State divers check bridges for safety

Swimming under bridges to see if they're safe might not sound like your average highway maintenance job, but this is not your average road crew.

Since two days of rain dumped up to 15 inches across the Merrimack Valley two months ago, the underwater operations division of the Massachusetts Highway Department has been looking for weaknesses in centuries-old stone stanchions to see whether they are still strong enough to support cars, trucks , or even the occasional dog walker.

``It can be scary," said John Desmond , head of the five-man team that was diving the Haverhill/Groveland Bridge last week.

``You see a loose rock, you don't touch it," Desmond said. ``Everyone understands: If you are uncomfortable you get out. If it looks dangerous, get out of there."

Everything appeared safe and secure on the Haverhill/Groveland Bridge after divers fanned out and inspected the six stanchions supporting it.

Strips of aluminum were poked into mortar joints to measure erosion. In shallower areas closer to shore, divers took off their flippers and just walked around looking for damage.

In the deeper areas toward the center of the bridge, flashlights were needed to penetrate the murky water, which swallowed any sign of the divers or their lights when they got five feet below the surface.

Desmond and crew clearly love scuba diving , but these are not ideal conditions. After the foul weather over Mother's Day weekend, MassHighway was closing bridges and roads all over the Merrimack Valley. That involved four of five spans leading into Ipswich, including the 1764 Choate Bridge in the heart of town, believed to be the oldest stone arch span in the country.

Ipswich merchants were distraught as the town was virtually shut down, putting the pressure on Desmond's crew to get the bridges reopened. But the Ipswich River was only reluctantly retreating , and the divers had to wait weeks before they could inspect the span.

``We couldn't get into the water until two weeks after the storms , and even then the currents were tough," Desmond said. ``You can't swim against that much current. When you have to hold on to your light and you have to hold onto the bridge and you can't see anything in front of you, you can't do an inspection."

The Choate Bridge inspection found three to five feet of the river bottom washed away, dangerously undermining the stanchions supporting the roughly 75-foot span. The Mill Street Bridge leading into Hamilton was another matter , with buckling in the asphalt pointing to much bigger problems below.

``There was huge undermining of the Mill Street Bridge," said dive team member Allen Bondeson . ``The stones had just blown out from there and were scattered on the bottom. . . . The flow was still so strong we were lucky to get in there to even look at it."

So far, the bridges along the Merrimack River have fared better. Last week Desmond's crew inspected the Route 125, Rocks Village, and Haverhill/Groveland bridges in Haverhill and the Deer Island/Amesbury and Interstate 95 bridges between Newburyport and Amesbury.

All checked out with only minor scoring from the debris that washed down river during the flooding, Desmond said. Next on the list of inspections are several more Merrimack River bridges, including the Route 28 span in Lawrence, a roughly 200 -yard structure that had about 100,000 cubic feet of water rushing past it per second when the river crested May 16.

``That bridge is sitting on ledge," Desmond said , referring to the bedrock foundation supporting the granite stanchions the bridge sits on. ``I suspect that will be all right. Eventually the water is going to wear away that ledge. But not in our lifetime."

The flood damage inspections have just added to the schedule of hundreds of routine maintenance inspections the underwater operations division does each year, Desmond said. The conditions noted during those regularly scheduled inspections helped the crew members measure more easily the recent damage done.

There are 20 divers on the team, but only five who work full time as divers. They were pressed into overtime duty to finish the flood damage inspections, Desmond said. That does take some of the fun out of the job, he said, but it still beats paving and filling potholes.

While the flooding made the dive team few friends in Ipswich when they shut down the Choate Bridge , crew members more often than not work in anonymity doing their regularly scheduled inspections .

``If we have to close down a bridge and then we find something wrong with it, we feel good; we know we're keeping people safe," said dive team member Randi Bonica . ``If a bridge has to get closed , it has to get closed. It's not our doing ; it's the environment."

The Choate bridge was reopened 27 days after it closed , earning praise and a ``thank -you" banner posted downtown by the merchants.

``The Massachusetts Highway Department did a fantastic job," said Ray Morley , president of the Ipswich Chamber of Commerce. ``They really took a lot of pride in what they had done."

That's prized praise for anyone who works for the Highway Department, Desmond said, whether it's above the road way or below it.

``It was nice to see that," he said of the banner. ``We don't get that too often."