3301 SEAWAY BLVD WHOLE SITE 2025-10-30

PUBLIC WORKS iii. I am concerned about the proposed location of the MWS, both from an access and geotechnical standpoint. The GULD for the MWS requires review and approval of the site plan by MWS to ensure that site grading and slope are appropriate for the use of a MWS unit; this review must occur for this site in addition to specific review of the location by the geotechnical engineer. In order to aid this review, two cross-sections of the unit must be provided, along its length and width, showing its location relative to the above grade and to the rockery between the unit and the NGPE boundary. The City must be provided a copy of MWS's written approval for the site grading and slope at the location of the proposed MWS system on-site. 3. Third Party Geotechnical Reviewer Comments (previous emailed to Barghausen on 10-17- 2016) a. We have reviewed the following documents you sent regarding the proposed development at 3301 Seaway Blvd: • Response to City of Everett Comments, Seaway Center, 36th Avenue West and Seaway Boulevard, Everett, Washington,prepared by Terra Associates, Inc., dated August 5, 2016. • Stormwater Site Plan, Proposed Seaway Center, NEC — 36th Avenue West and Seaway Boulevard, Everett, Washington, Prepared by Barghausen, revised date August 2, 106. Only Section 6.0 Special Reports and Studies was reviewed as it contains the original geotechnical report for the project site. • Plan Sheets C1-C12 of the Site Development for Bertch Warehouses/Seaway Center, revised date 8/3/16. • Lock and Load Retaining Wall Design, Seaway Center, Everett, Washington, reviewed and approved by Steve Miller, City of Everett 8/10/16. b. Regarding the slope stability calculations and factors of safety presented by Terra Associates, we ran slope stability analyses on Cross-Sections A-A' and B-B' as presented in the report using the program Slide V5.0. Using the soil parameters and geometries presented in the report, we calculated similar values of factors of safety. We do have concern with the following issues: • The stormwater pond sits at the crest of a steep slope. The slope is comprised of dense glacial till and advance outwash soils. If the pond were to leak, slope stability could be compromised and sliding could occur. Would an underdrain be feasible that could collect any leakage and direct it to an appropriate outlet? Is there a way to ensure the pond will not leak? • The onsite soils are subject to periodic shallow slides/slumps due to weathering of the upper layers, particularly during extensive wet periods. As the pond crest is located along the top of the steep slope is there a potential that shallow slides could undermine the pond embankment? 3 4/!--27)1 Page 3 of 4