3003 W CASINO RD BLDG 40-58 Geotech Report 2022-10-25

Structural fill will be necessary to support the Building 40-27 interior floor slab, the exterior concrete apron, and asphalt pavements. Only granular fill meeting the requirements of Crushed Surfacing — Base Course (CSBC), as described in Section 9-03.9(3) of the 2012 Washington State Department of Transportation (WSDOT) Standard Specifications for Road, Bridge, and Municipal Construction(WSDOT 2012)should be used within 6 inches of the floor slab and apron subgrade,except for a thin uppermost lift of Crushed Surfacing—Top Course. Structural fill behind tunnels, utilidor, and other retaining walls should consist of Gravel Backfill for Walls, as described in Section 9-03.12(2) of the 2014 WSDOT Standard Specifications. Gravel Backfill for Walls has a low maximum fines content, which is important for rapid drainage of backfill behind these structures. 3.3 WET WEATHER EARTHWORK CONSIDERATIONS The near-surface onsite soils and some of the potential fill sources are considered to be moisture sensitive. As a result, it may be difficult to control the moisture content of these soils during periods of wet weather. If construction is accomplished during periods of wet weather, we recommend that the selected Gravel Borrow, Select Borrow, and Crushed Surfacing contain less than 5 percent passing the U.S. Standard No. 200 sieve, based on a wet sieve analysis of that portion passing the 3/4-inch:sieve. In addition,if fill is to be placed or earthwork is to be performed in wet weather or under wet conditions,the contractor may reduce subgrade soil disturbance by: — Accomplishing earthwork in small sections — Sloping excavated surfaces to promote runoff — Limiting construction traffic over unprotected soil — Limiting the size and type of construction equipment used — Providing gravel"working mats"over areas of prepared subgrade — Removing wet surficial soil prior to commencing fill placement each day — Sealing the exposed ground surface by rolling with a smooth drum compactor or rubber- tired roller at the end of each working day — Providing upgradient perimeter ditches or low earthen berms and using temporary sumps to collect runoff and prevent water from ponding and damaging exposed subgrades — Stabilizing the soil with an additive (such as lime or cement kiln dust)to allow its use in wet weather. 3.4 FILL PLACEMENT AND COMPACTION Following compaction and proof-rolling of the existing subgrade, fill should be moisture conditioned (if necessary), placed in loose, uniform lifts, and compacted to 95 percent of its maximum 5/16/14 P:\1423\002\010\PileRm\R\Draft Bldg 40-58 Report\Bldg 40-58_draft rpt.docx INTERIM D RA F T 3-3