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Stormwater Permit Submittal Requirements

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Stormwater Permit Submittal Requirements Public Works Department 104 W. Magnolia Street, Suite 109 Bellingham, WA 98225 (360) 778-7900 STORMWATER PERMIT SUBMITTAL REQUIREMENTS Most development within the City of Bellingham that involves disruption of soils, or construction of buildings, streets, parking lots, etc. requires the issuance of a Stormwater Permit. This packet contains material that will aid you in providing a complete application for this permit. Stormwater Permit requirements are based on either the amount of soil to be disrupted (grading, vegetation removal), or the amount of impervious surface that is created or replaced on a site (building footprint, concrete, asphalt or gravel parking, sidewalk, etc.). A Stormwater Site Plan consists of plan sheets showing all proposed Stormwater systems and facilities, Stormwater Pollution Prevention Plan (SWPPP), and if applicable, a Stormwater report by a licensed civil engineer. Please follow the steps on the worksheets to determine the level of stormwater management required for your project. Many applications will not need to use all information provided in this packet. If you need assistance in your determination, contact the Development section of the Public Works Dept. located at 104 W. Magnolia St., Suite 109 or call (360) 778-7900. STORMWATER MANAGEMENT REQUIREMENT CHECKLIST Provide the following information as part of your submittal: □ Impervious surface calculation (see next page) □ Stormwater management requirement determination □ Stormwater site plan and/or erosion control plan as stated on the applicable Requirements List I, II, or III □ Attach a copy of a General Construction Stormwater Pollution Prevention Plan (SWPPP) to Site Plan (see Page 7 of this packet) and erosion control details (see Page 8) IMPERVIOUS SURFACE CALCULATION Per Bellingham Municipal Code 15.42 Stormwater Management (http://www.codepublishing.com/WA/Bellingham/?Bellingham15/Bellingham1542.html), “Impervious surface” means a hard surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development. A hard surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development. Common impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, packed gravel surfaces, packed earthen materials, or other surfaces which similarly impede the natural infiltration of stormwater. The total square footage of impervious surface on your project site will determine the storm water management requirements and the storm water utility fees. Impervious surface calculations must include all of the impervious areas on your project site. "New impervious surface” means impervious surfaces that replace or supplant existing pervious surfaces. For example, resurfacing by upgrading from dirt to gravel, asphalt, or concrete. "Replaced impervious surface" means, for structures, the removal and replacement of any exterior impervious surfaces or foundation. For other impervious surfaces, the removal down to bare soil or base course and replacement is considered "replaced". Provide detailed information about your project in the following table. Enter 0 in the sections that are not applicable to your project. Impervious Surface Area Existing Removed Proposed New Proposed Replaced (square feet) Totals LAND DISTURBANCE Land Disturbance* (square feet) *Greater than 500 square feet of land disturbance requires a Stormwater Permit. 2 | Page STORMWATER MANAGEMENT REQUIREMENT DETERMINATION Follow the diagram using information from your impervious surface calculation. Your answers will determine the stormwater management requirements list you will use. Is your project less than 120 S.F. new, replaced or new plus replaced imperious NO STORMWATER surface AND less than 500 YES PERMIT REQUIRED S.F. land disturbance? NO Is the total new or Address the requirements replaced impervious of STORMWATER surface greater than 5,000 S.F.? OR Does the MANAGEMENT YES project disturb more than REQUIREMENTS LIST III 1 acre of land? NO Is your project inside YES the Lake Whatcom watershed? NO Address the requirements of STORMWATER Is your project a new single YES family residence or duplex? MANAGEMENT REQUIREMENTS LIST II NO Does the project contain more than 2,000 S.F. of YES new, replaced or new plus replaced impervious area? NO Address the requirements of STORMWATER MANAGEMENT REQUIREMENTS LIST I 3 | Page STORMWATER MANAGEMENT REQUIREMENTS LIST I If the project includes less than 2,000 square feet of new, replaced or new plus replaced impervious surface (and is not a new single family residence or duplex) or land disturbance