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1 <br />RFR ZE '94 01026PM NN.PCR - HRZ.I4RSTE <br />EQ-1006 <br />Sinclair Oil Corporation <br />P.8/16 <br />-4- October 9, 1990 <br />have a screened interval ranging from approximately 10 to 25 feet below grade. Screen length <br />or screened intervals may vary based upon contaminant conditions encountered in the field. The <br />wells will be constructed of 2 -inch diameter, Schedule 40 PVC riser pipe with a 2 -inch diameter, <br />0.020 -inch slot PVC well screen. The borehole annulus will be filled with silica sand as a filter <br />pack to approximately one foot above the top of the screen. The remaining annular space above <br />the seal will be grouted with a neat cement grout. Each vapor withdrawal well will be completed <br />at a depth of 2.5 feet below grade so as not to interfere with the operation of the service station. <br />Each extraction well head will utilize airtight fittings to connect the extraction well to a horizontal <br />vapor discharge line. Each vapor discharge line will be installed at a depth of 2.5 feet below <br />grade in trenches. The vapor discharge line will then lead to a manifold that connects all three <br />extraction lines to a blower unit. Each vapor discharge line will have a regulator valve at the <br />manifold to adjust the system operation, and will be equipped with a vacuum gauge to monitor <br />the system operation. A sampling port will also be installed at each well head to allow monitoring <br />of vapor concentrations. <br />The wells will be manifolded to a surface - mounted regenerative blower. The vapors from the <br />blower will be discharged through a 2 -inch diameter stack with a final emission point at least 10 <br />feet above the ground surface. <br />It should be noted that changes in air emission regulations may require operation of the system <br />with vapor discharge treatment. If required, treatment is anticipated to consist of an activated <br />carbon filtration system. <br />The ultimate effectiveness of in -situ soil venting at the site cannot be predicted with any certainty. <br />However, it is likely that the granular nature of the soils will permit rapid volatilization of <br />hydrocarbon contaminants in the soils, although some residual contamination consisting primarily <br />of less volatile hydrocarbons will remain even after the system has been in operation for some <br />time. Operation of the system will likely continue for a period of one to two years. <br />Page 55 <br />Bwnun <br />