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