Storm water management is no longer just improving flood control. Integrating storm water management with water quality improvements is now on the minds of many municipalities and regulators. Municipalities and flood control agencies are realizing that applying best management practices (BMPs) not only attenuates flows to control flooding, but also can have the dual benefit of improving water quality. Low-impact development (LID) procedures also provide solutions for managing flooding and water quality in newly developing areas. Carollo Engineers helps clients utilize an integrated storm water management approach to address flooding through total maximum daily load (TMDL) development.
A storm water management pro gram typically results from the need to meet regulations based on existing practices or because of increased development that creates additional runoff. Flood control agencies typically need to meet FEMA and U.S. Army Corps of Engineers requirements. Municipalities are also faced with meeting water quality requirements through the National Pollutant Discharge Elimination System (NPDES) Phase I or Phase II storm water permit program, and may even be in volved with meeting TMDL requirements if they discharge into listed water bodies. Carollo helps clients navigate through the regulatory process to provide results that meet or exceed client expectations.
Carollo has successfully completed both monitoring and modeling programs to quantify wet weather flows. Depending on the type of project, our engineers measure flows/stages, as well as conventional and exotic pollutants. We use geographical information systems (GIS) to manage collected data as well as to interface with modeling software. This data provides the basis for hydrologic, hydraulic, and water quality models to quantify watershed flows and loads. We work with clients to identify which model will be most appropriate for each individual project. Carollo has used models such as SWMM, HECRAS, and HSPF for a variety of clients through out many different regions of the country. We also apply receiving water models on an as-needed basis. We have applied these and other models to watersheds that range from mountainous snow-covered basins to meandering deltas that are tidally influenced.
Many storm water projects still require conventional flood control facilities (i.e., culverts, pipes, channels, basins, etc.) to manage existing flows. However, the current trend is to manage storm water upstream before it becomes a problem downstream. This is where BMPs and LID come into play. By attenuating wet weather flows as they develop within a basin, downstream flooding is minimized while infiltration and residence time is increased. Increased infiltration and residence time provide water quality im prove ments. BMPs are an effective tool for existing developments, wereas LID provides a means of managing storm water in a newly developed area at the source—before it becomes a problem downstream. BMPs and LID can greatly reduce erosion and sediment within stream corridors. Carollo's experience includes assisting the U.S. EPA in the development of new modeling tools to better assess the impacts of BMPs and LID on water quantity and quality.
Financing is typically necessary to implement storm water improvements. If a municipality has not established a financing source, one alternative is to create a municipal storm water utility. Developing a storm water utility typically involves addressing legal issues (i.e., ordinances) and setting rates. However, it is also necessary to include public involvement, management, and assessment of current and future resources. Carollo helps clients create storm water utilities for their specific needs.
Carollo successfully applies an integrated storm water management approach to assist our clients through the life cycle of starting a municipal storm water utility, as well as implementing flood protection and water quality improvements. Whatever your stage in the process of protecting municipal storm water resources, we can help.