Pond Boss Forums POND CONSTRUCTION Soil questions Spring??? Yes or no.

I've been taking advantage of the dry weather to build a five acre fishing lake on my land. Mostly I'm digging down the bottom as deep as I can.

Along the edge of my shorline I have one strong spring at the surface. I built up the edges of it to hold in the water while digging. Further down the shoreline I found somehthing a little differet.

I've removed about six feet of soil and the next layer of clay is very dark and just like jello. Very squishy and jiggly.

The next day there was surface water, but not allot.

It was too scary for my dozer, so I used my backhoe to dig it out some. Most of the area I went down 4 feet.

In one corner I maxed out my digging depth and went 12 feet. The last 2 feet or so I hit gravel. It's small gravele, but lots of it. I don't have much rock on my land, but there are a few pockets of iron ore.

This hole is 12 feet deep and it had just a small amount of water at the bottome when I left.

Then next morning thre was 8 feet of water in that hole, but none in the rest of the 4 foot sections of the hole.

This morning, the water had come up another 6 inches and covererd the entrire floor.

My question is wether this is a spring or a drain?

If there's five acres of water, six feet deep on this, could it turn into a drain?

Is there a good chance that the spings are currently below normal levels due to the drought?

If somebody can explain how to post pics, I have some to share.

Eddie

Congratulations on your project. I will let some others help with the springs that have more experience with them. For the photos, you need some space on a server to hold your pictures. Most ISP's (internet service providers or who you pay monthly to provide your internet) will give you free space if you let them know that you need it. Most of the people use photobucket or some commercial server. Then you need a FTP (file transfer protocol)program to move the photos from your computer to the server area, where they will be stored so that the public has access. Here is some information on FTP:

http://www-medlib.med.utah.edu/netbasics/ib1195.html

They will then have a web address or a url like this one:

http://www.thejump.net/fishing/2-fish-6/80-pound-flathead.jpg

Then you need to surround the address in your post with [,IMG]yourURLaddressforphoto[,/IMG] (remove commas) and it will show up like this:


Now that is a trophy flathead!

Eddie,
We are also in the midst of a pond project, and when we purchased our property there was a small (150' dia) dish of water within the proposed site. The realtor and owner told me that it was spring pond...I maintained reservations to the accuracy of their belief, but nonetheless considered it may be correct. I talked with 2 different NRCS offices that I had made acquaintance with during my regional search for the right property, and they both had the same response regarding springs. Basically, a spring passage letting water in can reverse and let it out. The chances increase as the head pressure (created by depth of water) increases. They said that springs near the dam are the largest offender. All that being said, they also indicated that, more times than not, springs don't reverse. If you are experiencing radical changes in water depth based on a spring, it may not be good. The rest of the PB guys with more practical experience can kick in guidance instuctions.
Regarding the squishy soil and some gravel, look out! That doesn't bode well. You definitely want professional oversight.

Boy, do I have some practical experience here. I had a small marshy area back when it used to rain. I got a dozer in, dug it out and had a great little forage pond. Then, the droughts hit and it dried up. Except for a perennial wet spot. So, I got a backhoe and dug out the spring and created a drain. Wasn't that a great idea? I have recently brought in a bunch of bentonite for the bottom and am in the process of covering the bottom with clay. Hope it works. Essentially, the head pressure has reversed and I'm screwed. Since it is directly upstream from my main 1 acre pond, I have to take action.

My thinking is that a spring is nothing more than an aquifer, water bearing sand, with an outlet. That outlet can turn into an intake when the groundwater level changes or drops. The situation you are describing would scare the dickens out of me.

Eddie,

Some additional reading for you.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=20;t=002005

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=2;t=000094

Eddie,

If you read the links that Russ so considerately posted, you will see a similar situation to yours which was posed by ETW.

It really is a good news bad news joke to hit a spring. Someone mentioned above that according to the NRCS, "more times than not, they do not reverse". That isn't very good odds in my opinion...in fact just over 50/50. My own policy is to cover all springs with at least 2 feet of clay. I have not hit one as extensive as you described with gravel, but have seen many in the process of pond building and always cover them.

It might be worth your trouble to bring in a civil engineer to have a look at your situation. In the absense of an engineering evaluation, my advice is to mitigate your risks and cover it up.

Russ, thanks for the links. They are very informative.

The water keeps rising in the hole. Lots and lots of water, and here we are in the second driest year on record.

