The holes in the feed derived from the collapse vestiges of the New Jersey’s iron industry cause historic headaches for state officials, which close a widely used interstate link in New York City and increasing fears of more subsidence along the main roads in the immediate area.
The wear and tear of the holes began last December, when a 40 -feet depression appeared on the right shoulder of the interstate 80 in the east near the exchange of Route 15 in Morris County. On February 10, an 11×11 foot hole, 4 feet deep, was formed 75 feet away, in the lane of the center of the road, forcing a detour of all traffic in the east direction through the area. After testing, he revealed what the New Jersey transport department called “a significant gap” in the area, a geotechnical evaluation identified 90 possible areas of instability or gaps in the interstate state. The agency began the drilling and retaining operations to determine areas that require broader repairs.
Five weeks later, however, a new 15×15 feet hole opened to the median of a nearby I-80 work area. That incident forced the indefinite closure of the western lanes of the interstate, waiting for the evaluation of the needs for the integrity and repair of the roads.
New Jersey has mapped locations of about 590 iron mines closed now, and others from various northern counties, which began to operate in the eighteenth century and have left gaps that cause holes at the intersection-80 and threaten other key roads.
Credit: New Jersey Sig Office
Another hole in the County of Morris, apparently not related to the problems of the I-80, appeared on March 21 on the left shoulder of the I-287 in the north, closing two lanes of traffic. It is believed to be the result of a collapsed drainage pipe, which depression was repaired shortly after, according to Njdot.
The main contractor of the I-80 work is Iew Construction Group, Hamilton, NJ, with the geotechnical perforation that the Keller group performs. Companies and HNTB Geotechnical Consultant are working under emergency contracts/Call, confirmed the agency.
Agency officials have also directed inspections of their bridges near the holes, including those that exceed route 15. “There is a deterioration of the concrete roof in the piles of the bridge, which is the result of the aging of the natural bridge and not related to the emerging I-80 hole and the ongoing repairs,” said a NJDOT spokesman. Concrete maintenance repairs on I-80 bridges on Route 15 will be carried out in conjunction with the repairs of the interstate hole, he pointed out, with measuring instruments installed on the bridges to detect any movement or agreement.
He said on March 13 that the agency was “working closely with engineering and mines experts and our federal partners to further evaluate surface conditions, including the influence of abandoned mines.
Surface strains
I-80 holes have attracted new attention to the almost 600 abandoned iron mines underlying the nine counties of Northern New Jersey dating to the early 1700’s, but with most operations they closed since 1970. The I-80 Problematic Section was built in 1960. New Jersey directed the nation in mineral production until the deposits of the highest meter Michigan.
Other holes caused by ancient mines have been opened over the years, but those that affect I-80 are the first to cause a significant stop on the road. The Interstate manages about 130,000 vehicles daily, according to state statistics.
However, an update from 2020 to the Morris County Danger Plan states that widespread subsidence has accompanied the development of the area, as “many of the surface openings were filled inappropriately and roads and structures have been built next to these old mines.”
The possible guilty of the i-80 holes is the Mount Pleasant mine, which opened in 1786 near the current town of the road. For 110 years of operation, he extracted about 400,000 tonnes of magnetite mineral from the surroundings of the toilet holes through an now -antique technique called Stop Stoping, which extracts a block of ore from the upper one.
“This means that the upper part of the vacuum could be less than 100 meters from the surface,” says Robert Denton, Jr., a senior geologist of the Terracon consultant based in Ashburn, goes .. “The fact of removing so much mineral would create a huge gap.”
Denton, which is not involved in geotechnical evaluations of njdot, speculates that the most recent subsidence can result from a repeated cycle of humid and dry climate ends. “This would have a pumping effect that would cause significant variations in the groundwater level in the area,” he adds.
Since the last Active Mine of New Jersey closed almost 40 years ago, the State Agency has enlisted mining experts from Pennsylvania and other states to help develop a strategy to avoid additional holes on the I-80 and very busy roads. One of the factors that work in favor is that most of the region’s mines have been widely mapped, says Denton.
“This can help identify the locations where they intersect or approach the roads and configure appropriate test measures,” he adds.
Njdot says that the repairs of the east lanes of the I-80 will require about two months. Once the drilling and tearing work is completed in mid -April, the repair strategy calls for excavating the area, installing a large stone base with a wire mesh on top and adding more layers of stone and concrete. The additional filling and soil will be placed on the top of the concrete and the compacted stone before several layers of asphalt are applied. The crews will also install control systems in various places to track the surface and underground conditions.
After the second hole was developed, Njdot said that a plan was proposed to build a crossover for truck traffic to move it temporarily from the detours of the local road, while larger repair work continued. At that time, he anticipated that the lanes in the east of the I-80 would be closed for at least two months.
No calendar has been established for the repair and reopening of the lanes to the west.
State Governor Phil Murphy (D) in February declared an emergency state for Morris County and has requested emergency funding from the Federal Road Administration related to severe damage due to a natural disaster or other external cause.
During a visit to the place of March 22, the Secretary of Transportation of the United States, Sean Duffy, told the media that he would provide repair funding, but did not specify any amount. “I will do my best to get the resources,” he said. “We provide technical assistance. At a later time we will talk about money.” Duffy said that the legislation can ask the state to cover the gaps in federal allocation.
Murphy said the costs for road halt are more than $ 150,000 daily.
