Bridge/Culvert Update on 11th

A few of us met with Jerry Hertaus, who gave us an update on the Hwy 64 culvert replacement project.  As most are aware, MnDOT had moved forward with designs to replace the current 16×10′ arch-pipe culvert that was placed in the 1950’s with a 12×12′ inside dimension box culvert.  The original presentation was given to the Lake Asssociation in Fall of 2018.

As was reported at the Fall 2020 Lake Association meeting, money was set aside in the Mn Bonding bill for additional funds for a short span bridge to replace the current arch-pipe culvert.   The money was not earmarked however, and the official MnDOT course had not changed away from the 12×12 box culvert.   Although this sized culvert would allow many more boats to travel under Hwy 64, there are a significant number that still would be too tall to cross underneath (most pontoons and I/O or straight inboard boats with wake towers).

At this point, many of you helped write letters of support of a bridge crossing instead of the 12×12 culvert.  27 of them in fact!  These were forwarded along in a long string of official letters from Jerry detailing the history of Eleventh Crow Wing and how a 12×12 culvert will not sufficiently address boating needs for the future.   Pontoons are a very popular type of boat.  At least on the East basin where I spend most of my time, many if not most of the new boats have been pontoons.  This replacement will be with our residents and 11th Crow Wing lake for generations, so there is a lot at stake.

After a long period of discussions with MnDOT, the best course of action is to upsize the previously proposed 12×12′ box culvert to a 14×14′ box culvert.  The width of the smaller culvert would not normally be an issue, however imagine what happens when a cross wind is blowing across the culvert and your boat is trying to exit.  Then the extra 2′ of clearance will be very welcome.   The main factor has always been the air gap height from water line to the top of the structure.  Here are the stats:  Current culvert is 4’ from water to top center, but that is really only true on the east end.  Near the west end exit it drops closer to 38-40″ (likely due to settling).  And also remember the arch shape makes the usable height less as you move out to the sides of your water craft.  A box culvert won’t have this shape limitation.  Back to the concrete box culverts, the 12×12′ as originally proposed had a 6′ interior height.  Much better for full windshield boats of all sizes.  But only pontoons that sit low in the water with shorter furniture and side rails will fit through.   And certainly not comfortably.  With a 20′ wide short spanned bridge, the height was increased to 6.5-7′.   Obviously those extra 6-12″ are huge.  BUT, here’s where it gets good.  The 14×14′ box culvert with the same invert elevation (bottom of the culvert as current) has a 7.5′ waterline height.  This should be tall enough for most (if not all?) pontoons to get through the culvert.  About the only thing that might not fit are wake board boats with fixed towers.  Even some of these might fit through a 14×14′ opening.

Costs for a 14×14′ box culvert are lower and the design work is significantly less than a short spanned bridge.  Just as important is the extra time that would have been required to pursue a bridge option.  Unknown how long this process might have taken, but an extra 3-6 years is not out of the question.  So…despite the current plans not including a short spanned bridge, we are in a position to have an extra 6-12″ in height over the bridge option.  The extra 2 feet of width will also make navigation in a cross wind much easier for all craft.  The length of the culvert will be extended on both sides per MnDOT’s desire to remove the guard rails and keep ATV/UTV traffic off of Hwy 64.  The extra width will allow the trail to extend to the west of the highway, as it currently is for all but the Culvert crossing.

Last to talk about is timing.  The 12×12′ culvert project was scheduled to be installed in fall of 2021 (yep this fall).  With the recent design change to a 14×14′ culvert, a strong push was made to keep the same construction schedule to complete work in 2021.  Although this is still a possibility, it could slip to 2022.  Although a potential delay is a little disappointing, I think we would all agree the small extra wait would be worth it.  A huge thanks to Jerry for putting together strong logical arguments that are grounded with an engineering background!

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