Odors - Nuisance, Complaints and Best Management Practices for Compost Facilities

Blog ECS Staff 02/04/2021

Odor problems at commercial scale composting facilities are a far too well known problem. The resulting fines, lawsuits, disputed studies, and neighborhood organizations have been well publicized. Now when new composting facilities are proposed, the “No” folks can Google a large stock of horror stories to help them put up road-blocks in the permitting process.

Compost piles emitting odors

In an insightful article “Legal Perspectives on Odor Impacts” (BioCycle, March 2014) Bradley Jones, an attorney who represents community groups in suits against composting facilities with odor issues, has provided his point of view. To begin with, he stated that the most common odor-based damage claims are:

  • Property damages or devaluation of property
  • Personal damages for the annoyance, inconvenience, harassment or embarrassment of having to live with the odors

Mr. Jones also addressed this subject at the annual WORC conference (November 2013, Vancouver WA). Our “take-aways” from his talk were that the best chances for the community to win a large jury award if:

  • The composter denied responsibility for the odors and/or blamed someone else
  • The composter focused on a legal fight
  • The composter did not make significant, demonstrable, and scientifically based efforts to improve operations in order to reduce, capture and control odors

We think the smart money focuses that last bullet item…but in the affirmative.

Some truths about composting include: it always smells, the strength of odors depend on both facility design and operation, the larger the facility the stronger the smell, and the closer the facility is to a non-company nose, the more critical reducing, capturing and controlling odors become.

For most facilities the major risk factor you can control is your operations (it’s darn hard to move, change the weather, or buyout all your neighbors). We have visited/worked at quite a few facilities with odor issues. All of them could reduce their odors by better adherence to Best Management Practices (BMP’s). In most cases, implementing BMP’s throughout their operations was enough to take the bat out of the lawyers/regulators hand.

How To Avoid Odor Issues In Commercial Compost

The key steps (to put it way too simply) to BMP bliss are:

  • Start with a BMP Mix
  • Maintain BMP condition during active composting (especially during the first 10-15 days)
  • Practice good house-keeping
  • DON’T cut corners!

1. Start with a BMP Mix

Initial PropertiesBMP Mix Requirement in an aerated system
% Solids – by weight39% – 43%
Density< 915 lb/cy
Carbon/Nitrogen ratio25 – 35 to 1 (make sure the C is bio available)
MixingNear homogenous, good particle size distribution

2. Active Composting

  • Provide adequate aeration to maintain high oxygen levels (>15% during the first 10-15 days, >10% thereafter) and some temperature control.
  • Re-wet /Re-mix as necessary to prevent over-drying and densification (yes it’s a pain, but necessary!

3. Contact Water Management

  • Think closely about your grading and capture plan to prevent sheeting of this smelly liquid
  • If this water is going in a tank or a pond, make sure you have competently designed aeration system (an inadequate aerator will make more odor than it will prevent –we have stories)

4. House Keeping

  • Sweep regularly
  • Maintain your aeration system and biofilter as well as you do your front-end loader

5. Don’t Cut Corners

  • Don’t let tip fees design your mix (too heavy and rich).
  • Give the process time (too short of retention in the aerated portion will lead to odor later)
  • Make good compost that makes it easier to sell (avoid brown mountain syndrome)

We’ve helped a bunch of our clients resolve their odor issues following these general guidelines. Please email Steve with any questions.

Happy Composting!