The Nature Conservancy has great information about eliminating blackberry here.

I found the document named Controlling Rubus in the PNW to be especially helpful, as, at the end, it recommends removal techniques for blackberry stands of various sizes and discusses herbicide options.

The Northwest Coalition for Alternatives to Pesticides has fact sheets on herbicides and an archive of other information, click on Publications and Information.

Here is a pdf on blackberry control from NCAP: http://www.pesticide.org/blackberries.pdf

For additional information, phone the Master Gardener's DialExtension (King County) at 206-296-3425 (or 800-325-6165, ext.6-3425) and listen to tape #1274 about removing blackberries. However, the solutions given in this tape may apply to smaller areas, rather than the larger stand you mentioned.

An interesting idea that some people are trying locally is the use of goats. This article in the Seattle Post-Intelligencer mentions Healing Hooves of Spokane. There is at least one company on Vashon Island which offers this service as well. Another P-I article mentions Rent-a-Ruminant.
This directory of Pacific Northwest goat producers includes a few which mention brush control or vegetation management.
This document from Sound Native Plants contains contact information for several such services.

Season All Season
Date 2008-01-03
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