HOW DOES THE SET WORK?
The SET is a simple Microsoft Excel program that predicts the following pre and post-development stormwater quality and quantity effects:
- Total annual stormwater volume
- Total annual suspended solids (sediment)
- Total annual nitrogen
- Total annual phosphorous
The SET was designed by a team of local and statewide experts specifically for the Upper Neuse Basin. However, the assumptions are useful throughout the Piedmont.
You can use the SET on new development sites, redevelopment sites, stormwater retrofits, or to predict the impacts avoided through land protection. The SET can also predict costs for all scenarios examined.
Example A: Town Oversees Innovative Stormwater Management Using SET
Community adopts nitrogen or phosphorous performance standard, such as those recommended in the Upper Neuse Watershed Management Plan. Along with the new ordinance, the community will need an approved design manual (for example, the State Stormwater Manual or NC Low-Impact Development Manual currently being developed).
Community reviews all new site development proposals using the Upper Neuse SET. Like the current spreadsheet used for nitrogen control in the Neuse Basin, the Upper Neuse SET is used during the site review process and requires only basic site information. The tool provides information about total pre- and post-development runoff volume, total suspended solids, nitrogen, phosphorous, and cost estimates for proposed stormwater BMPs.
If the proposed development does not meet the performance standards, the developer changes the concept before losing valuable time and money in detailed design. The Upper Neuse SET allows all relevant town departments (planning, public works, etc.) and developer to analyze various best management practice configurations, their benefits, and their costs.
If the proposed site meets the standards, the site approval process continues.
Example B: Watershed Protection Group Assesses A Stormwater Retrofit Site
The Upper Neuse SET can help municipalities, agencies, private landowners, or watershed protection groups assess the costs and benefits of stormwater retrofit projects. Stormwater retrofits are practices that can reduce the stormwater impacts in already-developed areas. A potential retrofit site can be "redesigned" and evaluated in the same way as a new site.
A watershed group identifies an area where stormwater runoff problems exist and a potential "best management practice" such as a stormwater wetland, bioretention area, or a stormwater pond for addressing the problem.
Using basic mapping data or geographic information systems, the group assesses the current annual runoff volume, nitrogen loading, phosphorous loading, and sediment loading leaving the site.
The group uses the SET to assess several potential remediation scenarios, and their costs. If the group has the expertise, it can use the outputs of the SET in a watershed model to assess the cumulative benefits of multiple retrofit projects.
The watershed protection group uses the findings from the SET analysis to strengthen watershed restoration grants from their city, county, state agency, or other sources.