Enhanced Storm water Runoff Treatment Program

By Dennis Van Patter, CDOT Communications Office

April 2, 2015 

“Amber worked out a compromise with CDPHE regarding new equitable terms with CDPHE that will allow us to treat storm water runoff from our roadways more effectively while still helping us reduce costs and make compliance much easier,” noted DTD Director Debra Perkins-Smith. 

Under federal environmental regulations, CDOT is responsible for preventing or minimizing pollution that might be caused by runoff from the state highway systems, including prevention of pollution to adjacent waterways.  CDOT manages more than 9,000 miles of pavement, resulting in huge amounts of runoff.   Pollution prevention and minimization requirements are described in the MS4 permit governed by the CDPHE-Water Quality Control Division.  CDOT must meet these permit requirements. 

We have several programs in the permit to help prevent pollution,” noted Jean Cordova, a CDOT employee who serves as liaison to CDPHE.  “CDOT’s permanent water quality program requirements involve managing runoff from the highway system by utilizing a series of inlets, culverts, and storm water treatment structures such as retention ponds.  The purpose is to allow pollutants, including sediment, to settle out of the storm water runoff before they ever get to the waterways.” 

It is in this area that Williams further helped refine terms more favorable and realistic for CDOT while still meeting the intent of CDPHE’s requirements. 

“The original MS4 permit expired in 2012, and it was administratively extended,” noted Cordova.  During the extension, in May 2014, CDOT was able to get an interim permanent water quality program approved.  As a part of the program, Williams helped work out a key piece that was included in an amendment to the program this past January.  Everyone involved hopes the new terms for the interim program will allow CDOT to fulfill all permanent storm water obligations in realistically and economically.  Here’s how: 

“Basically, under the new terms, CDOT will have more flexibility on where permanent water quality structures will be built,” Cordova said.  “Since 2004, we’ve built over 400 of them on individual roadway projects, with the size dictated by the amount of pavement (i.e. ‘impervious’) are being drained into the pond.  There were a lot of constraints, including topography and available land.  When we had a narrow right of way, we often had to acquire more right of way in order to keep the structure the correct size and in the correct location.  Now, we have more flexibility to move these treatment structures to a more common sense location and still treat the requirement about of pavement runoff using an equitable benefit approach. 

The new terms appear to be a win-win situation all the way around. 

“CDOT certainly wants to live up to our responsibilities when it comes to managing storm water,” Cordova noted.  “Under the old requirements, we had to treat all impervious surfaces on specific projects, for example over one acre and in an MS4 area, resulting in difficult locations and huge amounts of permanent storm water structures. 

“This method of project-by-project treatment was not as effective and efficient at improving water quality in urban areas,” Cordova added.  “Now, we can treat storm water on a more regional basis while providing a stopgap treatment for those projects that have more immediate potential for localized water quality impacts.”  The details are very technical, but CDOT hopes that the result is less need to build additional permanent treatment facilities while still meeting permit requirements.  Among the benefits will be a reduction in the long-term maintenance of new facilities. 

“Now, thanks to what Amber Williams has been able to do working cooperatively with our fellow state employees at CDPHE, hopefully, we’re able to move forward in a more realistic and cost-effective manner,” Cordova said. 

Williams literally worked years in discussions with CDPHE to help bring the new terms to reality.  The terms were part of a larger regional approach that took teams of CDOT employees years to develop.  As a result, CDOT is the first state department of transportation in the nation to undertake this kind of program. 

“It’s a more holistic approach to the situation,” Cordova concluded.  “Moving forward, CDOT should be able to meet our permanent storm water requirements with larger, more central mitigation facilities rather than continuing to build individual, piecemeal treatment facilities.  This looks like a great solution for Colorado’s water quality as well as CDOT’s ability to be able to fund these facilities and keep required maintenance going.” 

Williams agreed.  “I was glad to be a part of this,” she said.  “I worked with a lot of good people at CDPHE and, as usually happens, good people working together cooperatively toward a common goal found the solution.”