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All new development and redevelopment projects are responsible for preventing erosion and the discharge of sediment and other pollutants into the storm drain system and receiving waters.

Projects meeting the state regulatory threshold of one-acre shall meet the following requirements:

(1) The WDOE has issued a construction storm water general permit that is applicable to construction sites that meet the state regulatory threshold of one-acre. The construction storm water general permit establishes standards and guidelines for creating a storm water pollution prevention plan (SWPPP) and implementing erosion and sediment control BMPs. It is incorporated by reference and made part of this chapter for projects meeting the state regulatory threshold.

(2) Projects meeting the state regulatory threshold that require coverage under the construction storm water permit, and not qualifying for an erosivity waiver, must complete a storm water pollution prevention plan (SWPPP). The SWPPP will aid in preventing erosion and the discharge of sediment and other pollutants into receiving waters. BMP selection, design, installation, operation and maintenance standards shall conform to the standards set forth in the Storm water Management Manual for Eastern Washington.

(3) Storm water pollution prevention plans shall meet the requirements of the Storm water Management Manual for Eastern Washington and provide for the following:

(A) Prevention of any discharge of untreated storm water off-site.

(B) Retention of all post-development storm water discharges on site, unless specifically approved otherwise by the city.

(C) Continuation of BMPs for appropriate periods of time.

(D) Protection of groundwater from instances of polluted runoff infiltration.

(4) Erosivity Waiver. Construction site operation may qualify for a waiver from the requirements to submit a SWPPP for local jurisdiction review if the conditions listed in Section 2.C of the construction storm water general permit are met.

(5) Exceptions to the construction storm water general permit requirements may be granted by the city, with WDOE concurrence, prior to project approval and construction following an application for an exception with legal public notice per the city's guidance and requirements for exceptions and variances.

All projects, regardless of the size, shall comply with the following requirements:

(1) Grading, erosion control practices, sediment control practices, and waterway crossings shall meet the design criteria set forth in the Storm water Management Manual for Eastern Washington, and shall be adequate to prevent transportation of pollutants and sediment from the site to the satisfaction of the city. Cut and fill slopes shall be no greater than 2:1, except as approved by the city to meet other community or environmental objectives.

(2) Clearing and grading of natural resources, such as forests and wetlands, shall not be permitted, except when in compliance with all other sections of this chapter. Clearing techniques that retain natural vegetation and drainage patterns, as described in the Storm water Management Manual for Eastern Washington, shall be used to the satisfaction of the city.

(3) Clearing, except that necessary to establish sediment control devices, shall not begin until all sediment control devices have been installed and have been stabilized.

(4) Phasing shall be required on all sites disturbing greater than thirty acres, with the size of each phase to be established at plan review and as approved by the city.

(5) Erosion and sediment control requirements shall include the following:

(A) Soil stabilization shall be completed within the following time frames: within thirty days in the dry season (July 1 – September 30), and within fifteen days in the wet season (October 1 – June 30).

(B) Special techniques that meet the design criteria outlined in the Storm water Management Manual for Eastern Washington on steep slopes or in drainage ways shall be used to ensure stabilization.

(C) The entire disturbed area must be stabilized, using a heavy mulch layer or another method that does not require germination to control erosion, at the close of the construction season.

(D) Techniques shall be employed to prevent the blowing of dust or sediment from the site.

(E) Techniques that divert upland runoff past disturbed slopes shall be employed.

(6) Sediment controls shall be selected based on the BMPs listed in the latest version of the Storm water Management Manual for Eastern Washington. Additionally, the following sediment controls shall apply:

(A) No sediment transport off the site will be allowed. All sediment shall be controlled on site.

(B) In addition to sediment transport by storm water runoff, sediment transport due to overwatering for dust control or site cleanup will not be allowed.

(C) The transport of construction materials from the site, including cement and other water-born materials, whether they are carried in storm water runoff or other runoff, is prohibited.

(7) Waterway and watercourse protection requirements shall include:

(A) A temporary stream crossing installed and approved by all authorized state and local agencies if a wet watercourse will be crossed regularly during construction.

(B) Stabilization of the watercourse channel before, during, and after any in-channel work.

(C) All on-site storm water conveyance channels designed according to the criteria outlined in the Storm water Management Manual for Eastern Washington.

(D) Stabilization adequate to prevent erosion located at the outlets of all pipes and paved channels.

(8) Construction site access requirements shall include:

(A) One single, stabilized entrance/exit to the construction site reinforced with quarry spalls or other suitable coarse rock material. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad.

(B) Other measures required by the city in order to ensure that construction vehicles do not track sediment onto public streets or allow sediment to be washed into storm drains.

(C) Tracking of sediment onto public streets shall be considered a violation of this chapter. (Ord. 1800, § 1, 2010.)