Saturday, February 1, 2020

HIGH WATER COMPLICATES FERRY OPERATIONS


Magnus and Hoyt Purinton at the new steel foundation box
formed for the Island's north ramp, adjacent to the Standard
Oil pier.  (R. Purinton)


Detroit Harbor, Washington Island -

When we had extremely low lake levels - January 2013 was the record low - we dredged to allow for ferry maneuvering.  Then the level of Lake Michigan began to rise, so that on numerous occasions by 2019 we were at near-record highs.

At least a dozen times water overtopped the Island docks - which are lower in elevation than the pier at Northport - and that created ankle-deep ponding for pedestrians trying to access the ferries.  Most of the time such extremes were brief, driven by winds or created by low pressure cells.  But the forecast for the coming year indicates a likely return to high, dock flooding levels, perhaps even a few inches higher than in 2019.

"Indications are we could easily see eight inches more in lake level this summer," Hoyt Purinton said, "and of course, more than that if its a wind-driven event."

What can be done about it, from a ferry operator's point of view?

Several feet of water currently flow beneath the
Island's south ramp. A steel ice barrier was
created using stacked H-beams that can be
removed when water levels drop.

A new, longer approach for the adjustable, south loading ramp at north port was completed last summer.  This winter, work began in December on several loading sites.  In December 2019, the ramp at the end of the Island pier, used most frequently for landing since it was installed in 2001, had footings driven.  This December, two long pipes, approximately 30-ft. each, were driven inside the steel sheeting, and the gap beneath the ramp was filled with stacked H-beams.  This was done to prevent ice from sliding beneath the ramp, possibly damaging hydraulic lines or cylinders.  (Similar work was accomplished at the pier end-ramp at Northport, where the ramp structure is exposed to lake swells and sloshing winter ice.

Following those two preventative measures, a major job of improving the north ramp began.

This adjustable ramp was originally installed in 1975.  Several minor improvements have been made from time to time,  but high water dictates more work be done now.  High water, gradually sinking dock fill and concrete, slight misalignments between dock face and ramp centerline, and the need for a quality, dependable landing for the new, 124-ft. Madonna dictated more extreme measures be taken.   

Thirty or more years ago, sheeting and pipes were driven 8-10 feet into the bottom, less if a large boulder was struck first.  Now, Mike Kahr has driven new, 30-ft. pipes to bedrock where mooring tires will be hung.   Interlocking sheets 25-ft. in length were driven along the face of the pier to square it up with the Standard Oil pier.  Along the face of that pier, where the side of the ferries moor, additional, heavier steel pipes were driven to provide mooring tire supports and absorb side-forces as ferries come up against them in stiff southerly winds.   The new Madonna has a 40'-7" beam, and that will require a slightly wider berthing area, another reason for the southerly shift in orientation of the north ramp.

Ferry Line crew welded (Con McDonald, top) cut and
bolted steel sheeting for the Island's north ramp.
(Jake Dahlke and Dave Heath, foreground)
Taken several weeks ago.
All of this takes a great deal of work, along with a long range plan for what might still work should the water level continue to rise.  Right now, according to Hoyt, winter's precipitation has been less than anticipated, so that by April we might find the level down a few more inches.  But, with lots of liquid still ready to flow downstream in the Upper Great Lakes, that may not be long-lasting, and no quick remedy is foreseen to combat every circumstance.

Changes to ferry landings are one thing: concrete, steel and lots of labor can make them serviceable for the coming summer.  But, what about dock surfaces?  They could be at or below water level, and that's not a good thing for pedestrian traffic heading to or from the ferries.  Fill of some sort can be helpful - it would have to be stone or gravel to avoid washouts - but too much fill can trap dock overflow, becoming isolated ponds.

Such remedies have their limitations in engineering solutions, cost and practicality.  No single solution seems to meet all foreseen challenges. Only a gradual drop in Lake Michigan water levels brings a certain solution to this problem.

-  Dick Purinton  

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