Oregon Air


It has become evident to the members of Oregon Air that the outdoor composting system currently under consideration for Grimm’s Fuel in Tualatin will generate a significant amount of offsite odor, and therefore not meet the air quality needs of the surrounding community.

Due to the short distance between Grimm’s and the local neighborhoods and businesses, we believe that an indoor composting facility, comparable to Alternative 3 in the Green Mountain Technologies report (see below), is the only solution that will allow Grimm’s to continue composting at their current location while also meeting our needs for complete mitigation of dust and odor.

Oregon Air proposes a group field trip to The Compost Factory in Puyallup Washington to see, smell, and learn about indoor composting. In August 2018, Oregon Air tried to arrange for a facility tour but the operators at Waste Connections declined our request.

We believe that the largest composting operation in the Portland metro region should be equipped with the “best system for encroaching neighborhoods and expanding site capacity.”

We believe that the enclosure requirements and odor performance standards that currently apply to transfer stations should also be applied to composting facilities.

We understand that this proposal may require new permitting, and we are prepared to offer our assistance to Grimm’s in the permitting process in order to make this building a reality. We also understand that this project will require a considerable amount of capital investment, and we are excited for the opportunity to participate in community fundraising efforts to help finance this proposal. We look forward to having a positive working relationship with Grimm’s Fuel.

We believe that an indoor composting facility will meet the needs of all stakeholders:

Grimm’s: Reduce odor complaints, increase throughput.
Residents: Mitigate dust and odor, improve air quality, protect our health.
Businesses: Protect property values and worker health.
Metro: Increase regional composting capacity, protect the environment.
DEQ: Protect air quality, protect water quality, protect human health.
City of Tualatin: Improve quality of life, allow surrounding development.
Tualatin River: Eliminate rainfall-generated leachate.

Green Mountain Technologies report Page 60 (


This is the Cadillac of composting systems. It is designed to be operated indoors for the first 20 days of composting and after that is operated on an aerated curing floor with a roof only. A biocover must also be utilized during this phase to insulate the surface to achieve PFRP. All aeration pipes are located below a concrete surface, so no pipe handling is required improving the efficiency of pile construction. The aeration system is both positive and negative giving superior temperature control and the oversized biofilters (about one acre) treat all of the indoor air. The piles are turned every 6- to 8-days and re-watered using a mobile compost turner. Finished cured product can be made in 47-days all under a roof so there is no leachate generated from rainfall. It is the best system for encroaching neighborhoods and expanding site capacity. 31,000 cubic yards capacity with a processing capacity of up to 337 tons per day over 40 days. A similar system has been in operation at the Compost Factory in Puyallup Washington since 1999 alongside residential communities and businesses. Due to the constructed enclosure, this system cannot be easily expanded.

Being fully enclosed, for the first 20 days, there is no dust impact from turning and odors are minimized to what the biofilter efficiency can achieve, usually over 95% reduction in odor.

The time line for a building construction project like this can be over 18-months to 2-years (assuming the land use approvals were in place) including engineering, permitting and construction. However, since the location of this facility would be on a separate parcel from the existing system, the transition would be much easier and impact to the business during construction would be minimal.

Proposed January 32, 2019