Kalispell develops new stormwater standards

Developers and contractors, take note: Kalispell has started the process of updating its stormwater discharge requirements.

Although it was just in 2004 when the city last revised its Standards for Design and Construction, the city now is regulated under what's called an MS4 permit from the Montana Department of Environmental Quality.

The city needs to meet those standards as well as keep abreast of new materials and methods in construction and follow best management practices. As staffers Paul Burnham and Susie Turner worked to meet those standards and mesh with current local practices, they surveyed local engineering contractors to get their feedback on the proposed changes.

Only six comments came back.

The department incorporated suggestions into the new regulations where appropriate, but took the light response as a sign that what's being proposed makes sense to the engineering community.

At a City Council work session Monday night, Burnham touched on changes such as "air entrainment" for concrete work. Trapping tiny air bubbles in concrete makes it more durable, but the high standards were nearly impossible to meet in today's more common practice of slip-forming concrete. So they reached a compromise that retains quality, Burnham said.

He also explained changes in boulevard width and sidewalk setbacks, and regulations on rocks and trees in the boulevard.

Turner highlighted changes to stormwater design standards. Required design review now kicks in on projects as small as 5,000 square feet instead of 10,000 square feet, and it now applies to redevelopment as well as new construction.

A new section on water quality treatment design requires the contractor to choose from a variety of impoundment and on-site drainage designs, she explained, and provide a way to handle a 1.5-inch runoff. Flow control standards for larger runoffs were boosted, from handling 1.2 inches in a six-hour storm to the new requirement for handling 2 inches in a 24-hour storm.

Turner outlined many other changes as well.

Public Works Director Jim Hansz told the council that the city committed to adopting updated standards during 2009. The proposal has been on the docket for a council meeting agenda item since January, he said, but has been pushed back for several reasons. Now he is asking the council to make it a priority.

Although council member Bob Hafferman asked for a cost analysis before new standards are adopted - enforcement of any standard will cost developers something, Hansz said - other council members argued that the standards are needed and should be put up for public comment regardless of cost.

The council agreed to hold a public hearing on the update. If approved, the standards could be adopted by resolution two weeks later.

Reporter Nancy Kimball can be reached at 758-4483 or by e-mail at nkimball@dailyinterlake.com