BioCycle May 2008, Vol. 49, No. 5, p. 39
Regulations and permits for storm water at composting facilities involve many site-specific criteria.
THE Clean Water Act of 1972 created the National Pollutant Discharge Elimination System (NPDES). Under NPDES, all facilities that discharge pollutants from any point source into U.S. waters are required to obtain a permit. The U.S. Environmental Protection Agency (EPA), which enforces the Clean Water Act (CWA), developed three types of NPDES permits for discharges comprised solely of storm water: individual, general and group (or “multisector”) general permits. Most states are delegated authority from EPA to regulate storm water discharges with these types of permits.
Individual storm water permits are very similar to standard NPDES permits, setting specific numerical effluent limitations on conventional, nonconventional and toxic pollutants, and on hazardous substances. General permits are largely used to control storm water discharges from construction sites disturbing one or more acres of land (some industrial activities fall under these baseline general permits). Multi-sector general permits (MSGP) are aimed at controlling storm water discharges from similar types of industrial activities, and are grouped along the lines of Standard Industrial Classification (SIC) Codes, in the belief that most industrial activities within a particular SIC Code were fundamentally similar with regard to potential storm water runoff contamination potentials.
The challenge for the composting industry is that its facilities do not fall neatly under one of the regulated industrial categories. None of the specified SIC codes apply specifically to composting facilities, although some composting facilities do use an SIC Code requiring coverage (SIC 2875 – Fertilizers, Mixing Only). Others that have been used include SIC 4953 (Landfills) for facilities that are located at landfills, and SIC 2499 (Wood Processing, Misc.). In addition, those composting facilities located on farms are exempt from the storm water permitting requirements of the CWA, yet some of those facilities rival the more “industrial-scale” facilities found elsewhere in size, scale and potential water quality impact.
Storm water discharge general permits issued to multi-sector SIC code industries (like composters in the SIC 2875 category), while called NPDES permits, do not have the same effluent limitations on pollutant concentration, pollutant loading and flow that is found in traditional end-of-pipe NPDES permits for point sources. These general permits are based on periodic monitoring of key pollutants (correlated with the typical storm water contamination profile of that particular SIC Code) and the preparation and implementation of pollution prevention programs.
The monitoring parameters are called “benchmarks,” and the permitted party is expected to monitor storm water runoff (during a rain event) for those parameters on a periodic basis, either quarterly, semiannually or annually. If it’s detected that benchmarks have been exceeded, the permitted party is expected to intensify their storm water pollution prevention activities. A Storm Water Pollution Prevention Plan (usually designated as a SWP3 Plan) consists of mapping showing locations of pollution sources, receiving streams and Best Management Practices (BMPs).
Operational BMPs are basic, everyday practices and relatively small structural or equipment requirements that can be effective in preventing pollution, reducing potential pollutants at the source. Operational practices would include housekeeping details like sweeping compost pads with a rotary broom and policies to require periodic inspections of storm water management facilities (i.e. looking for trash blockages of drains, etc.). Structural BMPs are measures that control or manage storm water runoff and drainage. Examples include covers and enclosures used to isolate composting and curing pads, and product storage areas from rainfall; swales, dikes and berms to divert up-gradient runoff from the facility; and storm water detention basins, vegetative filter strips, rain gardens (or bioretention ponds) and constructed wetlands to manage collected runoff.
Part I (February 2008) of this series on storm water management at composting facilities discussed methods for quantifying storm water runoff and some of the constituents in the runoff that are of concern in water pollution control. Part II (April 2008) focused on storm water treatment options. Part III reviews regulations in seven states.
STATE REGULATORY STRATEGIES
States vary widely with regard to how storm water from composting facilities is regulated. Regulators from several states were contacted for information about how compost facility storm water was regulated:
Kansas: Ken Powell, an Environmental Scientist with the Kansas Department of Health notes, “Compost facilities are split into five categories in our regulations: yard waste, manure, livestock (which means dead animals), source-separated organic waste and municipal solid waste. Leachate and storm water controls are required at all composting facilities. All of the facilities in Kansas are currently windrow facilities. Any leachate would mix with the storm water. With the exception of MSW composting, all of our facilities use either a grass filter strip alone or in combination with a storm water retention structure. Excess water in the control structures can be used for watering the windrows or irrigated on crop fields. We do not currently have any MSW composting facilities, but they would be required to be connected to a municipal sewer system or to haul the leachate to a municipal sewer system. MSW facilities are also required to be covered, so they should generate very little leachate. In Kansas we have not required NPDES permits since no unfiltered runoff should leave the facility.”
