9205 4TH AVE W 2025-12-03 - Laserfiche WebLink

July 2, 2008 Duplex Buildings L&A Job No. 8AO67 Page 5 Detailed descriptions of soils encountered during site exploration are presented in test pit logs on Plates 4 and 5. The test pits encountered a layer of loose organic topsoil, about 14 to 16 inches thick, mantling the site, except Test Pit 4 located at the west end of the site where it encountered 12 inches of fine sandy gravel fill with the topsoil having been stripped off previously. The topsoil is normally underlain by a layer of brown weathered soils of loose to medium -dense, silty fine sand, with a trace to some gravel, such as the layer of weathered soils, about 2.0 to 2.3 feet thick, encountered by Test Pits 3 and 4. The layer of weathered soils, however, was not encountered by Test Pits 1 and 2, indicating that it may have been partially removed off the site from previous grading. In Test Pits 1 , 2 and 3, the layer of weathered soils is underlain by a fresh till deposit or deposits of light -brown to light -gray, dense to very -dense, weakly -cemented, gravelly, silty, fine to medium sand with occasional cobble. This fresh till deposit is only about 1.8 feet thick in Test Pit I and is underlain by dense silty fine to medium sand soils which appear to be of an advance outwash soil unit. Test Pit 4 located at the west end of the site did not encountered the fresh till soils over its depth. GROUNDWATER CONDITION Groundwater seepage was not encountered by any of the four test pits excavated on the site. The fresh till soils and the dense silty advance outwash soils underlying the site at shallow depth are of extremely low to low permeability and would perch stormwater infiltrating into the more permeable surficial soils. The amount of and the depth to this near -surface, perched groundwater would fluctuate seasonally, depending on precipitation, surface runoff, ground vegetation cover, site utilization, and other factors. The perched groundwater may dry up completely during the dryer summer months and accumulate and rise in the wet winter months. LIU & ASSOCIATES, INC.