I have a pond about 35' round with a maximium possible depth (Below the spillway) of about 8 feet, it holds water very well up to about the halfway mark but loses it extremely quickly above that point, after our last rainstorm it lost about 3 feet in depth in 3 days. I'm surprised that it doesn't seal actually because we have super sticky clay soil here. There isnt any way to make it take on more water realistically, but it takes in tons, it sits at the bottom of a ~120* amphitheatre landform which all drains right into it.
What are the positives and negatives of sealing with a pond liner? I dont have any heavy earthmoving machinery but could borrow a small bulldozer if I had to for installing one.
Are there any other effective methods I could use to seal this terribly leaky pond?
My other possibility is the permacultural adage "The problem is the solution", and to fill it in slightly and just use it as a rice paddy but I already have 2 other prime paddy spots so id like to turn this into a pond if its realistic.
Here is a pic of the spot in early April when it was full from winter snow melt:
Ian Taylor : I will offer a slight modification of the plan offered by Cris Bessette, Do nothing permanent for a couple of years, live with your land and learn
Ianto Evans/ Cob Cottage Co. talks about a similar sounding Landform in his book ''The owner built home " . Here is what I think is happening !
It sounds like at some time in your lands history it was very much under water and the existing bottom has had an over burden or Blanket of Clay deposited
on it. The Thickness of your local clay deposit is unknown and can vary greatly within just a few feet !
If you could look down through the layers of humus, top soil, mineral soil and then down to clay, you would see that all these layers hug the natural flowing
topography of the original lake bottom ! A series of test holes will have to be dug to prove or disprove what is underneath there and I can not tell you where
to dig or how deep !
As you said, all of the land drains into the this natural Bowl, and eventually the water table rises to make a pond that eventually over tops the clay formation
and then runs/flows down and away! I expect that you will also find the remains of one or several old beaver dams at the outlet from your Pond !
The old beaver dams probably created the original pound, and deserve a few minutes consideration before we move on !
I have had Extensive experience with beaver dams, and have seen the ponds, and acres of land downstream from a beaver dam heavily damaged from the
scouring effect of the wall of water suddenly let flood downstream due to catastrophic failure of, or careless removal of a Beaver Dam !
Twice I have had the experience of shallow plates or pans of clay blanketing the 'Natural ' topography destroyed/scoured away and acres of land that had had
a naturally high water table damaged for all time !
Think of the beaver dam as a Hugel Mound set down in the stream bed, -properly built and maintained by an active family of beaver this structure becomes an
incredibly watertight structure that over years and years holds more and more water. Where I have have the experience of removing a decades old beaver
dam I have found the richest, and deepest accumulation of rich black earth I have seen East of the Mississippi ! Man made Hugel Mounds
So Your land now drains about the way it should, acting as a flood catch basin and then allowing the water to seep off slowly over the top of the Clay formations
low points, and past the now very porous Beaver Dam structure(s) !
In order to make improvements to the bottom to improve water retention you will have to drain what is there 1st ! Sep Holzer has had good luck
with Using pigs to turn the bottom into a type of homogeneous material called a Gley that will seal even a sandy bottom, penning in pigs into a section of the
impoundment area, allowing them to seal that section and then moving them to another section, has worked to create a sealed bottom and might increase the
depth of your original pond When you go to restore it !
As It will be difficult to 'hire' beavers to work for you, and impossible if you want to protect any existing trees, You will have to replace the original dam with a
Monolithic core of Dense clay that has been locked into a key way cut into the original clay bottom ! See my remarks above about what can happen to an existing
water table if too much Clay is removed or scoured away !
Even if you did decide to go with a 'pond liner' this should be a multi year project to improve your existing pond ! Hope this helps, and is timely, for the Good of
the Crafts,- Think like Fire, Flow like a Gas, Don't be the Marshmallow, As always your comments, and questions are Solicited and Welcome Big AL
Success has a Thousand Fathers , Failure is an Orphan
Alright well I got a bunch of information today from the previous inhabitant of the land, my grandfather. The pond was "formed" about 60 years ago on top of a shallow sink hole. His father thought it would be a good spot for a pond. The area nearby, probably due to a spring was always kind of marshy. So what he did was berm up around the sink hole hoping it would create a pond. It apparently didn't work very well though since the spring seems to act just as well as a drain than a filler.
So being spring fed that raises some issues with a pond liner, it seems like water would build up under it or I would just end up choking off the spring. I think i'm going to backfill it with about a foot or so of loose soil and lower the spillway and try growing rice in it. It is a prime location for a rice paddy.
I actually have another pond about twice that size that hold water perfectly but it is about 300 yards farther away and at the top corner of my property.