Missouri: Missouri uses the SIC 2875 industrial MSGP to regulate storm water from composting facilities. Missouri uses two different categories of composting facilities under this SIC Code, one for operations of less than 20 acres composed of feedstocks from agricultural, wood and food product sources (Permit No. MO-G090000); and the other for operations under 20 acres handling any sort of feedstock (Permit No. MO-G920000). Facilities permitted under this SIC Code category must be nondischarging, except in the event of “emergency discharges during catastrophic rain events.” This is defined as the 1 in 25 year, 24-hour rainfall, which ranges from 5.6 to 7 inches of rain in Missouri. Permits issued under the MO-G920000 category require composters to test feedstocks for heavy metals (not just compost). Benchmark monitoring requirements include BOD, TSS, oil and grease, fecal coliform, pH, temperature, ammonia-nitrogen, other forms of nitrogen and phosphorus. Land application of the retained storm water is limited to rates of less than 650,000 gallons per acre per year. These general permits are tailored to a particular facility’s operation.
North Carolina: Recent regulatory decisions in North Carolina have caused considerable concern for composters, as the state’s Department of Environment and Natural Resources (DENR) has decided to deny any future requests for storm water discharge permits from composting facilities. “Over the past year, we have seen an increasing number of composting operations seeking NPDES storm water discharge permits,” said Bradley Bennett, Stormwater Permitting Unit Supervisor at North Carolina DENR. “Based on the analytical data we’ve seen, pollutant levels in storm water are more characteristic of wastewater. It is also now clear that leachate from composting operations is a wastewater and poses water quality concerns without adequate treatment. We are also concerned about leachate from finished compost storage piles. Leachate and runoff from these piles can still introduce concentrated amounts of oxygen demand, nutrients, solids and other pollutants into surface waters. We have decided, unlike other states, that runoff from finished compost piles is not storm water, it is a leachate, and should be regulated as a wastewater.”
North Carolina DENR’s wastewater rule requires that all nondischarge alternatives be fully explored before a wastewater discharge permit is issued. Alternatives include: eliminate exposure to rain by enclosing the facility; internal recycling as irrigation water for compost process control; spray application on land; diversion to a wastewater treatment plant (WWTP) through the sanitary sewer system; diversion to a WWTP through a “pump-and-haul;” or treatment on-site through a permitted treatment system (i.e. a “package” WWTP, a constructed wetlands, an evapotranspiration drainfield, etc., or some combination of technologies). Only after demonstrating that none of the preceding is feasible, will DENR entertain an application for a discharge. Discharges will be subject to water-quality based effluent limits as needed (i.e., Total Maximum Daily Loads, whole effluent toxicity, etc.), and would have effluent limitations much like a regular point-source municipal or industrial wastewater discharge.
“Since the policy went into effect, Wallace Farms (a multi-feedstock industrial composter) has decided to divert to the sanitary sewer system, Brooks (a multi-feedstock industrial composter) is working on a plan for an on-site treatment system, the City of Durham (a yard waste composter) is considering a pump-and-haul to a WWTP and Warren Wilson College (an institutional in-vessel composter) is considering an exclusion from coverage based on being in-vessel,” said Frank Franciosi of the Carolinas Composting Council. Discussions are underway between the Council and DENR about the nature and types of cost-effective on-site treatment systems that will meet state water quality permitting requirements.
Oregon: One of the more progressive approaches to managing storm water may be found in Oregon. “We found that regulating storm water from composting facilities under the Industrial General Storm Water Permits didn’t adequately cover all on-site activities of composters,” says Jenine Camilleri, with the Water Quality Division of Oregon Department of Environmental Quality (DEQ). “So we developed a specific storm water permit for composters, known as the 1200-CP General Storm Water Permit.” This new permit is focused on the use of BMPs to treat storm water from compost. Quarterly monitoring will be required of BOD and phosphorus in addition to the standard industrial storm water monitoring parameters of copper, lead, zinc, pH, suspended solids and oil and grease. This permit also requires: public notice and comment on the application and on the storm water management plan; requires runoff meet in-stream water quality standards; and composting facilities obtain an individual NPDES permit if they have failed after the fourth year of permit coverage to consistently meet the monitoring benchmarks. (Table listing proposed benchmarks is a Web Extra). Exemptions from this rule will be limited to home composting, agricultural composting of agricultural waste and institutional composting of self-generated wastes (and on-site use of the resulting compost only).
