905 80TH ST SW MTORRES AMERICA 2018-09-18

February 22,2016 Project No. T-7364 • Lateral earth pressures for wall design • Slab-on-grade,floors • Infiltration feasibility • Stormwater pond • Subsurface drainage • Utilities • Pavements It should-be noted that recommendations outlined in this report regarding drainage are associated with soil strength, design earth pressures,erosion, and stability. Design and performance issues with respect to moisture as it relates to the structure environment (i.e., humidity, mildew, mold) is beyond Terra Associates' purview. A building envelope specialist or contactor should be consulted to address these issues,as needed. 3.0 SITE CONDITIONS 3.1 Surface The site is an approximately 16.2-acre assemblage of 4 undeveloped parcels located between 80th Street SW and 75th Street SW, approximately 1,100 to 1,700 feet west of the intersection of 80th Street SW and Hardeson Road in Everett,Washington. The approximate location of the site is shown on Figure 1. Existing surface gradients generally slope down to the north at inclinations ranging between about 10 and 15 percent in the southern and central portions of the site, and between about 5 and 10 percent in the northern portion of the site. Total relief across the site is about 90 feet: A north-trending natural drainage ravine bisects the central and southern portions of the site. The ravine is about 6 to 10 feet deep with sideslope inclinations of about 20 to 40 percent. The gradient along the axis of the channel is about seven to ten percent Portions of the drainage channel are erosional incisions with near-vertical sides about two to three feet deep. We observed light flow in the channel at the time of our site visit. The primary source of the water in the channel appears to be two culverts that daylight onto the site near the southern,site margin. The grading and drainage plan indicates that the source of water in one of the culverts is stormwater runoff from 80th Street SW. We did not observe any indications of instability on the site slopes. We did not observe indications of significant erosion excepting the erosional incision in the drainage channel. Site vegetation consists primarily of deciduous trees and brush. Page No.2