What we started with that needed replacement before it completely collapsed into the spring. It was made out of pressure treated lumber, plywood, and the thinnest metal roofing available 30 years ago. The replacement is only being made with untreated wood and the concrete we’re adding as a foundation is staying out of contact with the water.
We tipped the entire building over to minimize how much of it ended up breaking apart into the spring itself. The wood was so spongy and soft it was about as crumbly as cake in many places.
The spring was draining out over a single layer of loose stacked rocks, which allows backflow that brings bacteria from the bog into the spring. We stacked a stronger wall and sealed it with the natural grey clay dug from a hole in the sand of the creek. It has enough bentonite content to settle in and block water flow under the water level. Above the water, we used high-strength fast setting mortar to seal the rocks together. That’s the dark grey material in the wood frame at the top. The white pipe with water trickling out is the outlet. You can see that it’s higher than the drainage area, preventing water from flowing backwards into the spring. The other white pipe that goes down at an angle into the water is the supply pipe that runs to a pump and then into the cabin. It has a little screened valve at the end so it can draw water up but won’t release it back into the spring.
After the mortar had a week to cure, we added more forms and poured concrete. We also did a lot of work to line all the sides and edges with rock from around the area, which is why the water is so muddy. The actual spring that fills this area is at the bottom of the very left side in this photo. There’s no rocks stacked there and the rocks under that edge of the soil are loosely stacked to ensure they don’t block any flow. It’s very easy to accidentally close off or crush a spring opening, or to pierce the sealed area holding the water when trying to dig it out. Despite getting muddy, the spring was completely clear again 24 hours later. The concrete’s set and is curing slowly on its own since it’s so humid. After this we have to set a layer of cinderblocks, fill them with concrete, build some short walls and a lift-off roof all covered in metal siding/roofing, and we’ll be done!
This is how we’re keeping it covered (and keeping the bear from falling into it) in between stages.