ARCHIVED REPORTS_XR0005709 - Laserfiche WebLink

Home Browse Search

Iwo 16, 19 February 2002 AGE-NC Project No. 95-0173 Page 4 of 7 • Hydrologic Unit 6(HU6) -Located between 100 feet and 112 feet bsg and characterized by medium to predominantly high pore pressures; comprised primarily by less permeable silty clay and clayey silt zone identified at depths between 100 feet and 112 feet bsg. • Hydrologic Unit 7(HU7) -Located between 112 feet and 128 feet bsg and characterized by predominantly low pore pressures and localized high pore pressure intervals; comprised primarily by semi-permeable silty sand and sandy silt. t.. 0 Hydrologic Unit 8(HU8) -Located between 128 feet and 134 feet bsg and characterized by variable low to high pore pressures; comprised primarily by less permeable clayey silt/silty clay. • Hydrologic Unit 9 (HU9) -Located between 134 feet and 150 feet bsg and characterized by low pore pressures and localized high pore pressures; comprised primarily by permeable fine •, to medium sand with gravel. 2.4. PORE PRESSURE DISSIPATION TESTING Pore pressure dissipation tests were taken at various intervals to measure hydrostatic water pressures and approximate depth to ground water. The approximate depth to ground water was calculated using the equation(Appendix C): Dw=Dcone - Hwater imp where: Dw=Depth to Ground Water(ft) Done =Depth of CPT Tip Hwater=Hydrostatic Water Head (1 psi=2.31 ft) Pore pressure dissipation testing was conducted in the following informal hydro-geologic units: • HUI (35.3 feet bsg) - After 300 seconds, pore pressure stabilized at approximately 10 psi; depth to ground water was calculated at 12.17 feet bsg. • HU2 (41.8 feet bsg) - After 240 seconds,pore pressure stabilized at approximately 4.9 psi; depth to ground water was calculated at 30.5 feet bsg. 0 HU7(116.3 feet bsg) -After 100 seconds, pore pressure stabilized at approximately 38 psi; depth to ground water was calculated at 28.5 feet. HU9 (139.4 feet bsg) - After 60 seconds, pore pressure stabilized at approximately 43 psi; depth to ground water was calculated at 40.1 feet bsg. HU9(149.9 feet bsg) -After 850 seconds,pore pressure stabilized at approximately 51 psi; depth to ground water was calculated at 3 2.10 feet. Advanced GeoE nvi ronmental,Inc.