Concrete collar in partially raised pond

[Andyhos1]

I feel silly but I'll have a ton of questions before I touch a shovel. I've tried to research this but haven't reached a clear answer.
I'll be pouring concrete for a collar/bond beam for a two foot high wall in a partially raised pond (3ft below grade). It's on a slight grade with the highest level about 12-14" over the lowest. The plan was to have the collar about 10"deep. I need the wall to keep it's height above grade so the idea is to have the top of the beam be level with the highest grade. Seems I have a few logical choices 1) try to raise the level of the low area so it's up to the bottom of the beam (packed dirt/gravel?) , 2) just pour that low area deeper (12-14+") so the concrete sits on the current ground level and the top of the beam is where I need it, 3) dig the high area down and add an extra layer of block or 4) whatever someone who knows more than me suggests. The ground will be backfilled on the outside in any case.
I'd like to not have to lay extra courses of block but also not looking to cut corners. What do the experts think?

 

[Mmathis]

Hi! I’m sorry, but my ADHD stopped me after “collar,” so I can’t actually answer your question except to add my experience. We have a very high water table (NWLA) and very CLAY soil, and after a year or so, I realized I needed to rebuild the pond so that the water level would be [slightly] above ground level. No slopes or grades like you have, though. I used concrete blocks. It was the BEST decision I ever made! Lots of work, but fun at the same time. I think I had 2 or 3 courses…..I think, maybe 3?

 

[GBBUDD]

I'll have a ton of questions before I touch a shovel

some of the wisest words i've seen here.

But the rest has me spinning . but lets see if i can't answer some questions without a full understanding. your bond beam in right is a footing. and the easiest way to do that is by simply digging a trench before anything else is done. you won't need any wood nothing just pour your concrete in your neatly dug trench.

the high low edges you lost me on but then again its been a long day , week , month..

 

[Andyhos1]

some of the wisest words i've seen here.

But the rest has me spinning . but lets see if i can't answer some questions without a full understanding. your bond beam in right is a footing. and the easiest way to do that is by simply digging a trench before anything else is done. you won't need any wood nothing just pour your concrete in your neatly dug trench.

the high low edges you lost me on but then again its been a long day , week , month..

Let's see if a bad drawing is better than a bad explanation.
Here are the three options I can think of... I'm sure there are more. The pictures are exaggerated but represent what I'm dealing with. The diagonal line in each picture represents the current grade. In all cases the area around the pond will be backfilled/packed to be level with the top of the beam.
The first includes digging a trench in the higher grade but then building up the lower areas and using forms for the beam. This is probably easiest with respect to material costs and digging but seems like risky business especially since I'll be digging the inside of the ring out not long after the beam cures.
The second drawing still uses the forms in the lower area but pours much deeper so that I'm pouring on existing dirt and not freshly packed gravel or dirt.
The third digs down for the entire beam and gets back to grade with additional courses of block. This requires more digging and a ton more block. It's probably most stable but I do then have a few courses of block underground. Is there any considerations for cinder blocks before grade (sealing, mortar type, etc)?
Thanks for your help so far.

 

[GBBUDD]

1- i would not recommend as a good rain and a lot of hard work can be washed away or compromised.

2 is workable but requires more thought on your part . but if your in a cold area frost can be a problem.

3 is the best a structurally sound and easy to work with . i will add that adding some rebar in every other bay in the cinderblock that is pined in to the bond beam/ footing and then filled with concrete or mortar will be very sound.

I take it that note is 2 below grade courses

 

[Andyhos1]

1- i would not recommend as a good rain and a lot of hard work can be washed away or compromised.

2 is workable but requires more thought on your part . but if your in a cold area frost can be a problem.

3 is the best a structurally sound and easy to work with . i will add that adding some rebar in every other bay in the cinderblock that is pined in to the bond beam/ footing and then filled with concrete or mortar will be very sound.

I take it that note is 2 below grade courses

Thanks...as I drew them out or became more apparent #3 is the way to go. I was planning for rebar and filling with concrete. Probably going to have to drill the rebar in because I want to start this fall and not sure I'll get the blocks laid before the weather turns. I don't want a bunch of 2' rebar sticking up all winter...not trying to kabob my whole family and dog.
I'll have to break out the laser level again but I think I'll only need one course below grade... I'm about 8-10 inches difference between high and low points. My drawing had two courses just to show the concept.

Thanks again, I'll add more block and shovel time to the bill of materials.

 

[GBBUDD]

at the bottom of every post with my name is a link to my showcase i built cinderblock walls for the pond . it's down toward the bottom there are some tips you may not be familiar with