5034 OCEAN AVE Geotech Report 2022-10-25

51xx Ocean Avenue (Parcel#00571700100100) November 1, 2017 Everett, Washington Project#17110 Lateral Earth Pressure Cast-in-place, concrete foundation walls or retaining walls may be designed to resist the following lateral earth pressure conditions. For preliminary estimating purposes, "active" lateral earth may be assumed to be 40 pounds per cubic foot (pc)while "at-rest" lateral earth conditions should may be assumed to be 55 pcf. The structural engineer is responsible to determine if the concrete walls are free to yield laterally at the top a distance equal to 0.1 percent of the wall height, active pressure conditions, or if the walls are "fixed", not free to yield laterally at the top, "at-rest" lateral earth conditions. Surcharges from sloping backfill conditions or adjacent structural loads should be added to the above lateral soil pressures. Full height drainage of foundation walls will need to be installed to prevent hydrostatic pressures from acting on the walls.Surface runoff should be prevented from entering the wall drainage medium. Since the current structural plans that we reviewed did not have proposed grades or foundation retaining walls shown, South Fork Geosciences should be contacted to review the actual lateral earth pressure acting on any retaining walls greater than 4 feet in height once heights and surcharge conditions are available. Floor Support We anticipate that the proposed home will utilize slab-on-grade floors or a combination of slab- on-grade floors and structural/crawlspace floors. Slab-on-grade concrete floors should be cast atop a prepared subgrade of structural fill soil compacted to a minimum of 90 percent of the modified Proctor maximum dry density. A capillary break with a minimum thickness of 4 inches should be placed atop the prepared subgrade. The capillary break material should be a gap graded material consisting of pea gravel, %-inch washed drain rock, or clean crushed rock with less than 5 percent fines(material passing the No.200 sieve). The capillary break will reduce the potential for moisture wicking through the floor slab. A 10-mil thick plastic vapor barrier should also be placed atop the capillary break material. All concrete placement should follow the guidelines set forth by the American Concrete Institute (ACI). In areas that structural/crawl space-type floors are used, provisions should be made to slope internal crawlspace areas to lows that may be drained to the footing drain system around the perimeter of the foundation to prevent the accumulation of standing water within the crawlspace areas. The soil surface should be covered with a minimum 10-mil thick moisture barrier. Drainage Considerations Foundation Drainage A perimeter foundation drain should be established around the proposed homes to protect the floor slab and internal crawlspace areas from ground water intrusion. The level of the foundation drain should be set at, or slightly below,the base of the footing elevation. The drain should consist of 4-inch diameter, rigid, perforated, PVC drain pipe and should be set to allow for gravity discharge. The drainpipe should be surrounded by a minimum of 6 inches of pea gravel or washed drain rock. Roof drains should not tie into the footing drain but should be collected in a separate,tightline drain. The drain lines should be set to discharge via gravity to SOUTH FORK GEOSCIENCES, PLLC Page 7 PO Box 1275 NORTH BEND,WA 98045 425-831-2023 I ANDREW@SFGEO.COM