Mapping of basement-destroying mineral could lead to repair payments

DENVER, April 8 (UPI) -- A nationwide geological mapping of a mineral that eats away concrete foundations from within might help property owners obtain help from Congress for expensive repairs.

A new map report, released by the U.S. Geological Survey in March, shows the extent that iron-based pyrrhotite is found throughout geological regions of the country.

More than 35,000 homes in Connecticut and Massachusetts are thought to have basement foundations that contain cement-eating pyrrhotite, an iron-sulfide material quarried near the ancient volcanic geological area called the Brimfield Schist in Connecticut.

Homeowners have described hearing loud explosions or discovering cracks overnight in their basements as concrete foundations fail.

Discovering pyrrhotite in the basement of his 20-year-old home in 2005 led to months of repairs and a bill for $200,000, not covered by insurance, for Jim Okun, of Ellington, Conn.

"The cracks in the basement walls got bigger, faster than I would have expected," Okun said.

An electron-microscope lab analysis showed pyrrhotite had been present in the coarse aggregate gravel used in the foundation's cement, said Okun, an environmental scientist for an engineering firm.

A quarry in Willington, Conn., was the source of mineral-laced gravel used in basement foundations for decades all over the region. Homes nearby are affected, and a local school had to be demolished because of foundation failure, Okun said.

"[Contractors] had to dig a moat around our house, support the house with iron beams and tear out the foundation in pieces," he said.

Pyrrhotite hits concrete with a double punch that can cause foundations to fail quickly years after they were poured.

When exposed to water and air, a rusty sulfuric acid reacts over time with the calcium oxide in concrete, which dissolves the cement paste, scientists say. At the same time, a chemical reaction creates iron oxide that expands, cracking the concrete from within.

In the eastern United States, the map shows pockets of pyrrhotite in New England, as well as the Appalachian mountains, northern Wisconsin and the Upper Peninsula of Michigan.

The USGS Denver-based Geology, Geophysics and Geochemistry Science Center released the report funded by an amendment to the 2019 Consolidated Appropriations Act, sponsored by U.S. Reps. Joe Courtney and John Larson, both Connecticut Democrats.

"[T]his map makes clear that pyrrhotite is present throughout the United States, and much work is needed to ensure that other states and localities are not unknowingly utilizing aggregate containing pyrrhotite in construction involving concrete," Courtney said in a statement.

The congressmen are working to make basement foundation repairs eligible for a federal Casualty Loss Deduction tax break, and to make repairs eligible for grants and loans from three federal agencies.

Connecticut's Crumbling Foundations Assistance Fund distributes special state "captive insurance" claim money to help cover failed foundations. A November 2019 state Supreme Court ruling found that ordinary homeowners insurers were not liable for crumbling foundations unless a home was on the verge of collapse.

In Massachusetts, a task force in January estimated that repairing 2,000 crumbling foundations in western part of the state would cost $350 million.

"We've made some progress toward making [homeowners] financially whole, but we've got to make sure that the resources being pulled together for them at the municipal, state, federal and private levels are in step with the true scale of this catastrophe," Courtney said in a statement last week.