Town and DOT respond to sliding hill near Feura Bush Road
GLENMONT – The almost 4 inches of rain that fell on the area over the past 14 days did not mix well with the Albany Clay that makes up the banks of the Dowers Kill this week just South of Feura Bush Road causing a partial landslide on Ackerman Avenue.
On Wednesday, Dec. 20, the Town of Bethlehem declared a state of emergency when a bank adjacent to the town road began to slide into the creek and threaten critical infrastructure.
The emergency declaration, effective at 4 p.m., carried the authority to close roads in the town and implement mandatory evacuations by town Supervisor David VanLuven.
“I issued a State of Emergency declaration for Ackermann Avenue in Glenmont because of slope slippage between the road and an adjacent creek. Our highway and engineering teams, in close coordination with my office and the Town Board, worked with NYS DOT and the utility companies to stabilize the site,” he said.
The order directs “all departments and agencies of the Town of Bethlehem to take whatever steps necessary to protect life and property, public infrastructure, and provide such emergency assistance as is deemed necessary.”
“[The town] had to declare a state of emergency so that DOT and town could work on the property since it is all privately owned and outside of the right of ways,” Bethlehem Highway Superintendent Marc Dorsey said. “The emergency basically is for the potential to lose utility service and possibly a town road. If the road was impacted, the residents at the end of Ackerman would have no access.”
“It is probably an Albany Clay soil,” Paul Bailey, a geotechnical engineer for the town from Greenman-Pedersen Inc. said.
He said if the conditions are right, with that soil, the banks can slide.
There are many deposits of Albany Clay in Bethlehem. An example of its instability was seen with the 2000 landslide on Delaware Avenue. That closed the road for over six months.
“The rainfall came through [under the road] and hit at the toe of the slope and eroded it and caused the slope to shift,” Bailey said.
The toe of a slope is the bottom of the soil bank where it meets the creek. The top of the slope dropped about 18 inches along the western side of Ackerman.
A total slope slide would cut off the access to the road and also break utility lines for gas, water and sewer for the five houses on the street. Larger utility feeder lines also run along the south side of Feura Bush Road.
At first, the State Department of Transportation was going to manage shifting of the hill on Ackerman, but it became complicated with most of the property being owned by private landowners and the town, so they deferred to town crews. Feura Bush Road and the culvert under it are both owned and maintained by the state, but Ackerman is owned and maintained by the town.
“The town’s designated engineers recommended to take 18-20 loads of material off the top of the slope and that is what we did,” Dorsey said. “That relieved the pressure at the toe of the slope.”
Town crews also put plastic over the top to keep additional water from penetrating the slope, Dorsey said.
After the Town Highway Department finished stabilizing the slope on Saturday morning, DOT crews worked on the Dowers Kill. Its crews put a culvert pipe into the creek and covered it and the toe with aggregate rocks so if the slope did slide into the creek, water would continue to flow through the pipe. Also, if the pipe became blocked or creek overfilled, the water would run over the aggregate. Crews were finishing that work on Tuesday morning.
Harry and Cheryl Allen, who live on Feura Bush Road, across the creek from Ackerman, said that they had a knock on their door on Wednesday night from town officials.
“They said we should move our motorhome because the bank was sliding,” Cheryl Allen said.
The Allens said that when the water in the culvert under the road backs up, the flooding is severe and reaches structures.
If the culvert were to become completely blocked, the stream would rise almost 20 feet before cresting the road.
“When we had the heavy rain the other day the water almost reached the houses,” Harry Allen said.
They gave permission to use their property for mitigation work and said the state would return in the spring to clean up the property and make permanent fixes to the creek and hill.
“It was a difficult situation at a busy time of year, and I’m so pleased with the great work of our team,” VanLuven said.