rising water level in bog?

[allif]

Hi folks
I keep reading about how you need to leave room for expansion in a bog...rising water level as biomass increases the volume of material in the bog.
But I can't wrap my head around that. Wont that just force more water over the spillway ( I guess I'm just talking about raised bogs here) at any given moment,
rather than raise the water level?

 

[mrsclem]

If the spillway is not large enough to handle the flow, the water will go over the walls. My 1st spillway was 2" deep and 8" wide. Great for the first few years then we started having water go over the sides. Widened spillway and made it 3" deep. That lasted 1 more year. Finally took of edging boards and raised the edge of the liner.

 

[addy1]

My bog is big, my spillway is 3 feet wide, I had to raise the liner on the down slope side of the bog. Partly settling, partly the roots etc . I do have a 27 foot wall that the water does dribble over, but still needed to raise the back edge, about 3ish inches over the years. It was built on a dirt berm , dirt and rocks from the pond dig.

Had some folded over so it was easy to do

 

[allif]

I see. Hope we don't have issues since we ended up with very little liner left when all was said and done (my plan got modified but not necessarily optimized as we built). We might have enough to add a few inches, but sounds like that could be years away. We also might have enough leaks around the spillway to compensate. Honestly in our case it might be easier to remove the gravel and dig deeper if it comes to it.
Guess it's just wait and see.
Thanks for the replies!

 

[combatwombat]

@allif: Is your spillway designed in a way where you could just widen it if you needed to? That would also alleviate the problem. Regular, aggressive root pruning would probably also do it.

 

[allif]

That’s a good idea but it would be a substantial amount of work. That wall is reinforced with rebar. We’d have to deconstruct the whole thing.
It might be possible to add a second spillway if the flow is too much, I think that would be easier than modifying the existing one. I was already looking at that. Still a fair amount of deconstruction, but less involved.

I fully expect the flock to prune the greenery, which might help keep the root mass down too. Curious to see how it all works.



Thanks for the thoughts!

 

[brokensword]

I have ALL the water go over my bog edge, which is about 20' long, so mine only rose an inch and that's because I deliberately put some 'walking' rocks near the edge to also create some mini falls/channels. If I ever have more problems, the walking rocks will go and then all the water has access to the edge. Maybe you can lower the whole front edge to create one long spillway?

 

[allif]

That’s a great idea! Thanks!