June 23, 2018
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Sea wall protecting Maine Sea Coast Mission built ‘strong to the land, strong to the sea’

By Dominique Hessert, Special to the BDN

BAR HARBOR, Maine — A 4-foot-thick sea wall that since 1905 has protected a 6-acre lot and a brick Bar Harbor cottage from the ocean has undergone reconstruction that is expected to make it last another 100 years.

Time, weather and a relentless surf breached a 20-foot section of the old 120-foot wall, eroding stones and soil into Frenchman Bay.

Crews working to rebuild the wall this winter and spring battled the same elements, with one high tide in March peaking at about 12 feet and washing away two days worth of labor.

“I’d have to say that the wind and that cold blowing spray off the water that comes with the tide is the most unusual aspect of this job,” said Scott Morrison, an equipment operator with John Goodwin Jr. Construction of Southwest Harbor, which was hired to build the new sea wall.

During the shorter days and high tides of February, there often was 2 feet of water pressing against the old sea wall at peak tide. Many days the crew had to find other things to do during high tide before chasing the receding waters out to continue dismantling the old wall.

The work only became more difficult in March, when the tides increased in height by an average of 3 feet. Tides became such an problem that most crew members tracked the height and time of tides with their smartphones.

“Working around the tide is a pretty big issue,” said John Goodwin, the project’s field boss. “We’ll work up on the high ground when it’s high tide, and down on the beach when it’s low tide. It all works out, but it’s not as organized as I would like.”

Still, when the project is completed in another three weeks, the nonprofit Maine Sea Coast Mission, which has owned the property for the last four decades, expects the new barrier will last another 100 years and more.

Another challenge for workers came from what the tides have deposited since the last ice age: the mud flat. The stonemasons of 1905 built the wall at the base of the 30-foot bank it was protecting. Unfortunately, the ends of the 120-foot wall sat on bedrock but the middle was suspended on claylike mud. Over time the middle sank, causing the ends to crumble while the ocean waves pulled loose bank and stones slowly out to sea.

“If you pile up rocks in there it’ll hold up for a little while, but eventually the bottom will sag like a rope because the bottom is on the flats,” said Greg Johnston, the civil engineer who designed the new wall. “To prevent that from happening, we drove caissons [steel pilings] 10 feet through the mud and then 10 feet further into bedrock. Then we poured a grade beam [foundation] to actually form a solid base for the wall to be built on.”

The six stainless steel caissons drilled down into the ledge became a challenge themselves. It took four hours just to get a drilling rig from the street, down the 30-foot bank, to the beach. The delicate marine shell life on and under the flat had to be insulated from the big steel tracks of the rig. Six 10-by-12-foot blasting mats — rubber tires tied together with steel cables — were brought down to protect the beach ecosystem. The blasting mats constantly had to be repositioned to accommodate all of the earth-moving equipment, which included a 35-metric-ton excavator, four 15-ton excavators, five 20-ton dump trucks, one track hoe and a vibrating roller.

Getting the equipment to the flat without hurting beach organisms wasn’t the only accessibility challenge. The 608 granite blocks, each about 2 feet by 3 feet, that made up the old wall had to be plucked and brought to the top to be cleaned. After the grade beam was laid, they had to be hoisted back down to be set into the new wall. To accomplish this, half the entire bank slope was removed, forming an incline access road. Goodwin brought in a 35-metric-ton excavator that crawled back and forth on this road, its 30-foot jointed arm moving material where it needed to go.

Setting the blocks into their correct position on the grade beam, however, would not be enough to hold the wall for another century. Johnston and Goodwin worked with stonemasons from a Stonington quarry to learn how to work with the granite and pin the blocks to the foundation and each other.

“We drill through the rock that we’ve set on top of the ledge and then further down through into the ledge,” Goodwin said. “Then, we put nonshrink grout all the way down through both. Next we set the No. 10 galvanized rebar pin into the stone we’ve set and continue it down through into the bedrock. If it’s on the grade beam we drill down through into the concrete grade beam and do the same thing.”

Part of the special assembly involved pinning the first two courses of granite blocks. After learning the process, the crews decided to pin every stone at least twice. When finished, the wall contained 1,800 feet of galvanized rebar that secured the grade beam and stone.

Strength is important, according to Johnston, because the wall needed to be built to withstand the terrific forces exerted against it from both sides — the pounding surf on one and the steep slope pushing against the granite stones from the other.

Johnston had no doubts about the design of his wall lasting more than 100 years, however.

“It’ll be strong to the land and strong to the sea,” he said.

The new wall also was set in place without using mortar. Using pins and no mortar allows all of the cracks between the granite blocks to weep water in both directions, relieving some of the pressure on the wall.

Some drainage was built into the embankment behind the wall to redirect some rainfall around the wall. Also, black plastic “weep pipes” were set into the concrete allowing some rainwater to weep through the wall and onto the beach.

To prevent spring tides from reaching through these cracks into the slope and washing it out, a 2-by-2-foot concrete curb was poured on top of the slope side of the grade beam the entire length of the wall.

The need to make the wall weep presented the last big challenge. Every stone in the original wall had been cemented in place with mortar. The original stones used for reassembly were covered with natural irregular bumps and imperfections that needed to be addressed before they could be used on the new wall.

“We numbered every stone before we took them out and [put] them back as close as we [could] to that pattern,” Goodwin said. “After letting them dry and removing the original mortar, they [didn’t] fit the same.”

The entire crew worked for four weeks alongside accomplished stonemasons to remove the bumps and fit the stones.

Morrison said the workers had to learn to use torches and chisels to manipulate and reshape the granite blocks to “make them fit tighter than the original.”

The masons showed the construction workers how to “read the rock” by looking for grains in the stone, like a tree, to get clean cuts.

In the end, according to Goodwin, not every stone was put back “exactly where it was before, but it’s close, which is a great accomplishment.”

It took weeks of skilled labor and dozens of dump trucks of material to complete the sea wall before the end of April. Crews continue to work behind the wall on the slope and expect the entire project to be done on schedule.

Maine Sea Coast Mission President the Rev. Scott Planting said a special restricted fund was established by the building donors in 2003 to help pay for the roughly $360,000 sea wall rebuilding project. No Mission program funds are being used.

The old wall was constructed in 1905, the same year that the nonprofit Maine Sea Coast Mission was founded. The mission provides nondenominational religious and social outreach to island and coastal community residents throughout Hancock and Washington counties.

The Mission’s outreach presently touches the lives of 25,000 Mainers on both sides of the sea wall — the most in its history.

Both the Mission and its sea wall, as Goodwin put it, continue to be “strong to the land and strong to the sea.”

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