4730 COLBY AVE SEPA 016 - 027 - YMCA Geotech Report 2025-04-14

• October 25, 2015 YMCA - Everett L&A Job No. 15-089 Page 13 • The allowable soil bearing pressure for design of footing foundations, including dead and live loads, should be no more than 4,000 psf. The footing bearing soil should be verified onsite by a geotechnical engineer after the footing trenches are excavated and before the footings poured. • The minimum depth to bottom of perimeter footings below adjacent final exterior grade should be no less than 18 inches. The minimum depth to bottom of the interior footings below top of floor slab should be no less than 12 inches. • The minimum width should be no less than 16 inches for continuous footings, and no less than 24 inches for individual footings, except those footings supporting light- weight decks or porches. A one-third increase in the above recommended allowable soil bearing pressure may be used when considering short-term, transitory, wind or seismic loads. For footing foundations designed and constructed per recommendations above, we estimate that the maximum total post-construction settlement of the building should be 3/4 inch or less and the differential settlement across building width should be 1/2 inch or less. Lateral loads on the proposed building may be resisted by the friction force between the foundations and the subgrade soils or the passive earth pressure acting on the below-grade portion of the foundations. For the latter, the foundations must be poured "neat" against undisturbed soils or backlilled with a clean, free-draining, compacted structural fill. We recommend that an equivalent fluid density (EFD) of 275 pcf(pounds per cubic foot) for the passive earth pressure be used for lateral resistance. The above passive pressure assumes that the backfill is level or inclines upward away from the foundations for a horizontal LIU & ASSOCIATES, INC.