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Discharges to the public stormwater system from the following sources shall be conditionally allowed, provided each discharge is volumetrically and velocity controlled to prevent resuspension of sediments in the stormwater system and complies with the respective conditions attached hereto:

(1) Discharges from water pipe sources, including water line flushing, fire hydrant system flushing, pipe breaks and pipeline hydrostatic test water are considered conditionally allowable. Planned discharges shall be controlled to prevent contaminants from entering the stormwater system and discharging to the Columbia River. Chlorine levels shall be reduced to 0.1 ppm or less and pH adjusted between 6.0 and 9.0 S.U.

(2) Discharges from lawn irrigation shall be minimized through public education activities and water conservation efforts.

(3) Discharges from water used to wash down streets, sidewalks, and buildings shall be low in suspended solids and shall not contain detergents.

(4) Discharges from active construction sites need to comply with pollution preventions plan. Sites with curb and gutter shall use an approved screening protection system installed in catch basins and street sweeping must be performed prior to washing the street. Damage to street ditches or grass swales shall not be allowed. Construction sites disturbing one acre or more and construction projects of less than one acre that are part of a larger common plan of development or sale are subject to the construction stormwater pollution prevention requirements set forth in Chapter 7 of the Stormwater Management Manual for Eastern Washington (SWMMEW). The developer of subdivisions or site plans with constructed curbs and gutters shall be responsible for the protection and maintenance of the stormwater system for five years or until all the subdivision or site plan lots are developed with permanent improvements, whichever comes first. The protection measures and maintenance program shall be approved by the City Engineer in the form of a written agreement with the developer.

(5) Discharges from swimming pools, spas, and hot tubs shall be dechlorinated. The discharges shall be dechlorinated to a total residual chlorine concentration of 0.1 ppm or less, pH-adjusted between 6.0 and 9.0 S.U. and reoxygenated if necessary, and volumetrically and velocity controlled to prevent resuspension of sediments in the Municipal Separate Storm Sewer System (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 Municipal Separate Storm Sewer System (MS4). [Ord. 4640 § 1, 2023; Ord. 4309, 2016; Ord. 3935, 2009; Code 1970 § 13.60.150.]