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  • From: "Lawrence F. London, Jr." <lflj@intrex.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: [permaculture] Re: rock dust - questions to ask a supplier
  • Date: Sat, 21 Feb 2009 12:16:08 -0500

=https://lists.ibiblio.org/sympa/arc/permaculture/2009-February/032806.html
=[permaculture] rock dust - questions to ask a supplier
=Wendy S. Yu creeksinger at hotmail.com
=Fri Feb 20 22:30:08 EST 2009
=
=Hi everyone who's been weighing in on the rock dust discussion. I have found a local quarry (two actually, run by the =same company) and have received the following information from them:
=
=They produce dust from "crushing aggregates that are typically used to produce Hot Mix Asphalt." They provided =gradation information that indicated I could obtain the following:
=
= Sieve Size
= Percent Passing
= Granite Specification
=
= 75 µm (No. 200)
= 10
= 5 - 15

=The size looks right according to what I've read, but what do I need to ask them re: what kinds of rock makes up the =mix? Somewhere I had come across something that warned against something used in ReadyMix, but if I recall correctly =that mostly had to do with size. Yes?
=
=Is there anything I need to be aware of in terms of what kind of rock makes up their aggregate? Or am I pretty much ok =if I find out that this is just your average river rock? (if there is such a thing as average river rock)
=
=I suppose a basic question is going to be what a minimum order is (and then I'll have to find a truck to borrow and a =lot of other gardeners to share with if it's one ton!).

They offer products to sell at going market price. Screenings are what is used in asphalt and that has too large a particle size to be practical as garden soil amendment.

What you want is called "siltation pond fines" or rock dust. This is a byproduct that is dredged periodically from their siltation ponds and trucked to a dumped onto huge berms that surround their quarries. This a product they cannot sell
as only gardeners, landscape contractors, home owner-builders and farmers have any use for it and only in limited quantities at that. That give this material away usually and may or may not charge for loading it onto yours or a trucker's vehicle. Read: FREE. This is the only product they make that you will want to apply to your garden.

The crusher reduces rock size down to meet specs for all the products they
sell. Screenings are used in blacktop;
#67 is used to surface driveways and for fill within forms when pouring concrete slabs; other grades are used in making ready mix concrete; a mixture of sizes is used to make ABC or crusher run, used in road and driveway construction.
Water is used in great quantities to wash to rock being processed in the crusher. This is where the dust comes from. It is carried away from the crusher in trenches or pipes to be dumped into the siltation ponds or chained lagoons. Over time the silt builds up reducing the holding capacity of the ponds so then they dredge them and deposit the wet rock dust in piles to dry out awaiting disposal on the aforementioned berms or in piles or to be hauled offsite to a farm or jobsite.

What you want to do is call a local trucker and ask him to go to the quarry you choose and pick up a load of "siltation pond fines". As truckers use no less than tandem axle trucks these days you will get best dollar value if you have him haul a full capacity load to your site. This means up to 20 tons or less. The price for hauling will be the same regardless of tonnage delivered. The material should be free or very low cost from the quarry. If you find a trucker with a single axle truck you will be able to get a 1 to 7 ton load delivered, depending on size and weight of truck.

If you ask they will give you a MDSS (Materials Data Safety Sheet) with a complete chemical analysis of the rock they process. The EPA oversees many aspects of their operation, especially quality of water that goes offsite, i.e. the wash water that moves the dust to the lagoons which eventually overflows the last lagoon in the chain to enter some watercourse or impoundment on adjoining property (often to public reservoirs).



  • [permaculture] Re: rock dust - questions to ask a supplier, Lawrence F. London, Jr., 02/21/2009

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