Pond Boss Forums POND CONSTRUCTION Soil questions Pond Leak - any thoughts appreciated...

Hi all - new user here.

I have a leaking pond - here's the net.

Pond was dug 2 years ago - but never filled - It is oval in shape app 150' x 120' x 18' deep at its deepest.

After 1st winter contractor told me he 'hit shale'...so...

Last summer I found a different contractor - he lined the bottom of the pond (lower 1/3) with plastic sheeting - 6 mil stuff - overlapped it by 4-5' or so - it came in 20x120' rolls. They placed app 10 loads (15cu yds/load) of good blue clay on top and the sides - including the dam. This past winter the pond was app 1/2 full - but water level would fluctuate by 2' or more after a rain - it would just slowly seep out.

So...this spring - we drained it & lined the WHOLE pond again with more blue clay. Same result - water is just slowly leaking out - but it retains water close to the old plastic liner originally put in there...

Any ideas on what I can do next?

How would I locate a leak like this - there is nothing obvious on the dam side - no obvious leaks at all.

signed,

//puzzled in WNY state

Dear puzzled (rare chance for me to feel like Dear Abby),

Greetings and welcome to the forum.

How bad is the leakage? How far down is the pond (over it's high point back when?) and how much water (height) does it lose per day/week?

How thick was the clay layer that was applied?

Hi Theo - answers below:

a) It dropped a foot in 2 weeks after some hard rains

b) It is app only 40% full - has never gotten higher than that. After a hard rain - we can see it rise anywhere from 6-18" above it's current 'holding height' and it gradually gives it all back - and that translates to app 1" per day AFTER a hard rain.

c) The bottom of the pond has 2' or more - the walls taper up from there to app 8"-18" depending on which side. (shallow side closer to 8" - dam side 18")

1" per day in the summer is normal for evaporation. However if the pond goes down to the same level every time, then the leak is probably in the side at that level(or just below).

Otto could address this well. It seems to me if the clay put on top of the plastic liner were compacted at all, the plastic would have been destroyed.

You never said whether or not the blue clay was compacted.

lodestro

Welcome to the forum.
There are two kinds of leaks.
1 a hole like in a bath tub. This is easy to see om the back side of a dam.

2 This leak is just poor soil that does not hold water.

It sounds like you may have poor soils,

Try a few thing. Get a shovel and dig a hole as deep as you can in the side of the pond between the top and the water. Fill it with water. See what it does. do this in a couple of places around the pond.

Take some of the dirt mix it with water make a ball about the size of a golf ball. Take the ball but it in a bucket of water and see if it holds together..

This will give you a little more information.

Otto

The plastic liner is useless and should be removed some ponds in NY take 4to5 fillings before they bind the blue clay is bluestone that has broken down . If you are going to use this clay in existing soil it has to be knitted into the existing soil a min. of 10" it is hard to work with and should have little moisture.Follow Ottos advice and see if the water penetrates the sphere and falls apart and the perk.
If there is a lateral cracking in the shale against the layers then you will have drainage problems if not and he covered the shale it could take up to two years to form a seal. If you want to know if it is leaking out the bottom I would drain it and you will be able to identify the area. If it appears to be fully sealed with clay that has drained from the sides then look upwards.

good luck

I received your e mail Otto will also confirm that water pressure will walk under plastic and poly is not a water freindly product I could tell You all the water problems with this but I do not want to get a severe edit there might be a sponsor selling plastic I would ask Mr Bob
Good Luck

A liner that is not installed above the waterline can have water seep around the sides,

Let us know how your field tests went.
It is not unusual for a pond to take more than 1 filling to saturate all the ground and begin to stay full.

Otto

would a pond such as mine that filled up quickly be apt to go down severely after its first filling?

A quick filling does not mean it will go down. Keep a close eye on things. Keep up posted.

my pond dropped about 3/4" in 6 days after filling up quickly. i hope this is a good sign.