When it rains it pours, which means municipal officials must be sure they are prepared for wet weather events. Stormwater cannot be absorbed into impervious surfaces such as pavement, concrete and gravel. Even pervious surfaces such as lawns and soft landscaping are not able to take in much water from an intense rain, meaning that instead of soaking into the ground, the water runs across the surface which contributes to ponding and flooding issues. To remedy these situations, water must be managed through a stormwater collection system.
A stormwater master plan is a community’s long-term plan for how these systems work together in a larger solution of stormwater management.
Why a Stormwater Master Plan?
A stormwater master plan is the bedrock of a long-term strategy for your community’s future infrastructure projects and maintenance because it allows needs to be identified and options considered. The plan can be relied upon when strategizing for economic development, prioritizing funding and educating the public about drainage issues and what it takes to address them.
The main questions you need to ask regarding a stormwater master plan:
- What are the community’s drainage issues?
- Why is the community facing these issues?
- What are community officials' options for addressing these issues?
There are numerous reasons to update or create a stormwater master plan:
- aging infrastructure
- water in basements or crawl spaces
- standing water in roadways
- slow drain times in common areas of flooding
- development that adds impervious areas which contribute to more storm runoff
- ability to provide documentation for funding.
Understanding common stormwater pain points help officials plan, budget and prioritize future projects. Once community leaders have a solid understanding and knowledge of their stormwater problems and direction on how to correct them, the next step is creating the master plan itself.
What Goes into a Stormwater Master Plan?
The stormwater master plan should take a variety of opinions and viewpoints into account. Receiving information from residents, business owners and school officials provides different viewpoints and allows stormwater issues to be seen from all angles. This plan should highlight solutions that could work and do not work. This way, there is documentation of debunked solutions, but they are captured within the plan in case new factors arise (e.g., technological advancements or increased funding) that make an option feasible in the future.
First and foremost, city and town officials should have an updated geographic information system (GIS); a modern version of a system map. Like a traditional map, a GIS shows the location of the system components and also can include information such as size, condition and age of each component. The primary pain point municipal leaders face when formulating a stormwater master plan is the lack of an updated GIS.
With an updated GIS, the next step is an underground pipe infrastructure audit. In this stage, pipes, catch basins or manholes are inspected via closed-circuit television (CCTV). The video runs continuously so the operator can see any existing issues in real-time and address those problems.
When putting together the stormwater master plan, creating a dynamic document is the ideal way to build the plan. A dynamic document is designed to change over time and act as a “living document” since municipal growth and projects are non-linear. These plans are typically created to cover a 20-year planning period since any time after that is difficult to predict. The plan should take additional factors into account such as city or town leaders’ other project priorities, historical inflation rates to predict future costs and more.
In the modeling stage, it is crucial to estimate future growth via historical data and population variance trends from surrounding and similar areas. Accounting for future population growth provides a better look into all necessary infrastructure additions as well as potential maintenance projects on existing infrastructure.
A detailed stormwater master plan also should include what can and will happen if action is not taken, ensuring community officials know the severity of their municipalities’ stormwater issues which helps create priorities. Once the plan is laid out, the next steps are to secure funding and begin implementation.
All in all, stormwater master plans are an important piece of overall municipal planning because they help prepare for wet weather events that may cause issues within a city or town. Upgrading stormwater infrastructure may cost more upfront, but saves money overall on potential damages by creating a proactive approach and prioritizing the proposed projects through a cost/benefit analysis.
