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1. Participation in state and federal laboratory
<br /> accreditation/certification programs; 3. Standard operating procedures describing routine
<br /> and periodic instrument maintenance;
<br /> 2. Participation in both U.S.EPA Performance
<br /> Evaluation studies(WS and WP studies)and inter-
<br /> laboratory performance evaluation programs;
<br /> 4. "Out-of-Control"/Corrective Action documentation GROUNDWATER PURGING AND SAMPLING
<br /> procedures;and,
<br /> Prior to water sampling,each well is purged by evacuating a
<br /> 5. Multi-level review of raw data and client reports. minimum of three wetted well-casing volumes of
<br /> groundwater. When required,purging will continue until
<br /> either the discharge water temperature,conductivity,or pH
<br /> SOP-6 stabilize,a maximum of ten wetted-casing volumes of
<br /> HOLLOW-STEM AUGER MONITORING WELL groundwater have been recovered,or the well is bailed dry.
<br /> INSTALLATION AND DEVELOPMENT When practical,the groundwater sample should be collected
<br /> when the water level in the well recovers to at least 80
<br /> Boreholes for monitoring wells are drilled using a truck- percent of its static level.
<br /> mounted,hollow-stem auger drill rig. The borehole diameter
<br /> will be a minimum of 4 inches larger than the outside The sampling equipment consists of either a'Teflon"bailer,
<br /> diameter of the casing when installing well screen. The PVC bailer,or stainless steel bladder pump with a"Teflon"
<br /> hollow-stem auger provides minimal interruption of drilling bladder. If the sampling system is dedicated to the well,then
<br /> while permitting soil sampling at desired intervals. Soil the bailer is usually'Teflon,"but the bladder pump is PVC
<br /> samples are collected by either hammering(with a 140- with a polypropylene bladder. In general and depending on
<br /> pound drop hammer)or hydraulically pushing a conventional the intended laboratory analysis,40-milliliter glass,volatile
<br /> split-barrel sampler containing pre-cleaned 2-inch-diameter organic analysis(VOA)vials,with"Teflon"septa,are used as
<br /> brass tubes. A geologist or engineer from Apex Envirotech, sample containers.
<br /> Inc.,continuously logs each borehole during drilling and
<br /> constantly checks drill cuttings for indications of both the first The groundwater sample is decanted into each VOA vial in
<br /> recognizable occurrence of groundwater and volatile such a manner that there is no meniscus at the top of the
<br /> hydrocarbons using either a portable photoionization vial. A cap is quickly secured to the top of the vial. The vial
<br /> detector,flame ionization detector,or an explosimeter. The is then inverted and gently tapped to see if air bubbles are
<br /> sampler is rinsed between samples and either steam cleaned present. If none are present,the vial is labeled and
<br /> or washed with all other drilling equipment between borings refrigerated for delivery,under strict chain-of-custody,to the
<br /> to minimize the potential for cross-contamination. analytical laboratory. Label information should include a
<br /> unique sample identification number,job identification
<br /> Monitoring wells are cased with threaded,factory-perforated number,date,time,type of analysis requested,and the
<br /> and blank Schedule 40 PVC. The perforated interval sampler's name.
<br /> consists of slotted casing,generally with 0.020-inch wide by
<br /> 1.5-inch long slots,with 42 slots per foot. A PVC cap may be For quality control purposes,a duplicate water sample is
<br /> secured to the bottom of the casing with stainless steel collected from each well. This sample may also be analyzed
<br /> screws;no solvents or cements are used. Centering devices or put on hold at the laboratory. When required,a trip blank,
<br /> may be fastened to the casing to ensure even distribution of prepared at the laboratory,is placed in the transport cooler.
<br /> filter material and grout within the borehole annulus. The It is labeled similar to the well samples,remains in the cooler
<br /> well casing is thoroughly washed and/or steam cleaned,or during transport,and is analyzed by the laboratory along with
<br /> may be purchased as pre-cleaned,prior to installation. the groundwater samples. In addition,a field blank may be
<br /> prepared in the field when sampling equipment is not
<br /> After setting the casing inside the hollow-stem auger,sand or dedicated. The field blank is prepared after a pump or bailer
<br /> gravel filter material is poured into the annular space to fill has been either steam cleaned or properly washed,prior to
<br /> from boring bottom to generally 1 foot above the perforated use in the next well,and is analyzed along with the other
<br /> interval. A 1-to 2-foot thick bentonite plug is set above this samples. The field blank analysis demonstrates the
<br /> filter material to prevent grout from infiltrating the filter pack. effectiveness of the in-field cleaning procedures to prevent
<br /> Either neat cement,containing about 5 percent bentonite,or cross-contamination.
<br /> sand-cement grout is then tremmied into the annular space
<br /> from the top of the bentonite plug to near surface. A traffic- To minimize the potential for cross-contamination between
<br /> rated vault is installed around each wellhead for wells located wells,all well development and water sampling equipment
<br /> in parking lots or driveways,while steel"stovepipes"are not dedicated to a well is either steam cleaned or properly
<br /> usually set over wellheads in landscaped areas. washed between use. As a secondary precautionary
<br /> measure,wells are sampled in order of least to highest
<br /> After installation,the wells are thoroughly developed to concentrations as established by available previous
<br /> remove residual drilling materials from the wellbore,and to analytical data.
<br /> improve well performance by removing fine material from the
<br /> filter pack that may pass into the well. Well development In the event the water samples cannot be submitted to the
<br /> techniques used may include pumping,surging,bailing, analytical laboratory on the same day they are collected(e.g.,
<br /> swabbing,jetting,flushing,and air-lifting. All development due to weekends or holidays),the samples are temporarily
<br /> water is collected either in drums or tanks for temporary stored until the first opportunity for submittal either on water
<br /> storage,and property disposed of depending on laboratory ice in a cooler,such as when in the field,or in refrigerator at
<br /> analytical results. To minimize the potential for cross- Apex's office.
<br /> contamination between wells,all development equipment is
<br /> either steam cleaned or properly washed prior to use. SOP-8
<br /> Following development,the well is allowed to stand ROTARY DRILLING MONITORING WELL INSTALLATION
<br /> undisturbed for a minimum of 24 hours before its first AND DEVELOPMENT
<br /> sampling.
<br /> Boreholes for monitoring wells may be drilled using truck-
<br /> SOP-7 mounted drill rigs capable of air-and mud-rotary drilling,and
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