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soil sampling at desired intervals. Soil samples are collected analysis(VOA)vials,with"Teflon"septa,are used as sample-
<br /> by either hammering(with a 140-pound drop hammer)or containers.
<br /> hydraulically pushing a conventional split-barrel sampler
<br /> containing pre cieaned 2-inch4ameter brass tubes. A The groundwater sample is decanted into each VOA vial in
<br /> geologist or engineer from Apex Envirotech,Inc.,continuously such a manner that there is no meniscus at the top of the vial.
<br /> logs each borehole during drilling and constantly checks drift A cap is quickly secured to the top of the vial. The vial is then
<br /> cuttings for indications of beth the first recognizable inverted and gently tapped to see if air bubbles are present. If
<br /> occurrence of groun&,ater and volatile hydrocarbons using none are present,the vial is labeled and refrigerated for
<br /> either a portable photoicnization detector,flame ionization delivery,under strict chain-of-custody,to the analytical
<br /> detector,or an explosimeter. The sampler is rinsed between laboratory. Label information should include a unique sample
<br /> samples and either steam cleaned or washed with all other identification number,job identification number,date,time,type
<br /> drilling equipment bet.v9en borings to minimize the potential for of analysis requested,and the sampler's name.
<br /> cross-contamination.
<br /> For qual'ty control purposes,a duplicate water sample is
<br /> Ivlonitoring wells are cased with threaded,factory-perforated collected from each well. This sample may also be analyzed or
<br /> and blank Schedule 40 PVC. The perforated interval consists put on hold at the laboratory. When required,a trip blank
<br /> of slatted casing,generally with 0.0200.inch wide by 1.5-inch prepared at the laboratory,is placed in the transport cooler. It
<br /> long slats,with 42 slots per fact. A PVC cap may be secured is labeled similar to the well samples,remains in the cooler
<br /> to the bottom of the casing wit h stainless steel screws;no during transport,and is analyzed by'he laboratory along with
<br /> solvents or cements are used. Centering devices may be the groundwater samples. In addition,afield blank may be
<br /> fastened to the casing to ensure even distribution of filter prepared in the field when sampling equipment is not
<br /> material and grout within the borehole annulus. The well dedicated. The field blank is prepared alter a pump or bailer
<br /> casing is thoroughly washed and/or steam cleaned,or may be has been either steam cleaned or properly washed.prior to use
<br /> purchased as pre-cleaned,prior to installation. in the next well,and is analyzed along with the other samples.
<br /> The field blank analysis demonstrates the effectiveness of the
<br /> After setting the casing inside the hollow-stem auger,sand or in-field cleaning procedures to prevt-rt cross-contamination.
<br /> gravel finer material is poured into the annular space to fill from
<br /> boring bottom to generally 1 fact above the perforated interval. To minimize the potential for cross-contamination between
<br /> A 1-to 2-foot thick bentonite plug is set above this filter material wells,all well development and water sampling equipment not
<br /> to prevent grout from infiltrating the fitter pack Either neat dedicated to a well is either steam cleaned or properly washed
<br /> cement,containing about 5 percent bentonite,or sand-cement between use. As a secondary precautionary measure,welts
<br /> grout is then tremmied into the annular space from the top of are sampled in order of leas:to highest concentrations as
<br /> the bentonite plug to near surface. A traffic-rated vault Is established by available previous analytical data.
<br /> installed around each wellhead for wells located in parking lots
<br /> or driveways,while steel"stovepipes'are usually set over In the event the water samples cannot be submitted to the
<br /> wellheads in landscaped areas. analytical laboratory on the same day they are collected(e.g.,
<br /> due to wsekends or holidays),the samples are temporarily
<br /> After installation,the wells are thoroughly developed to remove stored until the first opportunity for submittal either on water ice
<br /> residual drilling materials from the wellbore,and to improve well in a cooler,such as when in the Feld,or in refrigerator at
<br /> performance by removing fine material from the filter pack that Apex's office.
<br /> may pass into the well. Well de•.,elopment techniques used
<br /> may include pumping,surging,bailing,swrabbing,jetting. SOP
<br /> flushing,and air-lifting. All development water is collected M EAS U R I N G LIQ U 1 D LEVELS USING
<br /> either in drums or tanks for temporary storage,and properly WATER LEVEL'METER OR INTERFACE
<br /> disposed of depending on laboratory analytical results. To PROS E
<br /> minimize the potential far cross-contamination between wells,
<br /> all development equipment is either steam cleaned or properly Field equipment used for liquid-level gauging typically includes
<br /> washed prior to use. Following development,the well is the measuring instrument(water-level meter or interface probe)
<br /> allowed to stand undisturbed for a minimum of 24 hours before and product bailer(s). The field kct also includes cleaning
<br /> its first sampling. supplies(buckets.solution,spray battles,and deionized water)
<br /> SOP to be used in cleaning the equipment between wells.
<br /> - 7
<br /> GROUNDWATER PURGING AND Prior to measurement,the instrument tip is lowered into the well
<br /> SAMPLING until it touches bottom. Using the previously established top-of-
<br /> casing or top-of-box(i.e..wellhead vault)point,the probe card
<br /> Prior to water sampling,each well is purged by evacuating a (or halyard)is marked and a measuring tape(graduated In
<br /> minimum of three wetted well-casing volumes ofgroundwater. hundredths of a foot)is used to determine the distance
<br /> When required,purging will continue until either the discharge between the probe end and the marring on the cord. This
<br /> water temperature,conductivity,or pH stabilize,a maximum of measurement Is then recorded an the liquid-level data sheet as .
<br /> ten w ded-casind vatumes of groundwater have been the'Measured Total Depth'of the well.
<br /> recovered,or the well is bailed dry. When practical,the _
<br /> groundwater sample should be collected when the water level When necessary in using the Interi`ace probe to measure liquid
<br /> In the welt recovers to at least 80 percent of its static level. levels,the probe Is first electrically grounded to either the metal
<br /> stove pipe or another metal object nearby. When no ground Is
<br /> The sampling equipment consists of either a'Teflon'bailer, available,reproducible measurements can be obtained by
<br /> PVC bailer,or stainless steel bladder pump with a'Teflon" clipping the ground lead to the handle of the interface probe
<br /> bladder. If the sampling system is dedicated to the wrell,then Casa.
<br /> the bailer is usuaily'Teflon,'but the bladder pump Is PVC with
<br /> a polypropylene bladder. In general and depending on the
<br /> intended laboratory analysis,40-mllifiter glass,volatile organic
<br /> SOP- Monitoring Wefts
<br />
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