§ 24.25.323. Stormwater facilities—Engineered stormwater dispersion.

The dispersion area of stormwater dispersion systems, as defined by the Thurston County DDECM, shall not be considered a stormwater facility as described in TCC 24.25.320, and regulated as such, unless a physical structure is incorporated within the design that impacts the FWHCA. Stormwater dispersion facilities whose dispersion area includes any portion of a FWHCA are allowed as an element of a stormwater system under the following circumstances:

A.

Dispersion of runoff from back yards of development and downspout dispersion, done in accordance with the Thurston County DDECM, is allowed at the outside edge of the FWHCA.

B.

Sheet flow and concentrated flow dispersion, done in accordance with the Thurston County DDECM, of stormwater meeting runoff treatment requirements of the Thurston County DDECM is allowed at the outside edge of the FWHCA.

C.

The required dispersion area for sheet flow and concentrated flow dispersion from other pervious and impervious surfaces, done in accordance with the Thurston County DDECM, may only include that portion of a FWHCA outside of the minimum area considered necessary for water quality protection or one hundred fifty feet whichever is greater.

D.

Native vegetation in the FWHCA may be increased but shall not be cleared or altered to accommodate stormwater treatment.

E.

In no case shall dispersion methods be approved that may cause water quality impacts to the FWHCA. If water quality impacts are anticipated or observed, additional stormwater treatment methods shall be implemented.

(Ord. No. 14773, § 3(Att. B), 7-24-2012)