Environment & Sustainability | Surface Water Management (Title 13)
a) Would result in a new single-family dwelling unit, accessory dwelling unit, multifamily, or commercial facility; or b) Would result in a net increase in impervious surface of 500 square feet or more; or c) Would involve 2,000 square feet or more of land disturbing activity; or vi. When located within a critical drainage area draining to a landslide hazard area and meets any one of the following conditions: a) Would result in a new single-family dwelling unit, accessory dwelling unit, multifamily, or commercial facility; or b) Would result in a net increase in impervious surface of 200 square feet or more; or c) Would involve 2,000 square feet or more of land disturbing activity; or vii. When located within a critical drainage area in the Tamarack or Inglewood Historic Plats and would result in any net increase in impervious surface; or meets one of these conditions; a) In Tamarack, any land disturbing activity greater than 2,000 square feet, or greater than 20 percent of the lot or tract area (whichever is less); or b) In the Inglewood Historic Plat, east of East Lake Sammamish Parkway NE, any land disturbing
activity greater than 2,000 square feet, or greater than 20 percent of the lot or parcel area (whichever is less); or viii. Is a redevelopment project proposing $100,000 or more of improvements to an existing high-use site. b. The drainage review for any proposed project shall be scaled to the scope of the project’s size, type of development and potential for impacts to the regional surface water system to facilitate preparation and review of project applications. If drainage review for a proposed project is required under subsection 1. of this section, the City shall determine which of the following drainage reviews apply as specified in the Surface Water Design Manual:
i. Simplified drainage review;
ii. Targeted drainage review;
iii. Directed drainage review;
iv. Full drainage review; or
v. Large project drainage review.
3. Drainage review – Requirements
a. A proposed project required to have drainage review by this chapter must meet each of the core requirements which are described in detail in the Surface Water Design Manual and as amended by the Sammamish Addendum to the Surface Water Design Manual.
Revisions | June 29, 2022 Effective | January 1, 2022
144 | Title 21: Sammamish Development Code
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