505 LAUREL DR 2025-03-12 - Laserfiche WebLink

Miles Residence Pool Everett, Washington Limited Geologic Hazard Reconnaissance occurring terraced topography, tension cracks, reversed drainage gradients, and large-scale unvegetated soil exposures at the subject site. An area of exposed soil is present along the steep slope to the west of the looping portion of Laurel Drive, suggestive of localized sloughing; however, the area of this apparent sloughing is more than 200 feet away from the subject residence and proposed swimming pool. Geologic Mapping As part of our work, we reviewed a geologic map of this area of Everett. Review of the regional geologic map titled Geologic map of the Everett 7.5-minute quadrangle, Snohomish County, Washington, by Minard, J.P. (1985) indicates that the area of the subject site is underlain by Vashon advance outwash (Qva) deposits, with Transitional Beds (Qtb) mapped along the steep slope downgradient of the subject site. CONCLUSIONS AND RECOMMENDATIONS Based on our field observations and project understanding, the currently -proposed swimming pool is to be located approximately 150 feet from the top of the steep slope leading down to the northwest. We understand that swimming pool installation will follow the pool manufacturers' guidelines. Given the surface, mapped subsurface, and topographic conditions, it is our opinion that the risk posed to slope stability by the proposed construction, at its currently proposed location relative to the steeply sloping ground, is low. Given the aforementioned separation of the pool and walls from the steep slopes, there will be no significant adverse surcharge on the slope from the pool/wall structures. No detailed modeling of slope stability was prepared as part of this report and none is warranted, in our opinion. Design Recommendations for Pool -related Retaining Structures We interpret the geology of the subject parcel, based on the above -referenced geologic map, as consisting of Vashon advance outwash. This material was deposited by rivers and streams in front of, and subsequently overridden by, the advancing glacial ice, resulting in a dense soil unit. This material should provide suitable foundation support using relatively shallow, conventional spread footings as described below. Landscape areas surrounding structures with daylight basements often have a thin layer of fill or disturbed soil associated with previous basement excavation, backfill or landscape activities. We anticipate that the planned pool/wall foundations will penetrate through these shallow soils to bear on undisturbed advance outwash sand. Foundations Conventional spread footings may be used for support of new retaining walls surrounding the swimming pool when founded directly on undisturbed, medium dense to very dense glacial deposits or on structural fill placed above these deposits. Footings may be designed for an allowable foundation soil bearing pressure of 2,500 pounds per square foot (psf), including both dead and live loads. An increase of one-third may be used for short term wind or seismic loading. November 15, 2022 ASSOCIATED EARTH SCIENCES, INC. JPL/jh - 20220343EO01-003 Page 2