A convergence of new environmental regulations and practical realities is creating a boatload of challenges for power producers. Impending regulations addressing raw water intake, wastewater discharges, and coal ash management—as well as issues such as drought, water scarcity, and public concerns and utility liabilities with ash ponds—are giving power plant owners much to consider. Add the fact that states are enacting their own, sometimes more-stringent requirements, and the horizon is anything but clear as utility decision-makers chart a course for compliance.
A Wave of Changes
Two anticipated regulations are of key concern to utilities operating coal-fired power plants:
- The U.S. Environmental Protection Agency’s (EPA) proposed regulations addressing coal combustion residuals (CCR) for electric generating plants.
- The EPA’s updated rulemaking for steam electric power generating industry effluent limitation guidelines (ELGs).
These issues primarily boil down to the need for either ash pond lining or replacement of ponds with wastewater treatment systems (for the first) and applying best available technology to treat flue gas desulfurization scrubber and other wastewater (for the second). The ELGs may also prohibit discharge of ash transport water, necessitating changes to plants’ ash-handling systems. Also on the horizon are changes to Sections 316(a) and (b) of the Clean Water Act, addressing power plant thermal discharge impacts and cooling water intake structure impacts on fish and other aquatic life.
Meanwhile, many power plant owners are facing, or already must meet, strict limits on contaminants in their plants’ wastewater discharges, primarily driven by regional water quality–based limits. As more receiving water bodies are listed as impacted or impaired due to metals, nutrients, or salinity, such limits will likely become more common and more stringent.
Don’t Wait for the Regulations
Prudence suggests doing more than treading water while awaiting the new regulations, the changes they will require, and the deadlines they will impose. Committing to specific modifications or new processes like zero liquid discharge (ZLD) too quickly, however, can be counterproductive, possibly resulting in overspending yet underachieving.
A good way to start is with the end in mind: Identify your specific goals—for example, complying with current and future regulations, reducing water use/increasing reuse, or closing ash ponds. Then gather the information needed to meet those goals. Next, fill any data gaps (using methods such as sampling and analysis, flow balance and mass balance, and modeling). Collecting data from multiple years will account for variability of coal composition and wastewater streams under different conditions and allow designs to reduce conservatism necessitated by lack of data. Finally, evaluate alternatives and make well-informed choices. Important screening criteria include compliance with current and pending regulations, long-term effectiveness and permanence, reliability, suitability for implementation, land availability, potential for adverse effects, and cost.
A practical approach to selecting cost-effective alternatives is to progressively evaluate their ability to meet the desired objectives, starting with the least costly alternative. For example, a first step might simply be to determine whether negotiating more-favorable permit conditions is possible. Once the best options are identified, conduct bench-scale or pilot-scale testing, if possible, to confirm that they work effectively under actual plant conditions.
This type of approach will help ensure cost-effective, sustainable solutions that address the myriad complexities inherent in coal composition and wastewater variability, water and wastewater treatment and reuse potential, CCR management options, and the flexibility to meet future regulations.
Plan to Be Flexible
Getting a jump on meeting upcoming regulations is a great start. Incorporating flexibility to meet stricter regulations in the future is even better. A Northeastern power producer, for example, decided to convert two coal-fired plants to tank-based wastewater treatment systems so it could close its ash ponds. CH2M HILL is working with the owner to meet its objectives and provide flexibility to accommodate expansion and the cost-effective addition of treatment for future trace metals limits. Anticipating that future discharge limits could necessitate additional, expensive treatment (such as ZLD), the system was designed to allow full effluent reuse in the future, eliminating virtually all of the nearly 8 mgd of wastewater discharge and reducing the size of any future ZLD system, if required, from over 10,000 gpm to 400 gpm.
For water scarcity issues, reuse of another type could be an option. In New York, the new Empire Power Plant’s water resource needs were matched with a nearby wastewater treatment plant, and a drilled pipeline was constructed to convey municipal effluent to the new facility. This effluent meets the power plant’s full process water needs, thus reducing freshwater consumption by up to 4,800 gpm. The WaterMatch Initiative (http://www.ch2mhill.com/ watermatch) promotes sustainable solutions like this by facilitating partnerships between alternative water sources and water users.
Go with the Flow
As the surge of regulatory change approaches, make the most of this “quiet time” to identify your goals, consider how you might meet them, and gather the necessary data. Starting now and taking a practical, comprehensive, forward-looking approach to compliance can help you keep an even keel as you meet the challenges of changing regulations in a changing world.
—Thomas Higgins, PE, PhD ([email protected]) is a technology fellow, vice president, and global technology leader of power water and process at CH2M HILL. This article was written in October 2012 prior to the then-anticipated December 2012 release of the EPA’s Draft Effluent Limitation Guidelines.