4027 4TH ST SE 2018-01-01 MF Import

January 14, 2003 HWA Proiect No. 2002-146-21 settlemcnt. Above that levet, preload soils may be placed without a comoaction specification. Typically, a moderate degree of compaction is applied by conshuction equipmrnt during placement of the surcharge. Construction encroachment into the adjoining drive azeas may be a design conce�n. To minimize encroachment into the adjacent azea, a temporary retaining well of lock-blocks could be constructed or the surchazged portions of the fills could be constructed with tecnporary side slopes of I'/.H: l V. Following preloading, the tempo�ary slopes should be re-graded to the design grades. Although it is our opinion that the temporary retainir.g wall or the steep temporary slopes will have adequate factors of safety wnsidering gross stability, HWA should review the pinnned slopes or wall design prior to construction. Steep slopes may be subject to surficial erosion and some sloughing during the preload period. Silt fences and other appropriate erosion control measures should be installed at the toes of the steep slopes. 4.5 SITE EARTHWORK RECOMMENDATIONS 4.5.1 Subgrade Preparation Site preparation should begin wiih the removal of organic material and topsoil from the site azea. In addition, all existing asphalt and other deleterious material within the project azea should be removed from azcas where the new pavement section will be conswcted. Following removal of all deleterious materials, roadway fill should be placed in accordance with the compaction criteria presented below in Section 4.5.2. 4.5.2 Roadway Fill Nlateriala and CompacHon Roadway fill materials should consist of relntively clean, free draining sand and gravel conforming to the Gravel Borrow specification, Section 9-03.14(1) (Gravel Borrow) of the 1996 WSDOT Srandard Specificntrons. If earthwork is performed during extended periods of wet weather or in wet conditions, the fill materials should conform to the recummendations provided in the Wet Weather Eazthwork section below. [n general, we anticipate that soil &om the on-site stock pile will be suitable for re-use as compacted fill. Portions of the stockpile which aze fine-grained (silt and clay), or organic-rich aze considered unsuitable. Sandy portions of the existing stockpile on site may be suitable for re-use as compacted roadway fill, provided that caze is taken to prevent mixing with unsuitable soils, and the compaction criteria presented herein aze mct. '_0021i6 rtpon • final ]4 HWA GEOSCIENCES INC. I