ARCHIVED REPORTS XR0003991 - Laserfiche WebLink

Home Browse Search

' 05 May 1997 AGE-NC Project No 95-0112 ' Page 6 of 14 3 3 1 PROBING AND SAMPLING ' On s were advanced at the site using AGES _6 February 199'1, two soil probe borings (probing ) g ' Geoprobe 5400 probing unit equipped with 125-inch diameter probe rods and a 2 15-inch diameter soil sampling assembly Probing P4 was advanced three feet north of MW-1, probing P5 was advanced approximately 4 feet north of the former US f location, south of P2 Each probing was advanced to a total depth of 55 feet below surface grade (bsg) Probang locations are shown on Figure 2 Soil samples were collected at 5 foot intervals, beginning at 5 feet bsg, for the total depth of each probing All samples were collected using the Geoprobe soil sampling assembly loaded with four 1 125 by 6-inch brass sleeves After collection, the ends of the second brass sleeve were covered ' with aluminum sheets, capped and sealed with tape The sleeves were labeled, placed in a chilled container and transported to Alpha Analytical Laboratories (AAL) under chain-of-custody ' All probing rods,sampling tools and sample liners used for sample collection were thoroughly rinsed with clean water after washing with a solution of Alconox between each sampling run All probings ' were backfilled over their entire depth with Portland Cement ' 3 3 2 LOGGING/STRATIGRAPHY Soil was extruded from the remaining brass sleeves and screened for the presence of organic vapor ' using a photo-ionization detector (PID Thermo Environmental 580A, 10 OeV, calibrated to isobutylene), and the readings were recorded on the boring logs Soil was described in accordance with the Unified Soil Classification System (see Boring Logs, Appendix A) Organic vapor was detected in probing P4 at concentrations as high as 116 part per inillion volume (ppmv) and in probing P5 at concentrations as high as 603 ppmv Higher organic vapor ' measurements were concentrated between 15 and 20 feet bsg and again between 40 and 50 feet bsg In probings P4 and P5, sandy silt was encountered from surface grade to approximately 16 feet bsg Clayey sand was encountered at 16 feet bsg grading to coarse sand by 30 feet bsg and back to clayey sand at 40 feet bsg Clayey silt was encountered from 40 feet bsg to total depth of 55 feet bsg Ground water was not encountered during probing General site stratigraphy consists of silt to silty sand fiom near surface grade to approximately 15 ' feet bsg However, a dense silt/clay layer is generally present from 12 to 15 feet bsg Sand is present • from approximately 15 to 40 feet bsg Silt is generally encountered from 40 to 60 feet bsg Clay lenses were observed in several borings at depths near 45 feet bsg Sand is present from 60 feet bsg 1