This summer the Alaska Department of Transportation will be repairing and replacing culverts and lining shorelines with rock at four sites on the Kenai Peninsula damaged by water and erosion in the autumn floods of 2012.
DOT Project Manager Matt Tanaka said the highest-priority repairs will be made at Mile 9.4 of Kalifornsky Beach Road, where a culvert allows water to flow under the road bed from the wetlands on the east into Cook Inlet on the west. The culvert was overloaded and damaged by the 2012 floodwaters, and since then, Tanaka said it’s outflow has created a growing gully that is in danger of reaching the road bed.
“Once the flood happened it exposed things, and the gully has enlarged over the years,” Tanaka said. “As it enlarged it worked its way back toward the road shoulder, and that’s a cause for concern that we need to correct with a project to repair the erosion damage. And also divert some the drainage so it doesn’t cause more erosion on the beach.”
Other local flood-repair work planned for the summer will be done near Seward at Exit Glacier Road and Nash Road, which runs along the east side of Resurrection Bay. According to DOT Environmental Impact Analyst Renée Goentzel, approximately 150 feet of a stream bank near Exit Glacier Road will be lined with pieces of rock — “rip-rap” or “armor” in civil engineering terminology — to prevent its erosion. At Nash road, Goetnzel said two locations have “small scour sites” that will be repaired.
Goentzel said the 3 Kenai Peninsula sites that will be repaired this summer are among 43 places where DOT shored up the road against flooding in late 2012 — a year in which south-central Alaska received about 200 percent of its normal precipitation during the month of September, according to the Alaska Climate Research Center. In some of those places the work done at the time is good enough to last, Goentzel said, but others such the three peninsula sites now being considered, need more thorough work against ongoing erosion.
“We did the initial repairs and stabilized things, because our initial goal is to put the road back together so people can drive on it safely,” Goetnzel said. “Now this is the permanent repair project… We did what we could to repair the road. And we’ve been monitoring that erosion ever since, to be sure it doesn’t get too close to the road.”
Though Goetnzel said specific design work on the projects is still being done by the Anchorage-based engineering firm R&M Consultants, she said the general plan of the work on K-Beach Road will be “to either plug that culvert or move it, then we’re going to put in a new culvert in a close, but not the same location under the road.”
“Then we’re going to have to grade the ditches so all the water flows to that new culvert, which has armor at the outlet which goes all the way down to the bottom of the cliff, so that it can hit the rip-rap and dissipate its energy, and it won’t erode anything anymore,” Goetnzel said.
Like the design, the scheduling and traffic control procedures for the repair projects haven’t been worked out yet, Goentzel said.
