By Tim Woodrow
We are rapidly approaching the one year anniversary of the publication of the U.S. Environmental Protection Agency’s (EPA) new regulations under Section 316(b) of the Clean Water Act for Existing Facilities and New Units at Existing Facilities. According to the EPA, the final rule affects 544 existing power generating facilities that withdraw more than 2 million gallons of water per day (MGD) from U.S. waters and use at least 25 percent of the water they withdraw for cooling purposes. The rule requires that the location, design, construction, and capacity of cooling water intake structures reflect the Best Technology Available (BTA) for minimizing negative environmental impacts.
Compliance with the rule requires all permit applicants to select an impingement compliance approach from seven options. Applicants with actual intake flows exceeding 125 MGD must first complete and file several study reports (§122.21(r9-12)) that will provide permit directors with the engineering, biological, and economic information necessary for an entrainment BTA determination.
|Hydrolox traveling water screens like the one in operation at Xcel Energy’s Wilmarth Station, Mankato, Minnesota, have very low associated O&M costs. Photo courtesy: Hydrolox.|
Following this determination, these applicants will then select their chosen impingement compliance approach from the BTA compliance options. The required studies, as well as the timely selection of a compliance option, will be a challenge for the industry, requiring the latest information on fish protection technologies (cost and performance); biological sampling methods and interpretation of results; and practical approaches and supporting information for assessing economic social costs and benefits.
Where Are We Now?
One of the fundamental requirements of the final rule is the parameters under which a plant must select a BTA to reduce the impact of impingement and entrainment. The timing of compliance also represents another major change from the draft rule.
Compliance is tied to the renewal application of a plant’s National Pollutant Discharge Elimination System (NPDES) permit. The 316(b) ruling provides a date (July 14, 2018) that dictates the timeline of compliance which all qualifying plants need to follow with regard to the renewal of their NPDES. Permit renewal is required every five years. Whether a permit is due for renewal before or after this date (or if it is working on an administratively extended permit) will determine the actions a plant must take over the upcoming period.
Plants will have to submit a host of reports to state agencies, including section 122.21 (r2-8) among others. For permit applications after July 14, 2018, plants that withdraw more than 125 MGD must submit application with the appropriate reports (section 122.21 (r9-12)).These reports will enable the permit director to understand both the social and economic costs and benefits that a selected solution may have. If renewal is due before July 14, 2018, a plant will negotiate a separate timeline for compliance.
In all likelihood, installing and optimizing traveling fish protection screens will be the lowest cost option for the majority of power plants. However, there is concern that operating traveling water screens whenever drawing water will dramatically increase operational and mechanical costs. This is where the industry may be missing an opportunity. While plants are preparing to submit their permit applications with the required data, they must ensure that they have studied the various BTA options from a mechanical performance perspective.
Currently, power plants operate their screens two to three times a day, about 20 minutes at a time, for a total of about an hour a day. Even with this reduced usage, they are still spending anywhere from $20,000 to $50,000 a year to keep the screens operating. Under the new rule, any time a plant turns on its water circulation pumps, it must also rotate its screens. In order to comply with the rule, then, these plants must now operate their screens up to 24 hours a day, seven days a week; this has many plant operators worried about costs.
The total cost of a screen is not entirely accounted for by its up-front capital expenditure. Operational and maintenance costs must also be added into this equation. Traditional screens are driven by large side chains which represent a large maintenance burden. A new screen technology has made it possible to eliminate this chain, making the screen nearly maintenance-free, which can dramatically lower maintenance costs, even when screens must run 24/7.
There are pros and cons related to each BTA, pre-approved and streamlined, and their associated costs and benefits.
Pre-approved BTA options include the use of an existing closed-cycle cooling system, or the installation of a new one. This can be very expensive to retrofit with costs ranging from $50 million to $300 million. Another pre-approved option involves the design of a cooling water intake structure that has an actual through screen velocity lower than 0.5 feet per second (ft/s), which would involve increasing the surface area of the screening system by a factor of two- to five-fold, an undertaking with significant associated costs.
The streamlined approach has a few options. The first option involves the installation of modified traveling water screens, perhaps the lowest capital-cost solution. Another streamlined option requires facilities to achieve an actual through screen velocity of 0.5 ft/s by increasing the screening area or via unit retirements. Additionally, the two streamlined options above can be combined to create an additional option for the streamlined approach.
The final BTA option requires facilities to maintain less than 24 percent mortality in aquatic life as a result of impingement. This option would require a plant to install modified traveling screens, as well as monitor and report their impingement mortality every month for the life of the plant-an option so tedious and expensive that most will not consider it.
316(b) Impact on Power Plants
Power plants have been approaching 316(b) in different ways. First and foremost, plants are assessing where they are on the NPDES timeline to determine the urgency of compliance and whether their facilities fall in the impingement or entrainment category. Plants with permit renewal deadlines that fall before July 14, 2018 will negotiate a separate compliance timeline, but those with permits due for renewal after July 14, 2018 will need to submit their data/reports and select one of the approved BTA technologies, as well as their entrainment solutions, if applicable.
After reviewing data from studies and analysis, some plants have already proactively installed fish screens and tested them for both aquatic protection and operating costs so that they have a clear understanding of the costs and work associated with living with traveling fish screens in a post-316(b) environment.
316(b) Impact on State Regulatory Agencies
Just as power companies and individual plants are assessing their positions and the workloads ahead of them, so too are state agencies. State agencies have been tasked with enforcing numerous new EPA regulations, including MATS and the Clean Power Plan under the Clean Power Act. Section 316(b) is just another regulation to be considered in this mix.
Response from state regulators has been mixed. Some regulators are only just getting up to speed on the regulation, while some are even proactively writing 316(b) regulation into their current NPDES permits. Others are asking the EPA for an extension beyond July 14, 2018. For the majority of states, the expectation is that the state permit writer will follow the guidelines as laid out in the rule. The relationship that a plant has with their local state permit writer will be crucial in determining the smoothness of the compliance process.
Where Do We Go from Here?
Plants are currently engaging in contracts with independent consultants to prepare the paperwork and conduct the studies necessary to submit their applications at the appropriate times.
As mentioned, the compliance schedule for facilities is driven by where their NPDES permit renewal date falls in relation to the July 14, 2018 deadline. All facilities are required to comply with one of the seven standards of impingent mortality.
Proactive plants will install test equipment ahead of their submission timeline to determine the most cost effective and reliable compliance option. With the modern technology available, plants will actually have the opportunity to reduce their operation and maintenance costs while meeting 316(b) compliance guidelines, depending on the BTA they choose.
Tim Woodrow is the U.S. Commercial Manager responsible for Hydrolox Water Screens