5900 36TH AVE W PRE APP 015 - 032 - SOUNDVIEW BUSINESS CAMPUS - VERITAS Geotech Report 2025-04-22

Veritas Construction Inc ES-4011.03 June 17, 2016 Page 13 Revised June 22, 2016 ' Finish grades must be designed to direct surface drain water away from structures and slopes. Water must not be allowed to pond adjacent to structures or slopes. In our opinion, foundation drains should be installed along building perimeter footings. A typical foundation drain detail is provided on Plate 4. Preliminary Detention Vault Recommendations ' Based on review of the preliminary site plan, we understand a series of stormwater detention vaults will be constructed along the north and east margins of Building C and the north and west margins of Building B. ESNW should review the vault design to confirm the recommendations provided in this report are followed and provide supplemental recommendations. The presence of minor perched groundwater seepage should be expected in the detention vault excavations, depending on the time of year grading takes place. ESNW prepared a Stability Assessment letter, dated October 6, 2015, relating to the proposed ' stormwater detention vaults. Slope stability analysis was completed as part of an overall evaluation for the proposed detention vaults in the referenced letter. Based on our field ' observations, grade cuts for the vault are likely to expose dense to very dense, undisturbed glacial till. ESNW should review detention vault designs, particularly with respect to location relative to sensitive site features and property lines when final designs are completed. The following values can be used for design of the vault: ' • Allowable soil bearing capacity 3,000 psf* • Active earth pressure (yielding condition) 35 pcf (equivalent fluid) • At-rest earth pressure (restrained condition) 55 pcf • Traffic surcharge for passenger vehicles 70 psf (rectangular distribution) ' (where applicable) • Passive earth pressure 300 pcf (equivalent fluid) • Coefficient of friction 0.40 ' • Seismic surcharge (active condition) 6H (where H equals retained height) • Seismic surcharge (restrained condition) 14H ' *Value is for native or structural fill subgrade condition. ESNW should observe grading operations for the vault and subgrade conditions prior to concrete forming and pouring. ESNW should be contacted to review final vault designs to confirm appropriate geotechnical parameters have been incorporated, as necessary. I ' Earth Solutions NW, LLC