interval from 35 to 40 ft. Based on our understanding of the <br /> site,we recommend a significantly different system. We propose to install two additional vapor <br /> extraction wells; one which would replace the proposed air sparging well near the northeast <br /> 40yA.P.} ��_ICL� �:Cr itf''n tr <br />