2414 BAKER AVE 2017-01-13 - Laserfiche WebLink

Tom Eiden June 21, 2010 Soi/ Conditions JN 10114 Page 2 Our hand auger test boring revealed 1 foot of loose silty sand fill overlying remnant topsoil to approximately 1.5 feet below grade. Loose, weathered, native, reddish-brown, moist, silty sand with occasional gravel was then encountered. This sand became grayish brown, less silty, and medium-dense to dense at 4 feet below grade. From 8 feet below grade to the bottom of our exploration at 13 feet, we encountered dense, clean sand that was moist. This sand became very dense at 10 feet below grade. Debris, buried utilities, and old foundation and slab elements are commonly encountered on sites that have had previous development. Cobbles or boulders are often found in soifs that have been deposited by glaciers or fast-moving water. Groundwater Conditions No groundwater was in our hand-auger test boring. Groundwater levels vary seasonally with rainfall and other factors. During the wetter winter months, we anticipate that some perched groundwater coufd be found between the near-surface weathered/loose soil and the underlying denser materiais. The stratification lines on the logs represent the approximate boundaries between soil types at the exploration locations. The actual transition between soil types may be gradual, and subsurface conditions can vary between exploration locations. The logs provide specific subsurface information only at the locations tested. The relative densities and moisture descriptions indicated on the hand boring logs are interpretive descriptions based on the conditions observed during excavation. CONCLUSIONS AND RECOMMENDATIONS GENERAL THIS SECTION CONTAlNS A SUMMARY OF OUR STUDY AND FINDINGS FOR THE PURPOSES OF A GENERAL OVERVIEW ONLY. MORE SPECIFIC RECOMMENDATIONS AND CONCLUSIONS ARE CONTAINED IN THE REMAINDER OF THlS REPORT. ANY PARTY RELYING ON THIS REPORT � HOULD READ THE ENTIRE DOCUMENT. Our hand-auger test boring indicated a layer of loose, fill, topsoil, and weathered soils on the order of 4 feet deep overtying medium-dense to dense, native, slightly silty to clean sands. We recommend that all of the new footings at the site be excavated to bear on the medium-dense to dense, native soils. Based on the explorations, it appears that the dense, native sands will be encountered above the bottom of excavation (BOE) for the basement, but that some overexcavation could be necessary if the basement is eliminated. Temporary cuts in the site soil can be inclined at a 1:1 (Horizontal:Vertical) slope. Based on the soil conditions and proposed cuts, it appears that the proposed excavations on the south and east sides of the excavation can be maintained on the subject site, but that shoring will be needed on the north and west sides of the excavation (along the alley and where the neighboring property to the north has parking). Along the northern edge of the basement, it appears (given the geometry of the cuts and the soils encountered) that temporary shoring in the form of Ultra blocks could be appropriate, if an agreement with the northern neighbor can be negotiated to allow temporary excavation across the property line to install the blocks and to avoid parking in this area above the GEOTECH CONSULTANTS, INC.