Pond Boss Forums INTRO Questions & Observations pH almost like battery acid.

Working with a new client in East Texas. He's built a new pond and lined with some black clay I've never seen in that part of Texas, south of Athens.
Filled the pond mostly with well water. I put in a few fish and they died muy pronto.
I presumed it was because the fish were mishandled during stocking.
Decided to check the water chemistry. Sent in a sample to Texas A&M and it came back an astonishing pH of 2.7. Thinking there was an error in my collection technique (I put it in an empty Diet Dr. Pepper bottle), I grabbed another sample, along with a sample from each well on the ranch.
Got the results today.
pH 2.9
pH from the well that fills it, 4.11.
So, the question I started asking is, "Can well water at 4.11 hit the air, oxidize something in it to make the pH drop to 2.9?"
So far, everyone I spoken with has said, "No, I don't think so."
All fingers are now pointing at that black clay. The ranch foreman just collected a sample and is taking it in to be tested.

Any other thoughts out there? As this little saga transpires, I'll post here. For the record, I've not seen many places where the pH is 2.7-2.9.

Have you?

How large is the pond?

Acid mine drainage, that is about the only places I have seen pH that low. There aren't many species that can live in water with a pH that low and I am not sure there are any North American species that can. Get it into the high 3's and then there are a few North American species that can.

It'll be interesting to see what the soil results come back as.

Only acid mine pits. Sounds like you need a lot of ag lime to fix the clay.

I'm trying to figure out where the black clay came from? Did the dirt guy use clay from that location, if so that's strange. I thought it was red all the way past Jacksonville.

Bob, what does the well water smell like - rotten eggs?
If SW of Athens, well water most likely from Tertiary formation lignite aquafer.
Black "clay" most likely tailings from Big Brown strip mine in Freestone County.
Best guess....

The color and pH drop by air oxidation sounds like sulfidic soil, usually seen along the coasts but if the soil is trucked in from somewhere I would guess Fe2S contamination from a mining operation.

Fe2S is jet black. Take a small sample of the soil and drip hydrochloric acid on it. If it has Fe2S in it, you'll immediately smell rotten eggs as hydrogen sulfide (H2S) is liberated. Aeration of sulfidic soils causes formation of sulfuric acid, which is exactly as you describe: battery acid (in lead-acid batteries).

If it does indeed come from a mine, I would be extremely concerned about acid liberation of the other heavy metal contaminants that might be present. The low pH will liberate metal ions that would otherwise be trapped as insoluble salts.

Ive seen strip mines around here with extremely low PH to the point of no living fish. Typically is pretty easy to sweeten the water with some lime, but your situation with black clay and Bocomo talking about the liberation of Fe2S and metal ion contamination possibilities sounds like you want to be a little cautious......send the intern in to get the future water samples.....

This is a two acre pond almost adjacent to a site where a 40+ acre lake is being built. The black clay was found about 15-20 feet below natural ground level as the contractor was excavating soils to build the dam on the big lake. The compaction was so good he decided to use it to build the core trench of the dam with it. The landowner liked it as well, so now they've used it to line the bottom of this pond and another one that's almost completed.
I don't think this is reclaimed mine country, though. The land is between Athens and Palestine, near Hwy 19.
By the way, I had them collect some of that black clay and send it to a lab for testing on Monday.

Old Land fill!

Will be interested to see the clay test results!!

2.5, 2.7 PH is only good for one thing. Killing germs! He needs to bottle that stuff and sell as a disinfectant! Sorry to hear of his troubles. Here I thought my 6.5 PH was low! I guess I won't be upset about my PH anymore!!

That clay sounds like the waste product from Amus in the Star Trek Next Generation episode, "Skin of Evil".

Obviously I don't have a clue.......

Why wouldn't you have tested the clay before doing all the work? Since it is foreign to the norm that seems prudent to me.

There was no logical reason to think that it would be chemically different. It sits in a zone around 15-20 feet below natural ground level. Go 30-35 miles northwest and you get into the Blackland Prairie, where soil at the top looks exactly like this stuff. It's texture is a little bit different, but when I saw this clay, I immediately thought it looks similar to the Blackland Prairie, but that it was out of place.
The water has no odor at all. It's not even that rich, cobalt blue color that goes with water in the 3.5-4.5 pH we see in other parts of the state.
I'll follow through as the information unveils itself.

I look forward to learning more.

Is the lake also in Henderson County? Take a look through here and see if they mention an ultra acid substratum in whichever town it is...

http://soils.usda.gov/survey/online_surveys/texas/TX213/Henderson.pdf

It would be interesting to take some of the water in a jar, and see how much hydrated lime it takes to neutralize it.

What would be even more interesting is take a lump of my crushed limestone clay and mix it with the black clay and stand back. I would be willing to bet there would be a lot of heat involved, and who knows what byproducts (probably salts).

Sounds like you found old deposits from perhaps a long defunct natural sulfur spring or some other type of hot-spring. Who knows? Pretty cool for curiosity sake, but lousy for a pond. I really feel bad for the owner.

Am I missing something? Why is his well water at 4.11? Is that natural in texas?

Soils are acid in much of the south and so are the effected groundwaters. Not all by any means but many. The waters that flow through limestone formations are not.

