Dangers of sand cave-ins in spotlight after Ocean City death
Staff reporter Reed Shelton and the Ocean City Beach Patrol demonstrate what it is like to be buried and extracted from a shallow hole. Produced by Ralph Musthaler
Digging on the beach is an innocent exercise for children and adults, but it could carry the risk of injury –– and in rare cases, death.
Ashley O'Connor of Plano, Texas, was found buried in a hole on Ocean City's beach early Monday morning. Police say she died of asphyxiation; her death was ruled an accident.
O'Connor, 30, was vacationing with her parents when she separated from them at about 2 a.m., according to police. At some point, she ended up in a hole on the beach around Second Street, roughly 30 yards from the high-tide line.
The sand hole collapsed around O'Connor. Sand covered her, blocking her airflow.
Holes on beaches — and their tendency to collapse — are far more dangerous than they appear at first glance.
A hole dug on a beach of sand reacts differently than a hole dug in a farm field, explains Stephen Van Ryswick, chief of the Coastal and Environmental Geology Program at the Maryland Geological Survey.
What makes holes in the sand so prone to falling in on themselves, or “slumping,” has to do with their low “angle of repose,” Van Ryswick said.
An angle of repose is the maximum angle an object can rest on an incline without sliding down. A rock, for example, would have a 90-degree angle of repose, meaning that its sides can be straight up off the ground. Beach sand, however, would have an angle of repose closer to 30 degrees, he said.
A grain of sand that reaches the beach has tumbled far through a marine environment, Van Ryswick said, making it round. All those grains on the beach add up to a wide expanse of tiny marbles.
“Think of it like a sandcastle, where if you add a little water to the sand, you can achieve even a 90-degree angle,” he said. “The water holds it together. However, too much water is going to liquify it. If you add a bucket of water to that castle, it’s all going to slump away.”
Holes are typically dug into the beach when the sand is moist, in a zone where the tide has recently receded. As the sand dries, its structural integrity gets weaker. And when disturbed — by a person or other vibrations — it can collapse suddenly.
If someone falls into that hole, it can quickly prove deadly.
That’s what police suspect may have happened to O’Connor early Monday morning.
A race against time
The risk with a sand collapse is similar to drowning in a liquid: oxygen deprivation leads to cardiac arrest and organ damage. The brain is particularly vulnerable, said Dr. Brian Delligatti, a physician and assistant medical director at the Peninsula Regional Medical Center emergency room.
“With drowning, you can inhale water and, to a lesser degree, sand particles,” Delligatti said. “They’re really very similar. The latter is almost like drowning in sand, essentially the same.”
After a few minutes without oxygen, Delligatti said, a victim would lose consciousness. The heart rate would drop, then stop. At that point, the victim would be without oxygen to his or her brain.
“It’s hard to say for certain, and it can vary from patient to patient, but within fewer than 10 minutes you’re in serious, serious risk of death,” he said.
Emergency responders must work fast, Delligatti said, because inhaling sand blocks air flow.
The first step would be a breathing tube and IV fluids. If that didn't work, experts would insert a tiny camera via a breathing tube directly into the patient's airway to help a pulmonologist determine if sand needs to be washed out, he said.
If sand or swelling in the lungs still prevents oxygen from entering, the final step would be an advanced procedure in which the blood would be passed out of the body and through a machine –– bypassing the lungs, to provide oxygen to the patient.
The weight of sand makes sand collapses even more dangerous.
According to the U.S. Natural Resources Conservation Service, sand weighs about 100 to 112 pounds per cubic foot. By comparison, a cubic foot of water (roughly 7.5 gallons) weighs about 62 pounds.
Each cubic foot of sand on a victim's torso is the equivalent of a 13- to 15-year-old boy standing on the victim's chest.
“Just from a mechanical standpoint, the muscles of the chest wall might not be able to overcome the pressure and expand to allow the patient to breath,” Delligatti said.
