Laserfiche WebLink
5.1.1 Well Development and Sampling <br /> Well development and sampling will consist of the following a) survey of the top of the wellheads <br /> and measurement of depth to water in the wells to evaluate the direction and magnitude of the <br /> groundwater gradient beneath the site, b) purging and sampling of the existing and three new <br /> tmonitoring wells to evaluate the extent of petroleum hydrocarbons in the first-encountered groundwater <br /> at the site <br /> 5.2 Vadose Zone Remediation Evaluation <br /> To determine if the subsurface conditions are favorable to soil vapor extraction remediation, vapor <br /> extraction wells will be installed and a vapor extraction test performed The vapor extraction system <br /> will consist of a regenerative blower which will create a vacuum in a series of extraction points The <br /> vacuum will induce the flow of air from the surrounding soil into the extraction points The draw of <br /> ' air through the soil will cause the gasoline hydrocarbons to volatilize and flow into the wells The <br /> airstream will be directed through a closed system of piping into an enclosed compound containing a <br /> vapor treatment unit <br /> 5.2.1 Vapor Extraction Well Installation <br /> RESNA proposes to install a vapor extraction system to evaluate site remediation options The vapor <br /> ' extraction system, if viable, will volatilize hydrocarbons contained in the soils within the impacted <br /> area. The proposed evaluation system will consist of three extraction wells completed in three bonngs <br /> ' (extraction points) located as shown in Figure 5 Precise well locations may be modified depending <br /> upon the results of monitoring well drilling The three vapor extraction wells will be used to better <br /> ' define the lateral extent of impacted soil detected beneath the former dispenser island Based on <br /> estimated soil hydraulic conductivity, a minimum radius of influence of 22 5 feet is expected <br /> Each extraction point location will be constructed of 4-inch schedule 40 PVC slotted-screen, filter <br /> packed with an appropriately sized sand and blank casing to surface (Figure 7) The extraction wells <br /> will be screened from approximately 15 to 45 feet below grade A cement seal will be placed above <br /> ' the screen <br /> R-042992 TJL 8 <br />