ARCHIVED REPORTS_XR0007263 - Laserfiche WebLink

Home Browse Search

i Mr Michael Infurna Page 4 of 6 iPurged groundwater was placed into DOT certified 55-gallon drums and temporarily stored on site g P Y pending disposal 2.5 MonitoringWell Surveying Y g As required by AB 2886, the wellhead elevations of the new monitoring wells were surveyed by a Registered Surveyor to a horizontal accuracy of less than one meter and a vertical accuracy of 0 01 feet On December 11, 2003 Morrow Surveying surveyed the latitude and longitude of the site wells relative to the North American Datum (NAD83), and surveyed the wellhead elevations relative to City of Stockton Benchmark No 85 A site map showing monitoring well locations, latitude and longitude coordinates and wellhead elevations is included in Attachment C 3.0 RESULTS OF INVESTIGATION 3.1 Subsurface Conditions Traditional soil logging methods (ASTM Designation D2488-90) were used to classify the soil found in borings MW5 through MW7 Boring MW1D was not logged due to the close proximity of I borings SB6/SB7, CPT 1 and MW1 Logs for borings SB6/SB7, CPT 1 and MW1 are included in Attachment A MW5 Silts and clays were the dominant soil types classified Sand beds of up to five feet in thickness were found at depths of 40 feet bgs and 75 feet bgs MW6 Fine grained soils composed of silts and clays were the dominant soil types Sand beds were found at depths of 20 feet bgs and 60 feet bgs Apparent bed thicknesss were approximately five feet and fifteen feet, respectively MW7 A silty sand bed was found at a depth of 60 feet bgs Other than this, silts and clays were the soil types classified in this boring Depth to first-encountered groundwater ranged from 58 5 feet below ground surface (bgs) in boring MW7 to 64 feet bgs in boring MW5 Subsequent measurements indicated that equilibrium was achieved at an average depth of approximately 56 feet bgs 3.2 Soil Analytical Results MWS and MW7 had non-detectable levels for all analytes of concern In MW6, only the sample collected from a depth of 65 feet bgs had detectable levels of benzene and 1,2 DCA Concentrations of those chemicals were 0 04 parts per million (ppm) and 0 011 ppm, respectively No other analytes of concern were detected in the other samples collected from boring MW6 Samples were not collected from boring MW 1 D (samples from the approximate location and depths were collected during Iprevious investigations) Soil analytical results are summarized in Table 2 Laboratory reports and . chain of custody documentation are included in Attachment D 11GZA FSIVOL_11DATA\GROUNDZEIHARRYSIReports\Well ReporC doc