2530 MADISON ST 2016-01-01 MF Import

�_ �.. AirTouch Cetlular 3 October 1997 7-97M-11905-0 Page 3 typically based on the moiswre content of soil samples, th ;✓vetted height on the drilling rods, and the water level measured in the borehole after the auger has been extracted. 3.0 SOTE CONDI710NS The foilowinp sections of text present our observations, measurements, findings, and interpretations regarding surface, soil, groundwater, and seismic conditions at the pruject sito. Interpretive logs of our subsurface explorations and graphic results of our lahoratory tests are enclosed with this report. �1.1 Surface Canditions �'he project site is located in a region characterized by modersiely ;ul{ing terrain and relatively dense residential development. The site is situated on srnall 4lateau on the dowrhill side of a hill, with moderate to steep slopes extending downward to the sast. Site vegetation generally consists of grass and scattered coniferous and deciduous tree gro�nrth. No ponding or significant amounts surface water were observed at the project site. l _ �.Z Soil ondi'i n According to pubiishad geologic maps, soil conditions in the site vicinity are characterized f by glacially deposited soils, which our on-site explorations confirmed. Specifically, the soil � p�ofile observed in boring B-1 consisted of a loose ,�rading to medium-dense, moist, silty sand with some gravel to a depth of 4 feet, mantling a 2-f�iut-thick zone of gravel �vith ( some sand and silt. Below 2 Jepth of 5%: feet, our boring e�countered a very dense, � moist, sand with some gravel and a trace of silt to a depth oi 12'/ feet. Between a depth of 12% and 28 feet, a very dense, wet to saturated, silty sand vvith a trace to some gravel f was encountered. Below a depth of 28 feet, we observed a vary dense, moist, silty sand grading to a sand with some silt, extending to the maximum depth explored (approximately � 35 feet). Although not encountered in our boring, large boulders (sometimes called glacial erratics) are commonly associated with glacially derived soils and may be encountered on a random basis. � 3_3 Groundwater Conditions At the time of exploration (October 1997), perched groundwater was encountered within � our boring at a depth between 15 feet and about 20 feet. Perched groundwater typically occurs when an underlyiny layer of lower permeability inhibits the downward percolation of v�ater. Water will build up on the low-permeability soil horizon and move lateraliy in the � more-permeable overlying soils. It should be noted that groundwater levels fluctuate and may vary in response to season, precipitation patterns, on- or off-site construction � activities, site utilization, and other factors. Seepage could aiso be encountered in the deeper sandy zones below a depth of 28 feet. ��eva-i+eosa