High water alters marina construction
By KIM FUNDINGSLAND, Staff Writer kfundingsland@minotdailynews.comArticle Photos
FORT STEVENSON STATE PARK When construction began on the new marina here, it was thought that the timing couldn't be better. Lake Sakakawea was very low, meaning only a modest coffer dam would have to be constructed to keep reservoir water from inundating the construction site.
Oh, how that has changed.
Instead of dealing with a lake level in the neighborhood of 1,812 feet above sea level, Lake Sakakawea has rushed upwards. It now appears the lake will approach the 1,825-foot mark by the end of this month. Members of Martin Construction, the company contracted to build the marina, and the U.S. Army Corps of Engineers, have suddenly had to renew their focus on the vital coffer dam.
"The construction contract has been modified for the coffer dam, the temporary structure," said Phil Brown, lake manager at the Corps' Riverdale office. "It is now being raised to the 1,830 elevation for obvious reasons."
"We just raised it and it's holding good," said Scott Samuelson, quality control officer for contractor Martin Construction, on Thursday morning. "We were a little concerned last week when all the waves were happening."
The increase in the required height for the coffer dam is the second since construction began. The outside of the dam is holding back several more feet of water than originally thought necessary. The barrier also takes an occasional pummeling from wave action in Garrison Bay. With workers and heavy equipment working below the water line just a few feet on the other side of the coffer dam, all precautions are being taken so that the dam doesn't succumb to increasing pressure from high water.
An imbalance in pressure delivered by high water on one side of the dam and a dugout on the other side could result in damage to the coffer dam. The situation is not unlike the concern over a year ago along the Snake Creek Embankment when Lake Audubon was much higher than Lake Sakakawea. The Corps lowered Lake Audubon as a precaution to protect the embankment that separates the two bodies of water.
A story being circulated along the lake has the Corps increasing releases through Garrison Dam in order to lower Lake Sakakawea and alleviate coffer dam concerns at the marina site. That has not happened and will not be happening.
"We are not increasing releases. We are not," said Brown. "For whatever reason, that rumor has been flying. That's a bad rumor."
Heavy equipment continues to excavate earth inside the area protected by the coffer dam. Plans call for the marina floor to be at 1,790 feet. Right now it is down to about 1,813 feet. Rip-rap is being installed along the interior walls of the marina. Crews thought they had stockpiled enough fieldstone last winter to do the job, but it now appears a few more truckloads of rock will be needed.
"We'll probably have to head out and grab some more," remarked Samuelson.
Construction on the concession building is expected to start next week. The concrete slab for the building was poured several weeks ago. Workers have been concentrating for the past several days on bringing the marina parking lot up to grade and covering it with gravel. The gravel lot will be used extensively during the Governor's Cup Walleye Derby, which began this morning and continues through Saturday. Once the pressure of the Governor's Cup crowd passes, emphasis will be on finishing the parking lot and the road leading from the park entrance to the marina.
"We'll be taking the curves out of the road to the south of the parking lot," said Samuelson. "Bechtold Paving will be here sometime in August. We'll get it all done this fall, hopefully, as long as we keep getting dry weather."
According to Samuelson, construction of the marina remains on schedule despite the additional work needed on the coffer dam. The marina is expected to be completed before winter and be ready for operation next spring.
