After a four-year delay and an added $78 million outlay to remove acid-bearing rock, the last 15-mile, $700-million link of Interstate 99 in central Pennsylvania will open to traffic Dec. 4.
New Interstate is to open after years of delays due to discovery of acidic sandstone.
The discovery of sandstone laced with pyrite halted construction along a 1.5-mile segment of a politically controversial 15-mile section of the new north-south route (ENR 4/19/04 p.25). When exposed to air and water, pyrite creates a sulfuric acid that can contaminate streams and underground water.
“One of the commitments we made was that there would be no earth moving work until a plan was in place for remediation,” says Pennsylvania Dept. of Transportation spokesperson Marla Fannin. In 2004 the state Dept. of Environmental Protection ordered all construction be halted after nearby wells were contaminated due to the pyritic runoff.
PennDOT mulled several solutions and hired a number of consultants to devise a plan to prevent contamination of two nearby watersheds. After more than a year, a plan was established to haul more than 600,000 cu yd of contaminated rock to a newly constructed permanent containment site two miles away.
The total cost of removing or covering the contaminated fill is expected to reach $77.7 million, according to Penn- DOT. The price has risen more than $25 million in the two years since the cleanup was announced due to increased fuel costs. HRI Inc., State College, Pa., the contractor on the $39-million, 1.5-mile segment, was awarded a contract to haul the material. “We have 12 off-road dump trucks working around the clock,” says Steve Merrick, an area manager for HRI.
Some pockets of acid-laden sandstone were found in sections that had been exposed during construction. Placement of an impermeable fabric and geotextile liners along with an aggregate ground cover are to prevent further water infiltration.
“The site is designed for 1.6 million cubic yards of material,” says Karen Finlan, a manager with Blazosky Associates, State College, hired to design the containment site. Finlan says bag-house lime is being added to the contaminated fill.
I-99 will link I-76 in the south with Interstate 80. It replaces U.S. Route 220, an aging, narrow route. In 1996, Rep. Bud Shuster (R) had the new highway designated an Interstate, and several environmental groups filed suit to stop construction (ENR 2/21/00 p.44). The suit ended in a court settlement and land swap between PennDOT and the state game commission.