Laserfiche WebLink
1«; <br /> Lastnersville school District <br /> 202/799-8221 <br /> - July 28, 1587 <br /> The geology at the site consists of a 100 foot thick <br /> sequence of alluvial clay, silt and sand overlying a clay layer <br /> _ which in turn overlies the Corcoran Clay. The Corcoran Clay is <br /> a major aquitard in the San Joaquin Groundwater Basin <br /> Groundwater in the area is divided into three water bearing <br /> zones : a lower confined zone below the Corcoran Clay : an upper <br /> zone above the Corcoran Clay. which contains both confined and <br /> unconfined aquifers; and a shallow , unconfined zone within 25 <br /> feet of the surface. <br /> The water quality in the Tracy area is being degraded by <br /> water as a result of the over draft <br /> intrusion of saline connarz <br /> of deeper aquifers in the Stockton &nd Tracy areas . Shallow <br /> is generally <br /> groundwater , though utilized for domestic purposes , <br /> poor along the western boundary of the San Joaquin Groundwater <br /> onsidBasin. However, all groundwater in the Tracy area is csuch. <br /> . red <br /> uch <br /> to be potential drinking water source and is treated as such. <br /> There are approximately 114 wells within a one mile radius <br /> of the site; 110 domestic, 3 municipal and 1 abandoned municipal <br /> well (see Figure 3, Well Location Map) . <br /> The soils encountered during the drilling of the borings for <br /> ilty clays and <br /> the monitoring wells were comporised mostly of s <br /> sands . In each well boring, several sand and clay stringers were <br /> encountered. Depth to groundwater was recorded at approximately <br /> 8 feet be16w grade . <br /> The five w^Ils were monitored on June 19 , June 22 and June <br /> 24 , 1987 for depth to water and presence of product, if any. A <br /> summary of the groundwater monitoring at the site is presented in <br /> on this data , the interpreted gro'.ndwater <br /> 10 <br />