ARCHIVED REPORTS_XR0005187 - Laserfiche WebLink

Home Browse Search

FOURTH QUARTER,2002 GROUNDWATER MONITORING REPORT AND ADDITIONAL ASSESSMENT REPORT JAMAR OIL DISTRIBUTION MARCH 2003 RECOMMENDATIONS Results of the additional investigation work described in this report provide definition of the lateral extent of hydrocarbon-impacted groundwater to the southeast but not to the east of the subject site Based on these results, two new monitoring wells are recommended at the locations shown on Figure 12 Both of these wells will allow for ongoing monitoring of the downgradient edge of the plume of hydrocarbon-impacted groundwater in both a southeasterly and easterly direction The new wells will also allow for a more accurate picture of the groundwater flow direction and gradient The proposed monitoring wells(MW-6 and MW-7) would be cluster wells constructed of two adjacent 2-inch diameter PVC casing with well screen extending from approximately 55-feet to 75-feet bgs in the `A' zone and 90-feet to 110-feet bgs in the `B' zone The upper screened interval would be placed to monitor the upper hydrogeologic unit, where groundwater was first encountered during the geoprobe investigation The lower screened interval would monitor the lower hydrogeologic unit identified during the CPT investigation A proposed well construction diagram is presented in Figure 13 GHH also proposes to install a 4-inch groundwater extraction well onsite The location for this well is shown on Figure 4 The groundwater extraction well will be used for groundwater pump testing at the site and will be screened in the upper groundwater zone GHH will also perform a sensitive receptor survey of all nearby water supply wells and those within 2,000-feet of the site, as well as surface water sources and other sensitive receptors in accordance with Section 2654(b)(2), Article 5, Chapter 16, Division 3, Title 23 of the California Code of Regulations. SCHEDULE The next quarterly monitoring event is scheduled for March 2003 The First Quarter 2003 Monitoring Report will be submitted by April 30, 2003 GHH is currently investigating the availability of a limited access drill ng to drill and complete the new monitoring wells Because both the locations are in the sidewalk on either side of Main Street, and there are overhead lines running along both sides of the street, a hmited access drill ng will be required GHH will install these new wells as well as the groundwater extraction well upon regulatory approval 12