5109 SOUND AVE 2017-08-02 - Laserfiche WebLink

July 21, 2014 Two Single-Family residences L&A Job No. 14-065 Page 6 to light-gray, loose to soft, silty fine sand to fine-sandy silt, about 3.9 feet thick. This layer of weathered soil is underlain to the depth explored by a deposit of gray, hard, clayey silt which appears to be of a Whidbey formation soil unit. Test Pit 2 located on top of an earth bank along the south side also encountered a layer of topsoil and/or disturbed soil of loose, organic, silty fine sand, about 3.0 feet thick. Test Pit 3, located in the northwest corner area, encountered a layer of topsoil, about S inches thick. Underlying the topsoil/disturbed soil in Test Pit 2 and the topsoil in Test Pit 3 is a layer of weathered soil of light-brown to brown, loose to medium-dense, silty to slightly silty, fine sand, about 4.0 to 4.3 feet thick. Underlying this layer of weathered soil to the depths explored is a deposit of brown-gray to light-brown to light-gray, medium-dense, tine to medium and fine to coarse sand, locally containing some gravel, which appears to be of an advance outwash soil unit. G120UNDWATER CONDITION Groundwater seepage w�as encountered by all three test pits at about 4.0 feet in Test Pit 1 and at 7.0 feet in Test Pits 2 and 3. The influx of groundwater seepage was estunated at about 1.0 to 3.0 gpm (gallons per minute). The Whidbey fonnation silt deposits at shallo�� depth are of extremely low permeability and would perch stormwater infiltrating into the more permeable surficial soils_ The level and amount of this near-surface, perched, groundwater seepage would fluctuate seasonally and would vary depending on type of soil, site terrain,vegetation cover, site utilization, etc. Groundwater may dry up in the dry summer months and accumulate and rise in the wet winter season. The perched groundwater on the hillside would flow laterally along the surface of the Whidbey LIU & ASSOCIATES, INC.