Laserfiche WebLink
Cie04MII Technics Inc, Page 2 <br /> 2n4 Quarter 2005 Groundwater Monitoring Report <br /> Project No 507 2 <br /> . June 30,2005 <br /> Since there is uncertainty regarding the soil profile at the site due to the 5-foot sampling <br /> ' interval GTI proposed performing several continuous core borings GTI developed our <br /> March 7, 2005 "Site Characterization Work Plan" that includes three continuous core borings <br /> to determine the presence of sand/silt layers in the core contaminant area SJC PHS/EHD <br /> issued an April 15, 2005 correspondence that requested additional information and denied <br /> approval of the work plan We submitted a May 15, 2005 work plan addendum and are <br /> awaiting a response from SJC PHS/EHD <br /> 1.0 GROUNDWATER MONITORING <br /> 1.1 Hydrogeology of Site <br /> ' The geology of the site is predominately clays and sandy clays with lesser amounts of inter- <br /> bedded silts and sands The average groundwater elevation was--8 92 feet below msl on May <br /> ' 27, 2005, which corresponds to approximately 13 5 feet below grade surface (bgs) This <br /> average elevation represents an increase of 122 feet since the February 17, 2005 monitoring <br /> event Groundwater gradient for this monitoring event was 0 002 ft/ft flowing N84°E This <br /> site consistently exhibits a flat groundwater gradient <br /> The gradient direction for the May 2005 monitoring event is shown in Figure 2, and the <br />' historical groundwater directions and gradients are shown in Figure 3, Groundwater Gradient <br /> Rose Diagram The groundwater elevation data are summarized in Table 1, Appendix A <br /> Table 5 provides a summary of monitoring well construction <br />' The groundwater gradient is relatively flat and the direction of groundwater flow has varied <br /> during the course of the investigation As evident in Figure 3, groundwater exhibited a strong <br /> bifurcated flow regime in 2000, trending predominantly to the southwest or north-northeast at <br /> approximately 180-degree direction reversal Since the installation of wells MW-7 and MW- <br /> 10 in May 2001, the direction has been predominantly to the northeast The site is quite close <br /> to the San Joaquin River and tidal fluctuations may contribute to some of the observed <br /> changes in groundwater direction <br />' Vertical Groundwater Gradients <br /> Under vertical groundwater flow conditions, the water level in a monitoring well is a function <br /> of the length of the well screen and its depth or vertical position in the aquifer As with <br />' horizontal flow conditions, the diameter of the well or piezometer is immaterial <br /> 1 <br />