This is not strictly on topic, but I'm posting it for the benefit of the 
backyard horsekeepers here who have their own buildings to maintain.  
I just got my March/April issue of THIS OLD HOUSE magazine, the companion mag 
to the PBS television show.  The main feature (and overall theme of the 
issue) is the spring maintenence guide -- fixing all the rot and other 
mishaps which may have happened during the winter, or which might come up in 
the spring rains.
Along with the maintenence guide, which is handy for the article on draining 
soggy yards, there are two articles which may be quite useful to barn 
ownwers.  The first is a feature on tree removal, which has a lot of good 
info about how to tell if a tree on your property is dangerous and needs to 
come down, and how to find a reputable company to take care of it.  
The other major article is on pressure-treated lumber, which is used in 
applications like fence posts for its resistance to insect damage and rot.  
You've all seen it -- that green-colored stuff.  The chemicals which protect 
the wood are forced into the wood under pressure (thus the name).  
I had heard that you were supposed to be careful when you handled this 
product, and that you weren't supposed to burn it, but I wasn't quite sure 
why.  Turns out that the most common formula used in making PTL is chromated 
copper arsenate --a mix of 1) copper, to discourage the fungi that cause rot; 
2) arsenic, a common pesticide in the 30's when this proccess was invented; 
and 3) chromium, which helps to bind everything to the wood.
There are two basic problems outlined in the article.  First of all, if you 
have acidic conditions, like acid rain, or if the wood is used in compost 
bins, the chemicals can leach out of the wood.  And if you burn the scraps 
left over from a construction project, the ash left over is contaminated with 
arsenic.  The article notes that a single 12-foot long 2-by-6 stick contains 
more than an ounce of arsenic, which (if ingested) is enough to kill 250 
adults.  Burning the wood concentrates all the chemicals in the ash, which 
will then contaminate all the ashes left behind from anything else which was 
burned at the same time.  
A top official in Florida's EPA is quoted as saying, "We call (arsenic) a 
three-fer.  It can leave you dead as a doornail at high doses.  It can kill 
you at moderate amounts over a longer period.  And it's a carcinogen at low 
levels."  
A sidebar in the article tells how dairy farmers in Minnesota lost 18 cows 
because they got onto a neighboring property which was contaminated with ash 
left over from burning pressure-treated wood.  The ash tastes salty, which 
attracted the cows.  Five tablespoons of ash have enough arsenic to kill a 
1000-pound cow; a single tablespoonful has enough to kill a 250-pound human.  
If you have decks or other structures and you're concerned about whether 
arsenic is in the soil under the decks, contact your local public health 
department.  For about $50, you can have the soil tested at an environmental 
laboratory.
--- QM v1.31 
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