Project to stabilize homes affected by mine subsidence to start in Derry Township
Work on a mine subsidence project involving 125 homes in Bradenville, Derry Township, could begin as early as next week.
The state Department of Environmental Protection has awarded a contract to Howard Concrete Pumping Inc., of Cuddy in Allegheny County. Howard was the lower of two bidders at $5.2 million, DEP said.
DEP officials plan to meet with representatives of Howard this week. Work likely will begin the week of July 15 or July 22, spokeswoman Lauren Fraley said.
“DEP has notified all eligible property owners within the scope area of the project in an effort to get 100% sign-on, but about 15 have not responded,” Fraley said, noting that the contractor has 30 months to complete the project.
DEP’s Bureau of Abandoned Mine Reclamation received funding for the project from the 2018 Abandoned Mine Land Grant Fund, which is supported by the mining industry via a fee on coal mined across the country.
The project, designed to help stabilize homes that have been compromised by coal mine subsidence, will consist of drilling four to six injection boreholes, each about four inches in diameter, around the homes and filling them with a cement-like grout material.
The method using flowable fill has been used with about 3,000 homes in Pennsylvania.
Workers will drill into the mine void below the houses in the hopes of preventing future subsidence. There have been 17 “subsidence events” in Bradenville, a former coal town, in the past 20 years, according to DEP.
DEP collected core samples from exploratory drilling in Bradenville in 2012 but got no further with the project.
The area under Bradenville was mined by the Latrobe-Connellsville Coal & Coke Co. until the early 1940s, according to DEP. The Derry No. 1 Deep Mine accessed the Pittsburgh coal seam, extracting coal through the room-and-pillar method.
Mine subsidence occurs when the ground above an old or abandoned mine cavity collapses. Subsidence usually is not an issue with new mines.
Stephen Huba is a Tribune-Review staff writer. You can contact Stephen at 724-850-1280, [email protected] or via Twitter .