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Comment period

Greenside Construction, Buttermilk Creek

Air quality variance

April 4, 2024 - May 6, 2024, 11:59 p.m.

We propose to approve Greenside Construction's Buttermilk Creek air quality permit variance.

Greenside Construction is requesting a permit variance for their portable carbonizer (air curtain incinerator), which may exceed the particulate standard (0.23 grams per dry cubic meter). An air curtain incinerator can be used to clear vegetation and reduce biomass waste (organic matter used as a fuel). The carbonizer will be located about 10 miles west of Twisp, up the Twisp River drainage, and 2.5 miles south on Buttercreek Road, in Okanogan County.

Operating under contract with the U.S. Forest Service, Greenside Construction's Buttermilk Creek project will convert about 55 piles (966 tons) of logging slash into biochar using a portable carbonizer. The slash may be legally burned under silvicultural rules. Using the carbonizer will reduce overall air emissions compared to slash burning. Using the carbonizer will allow more control over the burn. Testing shows it will reduce air emissions by 50-98 percent over silvicultural burning.

 The biochar created by the carbonizer will be stockpiled on-site for later use by the U.S. Forest Service as a soil amendment to improve vegetation growth in the Libby Creek drainage.

Documents for review

If we determine this proposal satisfies the requirements of Chapter 173-400 WAC, we plan to approve the permit variance.

Tentative public hearing

(if requested by May 6, 2024)
May 8, 2024, 6 p.m. online

If we receive a request for a public hearing, we will update this page with a link to the public hearing and will extend the public comment period through May 10, 2024. If we do not receive a request for a public hearing, we will update this page.

To comment or request a public hearing, use one of the ways listed below. A request for an online public hearing must include the interest of the person making the request and why a public hearing is needed. We will hold an online public hearing if there is significant public interest.

To find out if there are more records for this project, contact Ecology’s Public Records Office.

This notice was posted on April 4, 2024.


A notice of construction permit is required before installing a new source of air pollution or modifying an existing source of air pollution. This permit is sometimes called a "pre-construction permit" because a business must have one before starting construction or operating their business.

A notice of construction air permit limits the amount of air pollutants a business can emit.

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Lynnette Haller
Washington Department of Ecology Central Regional Office
1250 West Alder Street
Union Gap, WA 98903-0009
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Lynnette Haller
Environmental Engineer

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