A soil condition that’s helped farmers flourish for centuries in the Schoharie Valley is complicating design for the new flood protection system at the Schoharie County office complex.
Engineers found permeable soil extends 35 feet below the surface — a situation that requires extra material to keep floodwater from making its way beneath self-activating flood walls planned for the Main Street office building.
Engineers expected permeable soil would descend about 20 feet, but the extra depth shouldn’t impact the project’s timetable, according to County Treasurer William Cherry, who also is the county flood recovery coordinator.
But Cherry on Monday said more testing had to be done as part of the roughly $7 million project’s design to confront another issue: earthquakes.
Despite the rarity of devastating earthquakes in the Northeast, FEMA requirements call for protection both from flooding and from an earthquake — and from both at the same time.
“It’s certainly not an expected event,” Cherry said.
“They want to make sure that there is every assurance that the project is going to meet the expectations of all of us and that it is going to stand up to whatever gets thrown at it, whether it’s an earthquake or an earthquake combined with a flood,” he said.
Engineers evaluated the soil surrounding the county office complex and called for more and specialized testing due to what they found.
“In some of the soils they found, it could be susceptible to shifting under an earthquake situation,” Cherry said.
After learning of the soil conditions that relate to seismic activity, engineers organizing the flood wall project called for more-detailed testing. The results have not yet been presented to the county.
The largest earthquake on record in New York took place in Sept. 5, 1944, and caused about $2 million in damage near Massena in St. Lawrence County and across the border in Cornwall, Ontario, according to the United States Geological Survey.
The 5.8-magnitude quake destroyed chimneys in six different towns, wrecked plumbing and caused drinking water wells to go dry.
In order to prevent floodwater from surging into the county building from underground, contractors will be drilling holes down into the soil and filling it with a concrete-like material to create a barrier, or “grout curtain,” around the building.
“When it comes to water, it’s the most difficult threat to prevent because the tiniest opening means the water can get in. Even a small opening will allow an entire building to be flooded,” Cherry said.
County officials continue to wait for FEMA to respond to their request for approval to build the Schoharie County Jail outside of the flood zone. FEMA in September suggested the county rebuild the flood-damaged public safety facility where it is — in the flood zone — and county officials are urging reconsideration.
Tropical storms Irene and Lee wrought about $130 million in damage to public infrastructure in Schoharie County and damaged more than 1,000 houses.
By mid-October, the county had received $15.94 million in disaster funding from FEMA and approximately $5 million from New York state. The county’s insurer, NYMIR, paid out roughly $1.79 million and the National Flood Insurance Program paid about $3.1 million.