I have some ponds located in Western New York. Starting in about May, the water in the ponds starts to drop due to evaporation, and probably some wicking into the banks, and also maybe due to the water table dropping. By about August, the ponds are generally 18-24 in below the normal level at springtime. I wanted to dig a well, to run a pump to keep the ponds topped off and as close to the springtime level as possible. The total surface area of the ponds at springtime is about 1.33 acres. When it is really dry out, I can lose about 1 in of pond level per day. So I decided that I needed a well that could supply (1.33 acres x 1 in deep = 8342611 in^2 * 1 in = 8342611 in^3 = 36,115 gallons/24 hrs = 1,505 gal/hr = 25 GPM)
I did some reading and noticed that a single shallow well is probably not going to be able to supply that.
I decided to go ahead and dig the well, and see what kind of flow rate I got.
The well idea was one from a co-worker. 2 vertical 10 ft lengths of 4 in PVC with a T at the end, and 2 more 10 ft lengths of horizontal 4 in PVC with slots cut in the sides and caps on the ends.
The idea was to dig a trench 18 ft deep, place the T in the bottom of the trench and cover with stone.
It sounded like a good well plan, so I tried it.
It was a disaster. Let me explain the strata. Since I dug the ponds, I know the layers of soil I was going to be dealing with.
First 7.5 ft is sandy loam.
Next 2.0 ft is red silt clay.
Next 5.5 ft is blue-gray silt loam clay.
At 15 ft, glacial till, which consists of extremely hard & dense red clay that crumbles like concrete, mixed with tailings sized rocks up to 3-4 ft diameter boulders. All these are rounded stones, as this was the bottom of the ancient Great Lakes.
I've never been able to dig any farther than that, I can usually go to 18 ft with my excavator, but the glacial till is very hard to make any progress through it.
I knew I'd hit water at about 12 ft.
The nightmare was basically, the soil strata does not really allow for a trench that deep, the sides kept caving in on me, so I tried to step the trench a bit, even then, the sandy loam just kept giving-way and falling in the trench. I got the PVC T-assembly in the trench the first time, and as soon as I did, boom, a huge section of sandy loam caved in on one of the 10 ft sections of slotted pipe. So I yanked out the assembly, re-dug the trench, and in the process lost that one section of PVC. So I decided I'd cut the one 10 ft length in half, and make shorter handles on the "T". That was easier to manage. Had the trench cleared out, put in the PVC T-assembly, but before I could get any stone on it, about 3-4 ft of each end of the handles got covered in falling sandy loam, I was able to get stone on the rest of it.
Here are some pictures:
http://www.infinity-universe.com/~dev/WhiteDwarf/Projects/Well/
So in the end, I ended up with a "T" well casing 17 ft below grade, and a water table 11 ft below grade, so basically 6 ft of water from the bottom of the 4 in PVC T-fitting.
I bought some 1-1/4 in PVC and fittings, and a foot valve from Home Depot. I then purchased a cheapo Chinese hand pump from TSC. The foot valve has a short screen, the holes are maybe 1/16 in diameter. I only have the foot valve 14 ft deep, when I went to put in the 1-1/4 in PVC, the 4 in PVC was filled with sand about 3 ft high. All that sandy loam that caved in on my T-handles clogged the casing.
I am able to pump water, but it is just muddy and so full of sand, I think I will destroy that Chinese hand pump soon... I don't really know how to measure GPM, but it seems like I can only hand pump about 2-3 GPM, if I go any faster, I can hear the foot valce sucking air.
So, after all that crap, should I have just used a driven well point? I know there will be ZERO obstructions from grade down to 15 ft. I also know that the water table is currently at 11 ft, however, in August it is at its lowest, so not sure how much farther it can drop. In the spring, the water table is only about 5 ft below grade.
So, I need 25 GPM, and knowing the strata I described, what is the best way to go? Multiple driven sandpoints? If I used multiple wellpoints, is there a minimum distance between them? Can I gang them together and run just one pump?
I did some reading and noticed that a single shallow well is probably not going to be able to supply that.
I decided to go ahead and dig the well, and see what kind of flow rate I got.
The well idea was one from a co-worker. 2 vertical 10 ft lengths of 4 in PVC with a T at the end, and 2 more 10 ft lengths of horizontal 4 in PVC with slots cut in the sides and caps on the ends.
The idea was to dig a trench 18 ft deep, place the T in the bottom of the trench and cover with stone.
It sounded like a good well plan, so I tried it.
It was a disaster. Let me explain the strata. Since I dug the ponds, I know the layers of soil I was going to be dealing with.
First 7.5 ft is sandy loam.
Next 2.0 ft is red silt clay.
Next 5.5 ft is blue-gray silt loam clay.
At 15 ft, glacial till, which consists of extremely hard & dense red clay that crumbles like concrete, mixed with tailings sized rocks up to 3-4 ft diameter boulders. All these are rounded stones, as this was the bottom of the ancient Great Lakes.
I've never been able to dig any farther than that, I can usually go to 18 ft with my excavator, but the glacial till is very hard to make any progress through it.
I knew I'd hit water at about 12 ft.
The nightmare was basically, the soil strata does not really allow for a trench that deep, the sides kept caving in on me, so I tried to step the trench a bit, even then, the sandy loam just kept giving-way and falling in the trench. I got the PVC T-assembly in the trench the first time, and as soon as I did, boom, a huge section of sandy loam caved in on one of the 10 ft sections of slotted pipe. So I yanked out the assembly, re-dug the trench, and in the process lost that one section of PVC. So I decided I'd cut the one 10 ft length in half, and make shorter handles on the "T". That was easier to manage. Had the trench cleared out, put in the PVC T-assembly, but before I could get any stone on it, about 3-4 ft of each end of the handles got covered in falling sandy loam, I was able to get stone on the rest of it.
Here are some pictures:
http://www.infinity-universe.com/~dev/WhiteDwarf/Projects/Well/
So in the end, I ended up with a "T" well casing 17 ft below grade, and a water table 11 ft below grade, so basically 6 ft of water from the bottom of the 4 in PVC T-fitting.
I bought some 1-1/4 in PVC and fittings, and a foot valve from Home Depot. I then purchased a cheapo Chinese hand pump from TSC. The foot valve has a short screen, the holes are maybe 1/16 in diameter. I only have the foot valve 14 ft deep, when I went to put in the 1-1/4 in PVC, the 4 in PVC was filled with sand about 3 ft high. All that sandy loam that caved in on my T-handles clogged the casing.
I am able to pump water, but it is just muddy and so full of sand, I think I will destroy that Chinese hand pump soon... I don't really know how to measure GPM, but it seems like I can only hand pump about 2-3 GPM, if I go any faster, I can hear the foot valce sucking air.
So, after all that crap, should I have just used a driven well point? I know there will be ZERO obstructions from grade down to 15 ft. I also know that the water table is currently at 11 ft, however, in August it is at its lowest, so not sure how much farther it can drop. In the spring, the water table is only about 5 ft below grade.
So, I need 25 GPM, and knowing the strata I described, what is the best way to go? Multiple driven sandpoints? If I used multiple wellpoints, is there a minimum distance between them? Can I gang them together and run just one pump?
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