BLD20161389- Tiersma Stormwater Review -1.docx
Stormwater Review
Date of Review: October 26, 2016
nd
File/Address:BLD20161389, 22318 92 Ave W
Reviewer: Robert C. Edwards, PE, Stormwater Engineer, City of Edmonds
Background
This is classified as a Category 2 Small Site Project because it is part of a two-lot short plat with
impervious area exceeding 5,000 SF.
Category 2 Small Site Projects are subject to Small Site Minimum Requirements 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, and 11.
Minimum Requirement #1 – Preparation of Stormwater Site Plan
Comments:
1. Cat 2 Small Site Projects that involve 5,000 SF or more of impervious area must be designed by a
civil engineer. Please have the Stormwater plan stamped by a Professional Engineer, licensed in
the State of Washington in Civil Engineering. Sheet A1 does not meet this requirement.
2. Please provide details, materials, sizes, and inverts of all Stormwater control features, including
trenches, drywells, oil separators.
3. A CB is specified at the edge of driveway, yet no CB symbol is shown.
4. A circle is shown at the south end of the infiltration trench. It is not clear if this is a cleanout,
overflow, or observation well.
Minimum Requirement #2 – Construction Stormwater Pollution Plan
Comments: None
Minimum Requirement #3 – Source Control of Pollution
Comments:
1. The Drainage Plan states “No extraordinary measures are required….with the project below the
5,000 square feet threshold.” The project is “part of a larger development” that is therefore to be
designed as a Category 2 Small Site Project. Previously stated, the project exceeds the 5,000 SF
threshold.
Minimum Requirement #4 – Preservation of Natural Drainage Systems
Comments: None, as infiltration is specified.
Minimum Requirement #5 – Onsite Stormwater Management
Comments:
1. See comments related to this section from Minimum Requirement #1.
Minimum Requirement # 6 – Runoff Treatment
Comments:
1. See comments related to this section from Minimum Requirement #1.
Minimum Requirement #7 – Flow Control
Comments:
1. LID techniques are specified for this project. Reiterating from previous comments, for Category 2
Small Site Projects, the LID techniques must be designed by a Professional Engineer licensed in
the State of Washington in Civil Engineering.
Minimum Requirement #8 – Wetland Protection
Comments: None
Minimum Requirement #9 – Operation and Maintenance
Comments:
1. The site plan specifies two oil separators. Please provide O&M guidance for these structures with
respect to their oil control function.
Minimum Requirement # 10 – Offsite Analysis and Mitigation
Comments: None, as LID is specified
Minimum Requirement #11 – Financial Liability
Comments: None