Chapter 15.11
FEE IN LIEU OF
STORM WATER DETENTION Revised 7/17

Sections:

15.11.010    Definitions. Revised 7/17

15.11.020    Fee in lieu. Revised 7/17

15.11.030    Annual adjustment of fee. Revised 7/17

15.11.040    Use of fee. Revised 7/17

15.11.050    Payment of fee. Revised 7/17

15.11.060    Building permit. Revised 7/17

15.11.010 Definitions. Revised 7/17

For the purposes of this chapter, the following definitions shall apply:

A

“Applicable manual” means the Stormwater Management Manual for Western Washington (2012 manual as amended in 2014) prepared by the Washington State Department of Ecology in 2012 and amended in 2014.

D

“Developer” means the owner or builder of the property to be developed.

“Development” means new development, redevelopment, or both.

I

“Impervious surface” means a nonvegetated surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development. A nonvegetated surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, rooftops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled, macadam or other surfaces which similarly impede the natural infiltration of storm water.

N

“New development” means land disturbing activities; structural development, including construction or installation of a building or other structure; creation of hard surfaces; and subdivision, short subdivision and binding site plans, as defined and applied in Chapter 58.17 RCW. Projects meeting the definition of “redevelopment” shall not be considered new development.

R

“Redevelopment” means, on a site that is already substantially developed (i.e., has 35 percent or more of existing hard surface coverage), the creation or addition of hard surfaces; the expansion of a building footprint or addition or replacement of a structure; structural development including construction, installation or expansion of a building or other structure; replacement of hard surface that is not part of a routine maintenance activity; and land disturbing activities.

S

“Subdivision” shall mean the division of, or the act of division of, land into two or more lots for the purposes of building development including short subdivisions and long subdivisions. (Ord. 17C-09 § 3; Ord. 00C-08 § 1).

15.11.020 Fee in lieu. Revised 7/17

A. The developer may pay a fee in lieu of constructing the storm water detention facilities required by MICC 15.09.050, when authorized by the city engineer. The fee is based on 100 percent of the estimated cost of constructing a detention facility on-site and excludes the costs associated with designing such a facility. The developer shall submit a one-fourth mile downstream analysis and calculations determining the total new plus replaced impervious surface area as the basis for determining the fee amount by the city engineer.

B. A developer will not have the option to pay a fee in lieu of constructing a storm water detention facility if, in the opinion of the city engineer, undetained runoff from the development may materially adversely exacerbate an existing problem. (Ord. 17C-09 § 3; Ord. 00C-08 § 1. Formerly 15.11.030).

15.11.030 Annual adjustment of fee. Revised 7/17

The fees are established by the city engineer and shall be adjusted upward on July 1, 2001, and every July 1 thereafter by multiplying the rates in effect on the prior July 1 by 100 percent of the percentage increase in the Consumer Price Index (CPI) for the 12-month period ending the preceding April. The fees shall remain the same in the event the CPI indicates a decrease. If the index ceases to be published on a monthly basis, the adjustment shall be based on the CPI for the most recent 12-month period. The CPI to be used shall be the Consumer Price Index – All Urban Consumers as published by the United States Department of Labor for the Seattle/Tacoma/Bremerton Metropolitan area. In the event the Department of Labor ceases to publish such an index for the Seattle/Tacoma/Bremerton Metropolitan area, then its index for the Puget Sound region or the state shall be used. (Ord. 17C-09 § 3; Ord. 00C-08 § 1. Formerly 15.11.040).

15.11.040 Use of fee. Revised 7/17

A fee paid in lieu of constructing storm water detention at the development shall be held by the city of Mercer Island’s storm water utility for the construction of storm water management projects designed to serve the immediate or future needs of the city to reduce storm water flooding and/or erosion, and to enhance water quality, in ravines and watercourses. (Ord. 17C-09 § 3; Ord. 09C-02 § 1; Ord. 00C-08 § 1. Formerly 15.11.050).

15.11.050 Payment of fee. Revised 7/17

Payment of the fee shall be made based on the following:

A. Single-Lot Development or Addition. Prior to the issuance of a building permit; or

B. Subdivision. Prior to recording the final subdivision. Payment may be deferred by the city engineer to issuance of a building permit when determined to be in the best interest of the city. (Ord. 17C-09 § 3; Ord. 00C-08 § 1. Formerly 15.11.060).

15.11.060 Building permit. Revised 7/17

No building permit shall be issued for development as provided herein, until all requirements of this chapter are met to the satisfaction of the city engineer. (Ord. 17C-09 § 3; Ord. 00C-08 § 1. Formerly 15.11.070).

Appendix 1

Minimum Storm Water Detention Fee*

Impervious Surface Area

Fee

Less than 1,000 sq. ft.

$5,500

1,000 – 2,000 sq. ft.

$6,260

2,000 – 3,000 sq. ft.

$6,800

3,000 – 4,000 sq. ft.

$7,320

4,000 – 5,000 sq. ft.

$7,850

5,000 – 6,000 sq. ft.

$8,375

6,000 – 7,000 sq. ft.

$8,900

7,000 – 8,000 sq. ft.

$9,425

8,000 – 9,000 sq. ft.

$9,950

9,000 – 10,000 sq. ft.

$10,500

greater than 10,000 sq. ft.

**

* If the city engineer determines, in his/her sole discretion, that actual construction costs would exceed the fee determined in accordance with Appendix 1 by more than 25 percent, the fee shall be adjusted to be equal to city engineer’s construction cost estimate.

** Fees for impervious areas exceeding 10,000 square feet shall be determined on a case-by-case basis. The applicant’s engineer shall calculate the size of the detention system necessary for the project and develop a construction cost estimate. The cost estimate shall be the amount of the fee upon approval by the city engineer.