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1 Horizon's Field Methods and Procedures 4.0 GROUNDWATER GRAD SA�LE_S 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 ' 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 ' 5.0 SOIL BQRING AND SOIL SAMPLING PROTOCOL Soil borings and soil sampling will be performed under the supervision of a Horizon geologist The 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 ' 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 vapor meter(OVM) Another portion of the soil sample will be 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 EVALUATION Depth to groundwater will be measured to the nearest 0 0]-foot using an electronic hand held water level indicator The tip of the probe will be examined to evaluate whether a product sheen is ' present 7.0 MONITORINGWELL DEVELOPMENT I 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 bailer or centrifugal pump to remove sediment and enhance representative sample quality Groundwater sampling events conducted after purging a minimum of three well casing volumes as described above will precede the initial well development 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 After the water levels within the wells stabilize, a sample will be collected with a clean disposable bailer Samples will be contained in airtight vials and then packed on ice and sent to the laboratory for analysis Groundwater samples will be transported to the laboratory and analyzed within the EPA-specified holding time for requested analysis HORIZON ENVIRONMENTAL INC