30.63A.450 Minimum requirement 2: SWPPP - general requirements.
(1) All the SWPPP elements to be followed are in the Drainage Manual volume II, chapter 3.
(2) Applicants for all new development and redevelopment projects of any size shall be responsible for preventing soil erosion and the discharge of sediment and pollutants into receiving waters. A SWPPP must be submitted as part of the stormwater site plan. The SWPPP shall be implemented prior to initial soil disturbance through final stabilization.
(3) The SWPPP shall include a narrative and drawings. The narrative shall be a stand-alone document attached to the construction drawings. The standard SWPPP format for narratives is available from the Washington State Department of Ecology. The narrative shall include written explanations describing the pollution prevention decisions made for the project to comply with the SWPPP requirements contained in SCC 30.63A.450 and volume II of the Drainage Manual, including information concerning existing site conditions, construction schedules and other pertinent items not found in the drawings. Sediment and erosion control BMPs shall be selected and designed pursuant to volume II, chapters 3 and 4 of the Drainage Manual. The drawings and narrative shall describe when and where the selected BMPs will be installed, the performance that the BMPs are expected to achieve and actions to be taken if performance is not achieved. All relevant information shall be included on the construction plans for the availability of project inspectors.
(4) All new development and redevelopment shall be designed to prevent erosion and discharge of sediment and other pollutants into receiving waters.
(5) To control sediment transport and erosion during the wet season from October 1st through April 30th, seasonal work limitations shall apply, except as otherwise exempt per SCC 30.63A.450(6). Based on information provided by the applicant or local weather conditions, the department may expand or restrict the seasonal limitation on site disturbance. Land disturbing activities may only be authorized if silt-laden runoff will be prevented from leaving the site through any combination of the following:
(a) Site conditions including existing vegetative coverage, slope, soil type and proximity to receiving waters;
(b) Limitations on activities and the extent of disturbed areas; and
(c) Proposed erosion and sediment control measures.
(6) The following conditions or development activities are exempt from the seasonal clearing and grading limitations required per SCC 30.63A.450(5):
(a) Where there is 100 percent infiltration of surface water runoff within the site into approved and installed stormwater facilities;
(b) Routine maintenance and necessary repair of erosion and sediment control BMPs; and
(c) Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil. (Added by Amended Ord. 10-026, June 9, 2010, Eff date Sept. 30, 2010; Amended by Ord. 15-102, Jan. 11, 2016, Eff date Jan. 22, 2016; Amended by Amended Ord. 21-025, June 16, 2021, Eff date July 1, 2021).