Chapter 4 —
This chapter identifies the nine minimum requirements for stormwater management that pertain to new development and redevelopment sites. The minimum requirements are summarized in Table I-4.1, with a brief summary description of each and reference to the applicable section in this manual for detailed requirements.
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MR # |
MR Name |
Summary Description |
Manual Reference |
|---|---|---|---|
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1 |
Preparation of Stormwater Site Plans |
Projects shall prepare a Stormwater Site Plan, providing comprehensive reporting of the technical information and analysis necessary to review compliance with the Stormwater Code. |
Minimum Requirement #1: Preparation of Stormwater Site Plans |
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2 |
Construction Stormwater Pollution Prevention |
Requires projects to prevent erosion and discharge of sediment and other pollutants into receiving waters during construction activities. |
Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan (SWPPP) |
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3 |
Source Control of Pollution |
All known, available and reasonable source control BMPs shall be applied to all projects. |
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4 |
Preservation of Natural Drainage Systems and Outfalls |
Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site shall not cause a significant adverse impact to downstream receiving waters and downgradient properties. All outfalls shall provide energy dissipation. |
Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls |
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5 |
On-site Stormwater Management |
Projects shall employ On-site Stormwater Management BMPs in accordance with the prescribed projects thresholds, standards, and lists to infiltrate, disperse, and retain stormwater runoff on site to the extent feasible without causing flooding or erosion impacts. |
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6 |
Runoff Treatment |
Projects shall provide runoff treatment to reduce pollutant loads and concentrations in stormwater runoff using physical, biological, and chemical removal mechanisms so that beneficial uses of receiving waters are maintained and, where applicable, restored. |
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7 |
Flow Control |
Projects shall provide flow control to reduce the impacts of stormwater runoff from hard surfaces and land cover conversions. |
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8 |
Wetlands Protection |
Projects whose stormwater discharges into a wetland, either directly or indirectly through a conveyance system shall comply with Volume II, Chapter 6. |
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9 |
Operation and Maintenance |
An operation and maintenance manual that is consistent with the provisions in Volume II, Chapter 7 shall be provided for proposed stormwater facilities and BMPs, and the party (or parties) responsible for maintenance and operation shall be identified. |
Additional requirements beyond these nine minimum requirements apply to site development activities that require land use permits and approvals as defined in KCC 12.04.030 and Chapter 12.08 KCC. Review all permit requirements in the code, including but not limited to SDAPs (KCC 12.10.030), requirements for a professional engineer (KCC 12.10.060), downstream analysis (KCC 12.10.070), geotechnical analysis (KCC 12.10.080), soils analysis (KCC 12.10.090), and critical drainage areas (Chapter 12.28 KCC and Title 19 KCC). See Volume II, Chapter 1 for plan and submittal requirements relating to the minimum requirements and additional permit requirements that apply.
Sections
Figures
Figure I-4.1. Flow Chart for Determining Minimum Requirements for New Development Projects.
Figure I-4.2. Flow Chart for Determining Minimum Requirements for Redevelopment Projects.
Figure I-4.3. Flow Chart for Determining MR #5 Requirements.
Tables