Rain Gardens Across Maryland

Introduction
If you enjoyed reading Rain Gardens in Maryland’s Coastal Plain [and even if you haven’t read it], you will enjoy reading Rain Gardens Across Maryland. This new and improved “how-to” manual discusses the benefits of incorporating multiple small-scale practices into a rain garden design. You will also learn how to:

  • Reduce impervious surfaces
  • Size your rain garden to capture the maximum rainfall amount
  • Select rain garden plants native to Maryland
  • Install rain barrels
  • Measure your rain garden’s performance

Download here (scroll to bottom of page)

Environmental Site Design
For homeowners required to install stormwater management practices, this manual provides environmental site design, or ESD sizing criteria for rain gardens. Just look for “ESD criteria” text boxes. The ESD criteria outlines the minimum requirements homeowners shall implement in order to satisfy Maryland’s stormwater regulations and should be approved by your local approving authority before you begin building your rain garden. Homeowners installing rain gardens voluntarily do not have to meet ESD criteria.

Title 4, Subtitle 201.1(B) of the Stormwater Management Act of 2007 defines an ESD as using small-scale stormwater management practices, nonstructural techniques, and better site planning to mimic natural hydrologic runoff characteristics and minimize the impact of land development on water resources to the maximum extent practical. Under this definition, ESD includes:

  • Minimizing impervious surfaces
  • Conserving natural features e.g., drainage patterns, soil, vegetation
  • Slowing down runoff to maintain discharge timing and to increase infiltration
  • Using other nonstructural practices or innovative technologies approved by the Maryland Department of the Environment

Small-scale practices
Small-scale practices capture and treat stormwater runoff from impervious areas usually less than one acre in size. These practices typically include natural systems, vegetation, and soils and may be interconnected to create a more natural drainage system. Although this manual focuses on installing rain gardens, the ESD strategy requires that stormwater management practices, including the small-scale practices listed below, be integrated into one project to the maximum extent practical. Small-scale practices include:

  • Rain gardens
  • Rainwater harvesting
  • Submerged gravel wetlands
  • Landscape infiltration
  • Infiltration berms
  • Dry wells
  • Micro bioretention
  • Swales
  • Enhanced filters

Stormwater Design Manual
The primary goal of Maryland’s stormwater management program is to maintain predevelopment runoff characteristics as nearly as possible. The ESD criteria provides a comprehensive design strategy to achieve this goal and is described in Maryland’s Stormwater Design Manual. To learn more about the Maryland Department of the Environment’s approved rain garden ESD sizing criteria and other approved small-scale practices, refer to chapter 5 of the Maryland Stormwater Design Manual, “Environmental Site Design.” This document can also be found at http://www.mde.state.md.us/Programs/WaterPrograms/SedimentandStormwater/swm2007.asp.