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Re: waste gyproc




Can anyone help Tom?


David:
>> Do you have any information available concerning the disposal of waste
>> gyproc?  We are considering a pilot /  experiment filling an acid-producing
>> shale pit here in Nova Scotia


Hi David
Yes, I do mean sheetrock / drywall.  As thumbnail as possible,  a couple of
years ago the folks who run a salmon and trout farm at the mouth of Martins
Brook a few klicks away from here woke up one morning to find their tanks
all overflowing across the road: the drains being plugged with 60,000 dead
salmon.  Various govt agencies tested everything they could think of with
no significant results.  Four months later, it was 30,000 trout.  

Eventually  it was discovered that someone quarrying shale a couple miles
upstream had trenched into the brook to drain the water out of his pit.
The water tests pH 2.8 - 3.2, aluminum 4.33 mg/l etc.  The plugs of
drainwash had killed everything in the stream and left no sign of their
passage, other than a distinct dearth of living creatures.  Acidity is
produced by bacteria eating iron sulphide.  These "fools' gold' pyrites are
a common occurence in the Halifax slates that underly most of east-central
NS.  In the 325 km2 watershed we work in, there are upwards of 30 shale
pits condemned for their high sulphide/sulphate levels.

We have been looking for a cheap method of remediating these pits, and were
presented with this somewhat unexpected situation:  our local Regional
Solid Waste / Recycling / Composting facility has a large mountain of
asphalt shingles stockpiled.  A building materials recycler in Halifax (80
miles away) has a market for used shingles, and a mountain of scrap gyproc.
 They want to truck gyproc here and shingles back.  Since they are already
being paid / tonne to collect the gyproc they will give it to us for
nothing.  We have done some rudimentary testing and yes, the lime / calcium
in the binders etc do raise pH (from 5.2 to 6.5 in our one test)

What we are considering is plugging the 50-foot long. 4 foot wide, 3 foot
deep trench out of the pit with the same gravel etc fill that was dug out
of it (with geotextile curtains, armour rock etc as req'd) and then filling
the pit with this scrap gyproc, rotten hay, ditch cleanings from the Dept
of Transport etc, and doming it such that surface runoff is directed away
from the brook itself.  We would place 4" ABS pipe 'wells' as the filing
took place to enable us to monitor subsurface water chemistry into the
future.  The bacteria which makes the acid is aerobic, so by covering the
exposed rock with anything that will soak up surface and subsurface water
and keep things damp / wet will (in theory) prevent or at least reduce acid
production.

Physically it's a lens about 160 feet in diameter and 6 feet thick at the
deepest.  I'm looking at it as a solid waste disposal problem, even though
it's too small to require approvals etc.  I want to make damned sure I know
what is likely to happen before it gets done, because it will be a proper
pig to clean it up afterwards.  I'm looking at the project as a combination
of remediating acid run-off, a disposal-of-an-unwanted-waste-product, and a
very low-cost community-controlled-developed-based sustainability activity,
involving volunteer monitors (already in place for the past two years)
school class projects doing replanting, all kinds of ideas are around, keen
volunteers by the truckfull, hardly any money, if it works we can solve
major acidification problems all around us, blah blah blah

But I'm not moving an inch until I get some data back from anywhere I can
get it.  That's my story and I'm stickin' to it
<g>

I can send you a WP file that has this in more detail if you'd like


Tom Daly
Program Coordinator
Bluenose Atlantic Coastal Action Program
PO Box 10, Mahone Bay NS
B0J 2P0
902 624 9888
fax 624 9818
nstn1033@fox.nstn.ca