A key element of the adopted Tualatin Basin Fish & Wildlife Habitat Program is the encouragement of the use of habitat Friendly Development practices, including Low Impact-Development (LID) techniques, designed to reduce the environmental impacts of new development. and remove barriers to their utilization. The intent is to provide flexibility in the land development ordinances to encourage the protection of qualified Habitat Benefit Areas. The following table contains a number of recommended Habitat-friendly development practices that may be considered where technically feasible and appropriate.
Habitat Friendly Development Practices
Design and Construction Practices to Minimize Hydrologic Impacts
- Amend disturbed soils to original or higher level of porosity to regain infiltration and stormwater storage capacity.
- Use pervious paving materials for residential driveways, parking lots, walkways, and within centers of cul-de-sacs.
- Incorporate stormwater management in road right-of-ways.
- Landscape with rain gardens to provide on-lot detention, filtering of rainwater, and groundwater recharge.
- Use green roofs for runoff reduction, energy savings, improved air quality, and enhanced aesthetics.
- Disconnect downspouts from roofs and direct the flow to vegetated infiltration/filtration areas such as rain gardens.
- Retain rooftop runoff in a rain barrel for later on-lot use in lawn and garden watering.
- Use multi-functional open drainage systems in lieu of more conventional curb-and-gutter systems.
- Use bioretention cells as rain gardens in landscaped parking lot islands to reduce runoff volume and filter pollutants.
- Apply a treatment train approach to provide multiple opportunities for storm water treatment and reduce the possibility of system failure.
- Reduce sidewalk width and grade them such that they drain to the front yard of a residential lot or retention area.
- Reduce impervious impacts of residential driveways by narrowing widths and moving access to the rear of the site.
- Use shared driveways.
- Reduce width of residential streets, depending on traffic and parking needs.
- Reduce street length, primarily in residential areas, by encouraging clustering and using curvilinear designs.
- Reduce cul-de-sac radii and use pervious vegetated islands in center to minimize impervious effects, and allow them to be utilized for truck maneuvering/loading to reduce need for wide loading areas on site.
- Eliminate redundant non-ADA sidewalks within a site (i.e., sidewalk to all entryways and/or to truck loading areas may be unnecessary for industrial developments).
- Minimize car spaces and stall dimensions, reduce parking ratios, and use shared parking facilities and structured parking.
- Minimize the number of stream crossings and place crossing perpendicular to stream channel if possible.
- Allow narrow street right-of-ways through stream corridors whenever possible to reduce adverse impacts of transportation corridors.
Design and Construction Practices to Minimize Impacts on Wildlife Corridors and Fish Passage
- Carefully integrate fencing into the landscape to guide animals toward animal crossings under, over, or around transportation corridors.
- Use bridge crossings rather than culverts wherever possible.
- If culverts are utilized, install slab, arch or box type culverts, preferably using bottomless designs that more closely mimic stream bottom habitat.
- Design stream crossings for fish passage with shelves and other design features to facilitate terrestrial wildlife passage.
- Extend vegetative cover through the wildlife crossing in the migratory route, along with sheltering areas.
Miscellaneous Other Habitat-Friendly Design and Construction Practices
- Use native plants throughout the development (not just in Habitat Benefit Areas).
- Locate landscaping (required by other sections of the code) adjacent to Habitat Benefit Areas.
- Reduce light-spill off into Habitat Benefit Areas from development.
- Preserve and maintain existing trees and tree canopy coverage, and plant trees, where appropriate, to maximize future tree canopy coverage.
(Section 131B added by Ord. No. 5279/3-07)