We're looking for something cheaper and more permanent than a
There is no flow action and little wave action. Some seepage may be
The base to height can be 10:1 or more.
Local variables determine what will be the lowest cost solutuion.
Access to worksite, raw/reclaimed material characteristics, labor
costs, equipment costs, etc.
Hire a Local Engineer with dam building experience.
You'll need his seal & signature for the permits anyway.
I have some experience working with water in AZ.
Dirt dams can be as permanent as you want them to be.
Dirt is, well, dirt cheap. You don't have to worry about digging it
up if you can get it delivered. If you can't, you'll likely be using
the same equipment to build it that you'll need to excavate it with.
Tradeoff criteria are availability, budget, and so on. Shovels and
wheelbarrows are cheaper than cat tractors and semis but require more
What's this for; to keep water from going where you don't want it to
go, or to contain it for later use?
You say no flow; I take it that means no major penetrations.
Dam design is as much art as it is science. Start here:
They're diverting several hundred thousand acre feet/year from the
Salton Sea basin to San Diego. They can't save the entire lake so
they want to save part of it.
The current plan is a simple straight E-W dam for a large lake to the
north and a large brine basin to the south. Like many worthwhile
engineering projects it will be 100% useless until it is 100%
The problem here is future funding to complete the project is very
Why gamble what little money you have starting on something that will
never provide any benefit whatsoever until a tsunami of money comes
An incremental approach could start providing immediate relief.
Birds are happy with shallow water so a dam a few miles inside the
perimeter -- wherever it's less than a certain depth -- may be the
most cost effective way to get started.
Bite sized sections of a few square miles could be dammed off along
the perimeter with $3 million dredge using a tandem separator to dump
off the water before dumping the solids onto the sea floor.
Much of the original shoreline would be preserved. Eventually
evaporation would draw down the area inside of the dam to 10 - 40 feet
below the base of the dam. Brine could be dumped in this area near
the geo thermal plants.
If a lot of money comes in when the dam is half way around the lake
the project may be upgraded for larger lake sections, rocks for
protective barriers, etc.
Pipes or openings could be installed to connect the perimeter sections
but nothing that would disturb the earth dam during construction.
Near zero water movement.
Maybe no one has ever done anything with solids from a dredge funneled
directly onto a reservoir floor.
It may require a couple of strainers on both sides of the dumping area
to keep the fill from scattering too far off to the sides.
Completely stupid waste of time and money. The "sea" fills and
drains on its own every so often (for geological values of "often")
and is sitting squarely on the San Andreas fault.
In its current incarnation it's only 106 years old. Even the local
Native tribes don't remember it holding water before that.
The mere concept of "saving" any or all of it is a staggering
And 100% pointless. Also, unintended consequences?
Don't get me started on idiot enviros with no sense of history. If
the water goes away so will the birds, fish, etc. If the water comes
back so will the wildlife. That's why wildlife is called "wild". By
definition trying to manage it or its environment is a contradiction
Yeah, it's been done. The problem is getting the clay/silt : sand :
salts proportions right The salts are the important part; as the water
seeps into the dam structure the salts are dissolved and carried
deeper in. Eventually the concentration is too high to maintain
solubility and the salts deposit into what's called "caliche" or
hardpan, which is impermeable to water. The sand makes up the bulk and
the clay binds everything together.
Too much clay and it slumps, of course.
The salinity of the contained water is extremely critical as you can
imagine. If the water freshens (salt content drops) it will leach
salts out of the dam, weakening it. If it rises the caliche layer gets
thicker but less cohesive; IOW spongy. The only solution (pardon the
pun) is to make the dam thick enough to minimize the changes. This
cranks the costs way up though.
California is already broke. Damn fools.
Mark L. Fergerson
Do they use a gravity separator to dump the water off away from the
dam before dumping the solids onto the sea floor?
Do they use a retainer to keep the fill from washing away from the
The water from the dredge only has 30% higher concentration of salt
than sea water and most of that will be drained off. There will be no
solid salt in the dam during construction. After the drawdown and
drying solid salt would comprise a very small very dispersed % of the
Solid salt won't work if fish are the goal but a seep proof seal might
not be necessary anyway.