5900 36TH AVE W SEPA 016 - 035 - SOUNDVIEW BUSINESS CAMPUS - VERITAS Land Use Decision Documents 2025-04-21

The flows are then conveyed to west underneath the railroad track and into a catch basin on the west side. The outfall from this catch basin was not found, but during the downstream walk with Gary Gray, BNSF, it was assumed this stormwater outfalled into Japanese Creek that runs along the west side of the railroad tracks. This drainage system then continues north into regional detention ponds. The outfalls of this pond system was not reviewed at this time, but as discussed with Gary Gray the regional pond is adequate to handle the flows from our site. The flows from the regional pond are piped north, underneath 5t" Avenue and exit into the stream channel to the north. This system was not investigated at this time. The emergency outfall of the regional detention pond would travel overland through a riprap channel and into the 54"x36" CMP culvert. The culvert inlet is within a concrete headwall (see below) with a debris cage over the inlet. Soundview Preliminary Downstream Analysis