It's incredibly fascinating! My contractor was dicsussing in very general terms today about land formations and how they occured over the thousands of years. It's also amazing to listen to water well contractors talk about the weird things that water can do underground.
This update pretty much finishes up the project. We dug and back filled a core ditch as I mentioned above. This would be on the NW corner by the emergency spillway. The contractor said he would guess the sand pocket was about 4-5 feet deep and about 30 feet long as I mentioned above. We then plated over it with about 2 feet of good clay soil and covered that whole area from the water line out about 50 feet, totally covering all the suspect area. We extended that 150 feet or more I would guess down that side of the cove.
Today we went to the opposite side where I hit all the sand with a probe in late summer. I predicted it would be a solid sand vein all the way. It wasn't. It had a layer of fine white sugar sand on top for 2-3 feet and then good red clay. I couldn't have asked for another better underneath. We didn't find one suspected trouble spot in maybe two hours of trenching. We trenched about 125 feet and stayed in red clay all the way. We went down 8-10-12 feet in some places and stayed in red clay. We also spot checked some other areas and always hit good hard red clay every where we went.
We also checked an old beaver run in the back of one cove that would be about two feet under the water line when the lake is full. I don't have a feeder stream coming in so the beavers did that a good while ago and left. The tunnel was fairly shallow and not much to it really, and even if it had led to a sand pocket the whole deal would have been too near the water line to have caused any significant seepage. We saw no evidence of that whatsoever. We excavated all of that and it just made a shallow circle and came back out. We dug all that out and packed it good with clay.
Other than the shallow coves I've now cored the rest of the lake's water line. We did some in 2008 so we were eliminating suspect areas even back then.
We rode around it and in it on four wheelers, walked where we could, and spent the morning doing this. We didn't miss a visible spot. No evidence of any seepage on the lake floor. No sink holes, no mysterious low places, no nothing like that.
I asked time and again if there was any other pre-caution I could take while he was there with the big equipment. He said I had done practically all I could do other than just drain it dry and plate the whole thing. We decided to let the dirt pan take some more dirt farther into the cove on the side where the sand pocket was, and that will make it a solid plating another 50-75 feet.
I've watched and thought for two days and I can't think of anything else either. I think I'm going to keep them there till noon tomorrow and we might haul more red clay to the bed of that cove, but when we dig in the cove we hit clay, so I just can't think of anything else we could try.
We calculated the water loss again. My well does 60 gpm which is 86,400 gallons per day. When I turn it off the lake seeps about half that rate until it gets to a certain point and then it stops. This stopping point appears to be at the bottom elevation of the sand pocket, about 6-8 feet below the water line when it's full. The lake drops about half as fast with the well off as it rises with well on. So, we figure 25,000 - 40,000+ gallons a day would have to be going somewhere, and my contractor says that the 5 x 30+ sand pocket could easily do that. He owns a huge sand pit in the neighboring county and has told me quite a few water and sand stories this week. Some of it is just baffling to think what water can do underground. The water is naturally running in that direction to the levee and he thinks it hits that pocket and then runs on into the hill and may hit a deeper pocket and just goes where it goes with no visible evidence within my property, which extends over half a mile to the highway.
So gentlemen, you are my witnesses. I have done everything humanly possible short of plating the whole lake bottom. I've researched, I've studied, I've consulted, and I hired the best dirt man I know and we both agree there's not much else to do but hope for the best. I turned my well back on today. I calculated that it takes around 7-8 million gallons to fill the lake, so it will be running for a while. I also noticed the last time I filled it from this low of a starting point that it also rises pretty fast till it hits that same elevation where we found the sand pocket and then the filling shows down dramatically. We knew the water elevation the lake naturally tends to settle at is a certain set point, and the bottom of the sand pocket we found is approximately at that elevation, within a few inches. I'm still so cautious as to claim a solution until I fill the lake that I'm still leaving open the possibility that it's something else. But if it is it's going to be so deep and complex that nothing short of a solid plating of clay would fix it. We spent a lot of time in the lake bottom and examined every square inch visually and tested probably 300 feet with trenching. The only suspected problem we found was that sand pocket. I hope we finally got it right.
I wanted to have a secondary project that I knew would work and improve things in general, regardless of what the lake does. We cleaned off a lot of brush and made the hills look really good. Now I have 3-4 acres I can plant for deer and have it right across from the center of the levee so I can see them. I took back at least 5 acres of land total just with brush clearing. We pushed all that into the lake bottom so now I've increased my underwater cover several times over.
We also hauled some more dirt to the backside of the levee and now I'll be able to mow more of it in the conventional way. I also got to haul more dirt to level out some ground behind the cabin where I can now put another shed or workshop if I want to, and we got rid of some dry land brush piles along the way. So, at least I'll have made some permanent improvements I can enjoy long term regardless of the lake and we were able to work most of this into the project. We had basically finished the lake project shortly after lunch so I had them fill out the rest of the afternoon with some of these long needed and long wanted improvements. If the rain holds off we might go till noon tomorrow to clear some fire lanes and take back some corners with a little light brush cleaning. Then it's going to be a long wait and see until the lake is full again around January, and then to see how well it holds on into July.
Thanks guys. I'll probably add to this as a later follow up, but it will be months before I know anything on the holding capacity. I hope I hope I come back in late July and say....It Held!
Thanks again...and PRAY that this works!
Bill