Under new composting rules being prepared by Oregon DEQ Land Quality (which include the new storm water permit rules), leachate will have to be segregated from storm water and handled separately. If leachate is commingled with storm water, the facility is not eligible for the 1200-CP permit. “We’re considering a joint permitting process for both permits (Solid Waste and Water Quality) with one application,” notes Camilleri. The new rules (currently in draft form) will require that leachate production be minimized, that it be collected and directed to an impermeable containment structure, that tanks used to store leachate have secondary containment and that it be either directed to a treatment plant, or if treated on-site, then discharged under a NPDES permit with effluent limitations.
Virginia: Solid waste composting facilities (which includes everything from yard trimmings to commingled municipal solid waste) are required to capture, contain and prevent discharge of runoff from the 1-hour, 10-year storm. Runoff above that level is regulated under the Industrial Activity General Permit for SIC 2875 (Fertilizers, mixing only). Benchmark monitoring parameters are: Total Nitrogen (2.2 mg/l), Total Recoverable Iron (1.0 mg/l), Total Recoverable Zinc (120 µg/l) and Total Phosphorus (2 mg/l). Facilities are also required to conduct visual monitoring (recording their observations), annual monitoring and preparation and adoption of a SWP3 Plan.
Washington: Composting facilities in Washington are required to separate leachate from storm water; storm water running off a compost pad is considered leachate. “Compost facilities here usually require an Industrial Storm Water NPDES permit,” said Chery Sullivan, a composting specialist with the Washington Department of Ecology. “Washington has been delegated to run EPA’s NPDES permit program and is authorized to administer the Industrial Storm Water NPDES in lieu of EPA’s Multi-Sector permit.” She also noted that most facilities manage storm water onsite through detention and infiltration or discharge storm water offsite under a permit. “If they manage storm water onsite, they may not need a permit,” Sullivan said. “Depth to groundwater, runoff volume and risk of contamination all play a role in the determination of needing a permit for those who retain storm water on site.”
Wisconsin: In Wisconsin, leachate is regulated and is required to be segregated from storm water. “Leachate treatment is required to a varying extent depending on the facility,” said Gretchen Wheat, an engineer with the Wisconsin Department of Natural Resources (WIDNR). “It depends on waste types, facility size, location factors, etc. Berms, ditches or other means must be used to prevent run-on of noncontact storm water. Leachate includes water that comes in contact with materials in the composting process.”
Brad Wolbert, a hydrogeologist with WIDNR’s, Bureau of Waste and Materials Management, has recently taken the lead on solid waste composting. Wolbert explained, “Solid waste composting facilities with feedstocks limited to certain source segregated materials are regulated by s. NR 502.12. The rule is mainly for yard materials and vegetable food waste composted by low tech methods. Composting facilities that are small or have lower nutrient materials can generally discharge leachate or run off to a vegetated filter strip area. Facilities that are large or have higher nutrients need to capture leachate, and the rule specifies two management options: recirculate into the composting process, or discharge to permitted wastewater treatment facility. Potentially leachate could be discharged to a wastewater treatment strip, but a WPDES Permit may be required, and an applicant would need to demonstrate the effectiveness of any proposed treatment option. Composting of other feedstocks is regulated by s. NR 502.08, Wisconsin Administrative Code, a more generally written rule that allows flexibility to address processing of various solid wastes by any method shown to be environmentally sound.”
Wolbert went on to note, “Storm water from a compost pad is considered leachate, and a curing pad is considered a compost pad. So, runoff from curing pads is regulated under the same authority, but different (less) treatment might be needed. Product storage piles may also be regulated under the same authority, but again, required treatment would be less.”
Wheat added, “A starting place to guide compost leachate treatment design might be Natural Resource Conservation Service (NRCS) Standards 635 Wastewater Treatment Strip, 393 Filter Strip and 590 Nutrient Management. Treatment strip design commonly includes capture of more concentrated initial flow. However, manure has much higher nutrients than expected in compost leachate, so I’m not suggesting to directly use NRCS Standards.”
Craig Coker is a Contributing Editor to BioCycle and a Principal in the firm of Coker Composting & Consulting in Roanoke, Virginia (www.cokercompost.com). He can be reached at (540) 904-2698 or by email at firstname.lastname@example.org.
May 20, 2008 | General
Storm Water Management Regulations
BioCycle May 2008, Vol. 49, No. 5, p. 39