|
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 s k-barrel saris
<br /> Pl Pyr
<br /> containing pre-cleaned 2-4nch-diameter 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 drill A cap is quickly secured to the top of the vial. The vial is then
<br /> cuttings for indications of both the first recognizable inverted and gently tapped to see Hair bubbles are present. If
<br /> occurrence of groundwater and volatile hydrocarbons using none are present,the vial is labeled and refrigerated for
<br /> either a portable pLhotoionizabon detector,flame ionization dekivery,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 equipmentbetween borings to minimize the potential for of analysis requested,and the samplers name.
<br /> cross-corteminstioh. .
<br /> I
<br /> r; For quality control purposes,a duplicate water sample is
<br /> Monitoring wells are cased with threaded,factory-perforated collected from each wall. 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 slotted casing,generally with 0.020-inch wide by 1.5winch prepared at the laboratory,is placed in the transport cooler. it
<br /> long slots,with 42 slots per foot. A PVC cap may be secured is labeled similar to the well samples,remains in the cooler
<br /> to the bottom of th'i casing with stainless steel screws;no during transport,and is analyzed by the laboratory along with _
<br /> solvents or cements are used. Centering devices maybe - —the-groundwater samples"-Iri laddit�ion.e`fiild blink-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 after a pump or bailer i
<br /> casing is thoroughly washed and/or steam cleaned,or may be has been either steam cleaned or property washed,prior to use
<br /> purchased as pre-clsaned,prior to installation. in the next well,and is analyzed along with the other samples.
<br /> F; The field blank analysis demonstrates the effectiveness of the S
<br /> After setting the casing inside the hollow-stem auger,sand or in-field cleaning procedures to prevent crass-contamination.
<br /> gravel fitter material is poured into the annular space to fill from
<br /> boring bottom to generally 1 foot above the perforated interval. - To minimize the potential for cross-contamination between
<br /> A 1-to 2-toot 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 filter pack Either neat dedicated to a well is either steam cleaned or properly washed '
<br /> cement,containing!about S percent bentonite,or sand-cement between use. As a secondary precautionary measure,wells
<br /> graut is then tremmied into the annular space from the top of are sampled in order of least to highest concentrations as
<br /> the bentonite plug to near surface. A traffic-rated vault is established by available previous analytical data. l
<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 weekends 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 field,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 development techniques used `
<br /> may include pumping,surging,bailing,swabbing,jetting, SOP . 11 2
<br /> flushing,and air-lifting. All development water is collected MEASURING LIQUID LEVELS USiNG
<br /> either in drums or tanks for temporary storage,and property WATER LEVEL METER OR INTERFACE
<br /> disposed of depending on laboratory analytical results. To PROBE
<br /> minimize the potential for cross-contamination between wells,
<br /> all development equipment is either steam cleaned or properly Field equipment used for liquid4evel gauging typically includes
<br /> washed prior to use. f=ollowing development,the well is the measuring instrument(water-level meter or interface probe) I
<br /> allowed to stand undisturbed for a minimum of 24 hours before and product bailer(s). The field kit also includes cleaning i1
<br /> its first sampling. !' supplies(buckets,solution,spray battles,and deionized water)
<br /> to be used in cleaning the equipment between wells.
<br /> SOP - 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 cord
<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 of groundwater. hundredths of a foot)is used to determine the distance
<br /> When required,purging will continue until either the discharge between the probe and and the maridng on the cord. This
<br /> water temperature;conductivity,or pH stabilize,a mwdmum of measurement is then recorded on the liquid4evei data sheet as
<br /> ten wafted-casing volumes 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 interface probe to measure liquid
<br /> in the well recovers'to at least 80 percent of its static level. levels,the probe is first electricallygrounded 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 well,then case.
<br /> the bailer is usua0`Teflon,"but the bladder pump is PVC with
<br /> a polypropylene bladder. In general and depending on the
<br /> intended laboratory'analysis.40-milliliter glass,volatile organic
<br /> SOP Monitoring Wells
<br /> iii'
<br />
|