When it Rains, We Rise and Shine

By Scott Lange, Project Engineer (Louisville, KY)

While most might think a rainy day is a good day to stay inside, a rainy day means a busy day outside for some in the Stantec Louisville office. As a Project Engineer in Stantec’s Louisville office, I assist with Sanitary Sewer Overflow (SSO) monitoring, and we recently had a very busy week with several days of heavy rain in the Louisville area.

SSOs most commonly occur when stormwater from rain events gets into sanitary pipes through either cracks in the pipe, manholes, or through sump pumps that have been connected to the sanitary line. The combination of sanitary water and stormwater can sometimes exceed the capacity of the pipe resulting in the system purging the water through open surfaces (usually manholes) resulting in an SSO.

Monitoring for SSOs occurs mostly during major rain events; specifically, ½ inch of rain over a 24-hour period. During the third week in September we had three such events with the largest occurring on a Monday morning with rainfall totals between 3-4 inches in the Kentuckiana area.

SSO observed flowing
 near local golf course

As part of an ongoing contract with one of our clients, Stantec monitors three rain gages to determine when more than ½ inch of rain has fallen over 24 hours. For the storm on that Monday morning, the ½ inch mark hit shortly after 12am.

At that point, myself and another engineer were notified to load up the gear and travel the SSO monitoring route to determine if any SSOs occurred as a result of the storm event. The route consists of just under 70 sanitary manholes in locations ranging from major roads to dense woods.

If an SSO is observed it is documented and samples are taken if the flows are high enough to meet the sampling protocol. The observations continue until all SSOs have ceased and an estimate can be made about the volume of overflow.


Manhole which purged estimated
 3 million gallons of water
during April storm events.


 Depending on the duration of the storm this could mean that teams are out there for a few hours or even a few days. In fact, this spring we had several rotating teams that monitored for nine straight days due to the heavy storms we had in late April. On this particular Monday morning in September, our team was out from 1:45 AM to 7:30AM travelling the route and monitoring any SSOs we observed. Needless to say, the next step for the team was to get some much needed R&R.

Although the monitoring can be some long odd hours the project is crucial to reporting SSOs. So day or night, rain or shine…well mostly just rain, our teams are out there.