Jan. 16, 2012 04:27

Help! The River is Eating Our Fairway

A venerable southern New Hampshire golf club was having a problem that had nothing to do with hooks or slices. The broad Merrimack River, which winds its way south from the middle of the state to the Atlantic, borders two holes at the Intervale Country Club. On one of them—the picturesque par four, 342-yard sixth hole—the Merrimack was steadily chewing away at a 300-yard-plus stretch of the fairway at a clip of up to a foot a year.

Golf is tough enough without the fairway getting narrower each time you come out to play the course. Over the years, the club tried various methods to stabilize the riverbank. None proved a permanent solution. In 2002, the club realized that it had to take drastic action, says Mike Thibeault, longtime PGA director of golf at Intervale. “We had to arrest the erosion somehow, so we put the project out for proposals and bid.”

There was one bidder: Maccaferri, Inc., an international environmental solutions engineering firm whose American operations are based in Williamsport, Maryland. Ghislain Brunet, now marketing director for Maccaferri in North America—at the time its technical director—oversaw the bid.

“In the period since the Second World War, the fairway had lost about 25-feet of width,” Brunet recalls.

“In the ’70s, the club tried riprap over the whole bank. That didn’t work. In the ’80s, they tried a concrete retaining wall. Ten years later, there was an effort made with riprap toe, this time with vegetative stabilization higher up the banks. Unfortunately, none of these methods did the trick.”

The erosion problems with the river came less from ice floes and storm-induced flooding than from what are affectionately called “personal watercraft”—powerboats and Skidoos. In summertime, the river is heavily trafficked by recreational boaters and Jet-Skiers, whose vessels send three-foot-high waves crashing against the river banks.

The river has a storied history. Archeologists can trace back 12,000 years, to when the nomadic Paleo Indians used to fish the river, setting primitive nets and weirs to trap fish. During the Industrial Revolution, when Manchester was a leading manufacturing center, and textile mills were cranking out fabric used all over the world, the Merrimack was a commercial waterway. Neither the Indians nor barges did the kind of erosion damage caused by high-powered personal watercraft. Also, over the years, harsh upstream erosion control methods like concrete walls, funneled more water downstream. There was simply more slow-flowing water in the river for personal watercraft to disrupt.

At the outset of the project, Maccaferri analyzed the soil of the riverbank at the sixth fairway. The mix of sand and earth had little cohesive strength.

It just couldn’t stand up to the kinds of waves that were being generated. The riverbank needed help— fast.

“The fairway was sliding into the river,” Brunet reports. “In fact, when we got there, there was about a 12-foot shelf of shallow water extending out from the bank before you reached the main river channel. That shelf was caused by decades of erosion.”

The goals for the project were clear. Maccaferri had to stop the bank erosion in a way that blended with the environment. And they wanted to do it in a way that wouldn’t interfere with the members using the golf course while the work was underway.

Gabions ready to protect the golf course from further erosion.

Photo courtesy: Maccaferri

The logical thing to do would have been to work in wintertime, when the course was closed to members. That was the original plan, until Maccaferri ran into an environmental road block. The per mitting process was well underway when it was discovered that bald eagles used the open part of the river near the sixth hole for winter roosting.

Permitting ground to a halt, and the work process had to be rethought. Finally, after coordination with the New Hampshire Department of Fish and Game, and advice from New Hampshire Audubon, Maccaferri agreed both not to do construction during the winter months, and also to be extra cautious about felling trees as part of the project. In fact, no tree with a diameter more than six inches could be felled without state approval.

Faced with these significant limitations, Brunet crafted a creative solution: “green” gabions, in two different shapes—cylindrical and trapezoid.

Growth has filled in, obscuring the gabions.

Photo courtesy: Maccaferri

Gabions (from the Italian gabbione, or large cage) are a time-honored water erosion prevention technology that dates back to ancient Egypt, when the Egyptians wound reeds into baskets, filled the baskets with rocks, and used the filled baskets to slow erosion along the Nile. Modern gabion technology is far more efficient than reed baskets. These days, gabions are uniform-shaped metal cages. Stacked atop one another and filled with rocks or an earth/rock mix, and then wired together, they form a neat retaining wall.

Maccaferri’s green twist on gabions—a twist that lets the gabion blend neatly with the environment—is to weave natural yellow-brown coconut fiber matting between the usual wire mesh of the gabion itself.

“This coconut fiber matting idea was my baby,” Brunet says with pride. “The matting served three purposes. First, it looks better than just open cages. Second, since we were using a mix of gravel and topsoil inside each gabion, the matting helped keep the topsoil where it belonged. Lastly, the matting— which lasts about three years— made sure the topsoil was kept moist.”

That topsoil inside the gabions was critical to the project. Not only did Maccaferri need to hold back the river, but everyone wanted the bank to look natural to both golfers and those using the river for recreation. To accomplish this, Don

Wheeler Construction, Inc., the Bedford, New Hampshire company that did the work onsite, planted 4,000 potted willow and dogwood shrubs in and amongst the gabions.

Ed Ranger, company owner, says it was his first time ever working with gabion baskets. It was easy for his crew to learn how both to craft them and to place them. It didn’t take long before Ranger had one guy doing nothing but building gabion baskets, while the rest of the crew was busy filling them and placing them.

“They worked very well,” he reports. “Once the gabions were moved into place, we planted in between them, with the shrubs extending laterally toward the river. They’d grow out toward the river, and then up toward the sun.”

The gabions below and just above the water line contained more rock than topsoil. Gabions closer to the fairway were more topsoil than rock, and were planted more heavily. Ranger’s company mixed rock and topsoil right at the site for the lower gabions, while they filled the upper gabions with a pre-made mixture.

All the while, play continued, with golfers teeing off from a temporary green. Yes—the crew wore hardhats.

Ten years later, Thibeault sums up the project. “It’s there, but you can’t see it. The bank is still 15feet-high. There hasn’t been any more erosion. The thing worked.”

If you’ve got a river that’s eating away at your property, “The thing worked” is as precious as an eagle on a par four. If you can say, “The thing worked,” and the project is green, that’s a hole in one.

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