[CANUFNET] Effect of Bentonite on Trees?

[Cybulski, Cat]

Hello everyone,

Does anyone have experience with the effect, if any, that bentonite has
on nearby trees when this material is used as a lubricant/tunnel wall
stabilizer during directional drilling (e.g. to install a watermain)?  

Alternately can you point me to any literature about bentonite and
trees?

I did a quick search and came up with conflicting info - on the one hand
bentonite is said to be "okay" because it is all an natural clay, and
even is used in soil amendments (not to mention the many beneficial
health effects for humans).  On the other hand its use is not permited
within tree protection zones by some jurisdictions, and its sealing
off/waterproofing properties sound like injecting a concrete sarcophagus
around tree roots. One reference said it can be used as a root barrier
around newly installed trees.

Any info appreciaited!

Thanks,
C. Cat Cybulski, R.P.F., Certified Arborist | Area Forester, Natural
Heritage & Forestry Services
Environmental Promotion and Protection Branch | Environmental Services
Department
The Regional Municipality of York | 17250 Yonge Street | Newmarket, ON |
L3Y 6Z1 | 905-895-1200 ext. 5275 | 1-877-464-9675 ext. 5275 | Fax:
905-895-7735
www.york.ca <http://www.york.ca/>  | cat.cybulski at york.ca
Please consider the environment before printing this email.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.web.net/pipermail/canufnet/attachments/20120618/3b6d4fe0/attachment.htm>