landslide with house

A landslide beneath Allen Street in Sylva will close the road to thru traffic for the “foreseeable future,” according to Public Works Director Jake Scott. Groundwater from recent heavy rains is likely the culprit. This home at 573 Allen St. is not threatened, Scott said.

By Dave Russell

 

A long-awaited report from the N.C. Department of Environment and Natural Resources could bring long-awaited repairs to Sylva’s Allen Street, damaged in a March landslide. The town received the report on two slide areas from N.C. Senior Geologist Richard Wooten on Nov. 2.

Repair of the road is Sylva’s responsibility, and now the town has options to weigh and decisions to make.

Taking no action is not an option, Sylva Public Works Director Jake Scott said.

Spending at least $640,000 of town money on the repair is an option.

Sylva’s town board will hear the options and  discuss the issue at today’s (Thursday) 5:30 p.m. meeting (available for viewing live on the “Town of Sylva NC” YouTube page).

About 30 yards of Allen Street, referred to in the report as Slope Failure Area 1, fell about 3 feet lower than the rest of the roadway because of a landslide this past spring. Allen Street has since been closed to through traffic and will remain so for the foreseeable future. It has caused the asphalt drive leading into Bryson Park to buckle upward.

The slide is on town property, Scott said.

Slope Failure Area 2, about 260 feet southwest of the bigger slide, began sliding about five months after the first slide. It encompasses about .26 acres and led the N.C. Department of Transportation to block mud from seeping onto Chipper Curve Road with concrete barriers.

The slides overlook Jackson Paper, with SFA1 just above Bryson Park.

A DENR crew used drones equipped with LIDAR, a portmanteau of light and radar, to scan the area. LIDAR gives detailed topographic measurements by illuminating the target with laser light and measuring the reflection with a sensor.

According to Wooten’s report:

SFA1, with a recommended repair by Kessel Engineering Group costing $640,000, would provide safe roadway access through Allen Street with little likelihood that failure would advance further onto private properties. Stabilization of slide mass upslope would improve public safety in Bryson Park and decrease the possibility that the slide would have further impacts on Chipper Curve Road.

The SFA1 temporary repair option would see it dug deeper into the hillside and graveled. It could negatively affect emergency vehicle access to Allen Street and increase the potential to progress into private property. Unstable mass upslope could threaten public safety with the possibility of relocating vehicle access to Bryson Park or closing the park altogether. The slide could have further impacts on Chipper Curve Road.

The SFA2 long-term repair would result in long-term stability of Allen Street but could cost significantly more than the costs for SFA1. This would decrease the likelihood of failures advancing into private property upslope of Allen Street and involves no direct impacts on Bryson Park.

The short-term/no-repair alternative would consist of patching pavement, replacing pavement with gravel or no action, which would adversely affect emergency vehicle access. The short-term repair would be relatively inexpensive but comes with an increased probability that failures will advance into private property. There would be no direct impacts on Bryson Park.

The town would probably have to dip into its fund balance to pay for the repairs.

“We’re looking at some FEMA grants, and we might use some of our Powell Bill money,” Scott said last week.

Powell Bill funds are disbursed to municipalities to maintain roadways not under N.C. Department of Transportation purview.