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4 V � <br /> Groundwater Monitoring Activities: There are 19 wells sampled quarterly at the site. <br /> Groundwater samples are analyzed for TPHc and BTEX. The historical data indicate the <br /> following: <br /> • Zone A -The average depth to groundwater is 34.5 ft bgs and the groundwater flow <br /> direction ranges from southwest to northeast at gradients ranging from 0.001 to 0.05. <br /> Dissolved phase petroleum detections are limited well MW-2. Well MW-5A and <br /> well MW-15 contain minimal LNAPL. The remaining wells generally do not contain <br /> petroleum constituents. <br /> • Zone B-The average depth to groundwater is 33.8 ft bgs and the groundwater flow <br /> direction is northwesterly at an approximately hydraulic gradient of 0.01. <br /> • Zone C-The average depth to groundwater is 54.5 ft bgs and the groundwater flow <br /> direction is easterly at an approximately hydraulic gradient of 0.004. Dissolved <br /> phase petroleum detections are infrequent and no benzene has been detected. <br /> • TPHc detections in Zones B and C are infrequent and random, ranging from non- <br /> detect to 2,800µg/L. Furthermore,the random detections of TPHc are relatively low <br /> concentration and are typically flagged by the laboratory as "hydrocarbon result <br /> partly due to individual peak(s) in quantitation range." Particularly random are the <br /> TPHc detections at well MW-14B,which is located over 320 feet laterally(northwest) <br /> from the pipeline, and cross-gradient to the groundwater flow direction. Again, <br /> TPHc concentrations at this depth(125 ft bgs) and lateral distance (320 feet) from the <br /> pipeline is not consistent with the behavior of weathered crude oil particularly in the <br /> low permeability soils encountered at the Site. <br /> 060223(33) A-5 CONESTOGA-ROVERS&ASSOCIATES <br />