asphaltic roofing tiles

Dear Dr. James:

My chemistry prof at UBC almost 30 years ago was a Dr. James ...

A friend (yes, really) recently purchased a 5-acre country property which had been used for decades by a man who was in the roofing business. The man had evidently disposed of his surplus asphalt shingles and other roofing waste, both new and removed from clients houses, by dumping it on the property. Another method was by burning it (on the property).

My friend has removed a dozen truckloads of garbage, but has encountered stacks of old asphalt shingles among which large (6 metre) trees have grown up. He's thinking that the lesser evil at this point may be simply to leave them alone, or to cover them over with some clay (he could pile it on up to a metre in depth).

My friend asked me to investigate what further site consequences there might be. I've spend several hours on the internet, searching for such combinations as:
+PAH +asphalt
+"asphalt shingle" +groundwater

and have not found a single reference that says he can't just bury these shingles. I found some concern about PAHs and asphalt. I found no studies that said PAHs would leach out. I found two studies (I did look at the source, one was the Florida Department of Transport and the other was the Asphalt Institute, so I'm taking them with a huge chunk of salt) that said there was no PAH leaching from granulated road debris or new asphalt road-making material.

Are there any directions you can lead me, or any advice you want to give?

Thank you.
Sincerely yours,
Jonathan Berry
Nanaimo, BC

Jonathon and list

What a headache. Used asphaltic road pavement is required to be recycled. I suspect roof tiles should or could also be recycled to the industry, but don't have any idea if this is so. A call to your roofing contractor and/or sanitary landfill officer will indicate how used roof tiles should be disposed of in BC.

There is evidence that compounds in bitumen like PAHs and others are carcinogenic (some research papers in medicine, especially related to road construction). We found in a pavement runoff study enriched concentrations of phenols (nasty) from asphalt as opposed to concrete pavement. However I have no evidence (yet) that asphalt roof tiles and pavement cause environmental problems other than the obvious increased flows and heat transport. I would think that asphalt roof tiles are unsatisfactory as mulch or soil amendment even if in very small bits.

What to do? Dunno - all I can suggest for now is that your friend meantime undertakes the task as a long labor of love, removing a fraction carefully to the dump, or wherever, as and when. Anyone else have suggestions for Jonathon?

Thanks for the question, and sorry to be so helpless.
Sincerely, Bill James