I’m in the process of building about a 7,000 sqft pond. Lucky/unlucky for me I live in the south east and it has been raining every day. The first big rain filled the pond up half way, but was almost dry by the next day. Since this happened I started packing even more red clay. The forum I read before I started the dig said to pack red clay and leave loose clay on the top. Second rain pond filled up even more but water was gone by the next day. I’m out here again packing it with red dirt. I couldn’t attach pictures so here is a you tube video https://youtu.be/VwGL1IoBt1U Video of my pond hoping someone could tell me if they think this type of clay really obsorbs that much water or if I have bigger issues.

I think there is a couple ways to check to see if the soil holds water. "Just because the soil is red does not mean it is clay" (M.Otto). Take some of the damp clay or make it damp. You should be able to kneed it into different shapes which means it has a higher plasticity index. Squeeze it with your hand/s into a large golf ball size and drop it on the ground /cement from about waist high. If it breaks apart then it is not very good pond building clay.

Another test is get a 5 gallon bucket or similar container, put several drain holes(¼" - 3/8") in the bottom and several up an inch or two on sides above the bottom. Put a layer of gravel to cover the holes. Add 6"-8" of clay over the gravel. Make sure the clay is somewhat moist. Moist enough to make a ball out of the material is about optimum. Compact well it with a appropriate tool such as a sludge hammer or ball bat. Now fill the bucket with water and see how long it keeps water in the bucket. It should hold water for days if it is good compactable clay. If the bucket is set outside so it sees rain, you shouldn't see the water continually dropping and weeping out the bottom. Ideally the water level in the bucket (with normal rainfall) will stay the same (rainfall is keeping up with evaporation).

If the soil passes these tests then you should be looking into renting a sheepsfoot roller. Sheepsfoot machines are compaction tools. If it is a pull behind type, then get the double barrel type because it is heavier and does a better job of compaction. There are self powered models and even vibratory models which are the best. By 'the book' the bottom should be driven over 8 times for good compaction. Or roll the machine making cleat marks 5"-6" deep over the dirt until it is up out of the cleat marks leaving fairly smooth clay. Ideally this should be done in 6" layers called lifts until the bottom - sides layer is 16" to 24" thick.

Quote from Rainman: "all the pond basin needs to be well compacted during construction. Don't fall into the myth that a 50,000 pound dozer will compact soils, as there is less PSI of down pressure than a typical home refrigerator. Spending a little on insurance in the way of proper building will save huge dollars if the pond leaks and needs to be redone. I had a dirt pusher build a dam and the original build was $3800. The bills to "fix" all his mistakes topped $32,000."

Doesn't sound like you have the right soil. Compaction may or may not help. My pond is all clay and it really didn't get any compaction. No leaks.

Another thing from Otto. Make a ball of it and throw it at the side of your pickup. If it shatters, it won’t work.

Cody Note: Otto is the pond building dirt expert's expert.