I was interested in rehabbing some sites on my property that were springs at one time. I have installed a few wells and have water to spare. I was wanting to seal these depressions and make them ponds available to wildlife. Is it feasible to scrape them down to mineral soil and seal them? The soil is clay and sand with not a native rock on the property. I have review some old aerial photos that show water in the bottoms of the depressions. In one area I have found pump equipment. I do have areas to route overflow. Thank you in advance.
A short answer to your question is yes. If there is clay, and you can get it to the proper consistency, you can use a sheepsfoot roller and get enough compaction to seal it. If you can't get it sealed, talk to teehjaeh57 here on the forum. He can walk you through the process of sealing the ponds.
If you are going to try DIY for your small ponds, then I highly recommend Mike Otto's book, Just Add Water. He is a pond builder and a contributor to the forum. (The book is available at Pond Boss for $36.) The book might save you from several possible expensive mistakes.
If you have good clay, then your plan should work.
You need to dig out the ponds about 12" deeper than your intended final depth. Stockpile your best sealing material.
Scarify (till) the bottom and sides as deeply as you can, then wet to optimum conditions and then compact with multiple runs. Spread a 6" lift from your stockpile over the bottom and sides, then repeat the wetting and compacting process.
Do that step one more time so that you have 12" of compacted material above your base level. That SHOULD hold water up to 10 feet deep.
One of my concerns is the trees growing in your depressions. When you remove them, you are going to have lots of remaining roots that will eventually decay and provide paths for future leaks. If you can grub out the trees with an excavator to get all of the roots up to 5' below your intended pond bottom, then I expect your ponds will seal much better over the long term.
Totally changing gears - if the springs are still viable, then you could create "groundwater" ponds in your depressions. If you can start scraping and find the sand/gravel layers that provide the spring water, then that can set the level of your pond. You would dig and seal the soil below the level of the spring (as discussed above). A good spring would keep your pond full to the "spring layer" most of the time. In a drought period, you could supplement with well water and bring the water level in your pond back up the spring level. However, you need to design your pond around the normal water level being equal to the spring level. Typically, if you add water above the spring level, then the spring just takes that water away.
If you think that is the situation for your potential ponds, then come back with more info after you have done some excavation tests. esshup actually has a groundwater pond at his place and could give some good advice on optimizing that type of pond.
Hi, Thank you all for the friendly replies. I do not have much run off from the area. During heavy rains the water seems to find pathways to sand. The area was recently glaciated. I am at 2300' but surrounded by steep mountains up to 9000'. My land is in an area of what appears to be glacial till. I have varying layers of clay and sand. I find many areas where water bubbles up from coarse sand channels over clay. I think that I could do groundwater ponds but they would be too deep and dry. It is almost as if I would need to seal any new ponds from the sand lenses where the water originated to rest on the clay.... Does that make sense? Ive thought about putting a perforated tank below the new ponds in ground water and pumping to the surface but I would like to avoid liners if possible.
I do have an excavator and a skid steer so I will be sure to remove the roots.... the big problem when having machines is putting a very viable plan in place before you start breaking ground!
I will put a photo below of an area that had a very shallow groundwater pond. I was thinking of digging the whole area out to build a pond but it had a better potential for a food plot. Funny thing, the whole area looked like it was a pond a few hundred years ago. Now it is mostly alders reaching for the shallow groundwater.
A few starter questions, do I need to tear up natural damns and key them?... and if I can leave the natural structures in place, can I just reinforce a spillway rather than tearing the natural structure to create an overflow? Both sites that I am selecting are naturally higher than surrounding land and receive no runoff. My goal is to work with the natural structures that are a part of the natural landscape the best that I can.
Its hard to visualize the topo from your original photo, but the ground appears to be fairly flat, almost like what we have here in the area called sink holes, some hold water, some don't, basically a hole in the rock substrate that drains into the aqua fir, if I understand it correctly. but I may be seeing it wrong.
All the really good ideas I've ever had came to me while I was milking a cow.
Glacial till creates very atypical geologic deposits.
Almost all of the soils and subsoils we are used to dealing with to create ponds were deposited by water, and therefore have some sorting of the different grain sizes into layers.
Glacial till composed of rock components trapped in ice can be deposited completely unsorted as the ice melts.
Of course, there are then water-deposited features such as eskers that are deposited from the glacial meltwaters. These typically form long, narrow ribbons of sand and gravel - which later become excellent conduits for transporting groundwater in the present day. (The wiki entry on eskers is decent.)
I predict the geology of your depressions will be difficult to predict!
In that case, experimentation might be an excellent option. If you are going to run water lines to your ponds anyway, why not run some lines now? Pump water to fill a few of the depressions and monitor the response.
Some depressions might be so simple that you can deepen and then seal one sand/gravel layer coming into the side of the depression and then have a pond that seals well.
On other depressions, you might have to scrape and seal the whole bottom and cut into the "natural" dam to get it sealed.
I am just throwing out ideas for you to consider, since your observations are going to drive the success of your projects.
P.S. If your excavator has not yet been put up for winter, you might try a few test trenches the next time you have it out for another job. If you are digging with no water down to 6', and your hole quickly starts showing water, then you know you have cut into a porous and permeable layer that is tied to your local groundwater.
If the hole fills up to the top, then you have a pretty good "spring" that might be used to your advantage. If it fills up 1' off the bottom, then that shows the approximate normal water level if you tried to create some groundwater ponds. (Which would probably be too low for your use.)
However, as others have said above, that water-bearing layer you just revealed will NOT operate like a one-way valve. It must be sealed for your idea of pumped water ponds.
^^^ True. Locally we have thick areas of sand - up to 50 feet thick according to NRCS. Move 7 miles East and you run into clay within a few feet of the surface. Move another 50 miles East and ponds can be dug and filled without any compaction - the clay could be used to make pottery.
Here it was 11 feet of yellow beach sand, 1 foot of gravel, 1 foot of clay then another 7 feet of the yellowish beach sand, another foot of gravel THEN we finally hit at least 3 feet of blue clay. Not enough clay to use to seal the pond though.
Thank you for the reply. My land is much like you have described. We've received a ton of snow so far - most of my projects are on hold until thaw. I think you are right about experimentation. I will reach out again when I get started.
During construction of your groundwater pond, was it easy for you to discern the layer of sediment that tied your pond site to the local groundwater?
Or was there so much sand and gravel that MOST of your subsoil profile was directly tied to the groundwater?
If the latter, then have you been there during the construction phases of some of your client's ponds and observed thinner discrete layers that tied to the groundwater?
(Such that a less experienced pond builder could obviously conclude what they needed to deal with to either seal the pond, or leave that layer open for a groundwater pond?)
Yes to all except the latter unless you consider the last 10"-12" of gravel directly above the clay one of the discrete layers. Depending on the amount of soil moisture, I've seen water coming through just the gravel layer above the clay, or even through the clay and 4'-5' of the sand layer above it, sloughing off into the pond as it is dug. In those instances, the two choices are 1) keep the sides sloped back 4:1 as you dig to help prevent sloughing off and ending up in the bottom of the pond or 2) don't worry about the sloughing off, just dig a deep sump pit off to the side and keep pumping the water out of it as the pond is constructed.
It's been so bad that we've had to float the intake screen for the pump on an innertube to keep the intake hose from filling up with sand and getting completely blocked off. That happened, and it was so heavy that we ripped it in half trying to pick it up with the excavator and a 4" wide nylon strap under the intake pipe. Lots of dirty words said and then it was a run to the store to get banjo fittings to connect the now two piece hose back together once we got it cleaned out.