SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

L Lin depth from about 190 to 340 feet(not including pumping water levels),with up to 40 to 60 feet of Lseasonal fluctuation(80 feet at Brown's#I in 2012). In the early 2000s,seasonally high groundwater L levels in deep zone wells South Tracy#1,Brown's#1,and Brown's New Well declined by up to about 60 feet and,although substantial recovery occurred from 2004 to 2006,seasonally high water levels L remained lower than during the 1990's. Seasonal high water levels in Brown's New fell approximately 40 feet from 2009-2010 while levels in the other wells stayed relatively steady. Since early 2013,winter water levels have declined an additional 20-50 feet in these deep wells,while levels in Brown's New were the highest since 2000 in winter 2013/14. These lower groundwater levels likely reflect increased demand(pumpage)on the deep aquifer zone from local agricultural interests and industrial operators, which appears to be exacerbated by the ongoing drought(2012-present). For example, a number of deep wells are reported to have been installed in the area south and east of the Teichert Vernalis plant(Liese Schadt personal communication with P. Mercurio,Teichert,October 2002),and increased aggregate production in the early 2000s resulted in increased groundwater production. Further,reduced usage of local surface water supplies by local interests,which may have caused a corresponding increase in local L groundwater pumpage,has been reported(Liese Schadt personal communication with J.Muller,Teichert, October 2002). Water levels in the South Tracy#1 production well typically recovered to an elevation between 20 and 40 L feet(msl)each winter until 2001,when increased pump operation made the measurement of static water levels difficult. Upon Teichert's initiative, plant staff measured static and pumping water levels in the South Tracy#1 well more frequently from late 2001 to 2008,and these supplemental data are tabulated in L Attachment 2. Water levels in the South Tracy#3 production well were also monitored at a higher frequency. However,the sounding of water levels below a depth of approximately 273 feet has not been successful due to an obstruction at this depth;likely due to a problem with the well's access port. As a result,any water levels below a depth of approximately 273 feet(i.e., -28 feet,msl)erroneously appear as a constant water level on this well's hydrograph(see Figure 6 and the well's hydrograph in Attachment 1). The Petz irrigation well,which is located west of the Teichert Vernalis plant,is completed in both the shallow and deep zones of the underlying aquifer system,and its water level hydrograph reflects a composite of these shallow and deep zones(see Attachment 1). The early water level record of this well L (prior to 2000)shows groundwater level elevations between those observed in the discussed shallow and deep wells in the area. Similarly, seasonal fluctuations prior to 2000 appear to be a composite of observations made in the shallow and deep network wells. Specifically,seasonally high water levels in L this well rose from 72.46 to 86.58 feet(msl)between March 1994 and 1998,with seasonal fluctuations of almost 15 feet. Since then,water levels have been very similar to those observed in the shallow network i wells. L Contours of equal groundwater elevations prepared with data from the shallow network wells show that the general direction of groundwater flow during times of seasonally high water levels was typically to the east-southeast and east. This includes the first monitoring event in spring 1994 with comparatively L high water levels(Figure 7) and the period of the highest historically recorded groundwater elevations in spring 1998 (Figure 8). The water level elevations in spring 2000 were relatively low compared to groundwater conditions observed in previous spring seasons,however,the predominant direction of flow L was also to the east-southeast(Figure 9). In spring 2002,overall groundwater elevations were very similar to the spring 2000 elevations,but the groundwater flow direction was east-northeasterly as influenced by a relatively high groundwater level in the Koster irrigation well(Figure 10). Overall groundwater elevation differences across the monitored area have decreased over the period of record(see Figure 5). This is exhibited by contours of equal groundwater elevation prepared for February 2014(Figure 11) and November 2014(Figure 12). The February 2014 map indicates a L D ©LUHDRFF 6 SC LMANINI co s eeAs 5 L