13.45.030 Best management practices.
A. BMP Design. The owner or operator of a commercial or industrial establishment shall provide and maintain, at its own expense, reasonable protection from accidental discharge of prohibited materials or other wastes into the municipal storm drainage system or waterbody through the use of structural and nonstructural BMPs. Further, any person responsible for a premises which is, or may be, the source of an illicit discharge, may be required to implement, at said person’s expense, additional structural and nonstructural BMPs to prevent the further discharge of pollutants to the municipal separate storm sewer system.
For any activity which may result in illicit discharges, the use of the Washington State Department of Ecology’s Stormwater Management Manual for Western Washington, Volume IV, Source Control BMPs, and Volume V, Runoff Treatment, Flow Control, and LID BMP Library (hereafter “manual”), or other appropriate manual or guidance (as approved by director) is required. The manual outlines requirements identifying best management practices, including pollutant source control for any activity, operation, or facility which may cause or contribute to pollution or contamination of stormwater, the storm drainage system, or waters of the United States.
Compliance with all terms and conditions of a valid NPDES permit authorizing the discharge of stormwater associated with industrial activity, to the extent practicable, shall be deemed in compliance with the provisions of this section. These BMPs shall be part of a SWPPP as necessary for compliance with requirements of the NPDES permit.
B. Activities Requiring BMPs. BMPs shall be applied to any business or residential activity that might result in prohibited discharges. Activities that might result in prohibited discharges should use and maintain appropriate BMPs (as approved by the director), and may include but are not limited to the following:
1. Potable water line flushing (see subsection (C) of this section);
2. Lawn watering with potable water (see subsection (C) of this section);
3. Dust control with potable water;
4. Automobile and boat washing;
5. Pavement and building washing (see subsection (C) of this section);
6. Swimming pool, spa, and hot tub maintenance (see subsection (C) of this section);
7. Auto repair and maintenance;
8. Building repair and maintenance;
9. Landscape maintenance;
10. Hazardous waste handling;
11. Solid and food waste handling; and
12. Application of pesticides.
C. Conditionally Allowable Discharges. The following categories of nonstormwater discharges are allowed if the stated conditions are met:
1. Discharges from potable water sources, including but not limited to water line flushing, hyperchlorinated water line flushing, fire hydrant system flushing, and pipeline hydrostatic test water. Planned discharges shall be dechlorinated to a total residual chlorine concentration of 0.1 ppm or less, pH-adjusted, if necessary, and volumetrically and velocity controlled to prevent resuspension of sediments in the MS4.
2. Discharges from lawn watering and other irrigation runoff. These discharges shall be minimized through, at a minimum, public education activities and water conservation efforts.
3. Dechlorinated swimming pool, spa and hot tub discharges. The discharges shall be dechlorinated to a total residual chlorine concentration of 0.1 ppm or less, pH-adjusted and reoxygenized if necessary, volumetrically and velocity controlled to prevent resuspension of sediments in the MS4. Discharges shall be thermally controlled to prevent an increase in temperature of the receiving water. Swimming pool cleaning wastewater and filter backwash shall not be discharged to the MS4.
4. Street and sidewalk wash water, water used to control dust, and routine external building washdown that does not use detergents. The permittee shall reduce these discharges through, at a minimum, public education activities and/or water conservation efforts. To avoid washing pollutants into the MS4, permittees shall minimize the amount of street wash and dust control water used.
5. Other nonstormwater discharges. The discharges shall be in compliance with the requirements of a pollution prevention plan reviewed by the city, which addresses control of such discharges. (Ord. 3443 § 2, 2023; Ord. 2834 § 1, 2010)