Bio-Retention Facilities: What Are They and How Do They Work?

June 11, 2013 at 4:19 pm

Bio Retention FacilityContractors, property managers, and property managers prefer a full service landscape company. They value the design, installation, and maintenance professionals who can anticipate their needs, deliver practical solutions, and tend the landscape outcome well into the future.

In many regions, especially those with sensitive water tables or with potential for flash flooding or significant storm water run-off, a bio-retention facility is required. Designing and constructing the facility is the work of certified professionals.

What are bio-retention facilities?

Left unchecked, water will go where it wants. However, architects and contractors can direct the water where it can be managed. Depressions or shallow basins in the landscaping can slow and treat on-site storm water run-off. Once in the depression, the water will percolate down through a system of chemical, physical, and biological processes. Slowed and cleaned, the water infiltrates native soils or flows to storm water drains and receiving waters.

How do they work?

Experienced landscape designers know that every bio-retention facility requires focused thought and adaptation to the specific location. They work with architects and contractors to create a proven system to direct, gather, and clean the water shed by impervious surfaces like concrete parking lots.

  1. A grassy buffer reduces the speed of the run-off and removes solids suspended in the water through decorative vegetation that absorbs water and nutrients in the flowing water.
  2. Shallow areas store excess water and facilitate its evaporation and the settlement of particulate matter.
  3. Organic mulch reduces soil erosion and provides micro-biological degradation and filtration of petroleum-based pollutants.
  4. Soils are engineered to support vegetation and absorb pollutants along with sand for drainage and aeration.
  5. A subterranean drain system directs the excess treated water to a nearby storm drain or receiving waters.

As you can imagine, the construction of a bio-retention facility is not a weekend gardening project. It requires planning, engineering, and construction design knowledge.

Some considerations
As we stated above, there is no one “formula” for bio-retention facilities and every job site has different requirements that impact how they are designed. Here are some things to keep in mind:

  • Building codes and local, state, and federal environmental regulations govern the minimum and maximum applications.
  • Impervious surfaces come in a wide variety of compositions, but the most obvious locations are highways and large parking lots. Less obvious to most of us are the impervious materials used in the foundations of shopping centers, big box stores, or office complexes. And, if you add up the offset for housing developments, you see the problem.
  • Gas stations, garages, and convenience stores have contaminatedparking lots. The bio-retention facility for such an application requires an impermeable liner at the bottom of the basin to keep contaminated water from entering the water table.
  • While best suited for small or middle sized applications, bio-retention may be required when a site is retro-fitted, resurfaced, or mitigated.


Adding a bio-retention facility to your commercial property can result in substantial benefits, but to realize these, you will require:

  • Technical expertise. You need trained and experienced technicians able to deliver on the property plan. They need the know-how and team building skills to collaborate and deliver.
  • Creative landscaping skills to make the best use of materials and terrain. The best landscapers identify plants that reduce water volume through transpiration, remove nutrients and pollutants, and increase water percolation. They will use native plants, herbaceous materials, trees, and shrubs known to your habitat and its weather conditions.

Put simply, the landscape service you want and need is part architect, part engineer, and part artist. Here at E-Landscape, our team is comprised of experts in the field of commercial landscaping, and together, we can provide full service solutions encompassing design, installation, and maintenance. We have plenty of experience designing and building bio-retention facilities so if this is something you are considering for your commercial property, please give us a call!