It wouldn't take much to seal it, and that sounds like the smart thing to do, but for now I want to see how much water comes out of the hole.

Thanks,
Eddie

Many people confuse springs with groundwater. Most folks assume that if they dig and see water they've hit a spring. More often than not, they've dug into the water table. If the water runs into a hole quickly thru a sandy layer or lense, the greater the impression of having hit a spring. People often dig into clay and assume that the water table is deep because they don't see water running into the hole. Often the water is there but it takes a long time to flow into the hole due to the slow permeability of the clay. Under these conditions, it can take days (or weeks) for the water viewed in a hole to reach equilibrium with the surrounding "spring" or water table.

Springs, specifically contact springs, are the result of a water bearing soil layer overriding an impermeable (or nearly so) layer of densely packed loamy thru clayey material or bedrock. Other springs are formed where a fracture in water bearing fractured rock comes to or close to the surface at an elevation below the top of the water held in the rock. The easiest way to differentiate between a spring and groundwater is that a spring is under head and generally overlies an unsaturated layer. Where the edge of the slowly permeable layer comes near the surface, as on a slope, that is where you see the contact spring seep.

Whether a spring or perched groundwater, if you excavate thru the layer that perches the water or that the spring is flowing on top of, you may create a drain. That is where a good set of borings that stop above a clay or rock layer as well as some that penetrate is helpful to see what is really going on. If the level of water is higher in holes above the clay/rock than in those that penetrate it, chances are that you will create a drain if you penetrate or remove the clay/rock layer. You could realistically expect a spring to fill a pond up to the level that it stands in the borehole provided that everything below and the dam is sealed sufficiently and the flow rate of the spring offsets the evaporation and leakage loss. Apply more water (head) than you see in the borehole, and the spring will reverse and seek a lower point elsewhere to surface. Just to complicate things a little more, some soils can have a contact spring or perched groundwater that overlies the true (apparent) water table separated by a few inches or many feet.

Hope this makes some sense. Sometimes it is very difficult to really understand the hydrology of a site. All you really have to remember is that water flows from high head to low head and the rest sometimes falls into place or begins to make sense.

Great post! I'm saving that one.

We could get Dirtguy and Steve Young together and tape record a conversation and you'd end up with a really good college textbook.

Dirtguy,

If I understand you, it sounds like I've dug into the water table, not a spring. If the water table is high enough, than it will fill my lake. If it is lower, than my lake will never fill and only rise to the level of the water table.

There are two areas that I have surface water. This one at the bottom of my lake site, and another that is just below my shore line in an area that is very wet and extremly scary for my to drive my dozer. This other area was what led me to build the lake here in the first place. The bottom one was some thing that I found after removing the dirt above it.

My thinking, which very well may be flawed, is that since there is one area with surface water near the height of where I want the lake to be when full, that the water table must be at that level also.

To follow through with this thought, I'm thinking that I should dig some test holes above my shoreline on the side of the hill down fairly deep, but only as wide as the backhoe bucket. Then monitor them to see if they fill to the level I'm looking for.

Does this make sence? Am I being stuborn and ignoring good advice, or is there a chance I don't have to fill in the hole in the bottom of my lake?

Eddie

Eddie,

I'm not sure I understand you correctly. If you have "apparent" groundwater, the water level should be at similar depths at different holes around your pond. The "squishy area" may very well be a contact spring. Remember, you can have several things going on, one above the other.

You referred to hitting a layer of gravel and seeing the water level rise overnight but not seeing water in "the rest of the 4' sections of the hole". Do you mean that the water rose higher than the bottom of the other adjacent holes that didn't penetrate into the gravel or that the other holes just weren't deep enough to intercept the water? If the former, the water in the gravel may be under "head" due to an inclined orientation and an overlying clayey or confining layer.

I think you are on the right track in digging a few holes around the perimeter of the pond and letting the water come to equilibrium for a few days. If you can get access to a hand auger and a few extensions, you can bore a hole, drop in a piece of pvc pipe, add a little gravel around the bottom, and backfill the hole around the pipe back to the surface to make a rough version of a piezometer. Open holes can fill w/ rainwater and seal due to siltation giving the impression of having groundwater when there is none. Just be aware of going thru layers of clay and into something like sand and gravel. In that case you'd want a hole into but not thru the clay and a separate hole thru the clay and into the gravel (nested piezometers). Depending on what you see, you could be looking at perched groundwater above the clay, water in the gravel under artesian pressure, or both. Is there much relief in your area or is it relatively flat?