El Dorado
County
General Contact Number: (530) 621-5567

StormWaterManagement

West Slope Development and Redevelopment Standards and Post Construction Storm Water Plan Requirements

All qualifying cities and counties in California must comply with the requirements of a National Pollutant Discharge Elimination System (NPDES) permit administered by the  State Water Resources Control Board and the nine Regional Boards beneath it. The unincorporated portion of El Dorado County's west slope is covered under a  Phase II NPDES permit, which became effective on July 1, 2013. By July 1, 2015, this state mandated permit requires the County to address storm water runoff from new development and redevelopment projects, both during construction and after construction occurs. Projects subject to the requirements, as outlined below, must submit the appropriate Post Construction Storm Water Plan based on the project type. Discretionary projects with vesting tentative maps that have been deemed complete prior to July 1, 2015 are not subject to the current Phase II NPDES permit Post Construction requirements. Those qualifying discretionary projects must follow Section 4.5 Post Construction Runoff Control requirements of the Storm Water Management Plan (SWMP) for Western El Dorado County.  Additionally, applicants should be aware of the Post-Construction Standards provided in Section XIII of the State's Construction General Permit should that permit apply to a project. For additional El Dorado County NPDES information, please view the  El Dorado County Storm Water Homepage. 

Project Type 1:  Exempt from Post Construction Requirements  
Project Definition:  
  • Projects that create or replace less than 2,500 square feet of impervious surface
  • Linear Utility Projects that create less than 5,000 square feet of impervious surface
Project Considerations Your Submittal MS4 Permit Reference
  1. Limit clearing, grading and soil compaction.
  2. Minimize impervious surfaces.
  3. Direct runoff to landscaping and/or use porous pavements.
  4. Conserve natural areas as much as possible consistent with local General Plan.
  5. Comply with County slope and stream setback ordinances/requirements.
  6. Comply with Chapter 15.14 El Dorado County Grading, Erosion, and Sediment Control Ordinance.
 
  1. Refer to El Dorado County Building Services for Plan and application submittal requirements:  http://www.edcgov.us/Building/.
 

 

N/A
Project Type 2:  Small Projects and Single Family Homes  
Project Definition: Projects that create or replace between 2,500 and 4,999 square feet of impervious surface . Linear utility projects are exempt. Additionally, projects that have been submitted prior to July 1, 2015 are exempt. Small and Single Family Home Projects do not include interior remodels, routine maintenance or repair such as: roof or exterior surface replacement, pavement resurfacing, and repaving within the existing footprint. Decks designed with spacing between boards can be excluded from the tally of impervious surface. 
Project Requirements Your Submittal MS4 Permit Reference
  1. Implement Exempt Project considerations.
  2. Implement and direct water to one or more Site Design Measures. Click here for El Dorado County’s Site Design Measures requirements.
 
  1. Refer to El Dorado County Building Services for Plan and application submittal requirements: http://www.edcgov.us/Building/.
  2. Complete Step 1 Table from the Site Design Measures Manual.
  3. Include proposed impervious surface area and Site Design Measure(s) on your Site Plans (refer to the Site Design Measures Manual for guidance).                         
 


Section E.12.b. Site Design Measures (pages 48 and 49)
Project Type 3:  Regulated Projects 
Project Definition: Projects other than single family homes (unless they are part of a larger Common Plan of Development) that create or replace 5,000 square feet or more of impervious surface .  Single family homes shall meet the above Project Type 2 requirements. Regulated projects do not include interior remodels, routine maintenance or repair such as: roof or exterior surface replacement, pavement resurfacing, and repaving within the existing footprint. Decks designed with spacing between boards can be excluded from the tally of impervious surface.  
Project Requirements Your Submittal

MS4 Permit Reference
  1. Implement Exempt Project considerations.
  2. Implement Site Design Measures provided above for Type 2 Projects.
  3. Remaining runoff from the 85th percentile 24-hour storm event (~1.13 inches of water) shall be directed to one or more Storm Water Treatment and Baseline Hydromodification Measures using volumetric and/or flow-based sizing criteria.
  4. Identify potential sources of pollutants and implement corresponding source control measures. Click here to access CASQA Source Control BMP Fact Sheets.
  5. Provide ongoing maintenance of water retention and treatment facilities.
 
  1. Refer to El Dorado County Building Services for plan and application submittal requirements: http://www.edcgov.us/Building/.
  2. Site Plans showing Drainage Management Areas (DMAs), proposed impervious surface areas, Site Design Measures, Source Controls and Storm Water Treatment and Baseline Hydromodification Measures that are planned to be implemented on the site.
  3. Calculations demonstrating 85th percentile 24-hour storm event capture and treatment for each DMA (can be included in a Drainage Report).
 



Section E.12.c. Regulated Projects through Section E.12.e. Low Impact Development (LID) Design Standards (pages 49 -55)
Project Type 4:  Roads and Linear Underground/Overhead Projects (LUPs) (i.e., gas, water, sewer, and overhead power lines)
Project Definition: Projects that create 5,000 square feet or more of newly constructed contiguous impervious surface . Review MS4 Section E.12.c.(c) for specific exclusions. 
Project Requirements Your Submittal MS4 Permit Reference
  1. Implement Exempt Project considerations.
  2. Implement Regulated Project requirements. Requirements for Roads and Linear Utility Projects can vary. Refer to Section E.12.c.(c) of the MS4 Permit to review variations.
 
  1. Same as Regulated Projects. Refer to  Section E.12.c.(c) of the MS4 Permit to review variations.
 

Same as Regulated Projects
Project Type 5:  Hydromodifications Projects 
Project Definition: Projects that create or replace one acre or more of impervious surface.
Project Requirements Your Submittal MS4 Permit Reference
  1. Implement Exempt Project considerations.
  2. Implement Regulated Project Requirements.
  3. Implement Hydromodification Management Measures. Refer to Section E.12.f. of the MS4 Permit to review variations.
 
  1. Same as Regulated Projects. 
  2. Verification showing post project flows will not exceed pre-project flow rate for the 2-year, 24-hour storm (can be included in a Drainage Report).
 

Section E.12.c. Regulated Projects through Section E.12.f. Hydromodification Management (pages 49 -57)

 

For questions or comments about the Storm Water Management Program or Post Construction Storm Water requirements please click here or contact:

Storm Water  El Dorado County Long Range Planning Division 
  2850 Fairlane Court, Placerville, CA 95667 
  (530) 573-7906 /  stormwater@edcgov.us

                             

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