Let’s be real: Summer in the Pacific Northwest is not the time that its denizens are most vigilant about maintaining their stormwater facilities. It’s as dry as a bone and folks are doing everything they can to distract themselves from the looming winter rains.
In the summer, it seems like someone in a residential neighborhood is washing their car every day. Giant buckets of water are mixed with car soap and the car is scrubbed clean. Cleaning the car is not the problem, the problem is what happens after the wash is complete. After they finish washing their cars, people tend to toss the soapy water down the driveway, and leave it to eventually fall down a stormwater grate. While yes, what they are dumping is water, it is not water that should go through the stormwater system.
There are many factors that put pressure on water resources which effects the options and requirements for water management. Population growth is a main factor, creating demands for more water and producing additional wastewater and pollution. The increase can have significant negative impacts on local and regional water resources.
The Restoration and Recovery team recently attended the North Carolina State University Wet Pond and Wetland Design Update in RTP. As presented by university and state government employees, the course structured these design strategies within the framework of the recent drafts of Minimum Design Criteria (MDC) Rules for SCMs. As it stands, MDC rules are a voluntary alternative to the BMP Manual for permits from the state. Currently, local governments may adopt the MDC in their jurisdictions. In November the MDC revised draft is scheduled to be codified into rules and supplemented by a stormwater technical guidance manual. For post-construction stormwater management these criteria present a distinct opportunity for regulatory agencies to proactively and efficiently enforce and maintain the quality of SCMs within their jurisdictional boundaries.
Vegetation establishment is an important component of many stormwater control measures (SCM). Grasses, trees, shrubs, and other herbaceous plants help provide structural stability, conrol erosion, and naturally remove pollutants from rainwater runoff. However, if proper maintenance is not performed, undesirable vegetation will invade vegetated areas of the SCMs. If these undesirables go untreated, they can inhibit the function of the stormwater control to convey, treat, and/or store water from storm events. Furthermore, some desirable plants can become undesirable if they establish in unwanted areas. For instance, turf grasses invading a planted/mulched area or trees establishing on the floor of a dry detention basin.
Anyone walking along a degraded urban stream may see signs of the effects of urban development: heavily eroded stream banks, trash in overhanging tree branches, discarded tires, or remnants of stormwater conveyance infrastructure. It is obvious that intense alterations to the landscape and water network occur when land is developed. The most immediate consequences include an increase in impervious surface area with resultant increased runoff to receiving streams, higher peak discharges, greater water export and higher sediment loads during construction. In terms of stream hydrology, an altered flow regime with high peak flows and reduced baseflow is the prevalent effect of urbanization.
Headwater streams provide many ecologic and water quality benefits. In a natural setting, these small drainage tributaries filter rainwater, recharge groundwater, and dissipate water velocity while transporting sediment from upland elevations downstream to larger water bodies. It is not surprising that people tend to populate upland areas where flooding may be mitigated by hard surface stormwater conveyance structures. As a result of this trend, headwater streams fall victim to residential and commercial development, water quality suffers, and hard surface drainage methods give stormwate
There are many preventative measures that can be taken into account for a site-specific stormwater management plan, but even well-maintained and regularly inspected systems can be prone to nuisance issues. Some problems are elusive and could go undetected for a period of time while others are more blatant and are visible to the untrained eye.
Winter can often be very taxing on stormwater facilities for a variety of reasons. First, these systems are often neglected during the winter months which can result in damages, as well as sediment, trash and debris accumulation.