greater than 500 square feet, provide a simplified site plan which shows: Clearing limits and indicate how limits will be marked on property. Construction entrance location and silt fence location (show location on site plan and attach standard plan sheet, see page 8). Attach General Construction Stormwater Pollution Prevention Plan (SWPPP) to site plan (see page 8). If project is a new single family residence or duplex residence see Stormwater Management Requirements List II on page 5 In addition, consider the following elements for your project: Stormwater management (tight lined to City storm system or On-Site Stormwater Management, see Appendix B). Stabilize soils Protect slopes Protect drain inlets Stabilize channels and outlets Control pollutants Control de-watering Maintain "Best Management Practices" (BMPs) Manage the project 4 | Page STORMWATER MANAGEMENT REQUIREMENTS LIST II If your project is a new single family home or duplex or between 2,000 and 5,000 square feet of new, replaced or new plus replaced impervious surface or 5,000 square feet or more of land disturbance, the project requires compliance with the following listed minimum requirements. For specific information, please refer to the current edition of the Washington State Department of Ecology's Stormwater Management Manual for Western Washington (click on link: https://fortress.wa.gov/ecy/publications/SummaryPages/1410055.html). 1. Preparation of Site Plans The following elements must be considered during the development of the site plan: Existing public and private development, including utility infrastructure on and adjacent to the site. Minor hydrologic features, including seeps, springs, closed depression areas, drainage swales. Major hydrologic features such as streams, wetlands and waterbodies. Flood hazard areas on or adjacent to the site, if present. Geologic Hazard areas as defined by the local jurisdiction. Topographic features that may act as natural stormwater storage, infiltration or conveyance. Underlying soils on the site utilizing soil surveys, soil test pits, soil borings, or soil grain analyses (see http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm for soil survey information). Plat conditions or other restrictions on the allowed impervious surface coverage. Easements and/or other restrictions associated with the project area. 2. Construction Stormwater Pollution Prevention Plan (SWPPP) See the attached requirements for "General Construction Stormwater Pollution Prevention Plan" on page 8 3. Source Control of Pollutants See Appendix A for information about available source control BMPs 4. Preservation of Natural Drainage Systems and Outfalls Natural drainage patterns shall be maintained, and discharges for 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 must not cause a significant adverse impact to downstream receiving waters and downgradient properties. All outfalls require energy dissipation. Where no conveyance system exists at the adjacent downgradient property line and the discharge was previously unconcentrated flow or significantly lower concentrated flow, you may need to obtain an easement or consider an engineered storm system to prevent impacts to downstream property. 5 | Page 5. On-Site Stormwater Management Projects shall employ on-site stormwater management BMPs to infiltrate, disperse, and retain stormwater runoff on-site to the maximum extent feasible without causing flooding or erosion impacts. Roof downspout control BMPs (see Appendix B), and Dispersion and Soil Quality BMPs shall be required to reduce the hydrologic disruption of developed sites. 6 | Page STORMWATER MANAGEMENT REQUIREMENTS LIST III If your project is greater than 5,000 square feet of new, replaced or new plus replaced impervious surface. The project requires compliance with the following minimum requirements. The plan must be designed by a licensed civil engineer. For specific information, please refer to the most current edition of the Washington State Department of Ecology Stormwater Management Manual for Western Washington (https://fortress.wa.gov/ecy/publications/SummaryPages/1410055.html). 1. Preparation of Stormwater Site Plans 2. Construction Stormwater Pollution Prevention Plan (SWPPP) 3. Source Control of Pollution 4. Preservation of Natural Drainage Systems and Outfalls 5. On-site Stormwater Management 6. Runoff Treatment 7. Flow Control 8. Wetland Protection 9. Basin/Watershed Planning 10. Operation and Maintenance 7 | Page GENERAL CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN SWPPP Purpose To prevent the discharge of sediment and other pollutants to the maximum extent practicable
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