Chester County Planning Commission

Design Elements — Preserve Natural Resources

Preserving natural resources and integrating them into a new subdivision's site design can greatly reduce the development's impact on the site and the surrounding environment. Mature vegetation can provide screening, add shade, and enhance sense of place.

Ordinance Considerations

Preservation of natural features on the site should be approached from two fronts:

Municipal ordinances should contain resource protection standards that apply to all types of proposed development — residential and non-residential — in the municipality. Such standards typically include disturbance limitations for floodplains, wetlands, streams, riparian buffers, steep slopes, and woodlands.
Cluster subdivision design requirements should ensure that the most sensitive natural resources are located in the open space where they can be permanently protected. The location of all the resources on the site should be identified first and the open space located accordingly.

Some ordinances require natural resource areas like wetlands and very steep slopes to be subtracted from the total tract area and required open space to be based on the total developable tract area. Other ordinances permit the natural resource areas to be included in the total open space calculation. The latter should also require that some minimum percentage of the open space be unconstrained land so that it can be used and enjoyed for recreational purposes by the residents of the subdivision, even if that results in the requirement of a higher percentage of open space.

Minimum Recommended Protection Standards

Protected Resource	Protection Standard*	Suggested Location of Provisions	Other Protection Provisions
Floodplain	0%	Zoning	FEMA approved floodplain standards
Steep Slopes 15-25%	30%	Zoning	Standards to minimize disturbance, grading, and erosion Certain activities/uses prohibited on 25%+ slopes Provide a description of the slope measurement method
Steep Slopes 25% and up	0-15%	Zoning
Wetlands	0%	Zoning	Specific identification and delineation standards Require state and federal permits
Wetland Margins	20%	Zoning	Require 50-75 feet total margin width depending on conditions adjacent to the wetland
Riparian Buffer: Inner Buffer	0%	Zoning	75-100 feet total width depending on conditions adjacent to stream Two-tier standard with stricter standards applied adjacent to stream. Some use a 3-tier approach. Revegetation provisions for unforested buffers
Riparian Buffer: Outer Buffer	20%	Zoning
Woodlands: Residential	30%	Zoning and SLDO (tree replacement standards in SLDO)	Exceptions for forestry or timber harvesting, per MPC; consider requiring a timber harvesting plan which is compliant with PA state standards. Protection standards (from construction activities) for trees to remain on site Include hedgerows, specimen trees in protected vegetation Tree replacement requirements if more than specified area or number of trees are removed Establish a definition for "woodland" that can be measured
Woodlands: Non-residential	50%	Zoning and SLDO (tree replacement standards in SLDO)
Stormwater Management	n/a	Stormwater Management Ordinance	Stormwater standards that prioritize green infrastructure, promote infiltration and low-impact design
Site Plan Requirements	n/a	SLDO	Resources must be identified and mapped on site plan
Continued Protection of Resources	n/a	Zoning and SLDO	Provisions for permanent protection of preserved resources