I use concrete blocks.

Thanks for your response, waterbug guy, and your brevity! Pond bottom still looks wet this morning, but my repairs are not collapsed and that is good news. I don't think any new water seeped in overnight. Any warnings about going ahead with the liner even tho the bottom is muddy? Seems like it will dry up on its own, with or without my liner. Thanks for your help, all.

-Jo

That gravel extends pretty far. It is there to create drainage so water will spread out. Depending on the original perc tests and how heavily the system was used the loose gravel could be very deep. You need to isolate the area under and around the liner so you won't get a lot of moving water under it. The concrete blocks would probably work.

The gravel is placed in a trench that is usually fairly linear and then doubles back and forth several times to give the needed length. These tranches are only a couple of feet wide and usually around a foot or two below grade or so. The space between tranches is wider than the trench.

Thanks, sleepless and chas. It helped a lot to know where the gravel was and why.

I ended up digging out a LOT of gravel (crushed stone they call it around here), and stuffing the clay back in the hole(s), and shoring it up with pavers and rocks. I think I supported it pretty well. If it collapses, it just does, and we will deal with that, too. Very sadly!

For now, it is looking pretty good. I hope my goldfish survive for a little longer in the small trough pond. I don't think they are very happy in there. I tried hard to make em a great new house!

Thanks everyone!

-Jo

Chas,(love the name, my grandfather used it as a substitute for Charles)the shape of the drainage field can change drastically due to the topography of the land and the composition of the soil. The leach field at our last house was almost 50 feet from the house and downhill at least 15 ft. The gravel bed was 60 feet long, 12 feet wide, 2.5 feet of gravel depth with 18 inches of clay on top. It worked very well, needing cleaned only twice in twenty years and then it was because we got nervous.

Thanks sleepless. Yes, its Charles here too and I loved using it after I learned it was short for Charles (so cool); until the forth grade, when spaz became the popular derogatory word of the year (coolness factor zero)!

Its nice to know about that kind of leach field. It is new to me. Thanks. Just a big sump. I was aware of the 18" expected cover, but I have observed that things don't always end up to code

Quikrite, may help - just pour it into the gravel and form a good solid layer and it will usually form a pretty good base. Even with whast ou have alredy installed, the quickrite or just a concrete sand mix will normally get you to a good base - better to take the high road now and not have problems after the pond is installed - even if you have to put down a poured base via quickrtie bags or concrete mixer The concete block will hold well if on a good base - good base is the key.

Lime can also be used to help in soil stability

You can use panelling or plywood to rebuild you ledge. The wood acts as a form. Fill behind the wood a few inches then fill the pond with water a few inches. Repeat until complete. If the area around the pond has good drainage I would feel secure up to about 3 feet deep. After that I would be looking to raise the pond a few inches above the yard with a dirt berm.