yet another pond

OkeeDon · Oct 26, 2003

Like have_blue said, sand is an excellent filter. I'm not technical enough to know about mineral content, but, after ofver 30 years of observing Florida ponds in an empiri cal sense, I'm also not worried about it. I've never heard of a pond turning salty, so I supect what we have is just plain ol' water (which, of course, always has some mineral content).

Yes, the trees and such do love it. You can tell where there is often standing water or where the water table is very high for long periods - red maples, cypress, and other trees like to grow where there's a lot of water, and live oak, slash pine, etc., like it a bit dryer - maybe 6"-12" higher in elevation /forums/images/graemlins/grin.gif

As for septic fields, yes, the are very strict about that, but it's no an undue hazard. The minimum distance is 75'. I've got the pond about 100' from the approved location for the tank. and further than that for the drain field. It's just a standard old perforated pipe drainfield - the work exceptionally well here, again, because that sand is such an excellent filter.

Essentially, what they want you to have is about 18" to 30" minimum average distance for the waste to permeate before it hits the water table. In my case, my permit requires me to build up the elevation 9" above the current elevation, then lay the pipe on top of that and bury it - resulting in approximately a 3' or so mound. At the time they checked, they tried to take a core sample to about 6', but they hit water at about 32".

They know longer do perc tests in my area - they just take a core sample, look to see what kind of soil is there (sand is good, hard pan is bad), and they'll know from there how it will percolate.

OkeeDon · Oct 26, 2003

Oops. almost forgot, you also asked about pumps. Nope, no pumps. They just stick the bucket down into the water and when it hits something farly solid, they scoop it up. Above the water line, they're pretty concerned about getting the slope the way they want it. Below the water line, it's no as important. Since it's all sand, even if they dig straight dow to 16', is a short time it will have sloped sides and be 12' deep. Sand will take the shape they want.

Another issue is that hardpan. Hardpan is basically soil (in this case sand) which has become cemented together with calcium carbonate. When it's wet, the calcium dissolves and it's no longer hard. It's a lot easier to dig when it's wet. When we're digging a hole by hand, to plant a tree, for example, and we hit hardpan, we fill the hole with water, then resume digging when the hardpan is no longer hard.

OkeeDon · Oct 26, 2003

The sand is mostly coral and limestone, (right Don?) 

Yep. And the "rich source of calcium" is also what causes hardpan.

 I think your sand is from ancient meandering river, right? 

Actually, I think it's more because all of Florida was under the sea not all that long ago (in the grand scheme of things). I'm no geologist, but it sure looks like beach sand to me. The limestone was essentially formed from shells and coral. I've often mentioned shell rock, which is what we use instead of gravel. I need to take a close-up picture of the shell rock on my entrance driveway. It actually has fully-formed sea shells in it, such as mollusk shells up to 6" and 8" long. It came from a pit about 3 miles from my property, in pretty much in the central area of the state, and about 65' or so feet down.

have_blue · Oct 26, 2003

Don, I meant Jim's sand was probably from rivers. I know yours is from the ocean. /forums/images/graemlins/smile.gif

Please keep us posted. That'll have to do me, because work stopped on my pond yesterday. That's because we got 3" of rain. That's a day of pumping with a 3.5hp pump plus 4 days to dry out. /forums/images/graemlins/frown.gif

OkeeDon · Oct 26, 2003

I meant Jim's sand was probably from rivers. 

Oops. Well, it was late at night and I was prone to misinterpreting. Your comment not ony makes sense, now, it also clears up a minor mystery - I wondered how Jim could have streaks of sand.

jinman · Oct 26, 2003

have-blue: ( I think your sand is from ancient meandering river, right? )

I can't figure out where that river used to run...NOT! /forums/images/graemlins/laugh.gif (see attachment)

have_blue · Oct 26, 2003

( I can't figure out where that river used to run.../quote]

Uh huh! /forums/images/graemlins/wink.gif

bmac · Oct 26, 2003

Don,
I have certainly enjoyed your photographic and narrative documentation of this project. The transformation of your property from the native state to this point is amazing to me.

One question about your pond: I am familiar with the high water table in Florida and am not surprised to see your pond filling spontaneously as you dig. However, I am curious what keeps the water level up once the pond is filled above the level of the water table. It seems to me that any water pumped in from a well would seep through the sand almost as fast as you pump it in. Obviously, with the research you have done, this is not the case (or is it?). Will your pump run daily (or several times a day) in order to keep the pond at the desired level? Short of this, I am having a difficult time understanding how your hole will hold water.

Again, thanks for taking the time to share this adventure with us.

