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WIGS t I- RN CI- OLOCIC 171- 1, ou IC1� I-, , INC <br /> 0 <br /> STANDARD OPERATING PROCEDURES <br /> RE ITOLLOW-STEM AUGER MONITOR WELL INSTALLATION AND DEVELOPMENT <br /> SOP-3 <br /> The boreholes for monitor wells are dnllLd using a truck-mountLd hollow-stem auger drill ng The <br /> diameter of the borehole will be a minimum of four inches larger than the outside, diamLtLr (013) of <br /> the casing when installing well scrLen The hollow-stem auger provides minimal intc,rruption of drilling <br /> v � <br /> while permitting soil sampling at desired intervals Soil samples are collLcted by hammering a <br /> conventional split-barrel sampler containing pre-cleaned 2-inch brass sample, tubes A geologist from <br />^� Western Geologic Resources continuously logs each bort holL during drilling and constantly c.hc,cks drill <br /> a <br /> cuttings for odors The sampler is rinsed between samples and slLam-clLancd with all other drilling <br /> equipment between borings to prLvent cross-contamination <br /> r <br /> Monitor wells are cased with threaded,factory-perforated and blank SchLdulL 40 PVC ThL pLrforated <br /> interval consists of slotted casing, generally 0 020-inch wide by 1 5-mch long slot swe, with 42 slots pLr <br /> foot A PVC cap is fastened to the bottom of the casing with stamlc ss steel screws, no solvents or <br /> cements are used Centering devices may be fastened to the casing to assure LVLn distribution of lillLr <br /> material and grout within the borLhole annulus The wLll casing is thoroughly washed and <br /> steam-cleaned prior to installation <br /> After setting the casing inside the hollow stem, sand or gravel filter material is poured into the annular <br /> space to fill from the bottom of the, boring to 1 foot above the pc.rforatLd mtcrval A 1- to 2-foot thick <br /> bentonite plug is placed above this filter material to prevent grout from infiltrating down into the, filtc,r <br /> material Neat cement,containing about 5%bentonite, is then tremiLd into the annular space from the, <br /> top of the bentonite plug to the surface A lockable PVC cap is placed on each wLllhLad Traffic-rated <br /> Christy boxes are installed around the wellhead for wells in parking lots and drrvLways whdL-,ILLI stove <br /> pipes are usually set over wellheads in landscaped areas <br /> After installation, the wells are thoroughly developed to rLmOVe residual drilling matLrials from thL <br /> wellbore,and to improve well performance by removing any fine matLrial in thL filter pack that can pass <br /> from the formation into the well Well development techniques used mclude pumping,bailing,surging, <br /> swabbing, jetting, flushing, and airlifting All development water is collectLd in 55-gallon drums for <br /> temporary storage, and,s then disposed of properly depending on analytic results To assure that cross- <br /> _ � <br /> contamination does not occur between wells during drilling and devLlopment,all devLlopment equipmLnt <br /> is steam-cleaned <br /> G y i <br /> •"'hHr <br /> 6 <br /> J TL� <br /> y� <br />