Surviving the Sinkholes

After nearly seven months of 24/7 repairs, snarled traffic, lost business, and frayed nerves, the region is recovering from the mayhem on Route 80.

By Michael Daigle

Nature warns.

A plume of dust and gas from a rumbling volcano presages an explosive eruption.

For western Morris County, the ancient iron mine shafts under local towns and roads delivered a threat in December when a 40-by-40-square-foot sinkhole opened in the breakdown lane of eastbound Route 80. 

By March—and several sinkholes later—a detour at Exit 34 choked traffic on the vital six-lane east-west interstate highway in both directions while New Jersey Department of Transportation (NJDOT) engineers studied, designed, and executed repairs for the sinkholes..

NJDOT promoted detours with electronic road signs at Route 80 exits east and west of the work zone at Exit 34, pushing traffic onto local roads; GPS systems included instructions and alternate-route suggestions to avoid Route 80 and the state; the NJ511 traffic-alert system carried Route 80 updates.

The closures jammed local streets—Routes 46, 10, and 15, Landing Road, and others—with thousands of vehicles. But few rerouted drivers had time to shop at their usual places. No one grabbed a pizza, a six-pack, dry cleaning, flowers, groceries, or dinner at a favorite restaurant.

“We were crushed,” Wharton Mayor William J. Chegwidden says in the middle of May.  

He may as well have been speaking about businesses in Roxbury, Dover, Mine Hill, Jefferson, Mount Arlington, or Hopatcong. All are municipalities from 17 zip codes within a 5-mile radius, from Stanhope to Denville, whose businesses are eligible for state financial aid.

The first wave of relief came on May 21, when the detour at Exit 34 was lifted and two eastbound lanes opened. On May 30, two westbound lanes opened, completing the project's first phase. The remaining stabilization of land under the highway median was expected to be completed by late June.

New Jersey understands traffic in hours and minutes, but the volume of the rerouted traffic is startling:

• The Delaware River Joint Toll Bridge Commission, which operates bridges on Route 80 between Portland, PA, and Columbia, NJ, recorded 5.9 million two-way trips across its bridges between January and April. (While not all of that traffic was destined for Exit 34, it’s still 5,992,000 vehicles.)

• Drivers were crammed down a funnel that led to Blackwell Street in Dover, West Dewey in Wharton, the Route 10 shopping district in Roxbury, the already overburdened Route 46, the once main east-west highway, and Route 15 into Jefferson. Thanks to DOT directions, Picatinny Arsenal, a military installation and research facility, stationed police at the Route 15 entrance to deter lost drivers from entering, says Jefferson Mayor Eric Wilsusen.

• Chegwidden says the borough police department traffic counted 39,000 vehicles passing his home on West Dewey daily. 

• Roxbury Mayor Shawn Potillo says his department’s traffic counts often recorded 2,000 additional vehicles on the township’s smaller, residential streets.

Wilsusen says he altered his route to work several times. Hopatcong Mayor Marie Galate says she knew of borough residents who changed jobs rather than fight the traffic. Mount Arlington Mayor Michael Stanzilis says delivery company trucks were delayed. More importantly, emergency vehicles struggled to maneuver through the crowded streets.

Dover Mayor James P. Dodd says he had to request daily New Jersey State Police traffic patrols and open turning gaps on Route 15 at Grace and White streets, the one-way streets that allow buses, teachers, and students to access Dover High School. The mayor says the state police were assigned to multiple towns for traffic control.

Dodd adds that traffic on jammed four-lane Route 46 (McFarland Street) spilled onto two-way Blackwell Street in downtown Dover to avoid the mess.

The mayors all agree there was frequently no way to beat it.

WHAT LIES BELOW

This was iron mining country. Big mining. Big industry.

Beginning in the early 1700s, settlers and later companies hauled tons of iron ore from the ground, creating the first and perhaps most important early industry in Morris County's history. This industry attracted workers, skilled engineers and designers, and investors. In one way or another, the 17 towns listed on the state Economic Development Authority (NJEDA) grant eligibility list owed their existence to the iron mines.

Geologists named the area the “Dover District,” an 80-square-mile plot from Ironia in Randolph, 18 miles north through Jefferson, and 5 miles wide from roughly the eastern shore of Lake Hopatcong east to the hills in the Berkshire Valley.

The 1953 study, Geology of the Dover Magnetite District, Morris County, New Jersey, by Paul K. Sims defines the district as “the largest iron-ore-producing district in New Jersey.”

The report says, “The Dover District has been an important source of iron ore for over 100 years, and has been active since about 1710. The total production from the district is estimated to be about 26 million tons of iron ore valued at about $100 million. This is approximately 70 percent of the total iron ore production from New Jersey.”

Planning for Route 80 began in 1936, an alternative to the overburdened Route 46.

Construction began in 1956, under the Eisenhower administration’s Interstate Highway Act. The 2,909-mile highway runs from San Francisco to Teaneck, where it connects to the NJ Turnpike. The 68.5-mile Garden State leg was completed in 1973.

During that construction period and at the time of the state report’s release in 1953, three active mines—Scrub Oaks, Richard, and Mount Hope—were producing about 500,000 long tons of iron ore annually. All three mines would have been within 5 miles of the under-construction Route 80.

