Compost specific storm water management guidance

December 17, 2014 | Composting, Policies + Regulations

Maryland’s New Composting Regulations

Draft rules, several years in the making, are in the final comment period. Rules focus primarily on composting facilities processing source separated organics.

Marsha Johnston
BioCycle December 2014

After a year of comments and revisions, the Maryland Department of Environment (MDE) is scheduled to publish its new rules for permitting composting facilities this month (December) in the Maryland Register for a final 30-day comment period. Initially proposed last January, the slightly revised composting regulations are expected to take effect in early 2015, unless further changes are required. If they go into effect on schedule, existing facilities will have a grace period for compliance until January 2017, although they must submit a form within 60 days after the regulations become effective.
“The draft regulations create a new type of permit for a composting facility,” explains Hilary Miller, deputy director of the Department’s land management administration. “With increasing interest from some counties in composting, particularly food scraps, the legislature passed a law in 2011 asking for a study to determine how to encourage it. Indeed, in 2012, only 8.5 percent of food scraps in Maryland were composted. “We just had two county sites (Howard and Prince George’s) that have opened for food waste composting, and now they will be able to expand with the new regulations,” adds Miller.
The MDE utilized the US Composting Council’s (USCC) Model Compost Rule Template in the process of drafting its new rules. The USCC’s template was developed several years ago by a task force comprised of state composting regulators, composting facility operators and other stakeholders. The template includes a three-tiered permit structure, with design and operating requirements based on materials composted and technology employed. The foundation of the tiers is the feedstock categories, which are based on the materials’ potential risks to human health and the environment.
“The USCC template was a starting point,” notes Kaley Laleker, administrative officer at MDE. “We used its tiered approach and feedstock types. The template also utilized a concept of contact water vs. storm water, and the need to manage them differently.” Contact water is defined by MDE as runoff that has contacted raw feedstocks or active composting material.

Feedstock Types And Tiers

The draft regulations divide feedstocks into three general types: Type 1 is yard trimmings; Type 2 includes food scraps, nonrecyclable paper, MDE-approved animal manure and bedding, MDE-approved industrial food processing materials, animal mortalities and compostable products; and Type 3 covers biosolids, soiled diapers and mixed MSW. Natural wood waste, e.g., trees and stumps, is in its own category.
Facilities composting natural wood waste only and Type 3 feedstocks are covered under existing MDE regulations/permits and will not be subjected to the new rules. MDE created two new tiers, with Tier 2 divided into smaller and larger facilities. Tier 1 regulations are for facilities composting only Type 1 materials, i.e., yard trimmings. Tier 2 is for facilities composting Types 1 and 2 materials. Tier 2-Small applies to operations producing less than or equal to 10,000 cubic yards (cy)/year of compost. Tier 2-Large covers facilities producing >10,000 cy/year of compost.
The regulations allow for individual and general permit applications. Laleker notes that an individual permit would apply when the composter needed to include site-specific details or request a variance not included in the regulations. “If you wanted to propose a different kind of pad, for example, that is allowed if you can show that it would protect the environment in the same way as the new regulation,” she explains. A general permit would apply to a facility that can comply with all of the regulations without a variance. Miller notes that “pad size is likely to be most common variance” request.
Permit exemptions for nonfarm facilities include backyard composting, up to 5,000 square feet of composting area (community gardens, schools), and animal mortality composting at government-managed sites. On-farm facilities only composting their own residuals and using the compost on their farm are exempt.
Farms that are composting their own residuals, as well as Type 1 and manure/bedding feedstocks from off site are exempt if the operation is smaller than 40,000 sq. ft. and is operating in accordance with the Soil Conservation and Water Quality Plan or the Agricultural Waste Management System Plan. Nutrient management plans are additionally required under existing law and regulations where nutrients, including compost, are applied on site. Laleker notes that the 40,000-square-foot exemption for farms was added during the comment period. “We thought we had covered the universe in publishing the regulations, but we found that we hadn’t understood the importance of farms using manure from other farms,” she says.
All composting facilities, even those exempt from permitting, are subject to general restrictions such as: not create a nuisance, cause air pollution or illegal discharge of pollutants into state waters or otherwise harm the environment. Composting sites must be set back 50 feet from any property line not controlled by the operation and 100 feet from any well or surface water.

Compost Pads And Contact Water

For the composting pad, the MDE also took a tiered approach. For Tier 1 sites, feedstock receiving, active composting, curing and storage must be done on an all-weather pad. Small Tier 2 facilities also are required to have an all-weather pad, plus 6 inches of carbon-rich materials between the pad and an active pile of compost. Large Tier 2 facilities must have a low-permeability pad (1 x 10-5 cm/sec if on the surface; 1 x 10-6 cm/sec if buried) for feedstock receiving and active composting areas, and an all-weather pad for curing and finished compost areas.
Each facility must have an operations plan approved by MDE, with a timeframe to manage feedstocks. “All Type 2 feedstocks, especially large quantities of food scraps and manure that are subject to odors, must be incorporated into composting piles, mixed with bulking material and covered or transferred by the end of the operating day,” explains Laleker. “For Small Tier 2, they must cover active piles with 6 inches of compost or carbon-rich material by the end of the day the piles are formed and each time they are turned.”
With regard to contact water, the new regulations propose no specific management requirements for either Tier 1 or Small Tier 2; contact water is to be managed like storm water. But Large Tier 2 facilities must collect and contain contact water in a tank or a basin prior to reuse on feedstocks or active composting piles, transporting it off site, or discharging it pursuant to their permit. A containment system for contact water must be sized to handle at least a 24-hour, 25-year storm event. If a basin is used, it must have a liner with hydraulic conductivity of 1 x 10-7 cm/sec or less and if the liner is compacted clay, it must have a thickness of at least 1 foot. Tanks are typically not lined, but would need to be constructed of low permeability material. For storm water management, composting facilities must have berms or ditches to prevent it from running onto the feedstock receiving, storage, or active composting areas.
“Over time we have seen some composting facilities take more food scraps than they can handle properly, causing water pollution and odor problems,” notes Miller. “It is important going forward with these regulations that we don’t have those problems in the future.”
The revised proposed regulations are scheduled to be published in the Maryland Register in December and made available on the MDE website ( The final public comment period will be 30 days. “The amount of time it would take between the end of the comment period and publishing of the final rule will depend on the quantity and content of any comments received,” explains Laleker. “However, the very earliest that regulations are allowed to be adopted is 45 days from the date the proposal is published, i.e., 15 days from the end of the comment period.”
Marsha Johnston is a Contributing writer to BioCycle.

Sign up