When planning a new construction project for your business there are many issues to address. One of the lesser known and intimidating issues can be how you are required to deal with storm water management.
In this instance, storm water management can be defined as the run-off from your property to your neighbors during and after a rain event. In general, when a project is developed, the owner is responsible for ensuring that when the construction or development is complete, the rate of the storm water run-off does not increase over the pre-development rates.
An increased rate of run-off occurs when the amount of impervious surface is increased. If the site is currently a grass yard, or something similar, a building will add impervious area and increase the rate at which run-off leaves the site. Conversely, if the site is already 100 percent built out, or paved, new development would not increase the rate of run off, so nothing further would be required.
To deal with a project site where the impervious area is increasing, the storm water run-off is required to be detained on site and released at the pre-development rate. The on-site detention can be done in a number of ways. One way is to create a basin or swale in a lower area of the site that can catch the run off. The basin would have an appropriately sized out flow pipe to control the rate the water is released.
Another option is to pitch a parking lot to temporarily hold storm water and be released through a curb opening. This may be appropriate for smaller projects.
If there is not an option for either of these solutions, underground structures can be placed to hold the storm water as needed. In each of these cases, a civil engineer would be needed to review and design the detention strategy and provide the calculation documentation. The storm water management plan can be found on the City of St. Joseph website for Saint Joseph.