Best Management Practices
Site Planning Tools
This manual has three tools for site assessment and design.
Site Assessment Checklist
This is a comprehensive list of environmental, social and financial considerations for making decisions about best practices. Six steps, each with its own checklist items, are critical for planning:
- On-site natural resources
- On-site infrastructure/built environment
- Off-site natural resources
- Off-site infrastructure/built environment
- Municipal, state and federal guidelines/laws
- Programmatic requirements
BMPs Suitability Matrix
Many BMPs in this manual are suitable for most conditions, but a few are not suitable or desirable in some situations. This matrix can help identify the best BMPs for the conditions. It includes a relative measure of water quality treatment and protection (high, medium, or low) and predicted ease of implementation (1, 2, or 3).
- Water Quality indicates which BMPs address water quality on-site and which reduce runoff to protect against downstream erosion that re-pollutes waterways.
- Drainage Area indicates which BMPs can be applied to which surfaces.
- Challenging Sites indicates which BMPs are feasible where infiltration of runoff is not recommended.
- Flow Control indicates which BMPs are substitute for a detention basin, for flood control.
- Land Use indicates the land uses and zoning classifications where LID can and has been implemented in Oregon.
- Ownership indicates which BMPs may be used in private development or public development.
- Development Type indicates which BMPs may be used in a retrofit, redevelopment or new development.
- BMP Suitability Matrix
Operations and Maintenance
To function as intended over the long term, BMPs need maintenance. Private facilities such as rain gardens, stormwater planters and porous pavements on private property are the sole responsibility of the property owner. Before getting a development permit, the owner must sign an O&M agreement with the City (O&M Form), committing the owner and future owners to maintenance. This agreement is recorded with the deed during site-plan review.
The City is responsible for maintaining BMPs within public street rights-of-way and easements dedicated to the City. That responsibility includes removing trash, debris and sediment, along with repairing or replacing curbing, inlet drains and rock check-dams. The adjacent private-property owner is responsible for weeding, trimming or replacement of shrubs, grasses, or other plantings. Private-property owners must not place fill, trash, lawn trimmings, leaves or unapproved plants in public or private BMPs.
- Limiting Disturbance Limit disturbance in areas of the site that don’t need to be altered. When land is undisturbed and well vegetated, vegetation and soil work together to capture rainfall and reduce runoff. Clearing vegetation and grubbing or disturbing soils will disrupt the balance and could affect downstream waterways and watershed health. Some BMPs help limit disturbance during planning, design and construction of any kind of development, even retrofits.
- Minimizing Impervious Areas Minimize impervious pavement on new, redeveloped and existing sites. Other land covers drain better and reduce runoff.
- Preventing Runoff:Prevent runoff by protecting or restoring a site with features such as narrow streets and open spaces, or by adding features that evaporate or infiltrate rainfall. Include them in early planning, not as a late addition.
- LID Implementation Form This form steps through a preferred stormwater hierarchy, with the most preferred BMPs appearing first. The LID Worksheets help determine which information is most critical to implementing a BMPs, and assist with its sizing. A sample LID Implementation Form can be found on the Stormwater Management Draft Documents page.