If the acid clay is natural (not brought in or mine waste) then ag lime will work. If the clay is only a foot or two compacted then it should be an easy fix (10 tons of ag lime for the small pond). My concern would be if the clay has some other problematic constituent part.

Actually, this property is in northern Anderson County. I don't know the soil classification...or a name of it. Trying to read 137 pages of a soil survey and guess the right thing...give me a minute.

I am a chemical engineer and find this an interesting read. I would drop into the pharmacy and grab up some P.H. strip. Just fold it in a ball of that clay. Black should not be sulphur. More like nitric or phosphorus. It could be so green it looks black.

A cheap very fine highly available lime and is a waste product is kiln dust from a cement plant. Should get it for about $5 per tone and it has a P.H. of 11. You should get calcium nitrate, potassium nitrate, calcium phosphate, and potassium phosphate titrate out and sink to the bottom.

Ag lime calcium carbonate is the best for maintaining P.H. not dolomite lime with high magnesium content.

Keep us posted on clay content. You could have a high P.H. in the clay with a stronger covalent bond than the acid in the water and making the water P.H. spike. This would mean the P.H. rise is a gas and can be evaporated off.

Cheers Don.

Any news on this project? Very curious to what was found.

Bob, curiosity is killin' the cat!
How 'bout an update?

Ah, thanks for the reminder....
For this lake site, it's an interesting story I'll write about for future issues of Pond Boss, might even make a video about this project because there are so many elements to it.
Here's what we learned. As this 56 acre lake bed was excavated to build the dam, the earthmover came across a black dirt vein about 25 feet below natural ground level. He liked how it felt and moved with his dozer, so the team (landowner, contractor, executive assistant & engineer) had the soils tested for plasticity. Ended up being the most compactible soil any of them had ever seen. So, they excavated it and began to use it for the core of the dam for the lake. At the same time, the landowner wanted a smaller pond, which the contractor built. Keep in mind, that on any given day for this project there have been 6 scrapers, 2 bulldozers, an excavator, two water wagons,a sheepsfoot roller and a maintainer going all day, every day...so they can get lots of work done, fast.
When the new, small pond was finished, they lined it with about a foot of this fine "clay" and packed it with the sheepsfoot roller. Turned on the wells and about two weeks later, the pond was full. I put a few fish in it and they were dead the next day. I just thought we had mishandled the fish. As we tested further, and began to discover how low the pH was, we saw it slightly below 3.0. But, the pH wasn't actually accurately measured. The lowest the labs could go was 2.11. We think it was actually lower than that.
Here's what happened. That thick vein of black dirt was highly organic. It was full of sulfur and when contacted with water, the water reacted with the soil. We are pretty sure the Oxygen molecules in the water reacted with iron in this soil and oxidized it under water and the Hydrogen ions reacted with volatile sulfur in the soils to create sulfuric acid. There was no smell to the water at all. But, after the fact, we remembered a couple of contractors who were building a dock speak of their legs "burning and itching" when they were in the water.
We sent some of the soil to several labs for testing and the most confident of the engineers made educated guesses as what to do. They weren't totally sure because they couldn't determine the actual pH.
So, here's what we did.
By the time these tests were being run, we were building another pond and lining it with this "clay". After the clay was added in lifts, we added three tons of aglime per surface acre, tilled it in, compacted it and then added 12 inches of additional "neutral" soils on top of that.



This image shows the stuff being used to line a pond bottom.



This photo shows where the earthmovers stockpiled the black stuff to use later.


Well, back to the first pond. We amended it with aglime to raise the pH. That pond covers about four acres and it took almost 15 tons of lime to raise the pH to 7.0. By that time. the contractors had lined the basin of the 56 acre lake with the black clay, added aglime and then added another 12-18" of "normal" soils on top of that black stuff. We started pumping the water from the smaller pond into the big lake, once we knew the water was safe. It took about three weeks to get all the water out of that pond. The entire periphery and the bottom of that thing was orange, the color of oxidized iron, almost a rusty color. Then, the contractor moved all the existing black clay out of the pond bottom, replaced it with "new" black clay, limed it and then covered it up with nearby soils. The pond is now filling with well water.
The whole process has been expensive, but the landowner saw the necessity.
If it wasn't for losing a few nice fish, we might have figured out there was a problem...way too late. I can't imagine a 56 acre lake, with that black soil coating the bottom of it, filling with water and THEN figuring out there was a problem.

Take a look at this...if it works
This is a video I shot with my iPhone last week as the "old" black clay was being excavated and "new" black dirt was added. Then, they added the lime and coated the black stuff with nearby "normal" sandy soils. They pushed the black dirt up the sides of the pond, too.
Notice how rusty-red the slopes looked. This is the pond that started the whole issue. Here, it's been drained, most of the dirt excavated, new dirt brought in to line it. In this video, it's about three days away from being ready to fill with water. I'll shoot more video and photos next week when I'm on site.

Thanks for the update Bob - I am somewhat familiar with the geology of this area, having property on the other side of the Trinity River.
Both sulphur and iron are prevalent in our area and complicated by reworking of sediments by erosion and fill deposition.
very interesting - thanks.
George