Agreement addresses highway stormwater issues

For older state highways, the method of managing stormwater typically is to dump it directly into ditches and streams. This is the historical approach: get rid of the water as quickly as possible. But, as the result of a legal settlement announced this week, we are likely to see more retrofits in the future.

Washington Department of Transportation has been improving its stormwater systems for new highways and a few older systems, but the latest federal stormwater permit issued by the Washington Department of Ecology did not go far enough, according to the group Puget Soundkeeper Alliance.

Represented by Earthjustice, Puget Soundkeeper Alliance appealed the permit to the Pollution Control Hearings Board. The settlement was not everything the environmentalists wanted, but it is a solid step in dealing with aging highways.

Bob Beckman, executive director of Puget Soundkeeper Alliance, explained the group’s position in a news release:

“Government agencies, businesses, and citizens are all working together to protect and restore Puget Sound, but the state’s department of transportation wasn’t carrying its share of the weight. There is a lot more work to be done, but we feel that this is a step in the right direction. The state highway system should not be held to a weaker standard than industries, local governments and the public.”

So what was included in the deal?

The stipulation signed by the parties (PDF 476 kb) calls for retrofitting an entire highway in environmentally sensitive areas when substantial new impervious surfaces are added, provided that the retrofits are “feasible” and “cost-effective.”

Retrofitting is deemed “feasible” if there are no physical site limitations such as steep slopes, soil instability or high groundwater tables.

Retrofitting is “cost-effective” if the cost of dealing with stormwater on the old pavement does not exceed 20 percent of the cost of addressing stormwater on the new pavement.

If retrofitting is not feasible or cost-effective, the transportation department must choose to spend 20 percent of the cost of new stormwater controls to deal with the old problems, retrofit on another site for that amount of money, or put the money into a separate fund for retrofitting old highways.

The agreement also includes provisions for increased consultation with federal wildlife agencies to protect endangered species, even when not required by federal law. The pact also contains provisions for limiting particular contaminants as part of an overall pollution-reduction plan by addressing total maximum daily loads, or TMDL.

Gene Johnson, a reporter for the Associated Press, does a nice job of putting the issue into perspective and explaining why it is important to manage highway runoff.

Gary Chittim of KING-5 News also covers the issue well. (See video below.)

For background information, check out the Washington Department of Transportation’s extensive information on stormwater management.

Washington Department of Ecology discusses stormwater permitting issues.

King County’s Science of Stormwater page also is informative.

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