902 PINE ST NORTH SOUND BEHAVIORAL HEALTH TREATMENT CENTER 2025-11-04

GeoTest Services, Inc. November 16,2018 , North Puget Sound Behavioral Health—Treatment Center Addition Job No. 18-0770 passing the U.S. Standard No. 200 sieve. The purpose of this layer is to provide uniform 1 support for the slab, provide a capillary break, and act as a drainage layer. GTS recommends that material conforming to Washington State Department of Transportation Standard Specification 9-03.12(4), "Gravel Backfill for Drains", with the added requirement that the material consist of a crushed, angular aggregate that is to be used as capillary break material. To help reduce the potential for water vapor migration through floor slabs, a continuous impermeable membrane of 10- to 15-mil polyethylene sheeting should be installed and sealed in accordance with the manufacturer's instructions below the slab. If moisture control within the building is critical, we recommend an inspection of the vapor retarding membrane to verify that all openings have been properly sealed. The American Concrete Institute (ACI) guidelines suggest that the slab may either be 1 poured directly on the vapor retarding membrane or on a granular curing layer placed over the vapor retarding membrane depending on conditions anticipated during construction. We recommend that the architect or structural engineer specify if a curing layer should be used. Use of a curing layer is generally only recommended during drier months of the year and/or when limited rain is expected during the slab-on-grade construction process. If the slab will be constructed during the wet season, exposed to rain after construction or the site may be potentially wet, we do not recommend the use of curing layer as excessive moisture emissions through the slab may occur. Exterior concrete slabs-on-grade, such as sidewalks, may be supported directly on undisturbed native, existing structural fill over native soil or on properly placed and compacted imported structural fill. Long-term performance will be enhanced if exterior slabs are placed on a layer of clean, durable, well-draining granular material. Foundation and Site Drainage I To reduce the potential for groundwater and surface water to seep into interior spaces we recommend that an exterior footing drain system be constructed around the perimeter of new building foundations as shown in the Typical Footing and Wall Drain Section, Figure 3. The drain should consist of a minimum 4-inch diameter perforated PVC pipe, surrounded by a minimum 12 inches of filtering media with the discharge sloped to carry water to a suitable collection system. The filtering media may consist of open-graded drain rock wrapped by a nonwoven geotextile fabric (such as Mirafi 140N or equivalent) or a graded sand and gravel filter. The drainage backfill should be carried up the back of the wall and contain less than 3 percent by weight passing the U.S. Standard No. 200 sieve (based on a wet sieve analysis of that portion passing the U.S. Standard No. 4 sieve). The invert of the footing drain pipe should be placed at approximately the same elevation as the bottom of the footing or 12 inches below the adjacent floor slab grade, whichever is deeper, so that water will not seep through walls or floor slabs. The footing drain should discharge to an approved drain system and include cleanouts to allow periodic maintenance and inspection. Positive surface gradients should be provided adjacent to the proposed building to direct surface water away from the foundation and toward suitable drainage facilities. Roof drainage should not be introduced into the perimeter footing drains, but should be separately discharged directly to the stormwater collection system or other appropriate Page 10 of 17