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�5 SAMPLE IDENTIFICATION AND CIIAIN-OF-CUSTODY are sampled in order of lowest to highest concentrations as established by available ' PROCEDURES previous analytical data SOP-4 Sample identification and chain-of-custody procedures ensure sample integrity,and In the event the water samples cannot be submitted to the analytical laboratory on ment sample possession from the time of collection to its ultimate disposal the same day they are collected(e g.,due to weekends or holidays),the samples are sample container submitted for analysis is labeled to identify the lob number temporarily stored until the first opportunity for submittal either on ice in a cooler e,time of sample collection,a sample number unique to the sample,any name(s) such as when in the field,or in a refrigerator of on-site personnel and any other pertinent field observations also recorded on the field excavation or boring log. MEASURING LIQUID LEVELS USING A WATER LEVEL INDICATOR OR INTERFACE PROBE Cham-of-custody forms are used to record possession of the sample from time of SOP-12 collection to its arrival at the laboratory During shipment,the person with custody Field equipment used For liquid-level gauging typically includes the measuring of the samples Will relinquish them to the neNt person by signing the sham-of- probe(water level or interface) and a clean product bailer(s) The field kit also custody form(s) and noting the date and time The sample-control officer at the includes cleaning supplies(buckets TSP spray bottles,and detonized water)to be laboratory will verify sample integrity, correct preservation, confirm collection in used in cleaning the equipment between wells the proper contamer(s) and ensure adequate volume for analysis Prior to measurement,the probe tip is lowered into the well until it touches bottom If these conditions are met, the samples will be assigned unique laboratory log Using the previously established top-of-casing or top-of-box(i a wellhead vault) numbers for identification throughout analysis and reporting. The log numbers will point, the probe cord(or halyard) is marked and a measuring tape(graduated in be recorded on the chain-o custody forms and to the legally-required log boob hundredths of a foot)is used to determine the distance between the probe end and maintained in the laboratory The sample description,date received,clients name the marking on the cord This measurement is then recorded on the hquid-level data and any other relevant information will also be recorded sheet as the Measured Total Depth"of the well LABORATORY ANALYTICAL QUALITY ASSURANCE AND CONTROL When necessary in using the interface probe to measure liquid levels the probe is SOP-5 first electrically grounded to either the metal stove pipe or another metal object In addition to routine instrument calibration, replicates, spikes, blanks spiked nearby When no ground is available reproducible measurements can be obtained blanks and certified reference materials are routinely analyzed at method-specific by clipping the ground lead to the handle of the interface probe case frequencies to monitor precision and bras Additional components of the iaboratory Quality Assurance/Quality Contra]program include The probe tip is then lowered into the well and submerged in the groundwater An oscillating(beeping)tone indicates the probe is in water The probe is slowly raised 1 Participation in state and federal laboratory accreditation/certification until either the oscillating tone ceases or becomes a steady tone In either case this programs, is the depth-to-water (DTW) indicator and the DTW measurement is made 2 Participation in both U S EPA Performance Evaluation studies(WS and WP accordingly The steady tone indicates floating hydrocarbons In this case, the studies)and inter laboratory performance evaluation programs probe as slowly raised until the steady tone ceases. This is the depth-to-product 3 Standard operating procedures describing routine and periodic instrument (DTP) indicator and the measurement of DTP is recorded A corrected depth to maintenance groundwater to account for floating hydrocarbons can be calculated by using the 4 "Out-of-Control"!Corrective Action documentation procedures,and, following formula Multi-level review of raw data and client reports CDTW=DTW-(SP G-%LHT) 46OUNDWATER PURGING AND SAMPLING CDTW=Corrected depth to groundwater SOP-7 DTW y Measured depth to groundwater Prior to water sampling, each well is purged by evacuating a minimum of three SP G=Specific gravity unweathered gasoline= 0 75 diesel -0 80 wetted well-casing volumes of groundwater When requirt d,purging will continue LHT=Measured liquid hydrocarbon thickness until either the discharge water temperature conductnny,or pH stabilize to within 10%of previously measured values and a maximum often wetted casing�olumes The corresponding groundwater elevation is the difference between a previously of groundwater have been recovered,or the well is bailed dry When practical the determined well reference elevation dnd either the depth to groundwater or the groundwater sample should be collected when the water level in the well recovers to corrected depth to groundwater at least 80 percent of its static level Field measurements, observations and procedures are noted The process of lowering and raising the probe must be repeated several times to ensure accurate measurements The DTW and DTP measurements are recorded on The sampling equipment consists of a clean bailer or stainless steel bladder pump the liquid-level data sheet When floating product is indicated by the probes with a"Teflon"bladder If the sampling system is dedicated to the well, then the response,a product bailer is lowered partially through the product water mterfaie to bailer is usually'"Ceflon,"but the bladder pump may be PVC with a polypropylene confirm the product on the water surface and as further indication of product bladder Sample container type preservation,and volume depends on the intended thickness, particularly in cases where the product layer is quite thin Either this analyses measurement or the difference between DTW and DTP is recorded on the data sheet as"product thickness The groundwater sample is decanted into each VOA vial in such a manner that there is no meniscus at the top of the vial A cap is quickly secured to the top of the In order to avoid cross-contamination of wells during the liquid-level measurement vial The vial is then inverted and gently tapped to see if air bubbles are present. If process, wells are measured in the order of clean' to dirty' (where such none are present,the vial as labeled and refrigerated for delivery,under strict cham- information is available) In addition all measurement equipment is cleaned with of-custody,to the analytical laboratory Label information should include a unique TSP or similar solution and thoroughly rinsed with deionized water before use sample identification number, lob identification number date time, and the between measurements in respective wells and at the completion of the days sampler's initials activities For quality control purposes, a duplicate water sample may be collected from a well When required,a trip blank is prepared at the laboratory and placed in the transport cooler It is labeled similar to the well samples,remains in the cooler during transport, and is analyzed by the laboratory along with the groundwater samples. In addition, a field blank may be prepared in the field when sampling equipment is not dedicated The field blank is prepared after a pump or bailer has been either steam cleaned or properly washed,prior to use in the next well and is � lyzed along with the other samples. The field blank analysis demonstrates the etiveness of m-fieid cleaning procedures to prevent cross-contamination To mmunize the potential for cross-contamination between wells, all well , development and water sampling equipment not dedicated to a well rs enther steam cleaned or properly washed between use As a second precautionary measure wells