Rain Gardens

Rain Gardens, bioswales, and bio-infiltration basins are a cornerstone of low-impact development projects and green infrastructure practices. More than simply buzz words utilized in today’s green building scene, these practices are a new cornerstone of future land improvement projects. ENCAP, Inc’s project history and profile has enabled us to take a practical and effective approach to the design and, most importantly, the construction of rain gardens and other green infrastructure practices. In order for these practices to be successful on the long term, it takes more than just a standard detail on a plan set, or your typical contractor to construct. There are fine nuances and subtleties to the installation and implementation of these practices, that ENCAP, Inc. provides to your project team.

Standard stormwater management practices involve the use of drains and storm sewers to convey runoff water from developed areas to a stormwater detention pond.  This approach to stormwater management is generally effective at dealing with the quantity of water that runs off of developed land but does very little for water quality and causes potential problems for water resources downstream of the detention pond.

Three of the biggest problems associated with traditional detention areas include, fluctuating water levels, higher water temperatures, and concentration of runoff pollutants.  First, water discharging from the detention area into a stream is often restricted.  This restriction keeps the rate of flow constant but lengthens the time of the surge flow after a storm.  This prolongs elevated water levels and contributes to exacerbated erosion.  Second, the temperature of water in detention areas is typically warmer that the infiltrated water that would normally feed a stream in a predeveloped condition.  Warmer water cannot hold as much dissolved oxygen which limits habitat for fish and other aquatic life.  Third, pollutants that accumulate on paved surfaces and lawn areas between rain events are washed into the storm sewer system at concentrated levels.  The majority of this type of pollutant accumulation occurs in smaller more frequent runoff events.

The term “Rain Garden” has become popular amongst stormwater management professionals. Rain Gardens can range from a small depression to a complex system of engineered soils, overflow drains and native plants.   The primary purpose of a rain garden is to store the initial inch of rain, often referred to as “the first flush”, to help the water infiltrate into the ground and limit the amount of runoff pollutants continuing downstream.  Since there are many variables in each Rain Garden, including, site character and general design, it is difficult to get definitive numbers on the effectiveness of Rain Gardens.  Preliminary results for studies at the University of Wisconsin suggest that simple rain gardens can reduce pollutants in runoff by 30%.

The U.S. Army Corps of Engineers, county stormwater management commissions, and many municipalities are pushing for Rain Garden Systems on new development projects.  Heightened regulation and public concern has driven Stormwater Engineers and Ecological Consultants to work together to develop complete site specific stormwater management approaches. When developing land or retrofitting older sites, it is critical to analyze all the possible stormwater elements that can be used to make the most of the natural rain and snow that falls on a property.

ENCAP, Inc. has met the demand for rain gardens and similar best management practices by designing and installing systems for private homeowners, municipalities, commercial developments, and planned residential communities. If you have an interest in this approach to stormwater management please contact Carl Peterson at cpeterson@encapinc.net.