out my local rock crusher, their source of stone, and if they spray
floculants (which i know little about) for dust control.
I think EPA regulations would not allow using flocculants. The rock dust created in the crushing process is washed away
into a drainage channel as it is created. The crusher separates dust from screenings from pea gravel from #67 concrete &
driveway rock and on to larger sizes of road surfacing rock then larger riprap stone used for earthwork stabilization
and drainage channel lining; ABC material or crusher run is also created somewhere in the operation. Washwater from the
crusher is recycled after flowing through 2 or 3 settling ponds wherein the silt or "fines" separate out and accumulate
on the pond bottom; it is dredged out later for use as fill material, berm construction, driveway building, tennis
courts and for agricultural uses. Water pumped out of exposed water veins in the quarry pit is used to replenish the
wash water supply. There are environmental issues involving the purity of the wash water. Since it may migrate off site
into adjoining watersheds and will go into the aquifer through the settling ponds. The quarry operators are required by
the EPA to maintain high water quality standards; this also means keeping the site clean of oils, fuel and grease to
prevent these toxins from polluting the wash water. These quarries always offer MSDS to anyone who wants one.
I have a friend who runs a crusher at a quarry 6 miles away and he assures me that they keep that wash water really
clean. When the quarry pits are spent they are often allowed to fill up for use as municipal water reservoirs.