12815 19TH AVE SE 2022-05-06 - Laserfiche WebLink

Northwest Discharge Point (Downstream Map 2) The Proposed detention system will drain to a catchbasin near the northwest corner of the property in the Bothell Everett Highway. From this point the roadway drainage flows north, along the east side of the highway (Photo 1), in a 12" to a second catchbasin approximately 210 feet north. A 30" CMP culvert also connects to this catchbasin from the west, and flows from the west and south drain east through a 24 inch CMP pipe (Photo 3) to the approximately 1 acre Herschlip Pond (Photo 2.) Approximately 250 feet east of the pond inlet, a 47"x7l" CMP arch culvert (Photos 4 and 5) drains the pond, discharging to a protected outlet (Photo 10) approximately 350 feet further east. This culvert was installed to provide fish passage to the pond and was designed per State of Washington Department of Fisheries standards as part of the Herschlip residential development. At this point drainage from the Northeast discharge point, as well as most of the surrounding residential development, join the flowpath as they all enter a stream. The total distance from the detention system outlet to this point is approximately 800 feet. Photo 1. Facing North from existing Northwest Entrance. Approximate route of underground storm drainage conveyance.