Here's the updated story as it applies to this project.
Two ponds, Neighbors Pond (NP) and Long Pond (LP), surface elevation in Mar 2019 were 5' different - Neighbor pond was 5' lower than LP.
When the dam blew out of NP, it dropped NP level by about 10', LP by about 7'. Also in a 4-5 month period since NP dam failure another pond Figure8 Pond (F8P) water level dropped by 6' as well - it is about 120' from LP. In the Mar 2019 GOOGLE EARTH surface elevation, or height above MSL, of F8P it was the exact same height above MSL as LP so this activity 'should' fix both ponds water level issues. We are debating on raising the water level in Long Pond by 1' or 12" with the new overflow in Long Pond keeping the MSL surface height of both LP and F8P constant, they might go below the overflow in drought but will not go above that height which might have contributed to the cascading failure.
The plan changed over the last year in a couple key areas:
- Creating an overflow to the East of LP instead of through the highwall seep
- Creating a overflow on NP to regulate the height and prevent another catastrophic failure
- Closing and packing the seep with plug material including bentonite + 2' thick clay layer above and below the identified seep and 30' laterally
- Using Beaver resistant overflows to mitigate the ponds height rising and flows across the dams
My neighbor had a strip mine pond that didn't have an overflow, the water just ran over the berm of the "dam" which was a road used when the area was stripped in the late 40's 50's. Then reused as a forestry timber road since... O/A April 2019 the water flowing over the berm had cut through the berm enough to become a catastrophic flow and cut the berm about 20' wide and 12' deep (yellow X)losing the retention pressure and allowing the seep thru the highwall to flow unabated (red dots and arrow). The aqua dot and arrows are the new overflows to manage the surface heights of NP and LP.
Went thru Pond Boss and some other forums to review ideas and get some new ideas on how to attack this problem. Got several recommendations on a Amish pond/lake builder and had him out in Mar 20 to get a perspective on how to attack the problem (he'll be referred to as the Contractor) and he wasn't positive on just trying to fix the problem on my land. Talked it over with the neighbor and we agreed to have the contractor out again and look at the catastrophic failure on his berm.
We all met in early June walked the berm and reviewed where to get fill etc to fix that NP problem and perhaps raise the NP level 12"-18" on his side. We all shook hands and walked away from the problem with a positive sense that we could not only fix this mess but improve the outcome, add preventative measures so that it doesn't happen again and improve the quality and accessibility of both ponds.
I talked with the contractor this AM and should have a quote by the end of the week. Tentative start date on the project will be the first week of August starting with the work on the LP side, creating an overflow from Long pond to the natural fall line on my property to the East/SouthEast.
I'll be updating this thread (if) the quote comes in as expected and we move forward. Taking a knee and saying a lil' prayer that this will go as planned and the issues that can be mitigated are being done.
If it works as planned, then I'll revisit the re-stocking plan for the fishery in LP and F8P.
Asking for folks to red team this, this is a one chance, expensive endeavor so all observations are encouraged.
Looking to get a cement truck out with boom like you pour a foundation. or Oil and Gas crew with the mud/cement they plug wells with,
Plug the NP side with couple bags of quickcrete and shoot the slurry into the LP void side to plug +130' with hydraulic cement figure .75' opening 150' long at the outside Volume = π×.752×150 = 265.1 feet3 =~ 10 cubic yards of cement if it flows proper thru the void. let that harden and cap the LP side with a large patch of bentonite. Cover the whole thing with 2' of clay top to bottom and 30' to the sides.
So if everything works out, dam redone in NP, plug works in LP we'll have to drain the rest of the water out of LP to do the work in LP. So the amount of rain water to replenish that pond is based off the surface area that drains into it(531,000sqft)/a permeability ratio, /1000(sq ft) X 620 (1' of rain in 1000sqft = 620 gallons of water or .62 gallons/sqft) in an impermeable surface...
The figures for the touched-up i.e., completed LP are avg 11' deep, 65' wide, 1100' long = 5,875,155.00 us gallons.
With no "permeability" 1" of rain in the LP watershed would produce 531,000 x .62 = 329,220 gallons. or ~ 5.6% of the LP volume.
OH gets on avg 40" of rain a year so 40" x 5.6% = 336% of LP volume with no loss/ permeability so it'll take, most likely ~ 1 -> 1.5 years to fill LP to the overflow or 224% - 240% of LP water volume with loss and permeability.
1) Has anyone used hydro cement or a Oil/Gas to fill a rock fissure?
2) I assume the pH will be off as the new water fills the void to the overflow. What's the best method tocheck and correct lime in a ~7.5 million gallon pond?
Thanks - we're looking at starting work at he end of July and should take two weeks to have both ponds dammed and overflows installed. All observations are encouraged and appreciated.