Homemade hydro excavator?

I recently stumbled onto a website that sold a special hose and powerhead that allowed a typical pressure washer to be used as a sewer jetter (unclogging sewer lines).  I was blown away.  So simple.  Pure genius.

Then it occurred to me:  

A standard pressure washer could be used as part of homemade hydro excavator -- a digging tool that liquefies soil and removes it with a vacuum.  These machines can excavate around pipes without damage and make surgical-style incisions in the earth. Very precise. Very fast.  Factory made hydro excavators are *very* expensive and they typically rent for $350.00+ per day.  

To turn a pressure washer into a hydro excavator, you'd need an economical homebuilt vacuum tank to suck up the liquefied soil and a vacuum hose attachment for the wand.  The excavated liquefied soil is very heavy -- so weight considerations and spoil removal are engineering issues to work on.

So ..... anyone know how to build an economical vacuum tank?  






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I've seen this done with a kind of jet pump, so you don't need a vacuum tank, you just need a 100 CFM compressor @ 100 PSI

Steve
eric1967 (author)  steveastrouk5 years ago
Know of anywhere I could view a schematic or diagram??
I think it was made by a company called MBW ?
Perhaps periodically injecting blasts of high pressure air down the hose would help force the waste material out of the hole, although if you have sufficient flow to be effectively cutting, waste removal by shouldn't be an issue without a vacuum system.
eric1967 (author)  The Skinnerz5 years ago
A 3500-4000 PSI pressure washer has enough power to liquefy and dislodge the soil, but it's necessary to "slurp" up the liquefied soil to remove it from the area in a neat way. Hydro digging can dig up huge volumes of soil in a very short time.

The real engineering here would be to build an economical high-CFM wheeled tank for the spoil (liquefied soil) and an easy method of dumping it when full. For a home unit, maybe a tank holding 4 or 5 cubic foot would do......


ilpug5 years ago
Well, depending on how liquified the soil was and how much dirt you planned to dig, you could use a water pump wit ha tank in the line before it reaches the pump, or see if you can't find an old macerating pump unit online. I reccomend just asking around any junkyards or industrial areas. often, things like that are lying around going to waste in industrial lots.