4702 W GLENHAVEN DR 2018-05-16 - Laserfiche WebLink

� 47U2�'1'Glenhaven Drive CAO,Snohomish C��nty,Washiugton Materials Testing& Consulting,Inc. ,lulv 31. 2017 16}3030 plants. Minor burrowing of animals has exposed 6 to 8-inch diameter holes in locations across the slope face. Signs of slow shallow soil creep were observed, including some slightly tilted trees in various locations. No daylighting of surface water features were observed on site, despite the early morning drizzle. Pigeon Creek Number 2 was the closest surface water feature in the vicinity, approximately 750 feet east of the project site. Puget Sound was the next closest water feature but was approximately a half mile to the noirth of the project site and at a significantly lower elevation. Subsurface Conditions: Subsurface conditions were assessed by DCP results and observed directly from hand auger cuttings. Hand augers were advanced, by an MTC Staff Geologist, along the crest of the slope north of the proposed existing residence. Hand augers and DCPs reached refusal conditions at approximately 3.6 to 5.5 feet below present grade (BPG). DCP-1 was advanced at a location on slope crest near the center of the property, approximately 20 feet from the edge of the existing residence. Soils encountered were typically loose to medium dense to a depth of about 3.5 feet BPG, becoming medium dense to dense, and achieving refusal at approaimately 5.5 feet BPG. DCP-2 was advanced about 20.0 feet downslope of DCP-1, as access and slope conditions allowed. Soils encountered were typically loose to medium dense to a depth of about 2.5 feet, becoming dense to very dense, and achieving refusal at approaimately 5.0 feet BPG. DCP-3 was advanced at a location on the crest of the slope, near the west properry line of project site. Soils encountered were typically mediurn dense to a depth of about 3.5 feet, becoming dense to very dense, and achieving refusal at approximately 5.0 feet BPG. Soils encountered during hand auger advancement at HA-1 at the crest of the slope on the north side of the properry, appeared to be dark brown, moist, loose, silty sand with gravel, roots, minor organics and mulch, to depths of appro�imately 0.3 feet BPG. Belo��v, soils appeared to be gray-brown, moist, loose to medium dense, silty sand with gravel, to depths in excess of 3.5 feet BPG. Color variations were observed in the spoils ofHA-1,possibly indicating localized silt lenses or mottling. Surface and SubsurJ'ace Water Conditions: The project site is located at a localized high point relative to the adjacent properties, pr�venting the accumulation of surface ��ater from soui-ces outside of the site. While Pigeon Creek Number 2 is the closest water surface feature and it does not appear to influence the site in a significant way. Light rainfall from the morning of the investigation was mot observed perched on the site soils, however adverse weather conditions were not directly observed during our investigation. The presence of perched water on site may become more apparent during the rainy season. �