Bruce

Taylortractornut · Oct 26, 2003

One thing here that amazes me in the old limestone quarries here that when they flood after being abandoned they have a nice blue color. We have 2 types of gravel red clay gravel and ponds with deposits turn a clear green and the sandy gravel turns ponds a blue green.
In Alabama on the Tennessee river whe hit a spring in the bank that was in the limestone rock. We had a Coffer dam we built to alk and excavator and track drills on. we had to cut a trench in it to run an Intake pipe to the treatment plant. Where the spring was in the coffer dam you could see the bottom and even a streak in the river at the end of the pipe the water was very clear.
As for the under water digging that can be a pain especially trying to hold a grade. Dad worked on a job where they used Hydraulic excavation to make a port they dug a 6 acre lake and flooded it next to a river then used a hydraulic dredge to pum the sediment to a lage pond they dug and made levees. When they got the right grade they dug out the coffer dams and had a port. Later that year they used the now sollid dirt pond for fill to build a highway road bed. I cant remember the yardag but it was around a couple million yards.

OkeeDon · Oct 27, 2003

However, I am curious what keeps the water level up once the pond is filled above the level of the water table. It seems to me that any water pumped in from a well would seep through the sand almost as fast as you pump it in. Obviously, with the research you have done, this is not the case (or is it?). Will your pump run daily (or several times a day) in order to keep the pond at the desired level? Short of this, I am having a difficult time understanding how your hole will hold water. 

Good question. I'm not sure I know the technical answer. One of my frustrations has been that I like to know how things work, and it's really difficult to find information about this type of pond. My guess is that it just works, and all the good ol' boys know it works, so they don't bother to explain it - at least in any accessible internet site I've been able to find.

Here's my best guess. First of all, the level of the pond will never be below the level of the water table, and the water table never gets lower than the pond itself, as long as the pond is 6' deep or so. So, it doesn't "drain" out. Second, it seems to me that water would rather be in an open area than filtering through the sand, so it tends to find its way to the pond and mostly stay there. That's a seriously unscientific guess. All I know for sure is that my daughter and son-in-law next door have a small pond, not particularly well designed and not very imaginative (it's just a basic oval about 90' x 70'), and the water level in their pond is always a little higher than the water table itself. My pond is about 600' away and the substrata doesn't change; we hit water at about 6', but the level in their pond is down about 4' right now. Maybe someone with a knowledge of hydrodynamics can explain it.

Finally, we do plan to keep the level in our pond constant, rather than let it vary with the water table. I can only give a broad description of this technique right now. We won't be implemeting it until the well and electricity is installed, and that can't be until after we pull a building permit, under our local codes. Basically, once I explained to my water guy what I wanted to do (supply water to the house, the barn, the pond, to an RV location for friends, to a hookup for my own RV, and to several locations on the property for irrigation), he said that he would install a 4" well with a submerged pump that would supply enough water for a small village (probably a slight exxageration on his part). He will also supply a float switch of some sort that will activate a valve, probably some sort of solenoid, that will replenish the pond until the float switch turns it off again. I've done some rough calculations based on how quickly my kids' pond can drop in a dry spell, and I suspect it may run for several hours every day in some seasons. I expect fairly serious loss (down to the natural level) in dry times. It will seep out through the sides of the pnd above the water level. Of course, it will jut settle back in and replenish the water table, so it isn't exactly going to waste.

At first, I was distubed by the expense of running a pump that long, but then, I compared it to the expense of running a pool circulation pump, which I have been doing for over 20 years. The pool pump runs 6 to 8 hours every day (all year round, in Florida) and doesn't break the bank, so I decided I could afford the pond pump expense. We'll also be running a small, separate pump to create an aeration fountain in the center of the pond. I was going to use an air stone for aeration, but the CFO really wants a pretty spray. If I get ambitious, I'll probably install some sort of light on the spray.

Keeping the pond at a constant level is really important from a mosquito control point of view, as it is changing water levels which hatch the pests. My real concern is not loss of water, but the potential of pond overflow when the rains fall in earnest. Without level control, the pond is usually lowest when the rains start. With the pond at a high level when the rains come, it is subject to flooding. I'm going to take two steps to avoid that. First, I'm going to build a low mound all around the pond, giving it just a little more room before it floods, and preventing any flooding of the surrounding area from flowing into the pond. There will be some runoff into the pond, as the land around the house will be even higher than the pond, and will slope to it. Second, I'm going to install a primitive standpipe in the pond that will direct overflow through the pipe and out into the drainage swale along the highway. This won't protect me against serious flooding caused by a hurricane-driven rainfall, but nothing can protect me against that, and the pond will prevent it from being as bad as it could be.

There's a certain amount of hope and faith in all of the above - the good ol' boys all assure me that it will work as I intend, and all I know is that anything will be better than what we had in the past several months. The only alternative would be to truck in enough fill to raise the entire property. The pond is a cheaper alternative that also happens to add aesthetic and monetary value to the property.

The contractor is also going to swing over to my kids' property next door and reshape their pond before he leaves. It has nearly vertical banks and is impossible to maintain (it was like that when they bought the place). He's going to reslope the banks, drag it to clean it out, and reshape a portion of the banks to a more appealing shape. They have a line of oak trees alongside their driveway that will prevent the excavator from working on that side of the pond, so the long boom of the excavator will actually be used to scoop dirt from the near side of the pond and "throw" it across to build up the far side to a more gradual slope. Should be interesting.