ARCHIVED REPORTS XR0003291 - Laserfiche WebLink

Home Browse Search

J �Tc A S S O C f g T E S I M C . When the tool was advanced to the desired depth, extension rods were sent downhole to brace r F, the bottom of the sample screen as the tool casing was retracted. When the casing was retracted, approximately 41 inches of screen with slot sizes of 0.004 inches was exTeflontubing with a check valve attached to one end was inserted down the casing until it was immersed in groundwater. Water was then pumped through the tubing and to the ground surface b oscillating the tubing up and down. Groundwater samples were placed on ice a Y under chain-of-custody documentation to Argon Laboratories for chemical analysis. Following soil and groundwater sample collection, dissolved oxygen and oxidation reduction potential + measurements were taken in the field. The borings were then backfilled to the ground surface, led with neat cement grout The groundwater matrix sample from boring SBI through SB9 were by EPA Method 7199, and for nitrate and sulfate by EPA Method 300.0 analyzed for Chromium Vi Copies of the analytical reports and chain of custodydocumentation ntahon are included in Appendix C. 3.0 SUBSURFACE CONDITIONS Soil from borings SBI through SB9 consisted mainly of silts, silty clays, and clays to depths of 20 to 25 feet bgs. At depths of 15 to 20 feet bgs, some silty sands were encountered at borings ��- S132 and SBS. At 40 feet bgs sand-silts or sand-clay mixtures at bringSB2, SB5, and SB7. At 40 feet, clays and silty clays were encountered at SBI SB3aSB4,SB6s SBS, and SB9. Copies of boring logs are contained in Appendix B. 4.0 RESULTS 4,1 Soil Anal tical Results Chromium VI was detected at low concentrations in soil samples from borehole locations SBI through SB9 collected from the 20 and 40-foot depths with the exception of SB8 at 40 feet. The highest concentrations of chromium VI were detected in the samples from off-site boring SB9 at 1.5 and 2.6 milligrams per f kilogram (mg/kg) samples from borings SBI, SB2 and SB3 ed Concentr.09 mg/ations ons of chromium VI in the Concentrations of chromium VI were lowest in borings S134 through SB8,lranging from 0 010 4 mg/kg to 0.0074 mg/kg. Chromium VI was not detected in the soil sample from SB8 at 40 feet bgs above method detection limits. The Total Threshold Limit Concentration (TTLC) for chromium VI compounds is 500mg/kg. The analytical results are summarized arized in Table 1. Copies of laboratory analytical results are contained in Appendix B. w:lwordpro1625831reports\Subsurf repon.doc - 4