Exit 34 is located in the center of New Jersey's most vigorously mined areas. The Dover District study notes that about 25,000 feet of underground mine workings were mapped in the Scrub Oaks, Richard, and Mount Hope mines.

The report says the magnetite deposits are grouped into seven ore belts: Wharton, Hibernia Pond-Hibernia, White Meadow-Cobb, Dalrymple, Beach Glen, Green Pond, and Splitrock Pond-Charlottesburg. Among notable mines in this belt were:

• Scrub Oaks, which operated from 1859 to 1959; 

• Hurd, which operated from 1899 to 1903;

• Stirling, which operated from 1640 to 1885;

• Mount Pleasant, which operated from 1786 to 1896;

• Mount Hope, which operated from 1710 to 1985;

• The Richard Mine, which operated from 1856 to 1896. (No closing date was recorded.)

• The famous Dickerson mine, in Mine Hill, opened in 1713 and closed, after a short restart, in 1903.

Some of those sites were mined to 2,600 vertical feet and ran horizontally for miles. Mount Pleasant’s deposit was measured at 11,000 horizontal feet.

The 1953 report says the mine operators were sometimes uncertain where the bottom of the ore actually was. Dover’s Dodd says he spoke with some state engineers who say they drilled  500 feet or more before reaching bedrock.  

In his 1981 book, Port Oram, Circa 1882: A New Jersey Iron Town, (now Wharton), author Kenneth R. Hanson says there are about 600 million tons of iron ore left underground. However, the economies of the time and the lack of newer technologies meant the ore would remain in the ground.

So, why the sinkholes?

Summaries from more than 40 studies of the state’s iron mines and recent DOT analysis say that Morris County’s rock base includes a percentage of limestone, which is susceptible to dissolving in water. According to NJDOT officials, the sinkholes resulted from a collapse of an abandoned mine beneath the roadway, not natural limestone erosion.

Add the constant pounding of 130,000 vehicles a day, including a high percentage of modern 80,000-pound trucks (an average truck in 1936 weighed 40,000 pounds, according to industry records), and the highway got crushed. While the definitive cause of the shaft’s collapse remains uncertain, Steve Shapiro, press manager for NJDOT, says drought conditions over the past two years and the 4.8-magnitude earthquake on April 5, 2024, likely contributed to destabilizing the subsurface environment and leading to resultant road damage. 

He adds that, while heavy truck traffic factors into pavement and subsurface performance, there is no indication that the volume of tractor-trailers or other large vehicles caused the Route 80 sinkhole. 

The DOT initially discovered 90 spots for drilling investigation; the total reached 150. The state’s plan includes drilling to detect bedrock and create support structures and multiple layers of cement grout, stone fill of various sizes, and layers of compacted soil to support a large concrete slab across the affected area. The project will include several types of monitoring devices to detect surface and subsurface movement.

Shapiro says the repair anchors a concrete slab into the bedrock, topped with asphalt to provide the riding surface.

The state is constructing a 30-foot deep seal over the median voids.

Stanzilis says he is encouraged by that decision, and Roxbury’s Potillo cheers what he calls “the 75-year solution.”

Gov. Phil Murphy estimated in March that the project would cost $150,000 a day. Shapiro estimates that if completed by the end of June, total repairs will cost $20 to $25 million.

RESTORING THE LOCAL ECONOMY

“What’s next,“ Chegwidden says, “Is taking care of our own.”

He says that initially, that meant insisting the state offer grants, not loans, to the affected businesses. 

“Too many businesses were paying off COVID loans,” Chegwidden says.

Towns also pushed “shop local” days. Stanzilis hosted a Facebook post tour of Mount Arlington that generated over 20,000 hits.

The impact varied.

In Roxbury, Potillo says businesses lost between 10 and 40 percent of their income, though he was unaware of any closures.

The state responded, offering a grant program totalling $5.5 million, the Route 80 Business Assistance Grant Program. The grants offered ranged from $1,000 to $15,000 to businesses and nonprofits that could show income losses due to the sinkholes, depending on the number of employees.

The agency reported in May that 718 grant applications had been received.

Potillo says he was aware of 85 Roxbury businesses that applied for grants, and in Hopatcong, Galate says 35 businesses qualified.

The U.S. Small Business Administration also offers a loan program for affected businesses of up to $2 million.

In May, the agency reported that 132 businesses had applied for loans and that 16 businesses had received loans worth $645,500.

Stanzilis says the worry would continue for a town like Mount Arlington, one of four on Lake Hopatcong that rely on summer trade.

Memorial Day weekend is the traditional start of the season, and he welcomes at least the partial reprieve from the Route 80 closing, even if he can’t measure the full economic impact of the mayhem over the previous six months. He says he is optimistic about the summer season.

Wilsusen says fewer boats seemed to be out on the lake during the long Memorial Day weekend, but linked that to the cold, damp weather rather than the road closures.

Overall, the mayors learned much about the land upon which their towns rest as the sinkhole drama played out. They acted to support their residents and businesses and were encouraged as a group by the state’s response.

However, the old mines can be a tricky host, and leaders must watch for the warning signs.

When will the next 200-year-old pillar shift?

What else might get crushed?