Unit 7.2: State Regulation

State regulations are typically based on federal guidelines, but many standards are interpreted and adopted on a state-by-state basis. State regulations determine whether AD systems will be regulated at the state level with independent AD regulations, as solid waste facilities, under NPDES permits, composting regulations, as WWTP’s, a combination of these, or another regulatory system altogether. Common state agencies which determine and enforce standards include the Department of Natural Resources, Department of Agriculture, Department of Conservation or Environmental Conservation, or other similar regulatory arm within the state government. The state regulatory arm and the classification of AD systems within that arm can have implications to permitting requirements, design standards, emissions limits and exemptions, operation and safety, and digestate use. In many states, under what system the AD is regulated is dependent upon feedstock use. Typically, use of AD systems on-farm with on-farm wastes is covered under existing NPDES permits. Following the same logic, municipal and industrial solid waste streams are typically handled under state solid waste regulations, and wastewater streams under state WWTP regulations. Changes to feedstocks can affect NPDES permits. In some cases the change in feedstocks can result in changes to previous exemptions or decreased regulations, requirements for waste storage structures, disposal methods, permitting, and siting. Use of multiple feedstocks can result in use of only one of the regulatory standards associated with one waste stream or a combination of the two depending upon the state. Exemptions in many states allow use of a percentage of off-farm waste in an on-farm digester without changes to the responsible regulatory arm or permitting requirements. Although these practices are common to many states throughout the country, it is important to note again that there is large variation in the handling of AD systems in terms of regulation from state to state.

NPDES permits are commonly granted through state agencies (Figure 1) which outline waste management guidelines mandated by the state. Again, it is important to note that these practices are state specific and state agencies maintain specific requirements for system design, siting, operation, maintenance etc, to limit production and transport of pollutants to the environment and maintain a safe work environment. The basic outline and procedure for NPDES permits can be found in the federal regulations discussed above as the regulatory guidelines are determined at the national level.

Transport of digestate is commonly regulated through state agencies (typically transportation or solid waste agencies). The waste type will determine the regulatory procedures required. This may include the vehicle requirements, licensing requirements, and spill and leakage protection, among others. Transfer of digestate across state lines can be regulated under multiple state as well as federal statutes.

Land application of digestate is typically governed by state agencies (typically agricultural or environmental related agencies) and includes application timing, application rates, and setback distances to water sources and wells. Each state is also required to outline specific guidelines for discrete discharges as mentioned previously. This includes sources from land application in addition to structures and handling of waste material prior to land application.

Air emission regulations are based on those developed from the federal CAA. States can require permits for emission for construction and operation of AD systems. In some states, emissions permits are required for wastes governed by solid waste regulations, but can be exempt in some agricultural operations at the state level (note this does not affect requirements for permitting at the federal level). Some areas of the country where air quality does not meet federal standards (deemed nonattainment areas), such as California, have lost flexibility to issue air emission exemptions for NOX, SOX, PM, and CO. State nuisance and environmental laws may also require more strict regulations for odor. The state environmental regulatory agencies responsible for NPDES permits and air permits vary greatly from state to state, and many permitting requirements are conducted on a local level. Commonly state agencies responsible for regulating air emissions for AD systems are connected to environmental, natural resources or agricultural systems, but vary not only in name but regulatory structure as well.

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