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performance by removing fine material from th w pack that may marking on the cord. TV easurement is then recorded on the
<br /> pass into the well. Well development technigw sed may include liquid-level data sheet aj "Measured Total Depth'of the well.
<br /> pumping, surging,bailing,swabbing, jetting,flttsi ng,and air-lifting. When necessary in using.ne interface probe to measure liquid levels,
<br /> All development water is collected either in drums or tanks for the probe is first electrically grounded to either the metal stove pipe or
<br /> temporary storage,and property disposed of depending on laboratory another metal object nearby. When no ground is available,
<br /> analytical results. To minimize the potential for cross-contamination reproducible measurements can be obtained by clipping the ground
<br /> between wells, all development equipment is either steam cleaned or lead to the handle of the interface probe case.
<br /> properly washed prior to use. Following development, the well is
<br /> allowed to stand undisturbed for a minimum of 24 hours before its first The probe tip is then lowered into the well and submerged in the
<br /> sampling. groundwater. An oscillating (beeping) tone indicates the probe is in
<br /> water. The probe is slowly raised until either the oscillating tone
<br /> SOP-7 ceases or becomes a steady tone. In either case,this is the depth-to-
<br /> GROUNDWATER PURGING AND SAMPLING water(DTW)indication and the DTW measurement is made
<br /> accordingly. The steady tone indicates floating liquid hydrocarbons
<br /> Prior to water sampling, each well is purged by evacuating a minimum (FLH). In this case,the probe is slowly raised until the steady tone
<br /> of three wetted well-casing volumes of groundwater. When required, ceases. This is the depth-to-product(DTP)indication and the DTP
<br /> purging will continue until either the discharge water temperature, measurement is made accordingly.
<br /> conductivity,or pH stabilize, a maximum of ten wetted-casing volumes The process of lowering and raising the probe must be repeated
<br /> of groundwater have been recovered, or the well is bailed dry. When several times to ensure accurate measurements. The DTW and DTP
<br /> practical,the groundwater sample should be collected when the water measurements are recorded on the liquid-level data sheet. When
<br /> level in the well recovers to at least 80 percent of its static level. FLH are indicated by the probe's response, a product bailer is lowered
<br /> The sampling equipment consists of either a'Teflon'bailer, PVC partially through the FLH-water interface to confirm the FLH on the
<br /> bailer,or stainless steel bladder pump with a'Teflon'bladder. If the water surface and as further indication of the FLH thickness,
<br /> sampling system is dedicated to the well, then the bailer is usually particularly in cases where the FLH layer is quite thin. This
<br /> 'Teflon,' but the bladder pump is PVC with a polypropylene bladder. measurement is recorded on the data sheet as'FLH thickness.'
<br /> In general and depending on the intended laboratory analysis, 40- In order to avoid cross-contamination of wells during the liquid-level
<br /> milliliter glass,volatile organic analysis (VOA)vials,with 'Teflon'septa, measurement process, wells are measured in the order of'clean'to
<br /> are used as sample containers. 'dirty'(where such information is available). In addition, a9
<br /> The groundwater sample is decanted into each VOA vial in such a measurement equipment is cleaned with solution and thoroughly
<br /> manner that there is no meniscus at the top of the vial. A cap is rinsed with deionized water before use,between measurements in
<br /> quickly secured to the top of the vial. The vial is then inverted and respective wells,and at the completion of the day's use.
<br /> gently tapped to see if air bubbles are present. If none are present,
<br /> the vial is labeled and refrigerated for delivery, under strict chain-of-
<br /> custody, to the analytical laboratory. Label information should include
<br /> a unique sample identification number,job identification number,
<br /> date, time,type of analysis requested,and the sampler's name.
<br /> For quality control purposes,a duplicate water sample is collected
<br /> from each well. This sample may also be analyzed or put on hold at
<br /> the laboratory. When required, a trip blank, prepared at the
<br /> laboratory, is placed in the transport cooter. It is labeled similar to the
<br /> well samples, remains in the cooler during transport,and is analyzed
<br /> by the laboratory along with the groundwater samples. In addition, a
<br /> field blank may be prepared in the field when sampling equipment is
<br /> not dedicated. The field blank is prepared after a pump or baiter has
<br /> been either steam cleaned or property washed, prior to use in the
<br /> next well, and is analyzed along with the other samples. The field
<br /> blank analysis demonstrates the effectiveness of the in-field cleaning
<br /> procedures to prevent cross-contamination.
<br /> To minimize the potential for cross-contamination between wells, all
<br /> well development and water sampling equipment not dedicated to a
<br /> well is either steam cleaned or properly washed between use. As a
<br /> secondary precautionary measure,wells are sampled in order of least
<br /> to highest concentrations as established by available previous
<br /> analytical data.
<br /> In the event the water samples cannot be submitted to the analytical
<br /> laboratory on the same day they are collected(e.g., due to weekends
<br /> or holidays),the samples are temporarily stored until the first
<br /> opportunity for submittal either on water ice in a cooler,such as when
<br /> in the field,or in refrigerator at Apex's office.
<br /> SOP-12
<br /> MEASURING LIQUID LEVELS USING WATER
<br /> LEVEL METER OR INTERFACE PROBE
<br /> Field equipment used for liquid-level gauging typically includes the
<br /> measuring instrument(water-level meter or interface probe) and
<br /> product bailer(s). The field Idt also includes cleaning supplies
<br /> (buckets,solution, spray bottles, and deionized water)to be used in
<br /> cleaning the equipment between wells.
<br /> Prior to measurement, the instrument tip is lowered into the well until it
<br /> touches bottom. Using the previously established top-of-casing or
<br /> top-of-box(i.e.,wellhead vault)point, the probe cord(or halyard)is
<br /> marked and a measuring tape(graduated in hundredths of a foot)is
<br /> used to determine the distance between the probe end and the
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