Hydrodynamic Devices (HDDs) in Butte-Silver Bow County
In 2013, Butte-Silver Bow County (BSB) began installation of six hydrodynamic devices (HDDs) at the base of the Butte Hill. HDDs capture approximately 70% of sediments, trash, debris, and oils in stormwater. The six HDDs are located strategically at the bottom of stormwater drainage basins in Butte. Though stormwater is not treated before entering Silver Bow Creek, HDDs are simple, yet effective, engineering tools that result in water with fewer suspended solids flowing into the creek.
BSB inspects the HDDs at least every three months, and regularly vacuums them to remove sediment and debris. Maintenance is important to ensure that the HDDs work properly. Vacuuming the HDDs prevents flooding and scour damage to the HDDs.
Since installing the HDDs, the total suspended solids (TSS) flowing into Silver Bow Creek have decreased significantly, and BSB did not have an exceedance of TSS in the first reporting period of 2014.