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4. "Out-of-Control"ICorrective Action documentation bailer,or stainless steel bladder pump with a"Teflon"bladder. If the
<br /> procedures;and, sampling system is dedicated to the well,then the bailer is usually
<br /> "Teflon,"but the bladder pump is PVC with a polypropylene bladder.
<br /> 5. Multi-level review of raw data and client reports. In general and depending on the intended laboratory analysis,40-
<br /> milliliter glass,volatile organic analysis(VOA)vials,with Teflon"
<br /> septa,are used as sample containers.
<br /> SOP-6
<br /> HOLLOW-STEM AUGER MONITORING WELL INSTALLATION The groundwater sample is decanted into each VOA vial in such a
<br /> AND DEVELOPMENT manner that there is no meniscus at the top of the vial. A cap is
<br /> quickly secured to the top of the vial. The vial is then inverted and
<br /> Boreholes for monitoring wells are drilled using a truck-mounted, gently tapped to see if air bubbles are present. If none are present,
<br /> hollow-stem auger drill rig. The borehole diameter will be a minimum the vial is labeled and refrigerated for delivery,under strict chain-of-
<br /> of 4 inches larger than the outside diameter of the casing when custody,to the analytical laboratory. Label information should
<br /> installing well screen. The hollow-stem auger provides minimal include a unique sample identification number,job identification
<br /> interruption of drilling while permitting soil sampling at desired number,date,time,type of analysis requested,and the sampler's
<br /> intervals. Soil samples are collected by either hammering(with a name.
<br /> 440-pound drop hammer)or hydraulically pushing a conventional
<br /> split-barrel sampler containing pre-cleaned 2-inch-diameter brass For quality control purposes,a duplicate water sample is collected
<br /> tubes. A geologist or engineer from Apex Envirotech,Inc., from each well. This sample may also be analyzed or put on hold at
<br /> continuously logs each borehole during drilling and constantly the laboratory. When required,a trip blank,prepared at the
<br /> checks drill cuttings for indications of both the first recognizable laboratory,is placed in the transport cooler. It is labeled similar to
<br /> occurrence of groundwater and volatile hydrocarbons using either a the well samples,remains in the cooler during transport,and is
<br /> portable photoionization detector,flame ionization detector,or an analyzed by the laboratory along with the groundwater samples. In
<br /> explosimeter. The sampler is rinsed between samples and either addition,a field blank may be prepared in the field when sampling
<br /> steam cleaned or washed with all other drilling equipment between equipment is not dedicated. The field blank is prepared after a pump
<br /> borings to minimize the potential.for.cross-contaminadon, or bailer has been either steam cleaned or properly washed,prior to
<br /> use in the next well,and is analyzed along with the other samples.
<br /> Monitoring wells are cased with threaded,factory-perforated and The field blank analysis demonstrates the effectiveness of the in-field
<br /> blank Schedule 40 PVC. The perforated interval consists of slotted cleaning procedures to prevent cross-contamination.
<br /> casing,generally with 0.020-inch wide by 1.5-inch long slots,with 42
<br /> slots per foot. A PVC cap may be secured to the bottom of the To minimize the potential for cross-contamination between wells,all
<br /> casing with stainless steel screws;no solvents or cements are used. well development and water sampling equipment not dedicated to a
<br /> Centering devices may be fastened to the casing to ensure even well is either steam cleaned or properly washed between use. As a
<br /> distribution of filter material and grout within the borehole annulus. secondary precautionary measure,wells are sampled in order of
<br /> The well casing is thoroughly washed and/or steam cleaned,or may least to highest concentrations as established by available previous
<br /> be purchased as pre-cleaned,prior to installation. analytical data.
<br /> After setting the casing inside the hollow-stem auger,sand or gravel In the event the water samples cannot be submitted to the analytical
<br /> filter material is poured into the annular space to fill from boring laboratory on the same day they are collected(e.g.,due to weekends
<br /> bottom to generally 4 foot above the perforated interval. A 1-to 2- or holidays),the samples are temporarily stored until the first
<br /> foot thick bentonite plug is set above this filter material to prevent opportunity for submittal either on water ice in a cooler,such as
<br /> grout from infiltrating the filter pack. Either neat cement,containing when in the field,or in refrigerator at Apex's office. I
<br /> about 5 percent bentonite,or sand-cement grout is then tremmied
<br /> into the annular space from the top of the bentonite plug to near SOP-8 I
<br /> surface. A traffic-rated vault is installed around each wellhead for ROTARY DRILLING MONITORING WELL INSTALLATION AND
<br /> wells located in parking lots or driveways,while steel"stovepipes" DEVELOPMENT i
<br /> are usually set over wellheads in landscaped areas.
<br /> Boreholes for monitoring wells may be drilled using truck-mounted
<br /> After installation,the wells are thoroughly developed to remove drill rigs capable of air-and mud-rotary drilling,and continuous
<br /> residual drilling materials from the wellbore,and to improve well coring and/or drilling with tri-cane roller or fixed-blade drag bits.
<br /> performance by removing fine material from the filter pack that may Generally,rotary drilling is used when more conventional hollow-
<br /> pass into the well. Well development techniques used may include stem auger drilling either is or becomes infeasible. Various drilling
<br /> pumping,surging,bailing,swabbing,jetting,flushing,and air-lifting. fluids(mud or air),used to keep the borehole from caving and to j
<br /> All development water is collected either in drums or tanks for remove drill cuttings,are chosen according to the nature of the soils
<br /> temporary storage,and properly disposed of depending on and/or geologic formations expected to be encountered as well as
<br /> laboratory analytical results. To minimize the potential for cross- the monitoring program. Samples may be collected directly from
<br /> contamination between welts,all development equipment is either cores. A geologist or engineer from Apex Envirotech,Inc.,
<br /> steam cleaned or properly washed prior to use. Following continuously logs each boring during drilling and checks returned
<br /> development,the well is allowed to stand undisturbed for a minimum drill cuttings for indications of both the first recognizable occurrence
<br /> of 24 hours before its first sampling. of groundwater and volatile hydrocarbons,using either a portable i
<br /> photoionization detector(PID),flame ionization detector,or
<br /> SOP-7 explosimeter. All drilling equipment is either steam cleaned or
<br /> GROUNDWATER PURGING AND SAMPLING washed between borings to minimize the potential for cross- I
<br /> contamination.
<br /> Prior to water sampling,each well is purged by evacuating a
<br /> minimum of three wetted well-casing volumes of groundwater. Frequently,hollow-stem augers are used to drill and sample to either
<br /> When required,purging will continue until either the discharge water a minimum depth or auger refusal. In such cases,the augers may
<br /> temperature,conductivity,or pH stabilize,a maximum of len wetted- be left in place as temporary surface casing,with the center plug
<br /> casing volumes of groundwater have been recovered,or the well is removed and drilling/coring carried out through the augers, s
<br /> bailed dry. When practical,the groundwater sample should be Alternatively,a shallow conductor casing,or surface casing,may be
<br /> collected when the water level in the well recovers to at least 80 set by drilling to a desired depth with a large-diameter bit,then
<br /> percent of its static level. setting the casing and proceeding with the drilling/coring. After total
<br /> drill depth(TD)is reached,the borehole may be logged by
<br /> The sampling equipment consists of either a"Teflon"bailer, PVC geophysical means or hydraulically tested. If casing is not set to the
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