Area

LID Site Planning Concepts:

  - Use hydrology as
    the integrating
    framework

- Control storm
water at its
source

- Use simple, non-
     structural methods
     to the extent
     feasible

- Create a multi-
functional
landscape

LID Hydrology Concepts:

- LID Design Storm

- Drainage envelope
Tc

- Recharge volume

BMPs and IMPs:

- Bioretention

- Dry wells

- Grassed swales

- Infiltration
trenches

- Porous pavement

- Porous pavers

Low Impact Development

ATR Associates can help with all aspects of Low Impact Development (or "LID") projects - from initial planning through design and construction.

LID Site Planning

ATR Associates assists planners and developers in developing LID site plans. We follow the 9-step process outlined by Prince George's County, Maryland. The steps are:
   • Identify applicable zoning, land use, subdivision and other local regulations
   • Define the drainage envelope
   • Use drainage/hydrology as a design element
   • Reduce/minimize total site impervious areas
   • Integrate preliminary site layout plan
   • Minimize directly-connected impervious areas
   • Modify/increase drainage flow paths
   • Compare pre- and post-development hydrology
   • Complete the LID Site Plan

Hydrologic Analysis

ATR Associates performs comprehensive LID hydrologic analyses to serve as the basis for BMP/IMP design. These analyses include:
   • Development of the LID Design Storm
   • Determine times of concentration for drainage envelopes
   • Determine the runoff and infiltration volumes to be maintained

BMP/IMP Design

ATR Associates prepares detailed engineering designs of Best Management Practices (BMPs) and Integrated Management Practices (IMPs).
   • Grading plans
   • Input and Output hydrograph analyses
   • Nutrient reduction analyses
   • Piping specifications
   • Pond design for hybrid management

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