As water from the water main break receded Tuesday in Boiling Springs, a second problem became apparent very quickly.
In a part of the county and state where sinkholes are common, the extra amount of water prompted many depressions and sinkholes to start opening up in Boiling Springs.
With water pressure and levels starting to get back to normal, there is a question now of what to do with all of the sinkholes.
Sinkholes start with a void or space in the rock beneath the soil, which eventually moves up, creates unstable ground and causes the sinkhole to open up. The process is natural and occurs over time, but interference can speed up the process, especially if it involves heavy pressure on the ground above the void or sudden large amounts of water from heavy rain, or in this case, a water main break.
Dave Shatto is the residential manager at the Carlisle excavating company John W. Gleim Jr. Inc. Shatto said about 30 percent of his work concentrates on sinkholes, though most of that work comes in the spring and fall.
He’s seen small holes in yards with equally small sinkholes to a sinkhole near the runway of the Carlisle Airport that measured 16 feet across and 22 feet deep.
Whatever size it is, a major challenge for excavation crews in refilling a sinkhole is simply getting to it.
“Half the challenge is getting to it, especially with the right size of equipment,” Shatto said. “It can be hard when you live in a duplex with houses tight together.”
Filling a sinkhole
Once an excavation company gets to the sinkhole, Shatto said there are a number of options available to fill the sinkhole.
After using water to get the sinkhole to fully open up, Shatto’s preferred method is to use clay.
“Normally what we use is a clay backfill,” he said. “It’s the least expensive for most homeowners, and it works about 90 percent of the time.”
Shatto said another common method is the “inverted rock filler.”
The method was featured on South Middleton Township’s website as a way to fill sinkholes. In this method of repair from the Cumberland County Cooperative Extension website, a company excavates the sinkhole down to the rock if possible, puts a layer of cabbage-sized large stones at the bottom, smaller fist-sized stones on top of that, a layer of gravel on top of that and then covers it with geotextile fabric and soil.
The method allows for water to filter through and avoid carrying away soil, which could cause another sinkhole.
Shatto said that method only works some of the time, and he prefers clay, which doesn’t allow for water at all and would better prevent a sinkhole from opening back up.
Concrete can also be used to fill a sinkhole, but Shatto said that usually works when it’s in a roadway or near a structural area.
Shatto said he used concrete with the Carlisle Airport sinkhole, but he usually only uses it when there are at least two or three sides of the sinkhole bordered by rock.
Shatto said he’s seen plenty of people try to fill the holes themselves, but getting a company involved is usually a better idea.
“Some people try to backfill a sinkhole with bags of gravel, grass clippings and tree branches. That doesn’t fix the hole. It just makes a mess when you have to clean it up later.”
The problem with any of the professional methods is there is not a 100 percent guarantee the sinkhole will not come back. And some methods, particularly concrete, can be a more costly decision than others.
“I try to not make it any more costly than I have to,” Shatto said. “When you have to get an engineer involved and the township involved, it gets expensive in a hurry. No one wants to see a 3-5,000 dollar bill, or if it’s a structural sinkhole, $10,000. Nobody is set for that.”
There is potential for financial help, but only if a homeowner has specific sinkhole insurance.
Rosanne Placey, press secretary for the Pennsylvania Insurance Department, said most homeowner’s policies do not cover “earth movement,” which includes earthquakes and sinkholes. Some policies will even specifically say sinkholes are not covered.
“That has to be purchased by an endorsement to the homeowner’s policy or as standalone coverage, but that would be more expensive,” Placey said.
Sinkhole coverage would not be retroactive, so any insurance policy or endorsement purchased now could not help in paying for sinkholes that already exist on the property.
One other thing Shatto said residents should keep in mind is what kind of coverage sinkhole insurance gives.
He said he’s worked with plenty of residents who say they have insurance but find out it won’t help them pay to fill a sinkhole in the backyard.
“From what homeowners have told me, if the sinkhole gets into the foundation, then sinkhole insurance will cover it,” Shatto said. “They need to look at (the policy) and see what it actually covers.”
In reading a template for a sinkhole policy, Placey said the policy only covered structural damage to the home caused by a sinkhole. She said it would be similar to flood coverage, which protects the home.
Placey suggested anyone with questions call the Insurance Department toll-free at 877-881-6388 or visit them online at www.insurance.pa.gov. Residents can also call their homeowner’s insurance carrier to get information about what their policy covers.
Shatto warned it is always good to check, especially for residents of Cumberland County, many of whom from Shippensburg to the West Shore fall in a limestone area conducive to sinkholes.
“I’ve met people who have said ‘I’ve lived in this house for 40 years and never seen a sinkhole.’ And in the last two or three years, I’ve been in their backyards filling a sinkhole,” he said. “They pop out of nowhere.”