Environmental Site Design
Design guidelines should be developed that promote protection & accommodation to sea level rise, including requirements for flood-proof building materials, low-impact development, natural infrastructure & open space preservation.
Low impact development & the creation of compact development, which conserves open space & prioritizes on-site stormwater management/flood storage, can help promote resiliency in areas vulnerable to increased storm surge as sea levels rise.
Stafford County, Virginia was an early adopter of LID techniques. The County partnered with the Friends of the Rappahannock, who oversaw a number of educational projects to inform local staff on LID implementation. In the early 2000’s, the County amended both its Subdivision Ordinance & the Stormwater Code. Barriers to implementation in the ordinance language were removed, the national LID manual was adopted, Stafford’s ordinance for technical guidance & incentives were established to support the use of LID over conventional stormwater management. In 2004, Stafford County required the use of LID on new development projects to the maximum extent practicable.
Washington, D.C. uses a Green Area Ratio to set standards for the environmental site design of new and redevelopment. Ratio requirements range from 0.1 to 0.4 landscape elements to land area, depending on zoning districts. Qualified landscape elements include bioretention facilities, tree canopy preservation, permeable paving, and vegetated walls/roofs, among others.
City of Fredericksburg Code Sec. 78-1063-21: Minimum Design Standards:
"Within… the “Volume Control Area” for new development and redevelopment, the first one-half inch of runoff from all new impervious surfaces shall be removed from the runoff flow… A 1-year 24 hour extended detention may be used to satisfy up to 70% of this volume. The remaining 30% shall be removed from runoff flow. At least 50% of the parking lot surface shall drain to a filtration practice."
New Kent, VA Code Sec. 91-66:
"It is the policy of the county to maintain the rural character of the county throughout the development process. As such, the natural terrain and features of the land, including heritage, memorial, significant and specimen trees, natural watercourses and other water areas, historic and archaeological sites, scenic areas and other features and resources worthy of preservation located within the area encompassed by any proposed subdivision of property in the county shall be preserved and protected during the development process to the extent possible while enabling reasonable development of property. In this regard, no more land disturbance than absolutely necessary to accommodate reasonable development shall occur and extensive cut and fill of the natural topography shall not be allowed."
Credit-generation (MS4/TMDL/CRS) is one of the biggest drivers motivating localities. As such, local design guidelines should encourage strategies that achieve multiple benefits, like open space conservation. Urban tree planting is a credited BMP for the Chesapeake Bay TMDL, and there is also a MS4/TMDL designation for tree canopies (trees on both private & public property generate credit). In its current zoning rewrite, Norfolk is including provisions to protect specimen trees on private property & considering further protection of street trees on private property.
Reducing or limiting new impervious surfaces is a fundamental way of mitigating floodwaters. Building codes can be used to limit a building’s footprint. To reduce transportation-related impervious surfaces, localities can require a shared parking plan be submitted. These arrangements can be incentivized through reductions in parking requirements if shared plans are in place. Localities have also reduced parking requirements if mass transit options are nearby. Better Site Design recommends < 4.5 spaces per 1,000 ft. of GFA.
Development standards should preserve and enhance the urban tree canopy, which has a litany of multiple benefits (stormwater, aesthetic, property value, etc.). Localities should create guidelines for planting, sizing tree wells, maintenance, replacement of aging/dying trees & engaging landowners about the benefits of maintaining the canopy on private land.
Ex. Fairfax County Code has stringent tree canopy requirements for new development, canopy health standards, & incentivizes tree preservation.
Ex. San Antonio, Tx: Green Shade rebate program provides property owners a $50 rebate on energy bills for tree planting.
Design standards are an important component of adaptation efforts, but they are reliant on the strength of related programs & policies to be effective. Flood-resistant building materials & freeboard requirements are not sufficient to overcome siting development without consideration for sea level rise or coastal erosion.
- Require new development to manage stormwater with on-site BMPs
- Increase open space conservation through cluster development and LID
- Require flood-damage resistant building materials in SFHA
- Implement more stringent development requirements in areas that flood often, but aren’t mapped in the FIRM
- Ex. Woodstock, NY - Flood-Fringe Overlay District: The FF-O District may include other lands which experience periodic flooding.
- Maintain/enhance the tree canopy by creating an ordinance that includes priority areas for canopy retention, retention standards for development, maintenance & guidelines for replanting.
- Use reductions in parking requirements to incentivize LID or open space preservation
- Ex. Chesapeake Code of Ordinances Sec 19-416: The planning director may approve preliminary site plans, which provide for the preservation of mature trees existing on the site in exchange for a reduction in the number of parking spaces required under this ordinance or a reduction in required parking area setbacks.
For more information on conserving open space in new development, see Resilient Zoning.
Credit for regulations that require LID to mitigate runoff for new development
Code of Virginia, § 15.2-2280:
Zoning ordinances generally
Code of Virginia § 15-2-2223.1:
Localities can establish urban development areas for high intensity growth, which must incorporate principles of traditional neighborhood design.
Code of Virginia § 36-98:
Code shall not supersede proffered conditions accepted as a part of a rezoning application, special exceptions, variances, clustering of single-family homes and preservation of open space development…& local floodplain regulations adopted as a condition of participation in the NFIP
Low Impact Development Checklist for Hampton Roads (Hampton Roads Planning District Commission)
Model Shared Parking Lot Agreement (Metropolitan Area Planning Council)
Low-Impact Development Design Strategies Manual (Prince George’s County, Maryland)
Northern Virginia-specific guide to Rain Garden design and construction (Friends of the Rappahannock)
Better Site Design Principles for Communities Implementing VA’s Chesapeake Bay Preservation Act (Center for Watershed Protection)
Stormwater Management Model (EPA): The newest SWMM update includes Low Impact Development controls
ASFPM (2016) “Case Study: Stafford County, Virginia Low Impact Development Ordinance.” ASFPM NAI in the Coastal Zone Case Study. Association of State Floodplain Managers, n.d. Web. 19 July 2016.
FEMA. (2010). Home Builder’s Guide to Coastal Construction: Technical Fact Sheet Series
James River Association. (2010). Examples of Code and Ordinance Language for Better Site Design. Greener Results Consulting. Richmond, Va
Jarbeau, S. H., & Stiff, M. C. (2015). Flood Protection Pay-Offs: A Local Government Guide to the Community Rating System. Wetlands Watch.
Jones, C., Coulbourne, W., Marshall, J., & Rogers , S. (2006). Evaluation of the National Flood Insurance Program’s Building Standards. American Institutes for Research.
Schechtman, J. & Brady, M. Cost-Efficient Climate Change Adaptation in North America. Rutgers University.