5720 EAST DR 2018-01-02 MF Import

Geotechnical Engineering Report Parcel 00471700002401- 57XX East Drive Everett, Washington December 12, 2009 RMI Pile No. 53409 Page 8 native soils. If footings are supported on structural fill, the fill zone should extend outside the edges of the footing a distance equal to the depth of overexcavation below the footing. Footings, including interior footings, should extend at least 18 inches below the lowest adjacent finished ground surface for frost protection and/or bearing capacity considerations. Minimum foundation widths of 18 and 24 inches are recommended for continuous and isolated spread footings, respectively. Standing water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation prior to pouring of the concrete. For foundations constructed as outlined above, we recommend an allowable design bearing pressure of not more than 2,000 pounds per square foot (psf) be used for the footing design. Current International Residential Building Code (IRBC) guidelines should be used when considering increased allowable bearing pressure for short-term transitory wind or seismic loads. Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less than I inch total and 1/2-inch differential between adjacent footings or across a distance of about 25 feet. Lateral loads may be resisted by friction on the base of the footing and passive resistance against the subsurface portions of the foundation. A coefficient of friction of 0.35 may be used to calculate the base friction, and should be applied to the vertical dead load only. Passive resistance may be calculated as a triangular equivalent fluid pressure distribution. An equivalent fluid density of 200 pounds per cubic foot (pcf) should be used for passive resistance design. These recommended values incorporate safety factors of 1.5 at d 2.0 applied to the estimated ultimate values for frictional and passive resistance, respectively. To achic a this value of passive resistance, the foundations should be placed "neat" (without forms) against the native medium dense or better soils or compacted soil should be placed against the front of the footing. We recommend that the upper foot of soil be neglected when calculating the passive resistance. The soil surface should be horizontal in front of the footing for a distance equal to at least three times the depth of embedment of the footing. Excavations for basements are acceptable outside of the setback area but excavated soil should not be put in the setback area nor should heavy construction machinery operate there. RMI ASSOCIATES LLC Dqll