5700 23RD DR W 2018-06-28 - Laserfiche WebLink

November 29,2016 Project No. T-5922-6 It should be noted that the 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 are beyond Terra Associates' purview. A building envelope specialist or contractor should be consulted to address these issues,as needed. 3.0 SITE CONDITIONS 3.1 Surface The project area is located within the northern portion of the Northshore Christian Church and Academy property Iocated at 5700 — 23rd Drive West in Everett, Washington. The approximate location of the site is shown on Figure 1. The project site is bounded to the north by a stormwater detention pond, to the east by a graveled access driveway,to the south by paved driveway and parking for the adjacent buildings,and to the west by Building E. The site is currently used as a level, gravel-surfaced parking area. North-facing slopes extend from the site's northern margin downward to the adjacent stormwater detention pond. The slopes are inclined at approximately 3:1 (Horizontal:Vertical) and vegetated with grasses. During our reconnaissance, we observed no indications of soil movements or groundwater seepage on the site slopes. 3.2 Soils The soils observed in the test pits generally consist of two to three inches of gravel surface fill overlying one and one-half feet to two and one-half feet of dense, inorganic, fill material consisting of sand with some gravel. Underlying the dense sand fill, we observed medium dense, inorganic fill material consisting of silty sand with variable gravel content, trace cobbles, and trace organics. The silty sand fill material was observed to depths ranging from 9 feet in Test Pits TP-101 and TP-103 to 11 feet in TP-102. Under the fill material, we observed dense sand and silty sand with few gravels(Advance outwash)to the termination of the test pits. Test Pits TP-2 through TP-4, logged by our representative at the site in November 2010, indicated soils that are generally consistent with those observed for this study. Test Pit TP-3 indicated that the silty sand fill soils are in a loose condition. Since our initial explorations in November 2010, the site has undergone significant grading. Therefore,the depths shown on the November 2010 test pits are not reflective of the current site grades. Review of the Distribution and description of geologic units in the Mukilteo quadrangle, Washington, by J.P. Minard (1982), shows the soils in the vicinity of the site mapped as Advance outwash (Qva). The dense,native sand observed below the fill material in our test pits is consistent with the mapped soil type. The preceding discussion is intended to be a general review of the soil conditions encountered. For more detailed descriptions,please refer to the Test Pit Logs in Appendix A. Previous Test Pit Logs are included in Appendix B. Page No.2