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n�i 1 I� Horizon's 100 cubic yards of soil. All samples collected will be prepared and chilled for transport under !3 Chain-of-Custody protocol, and sent.rto estate-certified laboratory for the analyses requested. 4.0 GROUNDWATER GRAB Groundwater grab samples will be obtained from the excavation using a clean disposable bailer: The samples will be transferred to appropriate clean containers in such a manner as to minimize loss of volatile constituents, so that there,is no headspace in the sample container and air bubbles are not fi present in the samples when they are inverted. If air bubbles are found, resampling will occur. The samples will be refrigerated and transported promptly to the laboratory: r iM 5.0 SOIL BORING AND SOIL SAMPLINRS2JOCOL �I Soil borings and soil sampling will be performed under the supervision of a Horizon geologist. The ;I soil borings will be advanced using a truck-mounted hollow-stem auger drilling rig. To reduce the chances of cross-contamination between boreholes, downhole drilling equipment and sampling equipment will be steam cleaned between borings. To reduce cross-contamination between samples, the split-barrel sampler will be washed in a soap solution and double-rinsed between each sampling event. f Soil sampling will be conducted in accordance with ASTM 1586-84. Using this procedure, a split- barrel sampler (California-type sampler) lined with brass sample sleeves is driven into the soil at approximately 5-foot intervals by a 140 pound weight falling 30 inches. The number of blow counts { !, required to advance the sample 18 inches will be recorded at each sample interval. Upon recovery, a portion of the soil sample will be placed in a plastic bag and sealed for later screening with an hNu type organic�rvapor meter(OVM). Another portion of the soil sample will be 1, used for classification and description. Generally, the bottom sample will be sealed in the brass {, sleeve and stored at approximately"'4°C for transport to the laboratory. After the portion of the soil sample is placed in the plastic bag, it will be allowed to warm, inducing volatilization of petroleum hydrocarbon vapors. The headspace vapors will be screened with the OVM. The highest observed ` reading will be recorded on the boring logs. 6.0 GROUNDWATER DEPTH EVAMIATION Depth to groundwater will be measured to the nearest 0.01-foot using an electronic hand held water j ' level indicator. The tip of the probe will be examined to evaluate whether a product sheen is I j. present. 1, `l 7,0____ MONITORING WELL DEVELOPMENT 1 PURGING AND SAMPLING Following installation, the wells will be surged with a surge block to remove fines from the sand pack. After surging, ten casing volumes of groundwater will be purged from each well using a i bailer or centrifugal pump to remove sediment and enhance representative sample quality. Groundwater sampling events conducted after the initial well development will be preceded by [� purging a minimum of three welfl casing volumes as described above. Purge water will be monitored for the parameters temperature, pH, and conductivity until stabilized. Wells will recharge to 80% before sampling. If wells dewater, they will be allowed to recharge for a minimum of one hour prior to sampling. ; i + HORIZON ENVIRONMENTAL INC. • i; a N