Best Management Practices
Best Management Practices (BMPs) are actions done to control water pollution and improve water quality. Throughout Aspen many BMPs are implemented to reduce runoff and keep pollutants out of the Roaring Fork River. Below is a summary of BMPs that are utilized in Aspen. Further information on BMPs can be found in the Urban Runoff Management Plan in the sections listed with each summary.
Street sweeping plays an important role in keeping pollutants out of stormwater. Debris, dirt, sand and silt collect in gutters and along the sides of streets. Sweeping and collecting this material keeps it from entering the river.
The city of Aspen has installed vaults to help improve stormwater quality. Sediment stays suspended in water when water moves. You can visualize this by picturing a jar filled with water and dirt. When you shake the jar the dirt mixes with the water and the water becomes murky. However, if you leave the jar sitting on a table the dirt will eventually settle to the bottom. Stormwater vaults work in the same manner. Water running off the streets is turbulent, mixed, and carries high concentrations of sediment.
When the water reaches a vault a couple things happen that remove unwanted pollutants. First, the water passes through a trash rack. A trash rack is a series of bars that stop large debris. The water also slows down greatly. The water is deep and slow moving. This allows sediment to settle to the bottom of the vaults. The water then has to pass under a structure which essentially “skims off” any pollutants floating on the water. This helps keep oil and gas, which floats on top of water, out of the river. At the end of the vault a structure comes up from the bottom of the vault. Only water on top pours over and out of the vault. This keeps the sediment on the bottom from flowing out of the vault.
Aspen has vaults located above the Jenny Adair wetlands located on the south side of Puppy Smith Street, as well as underneath the parking area in the Rio Grande Recycle Center. The Jenny Adair vaults treat stormwater that drains from nearly the entire town west of Mill St, while the Rio Grande Recycle Center treats drainage from the east and middle portion of town as well as drainage from Aspen Mountain’s two major gulches, Copper and Spar.
Section 18.104.22.168 of the Urban Runoff Management Plan has more information and specific requirements for stormwater vaults in the City of Aspen.
Bioengineered Wetland - Jenny Adair Wetlands
A constructed wetlands basin is a shallow retention pond that has a continuous base flow which promotes the growth of rushes, willows, cattails and reeds. The shallow pond, along with vegetation, slows down runoff and allows time for sedimentation, filtering, and biological uptake. Wetlands greatly improve water quality while at the same time providing natural aesthetic areas, increasing wildlife habitat, and providing erosion control. Constructed wetlands are engineered to mimic natural wetlands which can be viewed as the “kidneys” of the hydrologic cycle due to their filtering and cleansing capabilities.
More information on constructed wetland basins can be found in section 22.214.171.124 of the Urban Runoff Management Plan.