ARCHIVED REPORTS XR0009905 - Laserfiche WebLink

Home Browse Search

s r} Results of Groundwater Pumping Tests - 152 East 11th Street, Tracy Page 5 affecting the subsurface Specifically, they should not be used for reaching a conclusion as to whether or not groundwater affected by hydrocarbons that may have been released into the subsurface on the 152 E 11 th Street site has, or has not, coalesced with fuel components released into the subsurface on the Beacon Station site However, when taken together, the available geotechnical, geocherrucal and hydrological data support an interpretation that gasoline that leaked from underground tanks, or the associated piping, that were on the 152 East 11th Street property has moved downgradrent, from the point where those tanks and piping were formerly located, toward the East 11th Street frontage of the site and has probably nugrated some distance northward under the street GROUNDWATER PUMPING TESTS Groundwater pumping tests were performed on December 21st and 28th 1993 and on January 18th 1994 Pumped Well and Observation Well Well NAV 6 was used as the pumped well for the groundwater pumping tests and Well NAV 3 was used as an observation well The locations of these wells are shown on Figure 2 Well NAV 6 was selected to be the pumped well because 1 ) repeated rounds of groundwater sampling have shown that water in this well is not contaminated and it could be used as the pumped well without large quantities of contaminated water having to be managed and disposed, 2 ) review of the logs for all of the wells installed in the area showed the stratigraphy at NAV 6 to be similar to that at other locations within the study area including locations within the area beneath the 152 East 11 th Street property that is affected by gasoline, and 3 ) it is possible to run instrument-signal conductors from NAV 6 to a suitable observation well (NAV 3) without having to cross a heavily trafficked street The depth to static groundwater in both Wells NAV 6 and NAV 3 is about 8 ft NAV 3 is located 86 00 ft to the East of NAV 6 The logs and construction details for both of these wells are included in Appendix A Pumping Trials and Equipment Selection As noted above, the tests were performed by pumping groundwater from Well NAV 6 and observing the resulting drawdown to that well and in Well NAV 3 The pumped water was discharged to the sanitary sewer via an existing sewer connection located close to Well NAV 6