Meyrik Farm has a small dam, about the size of a large pool, at the edge of a cliff with beautiful views of the valley below. It used to be bone dry due to many years of drought in the region, but has received water since.
We noticed that a lot of silt would run off into the dam during downpours and that the water level would drop significantly on a daily bases once it stopped raining, a lot more than could be explained by evaporation. The best soil for building a dam is clay soil which is not what this dam soil's composition is, being more sandy and rocky.
Researching dams, water leakages, and how to seal dams, provided some interesting information similar to that provided by Big Ditch who have found that common solutions to this problem included:
- compacted earth clay lining
- bentonite dry blanket
- bentonite wet blanket
- concrete linings
- bituminous sprays or coatings
- pre-fabricated lining membranes
- polymer plugs
The first thing we did was off course to dig out all the silt which required an escavator and some hand digging in parts we couldn't reach. Too much silt running off into dams can make the soil more porous.
Clay Lining
Our first attempt at sealing the dam was to dig up high quality clay soil from other parts of the property and dumping it into the bottom of the dam. When it rained and turned into a muddy clay-mess we danced around the bottom of the dam in bare feet trying to spread it around to fill the cracks.
We didn't have much success with this method but we also gave up pretty early on as the amount of work to try and get clay up the dam walls just seem too big a job for us at the time.
At the end of the day clay-soil is the best soil for building a dam.
Pre-fabricated Membrane Linings
Some of the farms in the area use these to line their dams. They probably work great, but we didn't try these out due to:
Cost.
The artificial look when we wanted to maintain the raw natural feel of the property as much as we could.
According to Big Ditch these membranes can start to leak over time anyway and deteriorate due to UV light exposure depending on the quality.
Polymer Plugs
This is the method we ended up going for. The cost was significantly cheaper than other methods we looked at, so we thought we would give it a go as we had nothing to lose.
This is the product we ended up using:
Meyrik Farm is not affiliated with the company.
After applying this to the water in the dam it started holding water for the first time that we've been there. Every time it rained and would fill up we would apply a little more as it needs the pressure of the water to push the polymer into the small cracks to plug the walls.
There was still some leakage from the dam wall that we could see on the cliff side, and by adding more of the polymer to those areas it became less and less. We still lose some water, but our dam gets to a point now where it stops and stays full which is a major improvement from where it was. Needless to say the dam is now holding water better than before and we're very happy with the result for the cost outlay.
A Few Things to be Aware of with Polymers
Follow the instructions and don't let livestock drink from this water in the first few days. The polymer will tend to float on the water after changing into a clear jelly-like substance which may be harmful to animals if ingested. This will take a few days to settle to the bottom.
Don't use too much at the start. The temptation would be to think that more is better, but this stuff swells up quite a bit. We made this mistake and had to sort of scrape excess gel off the water surface at times.
It is best applied before rain as the additional water creates a pressure that pushes the polymer to the bottom and sides. You also only have to apply it to areas where there are leaks, and not the whole dam. We didn't know where the leaks were at the start and considering that our soil is not really the best for a dam we covered the whole area.
We've only used one container and still have more left over. Keep in mind that our dam is not big compared to many other dams and depending on the size and severity of leaks you may need more.
