10630 EVERGREEN WAY BASE FILE 2016-01-01 MF Import

Geotcchnical E�:gincering Report Proposed New Stom�Water Vault Northwest Mitsubishi November I8, 2002 CG File No. 1397 Pagc( compacted to at Icast 95 percent of its maximum dry density. Maximum dry density, in this report,re(ers to that density as determined by the ASTM D 1557 compaction test procedure. Fill mom than 2 feet beneath sidcwalks and pavement subgrades should be compacted to at least 90 percent of the maxinwm dry density. The moisture contcnt of the soil to be compacted should'ue within about 2 percent of optimum so that a readily compactable condition exists. It may be necPssary to overexcavate and remove wet :;urficial soils in cases w�here drying to a compactable condition is not Ceasible. All compection should be accomplished by equipment of a type and size sufficient to attain the desired de6Ree of compaction. The above fill placcment recommendations are intended ta minimize thc amount of scttlement. Since the parking area will be gravel covered, compaction to the above specificatious is not necessury provided thc owncr is comlortable with the expected setAcment of the backfill. Vault Foundation It is our opi�ion that thc dctcntion vault may bc supported on shallow continuous footings. �oundations should be foundcd on medium dcnse or better nauvc soils. [f wet conditions are encountered, [hc subgrade should be co��cred with rock spalls using a thiclmess as needed to prepare a firtn anJ non-yielding condition. Continuous footings should be a minimum of 2.5 1'eet wide. For foundations conswcted as oudined above, we recommend that an allowable design bearing prcssure of not more than 2,500 psf be used for design. Uniform Building Codc (UBC) guidclincs should be followcd when considering short-term transitory wind or seismic loads. Potential foundation settlemcnt using thc recommended allowable bearing pressure is estimated to be Iess than 1-inch total and V2-inch differential beh��n footings across a distance of about 30 fcet for foundations cast on the same soil type. These estimates are based on our experiencc with similar projccts. I,ateral Pressures The lateral earth pressure acting on rctaining «�alls is dependent on the nawre and dens�ty of the soil behind ihe wall, die amount of lateral wall movement that can occur as backfill is placed, and the inclination ot tiic backfill. Walls that are free to yield at least one-thousandth of the height of Cornerstone Geotechnical, Inc. (7/� �