Laserfiche WebLink
June 13,-2005 _ =. <br /> NOA-Project Niumber 'E05042A - _ " <br /> - oundwater lume rel - - <br /> gt p eased from the Tracy Defense Depot. Through several methods including <br /> `..`soil vapor extraction" and "pump and treat" there has been significant progress to stabilize the'... <br /> _plume with concentrations dropping from 50-100 micrograms per liter, down to 1"0 mg <br /> icro rams per <br /> liter:Pierce reported that there has been an agreement with numerous water quality control _ <br /> _ - <br /> regulatory agencies not to treat;groundwater east of Banta Road and to let the plume assimilate <br /> naturally over time -There is a netarork of groundwater monitoring wells in the path of the <br /> northeastern migration of the plume. The most recent monitoring has revealed that the plume's <br /> -- <br /> current "maximum levels of concentration" are being reported from=the monitoring wells located <br /> near'the subject Property- <br /> -4.3 --,- Water Sample Location_ <br /> r- According to Mr.Jeff McClellan (personal communication April 28, 2005), one residential"well is - <br /> 3 =located-on the property.-The following permits were found for the subject property address of 2.490_1 <br /> r South Bird Road during File Review on March 30, 2005. <br /> F11 <br /> = 77 Table 3. <br /> _ - On-site Well Permit History. <br /> _ Date - _ Comments <br /> i [ _ 7-22.93 Pump installation <br /> 7-25-02 <br /> - Pump repair <br /> A water sample was taken from thepipe manifold near the well head by the house on April 5, 2005 <br /> ` (Plate 1). The well has a pump set at 180 feet. <br /> 4.4 ,v Water Sample Constituents <br /> The water sample was analyzed for nitrate and DBCP. Neither DBCP or nitrate were not detected in <br /> �. the water sample:The analytical reports prepared by Precision Enviro-Tech can be found in the <br /> appendix of this report. <br /> i <br /> —Well construction, seals, age and depth of the well screens may play significant part in assessing the <br /> levels of Nitrate and DBCP in various aquifers. Without knowing specific details regarding well <br /> M1 construction and"condition;it would be difficult to accurately comment of the condition of the <br /> aquifer. Essentially, the water sample"concentration approximately indicates the contaminant <br /> = concentration level of the aquifer from which-the well is drawing water. It is Neil O. Anderson and <br /> Assor- <br /> ctate's opinion that neasurface aquifers are more likely to have elevated concentrations of <br /> * "Nitrate and-DBCP than the deeper aquifers. However, the contaminant concentration in one aquifer <br /> does not give any iiidication as to'the concentrations of any other aquifer regardless of proximity. <br /> F1 <br /> :T 6 <br />