“That’s a complication that’s actually not present in drowning, and one that can really lessen the time a victim has before rescue is an absolute necessity.”
First response to collapse
The death of O’Connor mirrors recent experiences of the Rehoboth Beach Patrol. Capt. Kent Buckson said Rehoboth, like Ocean City, also places an emphasis on teaching sand safety to the constant flow of visitors.
“It caught my attention immediately because during the job we do out here, we’ve had a lot of situations where we’ve had to tell people to fill the holes that children and even adults are digging,” he said. “A lot of people that are walking at night end up falling in holes dug during the late evening after we’ve gone off duty.”
Buckson said rescuing people from sand collapses is a “delicate” process, and one more complicated than simply "digging straight down," as some might suspect.
“The sand will flow back in and constantly keep the hole filled unless the rescue is done properly,” he said, adding that educating the public on the risks of holes on the beach is a major effort of the beach patrol.
According to a 2007 report in the New England Journal of Medicine, 52 cases of collapsing sand holes during a 10-year period resulted in 31 deaths in the 12 U.S. states examined.
The author of the report, Dr. Bradley Maron of Harvard Medical School, wrote that while uncommon, the possibility of a sand hole collapse is still an important risk to consider, and one he believes is more frequent than his findings indicate.
"The risk of this event is enormously deceptive because of its association with relaxed recreational settings not generally regarded as hazardous," he wrote. "However, we believe these personal and family tragedies probably are more common than this report suggests."
Numerous news reports since the paper was published indicate Maron’s belief may have been correct.
In July, a 12-year-old boy in California died after digging a tunnel into the side of a sand dune, which then collapsed on him, according to a recent ABC News report.
In June, an Indiana teen was severely injured after jumping into a 7-foot pit he’d dug in the sand, which caved in and buried him. And a 16-year-old boy was buried after a tunnel he was digging in the sand on a New Jersey beach collapsed.
In 2012, The Daily Times reported that a man attempting to connect two 6-foot holes through an underground tunnel on Rehoboth Beach was resuscitated by emergency medical technicians after the tunnel collapsed.
And in 2007, an 11-year-old Pennsylvania boy was resuscitated by emergency responders after he suffocated under a collapsed tunnel dug on the beach in Ocean City, The Daily Times reported.
Shawn Evans, head medic with the Rehoboth Beach Patrol, explained how lifeguards typically perform a rescue in the event that someone is buried by a collapsed hole in the sand.
Immediately, first responders clear everyone from the scene, he said.
"When you have everyone around the hole the victim is in, sand tends to just keep drifting onto them from the weight and vibrations they're causing," he said. "It just slides back in so much more quickly than dirt."
Rescuers then grab backboards, surf rescue boards or even body boards from onlookers and surround the area the victim is in to disperse the weight of first responders.
"Then, we start digging in a process," Evans said. "We dig toward one side or the other, but we're ultimately searching for the head of the victim, which is, of course, what we ideally want to expose."
Evans said it's a methodical, if hasty, procedure. Unfortunately for victims fully buried, the outcome is "usually not very good."
"The percentage of fatalities is really high, no matter how effective or well-trained we are," he said. "That’s why we spend so much effort on preventing the holes in the first place."
Echoing statements from other experts, Evans said the problem is that sand doesn't respond well to digging. Rather, it just gives way and fills back in.
"With dirt or clay or mud, you can scoop it out and get rid of it," he said. "That’s just not the case with sand. And once you get weight on you up to your chest, every time you exhale, more sand is squeezing in on you, and that’s when you suffocate."
The Rehoboth Beach Patrol, as with Ocean City's, enforces a rule that holes dug in the sand can't be deeper than the knees of the smallest member of the beach-going group.
"The most effective response to this situation is pre-emptive," Evans said.
Ocean City police are looking for information about a body that was found on the beach near Second Street on Monday, July 31, 2017. Megan Raymond video