On September 23, 2024, the Sacramento-Metropolitan Air Quality Management District (SMAQMD) released the Proposed Rule 489 – Greenwaste Composting Operations which will apply to greenwaste composting operations that are subject to Sacramento County Environmental Management Department permit or notification requirements. If triggered, the rule will require greenwaste composting operations to reduce volatile organic compound (VOC) emissions through specific operational practices. Per California regulations, this rule will apply to any facility producing active or finished compost from greenwaste. SMAQMD predicts a 40% reduction in VOC emissions as a result of the Proposed Rule.
 

Background

Composting refers to the biological process in which organic material is decomposed by microorganisms under controlled conditions. This typically takes place in three stages: active composting, curing or finishing, and storage. The first 15 days of active phase composting results in 87% of total VOC emissions from the complete composting process. Typically, static pile composting and turned windrow composting methods are utilized. Static pile composting refers to infrequent turning where material is placed in piles with little to no mixing. Turned windrow composting is the predominant method of greenwaste composting, where material is mixed and aerated using front-end loaders.
 
Sacramento County is located within the Sacramento Federal Nonattainment Area (SFNA), which is classified as “serious” ozone nonattainment for the 2015 National Ambient Air Quality Standards (NAAQS). SMAQMD is seeking to reduce VOC, an ozone precursor, emissions from composting piles with proposed Rule 489. Proposed Rule 489 uses water irrigation to reduce VOC emissions from greenwaste composting operations. When at least three inches of water is applied to an active phase compost pile, VOC emissions are reduced by 80%. SMAQMD projects this new management requirement will reduce composting VOC emissions from 0.0921 tons per day to 0.0915 tons per day during high temperature summers. If adopted, the proposed rule would take effect if the contingency condition is triggered for either the 2008 or 2015 ozone NAAQS.
 
Currently, SMAQMD does not have a rule regulating the VOC emissions resulting from composting operations, but they have modeled Rule 489 off similar rules in effect in the San Joaquin Valley and South Coast air districts. Proposed Rule 489 would introduce a variety of operational and recordkeeping requirements to Sacramento region greenwaste composting operations. The below sections summarize the requirements introduced by Proposed Rule 489 in an effort to reduce VOC emissions.
 

Applicability and Exemptions

Facilities subject to Proposed Rule 489 include those which are already subject to Local Enforcement Agency notifications or permitting requirements. Subject facilities include all green waste compost facilities not listed as an exempted facility per 14 CCR § 17855. In Sacramento County, the Local Enforcement Agency is the Sacramento County Environmental Management Department. Proposed Rule 489 would not apply to “Minor Composting Facilities” which includes community composting in a residential neighborhood, backyard composting conducted by a household, nursery composting, or recreational facility composting at parks or other recreational areas. The proposed rule defines greenwaste to include any organic waste generated from agricultural, landscaping, or other activities producing plant remains, any of which can contain up to 20 percent manure by volume. The definition of greenwaste in Proposed Rule 489 does not include food waste.
 

Operational Requirements

Within one year of rule adoption, applicable facilities must comply with the following best management practices:

• Chip or grind greenwaste for on-site composting within 10 days or an earlier date as required by the Sacramento County Environmental Management Department.
• Each active phase pile must be covered with at least six (6) inches of screened or unscreened finished compost within 24 hours of pile formation. The pile must not be turned for the first seven (7) days of active phase composting, except as required to manage temperatures or pathogens.
• Water must be applied no earlier than six (6) hours before pile turning for the first 15 days after the initial pile formation. The squeeze ball test should be used to determine pile wetness. The top one half of the pile should be wet at a depth of at least three (3) inches. Operators may also use a windrow equipped with a water sprayer to satisfy this requirement.
• The facility is not required to water the pile if a rain event occurs and the pile is sufficiently wet.
• Facilities may opt to use alternative controls if they allow for emission reductions of at least 40% VOC by weight.

Monitoring and Recordkeeping Requirements

Facilities will be required to regularly conduct squeeze ball tests of the active compost to determine if the pile is appropriately wet. The Solvita Maturity Index and Specific Oxygen Update Rate test methods are incorporated to determine compost maturity.
 
Facility operators must keep records including organic waste throughput, watering, and active composting cover on site for a period of five years. These records must be submitted to the Air Pollution Control Officer by March 15th of each year in an electronic format.
 
If adopted, this rule would apply to all greenwaste composting operations in Sacramento County. Facilities will be subject to additional testing, monitoring, recordkeeping, and submittal requirements beyond the current Enforcement Agency notifications or permits. Facilities may also be required to change their daily operations to accommodate the additional watering requirements.
 
A public hearing is scheduled to occur on October 24th, 2024. Interested parties can find additional information on SMAQMD’s website. If you would like to discuss the proposed adoption of this rule and how it may impact your facility, please contact Trinity’s Sacramento Office or call 916.444.6666.