Best Management Practices for Storm Water Put to the Test

Recent heavy rains, reportedly as much as six inches, fell over the Detroit metropolitan area in a relatively short time period (36 hours), resulting in substantial flooding and damage to properties.  Heavy rainfall was also reported on the east coast of the United States as slow-moving weather systems moved from west to east.  These flooding rains may have taxed or over taxed your Best Management Practices (BMP) for your storm water management at your industrial or construction site.  Certainly, you were able to see a “worst case” scenario storm event at your site!

Who is required to have permits?

In general, a surface water discharge permit is required for most industrial and construction sites.  The storm water permits require installation and implementation of “control measures” to minimize or eliminate pollutants in storm water runoff.  These permits also generally require regular inspections after a significant precipitation event, such as the one that recently occurred.  The inspection is required because the storm water may have come into contact with equipment and materials that could negatively impact the water quality.  For example, in a flooded building, the water quality will be impacted if it came into contact with materials and equipment stored in this area.

What you should do after a heavy rain

During a significant rain event, the control structures are subject to “exceptional conditions.” Storm water discharge features, as indicated in the permit, need to be inspected to determine whether or not the control structures “resisted” under the extreme conditions.  If the structures were found to be damaged, determine whether or not a non-permitted release occurred.

Pay attention to and check these five areas:

• Control structures (i.e., secondary containment, storm sewer on the site, drip pan, pond, diked area, etc.) for evidence it may have overflowed.
• Surface water at the discharge point for visual evidence of excessive scum, sediment, other material or unusual odors.
• Significant changes to water quality monitoring data.
• Storage areas for signs of excessive erosion.
• Threshold reporting quantity exceedence.

If a release has occurred, follow the reporting and other requirements outlined in the permit.  The release may indicate that your BMPs are inadequate, and you may have to make some modifications.

The recent heavy rain event certainly put many storm water BMPs to the test.  It was also a reminder that BMPs must work in the “real world,” not just on paper.

Do you need a storm water plan?  Do you have questions about storm water plans or how you might upgrade your existing plan?  If so, please feel free to contact me (mresch@dragun.com) at 248-932-0228, ext. 133, or my colleague, Khaled Chekiri, P.E. (kchekiri@dragun.com) at 248-932-0228, ext. 138.