I’m on page 29 of the bog thread. I’ve seen pictures so the idea is more clear and I can imagine how I could cover it generally, but I still have issues.
1. Still size. Measured an 18x18x box to visualize on the soil area and it’s tough to see the with the grading of the hill LxW. I’d have to…
okay, replies first, designs second;
From what I see, you have enough room for a box shape either dug or built from wood and lined both ways. Don't sweat the actual dimensions; work with what you have. I'm sorry to say, you'll have to dig the dirt out and make room for what you're attempting, no matter the direction.
2. Our retaining wall is purposely higher on one side. I’d have to rebuild it all the way around. Appearance eh. Where the mound is now would drop into the river and large open area to right where former spillpool was.
Wall/Mound being built/leveled on the right more could give room for a rectangular bog box say 12-15” x 3’.
no, your wall is just fine. We're going to take out some dirt and install some conc slabs (for sturdy waterfall support) and the bog box, plus your shallow pool.
3. Issue with above rectangle is mound/drainage tube. hydrostatic pressure issues in our area due to soil/Lake Michigan, so mound has drainage tube at a slant to about 12” from soil top. (Bog box depth)
can't see how this is a problem; just incorporate it into the bog/stair design. There's plenty of latitude to just build over/around it.
4. We live in northern Wisconsin. It’s negative degrees often and even the lake freezes over. I don’t have much belief the pond would stay circulating or the bog box freezing due to the size.
it's okay to have your bog freeze, including the pvc pipe. Now, I suggest rigid pvc in the designs below but what I did was use 4" drain tile piping and it won't crack like pvc might. The flex pvc pipe I show as your lead in should have a T and screw piece so when winter approaches, you can open this and there won't be any siphon effect. If your pond is at least 24" below ground, I believe you'll be okay, but there ARE ways to keep ice from getting too deep and affecting your system. Easy ideas later.
5. Frozen water + pvc = not good so I’d be inclined to drain the entire pond in November before it snows and refill in March. This would have pvc pipe all the way from the bog to the pump? My worry is water build up over time backing into the pvc and freezing (if the pvc runs all the way and down 2’ for a connection port to pump). I’d have less worry if the pvc ran parallel w the ground, and then the pump connected to it somehow via say 2’ hose from where it is in the water. (Is this possible?)
You don't need to worry; the flex pvc can 'flex', and I've not heard any stories yet about peeps having issues with flex pvc, but I HAVE heard re rigid pvc. You'll see I advise to route your flex pvc pipe feed from your pump up the river and then, up your hill and going in over the bog box where it will attach to your manifold. You can easily camo such a design (it's what I did). So, no rigid water filled pvc to worry about. When you open the tee mentioned earlier, you'll allow the water to drain OUT of your flex until it gets to river/pond water level. So, that's safe too, even if not necessary.
Edit in 6. In the bog thread there were concerns of freezing water in straight sides bog boxes and expanding water busting them. Considering I’d drain my pond for winter, I’d imagine this would be a non issue correct?
see above; releasing the water so it can't siphon means you'll only have water in the flex pvc that is at river/pond level. You're good.
Edit in 7. Does the pvc for the bog box come in from the side near the bottom, or directly up from the bottom (would need a 90deg elbow/head pressure?)
Try to avoid straight 90s as it adds head pressure. What I did was route the flex pvc (it flexes, so you can conform to your situation without ANY fittings except ball valves and unions. USE UNIONS wherever possible; you'll thank me later! I suggest just looping the flex pvc up and over the bog box, shoving it down into your box, attach at the bottom to your manifold, and you're done. A manifold is a pipe with slits cut (details in my design drawings) where the water gets out and then rises up through your gravel/stone. You CAN use bulkhead fittings for both but it's just another leak point, more labor, and not necessary, as long as you're okay with camo later re rocks, etc. Again, it's what I did. I have two leads that are 'exposed' above my bog and I hid them with 'fake' rocks.
Edit in 8. The pond came w a Latina power jet 2000. I plan to upgrade. Any difference in calculating the head height pressure for finding a pump? People mention adjusting theirs? Does it matter?
If that all checked out, my visual sense w the mound and river is to do the rectangle size have it empty more to the right side so it fall into the existing spillpool. The weir(or is it called spillway?) would be at a 45 degree angle to help create a tier.
Look up the head pressure charts associated with each pump; get something that will be more than enough at the head height you're working with. If you get an underpowered pump, you'll not be a happy camper. With my suggestion of 'two leads' FROM your pump, you'll get better efficiency and that will help, not to mention giving you options. Each of these two leads should have a ball valve so you can control exactly how much water goes where. Put one near your bog to manifold feed, and one from a tee that supplies your weir. The other lead, can just lay in your pond and cause some circulation or you can hook it up to a water feature or even create another waterfall, somewhere. It too should have a ball valve so you can shut it down if you need more for the other lead. I had one 'extra' lead on mine and just let it exit the pond then lay at an angle and pour back into the pond. Eventually, I used this as my log waterfall. Pics in my showcase, if interested.
I don't like the adjustable volume control pumps; I'd rather do it with ball valves and multiple leads. Same effect, no electronics/working parts to go wrong and cheap. More options this way, too.
IMO, having your fall pitch right will give you more issues re 'how the water gets down to your river' than if you go front face forward. Front face forward means you don't need any 'river' route down the hill as you already have the pitch. Stack up rocks and let the water pour, splash, meander between; it's all aimed toward your shallow pool anyway. The designs below incorp those ideas. To do it to the right would involve similar ideas but you have less lineal distance to get that water back to your river. You'd be creating a river with the same liner beneath, same rocks as deco/structural entities, but have to do hairpin turns and visually, you'd not see it from that doorwall. The other pic I posted showed you visually, the type display you can create. I see meandering streams down hills as needing a lot more length and breadth than I think you have.
Basics are; dig a box, fill with stone over piping, let it overflow as a waterfall. Using your weir also gives you a 'sheeting' waterfall within your bog overflow. The shallow pool below catches it all, then it overflows into your river. Easy peasy, just got to move some dirt and build a nice stable base for the box and weir, and your camo/deco waterfall rocks.
okay, pics, finally! First shows the plumbing at the pump, in your pond; (I forgot to add the unions at #3 so you can easily disconnect the lines from the pump, if you have to clean/replace/service the pump.)
second pic is basic front facing bog build, similar to what I already posted;
third pic shows cross section and 3/4 views + more instructions;