Implementing LID

Stormwater Management Hierarchy

Choose BMPs based on their ability to mimic pre-development hydrology, following the preferred hierarchy:

  1. Lay out the site to minimize impacts to natural resources and to minimize impervious areas.
  2. Prevent runoff by intercepting, evaporating and/or infiltrating rainfall.
  3. Reduce runoff using BMPs with surface storage (such as ponding) that infiltrate and to a lesser extent, intercept and evaporate runoff and the rainfall they receive.
  4. Reduce runoff using BMPs with underground storage that infiltrate runoff.
  5. Reduce runoff using flow-based BMPs without storage (i.e. conveyance) that infiltrate lower volumes and to a lesser extent, intercept and evaporate runoff and rainfall.
  6. If the first five choices are not feasible, then the only remaining LID choice is to improve the water quality of runoff without significantly reducing the volume, using a lined BMPs or proprietary device. This is not preferred. (See Chapter 1)
  7. To manage stormwater water quality and flow control on larger sites when LID facilities are not sufficient, use a Wet Pond, Extended Wet Pond, or Dry Detention Pond. (See Chapter 4) Consider steps 1-6 before using ponds, especially at sites with higher infiltration rates.

LID Implementation Form Requirements

Complete the LID Implementation Form at the beginning of a project, during site planning. Revisit it when detailing a set of plans for construction.

If using the Simplified Sizing Approach to design BMPs, submit all LID Forms for the permit application package:

  • Project Summary Form
  • LID Forms A through C once.
  • LID Forms D through J for each basin
  • A relevant Worksheet for each BMPs

If using the Engineered Design Approach to design BMPs, LID Forms and worksheets are not required. The permit application package should include the following along with a drainage report:

  • Information on project summary form
  • Any sizing factors used to design BMPs on-site

Refer to Chapter 3 for further requirements.