City of Norfolk

Norfolk Stormwater Design and Construction Manual

CityVirginiahighNo

Open source PDF ↗Official agency page ↗

Other manuals in Virginia: City of Chesapeake, Virginia Department of Environmental Quality (DEQ)

Document Metadata

Jurisdiction level

municipality

“CITY OF NORFOLK, VA STORMWATER DESIGN AND CONSTRUCTION MANUAL”
Header / Title

State

Virginia

“CITY OF NORFOLK, VA”
Header

Version / edition

Rev 3, July 1, 2024

“Rev 3, July 1, 2024”
Page i / headers

Adoption / effective date

2024-07-01

“The effective date of this design and construction manual is July 1, 2024.”
Section 1.1 Purpose

Last revised date

2024-07-01

“Rev 3, July 1, 2024”
Page i

Relationship to state manual

independent

“In addition to the requirements specified in the Virginia Stormwater Management Handbook and the Virginia Stormwater BMP Clearinghouse, the following requirements must be complied with when designing stormwater management systems for new development and redevelopment projects in the City of Norfolk”
Section 5.3 City of Norfolk Design Criteria

Design Criteria

Design storm return periods (years)

1-year, 2-year, 10-year, 100-year

“The prescribed design storms are the one-year, two-year, and 10-year 24-hour storms using the site-specific rainfall precipitation frequency data recommended by the U.S. National Oceanic and Atmospheric Administration (NOAA) Atlas 14.”
Section 5.2.4 Design Storms and Hydraulic Methods

Water quality volume method

Virginia Runoff Reduction Method (VRRM) per Part II B / 9VAC25-875-590: new development total phosphorus load shall not exceed 0.41 pounds per acre per year. Redevelopment reducing P load at least 10% below predevelopment if disturbing greater than 2,500 square feet and less than one acre, or at least 20% if disturbing one acre or more. BMPs from the Virginia Stormwater BMP Clearinghouse; plan elevations include the water quality (1-inch) storm event plus 1-, 2-, and 10-year 24-hour storms (NOAA Atlas 14).

“The total phosphorus load of new development projects shall not exceed 0.41 pounds per acre per year, as calculated pursuant to 9VAC25-875-590. Please verify alignment with the latest approved Virginia Runoff Reduction Method (VRRM) criteria from DEQ.”
Section 5.2.1 New Development

Peak flow calculation method(s)

Rational Method (≤20 acres), Modified Rational Method (peak discharge only; ≤20 acres), SCS Graphical Peak Discharge Method (peak discharge only; >20 acres), SCS Tabular Method / runoff hydrograph (>20 acres), NRCS synthetic 24-hour rainfall distribution with TR-55 and TR-20, U.S. Army Corps of Engineers hydrologic and hydraulic methods

“Table 5.1: Runoff Calculation Methods... Rational Method... Modified Rational Method (peak discharge only) ≤ 20 Acres... SCS Graphical Peak Discharge Method... SCS Tabular Method (runoff hydrograph) > 20 Acres”
Table 5.1, Page 5-37

Required hydrologic/hydraulic software

Virginia Runoff Reduction Method (VRRM) Compliance Spreadsheet / worksheets

“1D - Virginia Runoff Reduction Method (VRRM) Worksheets All VRRM calculations shall be performed using the 2011 Virginia bmp Clearinghouse Standards. The most current version of the worksheets may be found at Guidance & VRRM | Virginia DEQ”
Plan checklist / VRRM worksheets

Approved BMP categories

Manufactured Treatment Devices (Virginia DEQ BMP Clearinghouse MTDs), Underground storage/detention, Extended Detention Pond, Wet Pond, Grass Channel, Rooftop (Impervious Surface) Disconnection, Sheet Flow to Vegetated Filter Strip/Conserved Open Space, Vegetated Roof, Rainwater Harvesting, Dry Swales, Wet Swales, Constructed Wetlands, Filtering Practices (non-cartridge), Soil Compost Amendment, Permeable Pavement, Infiltration Practices, Bioretention (including Urban Bioretention), Virginia Stormwater BMP Clearinghouse BMPs (Coastal Plain design considerations required where listed)

“Best Management Practices that are preferred on City property: 1. Manufactured Treatment Devices... 2. Underground storage/detention 3. Extended Detention Pond 4. Wet Pond 5. Grass Channel 6. Rooftop (Impervious Surface) Disconnection 7. Sheet Flow to Vegetated Filter Strip/Conserved Open Space 8. Vegetated Roof 9. Rainwater Harvesting 10. Dry Swales 11. Wet Swales 12. Constructed Wetlands 13. Filtering Practices”
Section 5.1, Pages 5-31–5-32