ARCHIVED REPORTS XR0012689 - Laserfiche WebLink

Home Browse Search

} < w. w Geological Technics 2601 River Road ErrAronnenW Specialist Modesto,CA 95351 209-538-7805 Please Contamination ASSM100111. Report -- William Stewart's Property 515 W. Eleventh, - Tracy.California 1.0 PURPOSE AND SCOPE OF WORK The purpose of this Phase I contamination assessment was to,complete the task of evaluating the vertical and lateral extent of soil contamination,determine if grouro water. is contaminated,and determine the hydraulic gradient on the subject property. The - - project was conducted as proposed in the work plan dated March 25. 1988 and tt* - - addendum dated May 16, 1988. Four soil borings were drilled around the tank and 3 monitoring wells were installed,developed and sariplod. 2.0 PROJECT SUMMARY AND HISTORY - 2.1 Project Summary The upper 21 feet of strata was investigated during this project. in this interval,the soil is characterize by fine grained sediments which are dominated by clay rich horizons Interbedded with thinner silt or sand horizons. Below 20 feet is a silty clay;a water i - bearing zone of silty and clayey sand is located between 20 to 17 feet,acid from 17 to 14 feet is a soft wet smdy clay. From 14 up to about 11 or 10 feet is a clayey sand that is also water barring, This sand grades Into a si It to the north. Above I I or 10 feet is a saindy clary unit that has a few fest of organic rich top sot near the surface. The ground water gradient is to the north,which Is reflected in the migration path of contamination. Analytics!data shows that sot or ground water contamination has not moved south of the tank,but has moved at least 50 feet to the north, Soil contamination = --— =_------ --------has two modes of dispersal:-that migrating out directly_from_the_tank and that which ls_—___---- Dispersed by ground water movement: The cross section given In Figure 3,0 rs the - --- -- —- contamination distribution.