Arrow-right Camera

Washington Voices

Plan updates street standards

City hopes to prevent premature asphalt failure

A new set of standards for Spokane Valley streets aims to provide more clarity for contractors and better quality for citizens.

If endorsed by the Planning Commission and adopted by the City Council, the standards would replace a code that was borrowed from Spokane County when the city was incorporated. City officials say the current code is vague in places and designed more for rural projects than suburban in-fill development.

The new code was to have received a public hearing before the Planning Commission on Thursday, but the hearing has been delayed until May 7. It will start at 6 p.m. in City Hall, 11707 E. Sprague Ave.

The proposed regulations were developed with help from JUB Engineers, a consulting firm the city hired to study its street maintenance needs.

John Hohman, the city’s senior engineer for development, said some changes proposed in the new regulations are intended to prevent the premature pavement failures some city streets have experienced.

Pavement ordinarily is expected to last about 20 years, but portions of Sprague Avenue, Appleway Boulevard and Dishman-Mica Road are failing in less than half that time, according to Hohman.

“We’re seeing some pretty dramatic failures at the seven- to eight-year period,” he said.

Hohman said tests by JUB indicated some pavement was too thin and some problems were caused by the round river rocks available from Spokane Valley quarries.

“They just rolled around like marbles and didn’t provide the locking that we were looking for,” he said.

Hohman said proposals to make roads thicker and to use rock with more flat, interlocking surfaces – requiring additional crushing for river rock – have been controversial among developers, contractors and suppliers. He said one supplier plans to propose alternatives, and city officials have asked JUB to estimate how much the changes would cost.

There would be no change in the current requirement for arterials to have at least four inches of asphalt over six inches of rock, but the minimum asphalt thickness for “commercial local access” streets would double to four inches.

Minimum asphalt thickness for public and private residential streets would go from two to three inches, and now-unregulated private driveways would need two inches of asphalt over six inches of rock.

Another controversial proposal, to end the practice of contractors hiring their own inspectors, was abandoned after discussions with contractors and inspectors. Hohman said the plan now calls for tightening inspection standards, requiring inspectors to be nationally accredited and clarifying the city’s right to shut down a job if problems are found.

City officials had their own concerns about the original proposal.

“We didn’t want to add on a lot of extra staff to manage this process, so it was pretty much an across-the-board consensus” to try a less aggressive approach, Hohman said. The proposed measures are to be re-evaluated after a year.

Private streets are another problem the new code addresses. Hohman said Spokane Valley has a long history of developers creating substandard private streets that restrict emergency access, limit in-fill development and destroy opportunities for connecting streets.

He said a survey of 23 Washington cities found that 18 of them prohibit private streets from serving more than nine lots. The proposed standards would apply that rule to Spokane Valley, which now allows private streets to serve four or more lots.

Currently, up to three lots may be served by a single private driveway, but the new rules would limit driveways to one lot and would require them to be wider as they get longer.

Private streets, now unrestricted, could be used only if a public street weren’t planned or possible. Also, private streets wouldn’t be allowed to landlock present or potential lots.

Dead-end streets would be limited to 600 feet. No public dead-end streets would be allowed unless it were impossible or unnecessary to connect them to other streets.

Analysis of sight distances from new intersections and commercial driveways would become mandatory. Distances between intersections and driveways would be increased on arterials.

Click here to comment on this story »