The conservative assumptions behind Virginia water-discharge permits, says DEQ, reduce the odds of harming aquatic wildlife to fewer than three incidents in a thousand years.by James A. Bacon
Earlier this year Dominion Virginia Power was granted permits to drain water from coal ash ponds at its Bremo and Possum Point power stations, treat the water to remove heavy metals, and discharge the effluent into the James River and Quantico Creek. Citizens have understandable concerns. What limits did DEQ place on the heavy metals in the wastewater? How were the limits determined? And what assurances do Virginians have that those limits will safeguard the public health and the health of aquatic species?
In a nod to transparency, Virginia’s Department of Environmental Quality (DEQ) has posted the permits online. To get a flavor, you can view the Virginia Pollutant Discharge Elimination System (VPDES) permit for the Bremo Power station here. Unfortunately, that document is indecipherable to the layman. DEQ permit writers live in a world all their own, replete with jargon, acronyms, arcane regulatory procedures and complex statistical formulations that only DEQ, power companies and the environmentalist groups that sue them seem to understand.
Wondering how DEQ set the heavy metals limits listed in its permits, from arsenic and mercury to lead and selenium, I sat down recently with Fred Cunningham, DEQ’s manager-office of water permits, and Allan Brockenbrough, manager-VPDES permits. The two career DEQ employees walked me through the process. Because the Possum Point permit is under appeal, they did not address the coal-ash permits specifically. But they said that the procedures for apply to all industrial sites, including power stations with coal ash ponds.
The primary message they wished to convey is this: DEQ permits create an ample safety buffer. Accounting for just two of the conservative assumptions built into the process, say Cunningham and Brockenbrough, the chances of a scenario occurring that endangers either the public health or aquatic life are in the realm of thrice every thousand years. The incorporation of other conservative assumptions reduces that incidence even further.
Brockenbrough put it this way: “When you make one conservative assumption, and a second, and a third, and a fourth, they all build on each other.”
Virginia environmentalists active in the coal ash debate have not taken issue with the DEQ methodology, which they neither criticize nor endorse. Their main thrust has been to ensure that wastewater is monitored and tested with sufficient frequency and duration to make the public comfortable that Water Quality Standards are being met. Also, in the case of Possum Point permit, the Potomac Riverkeeper Network has appealed on the grounds that Dominion should employ Best Available Technology, even if the resulting water quality exceeds DEQ standards. If Virginia can reduce at reasonable cost the level of pollutants released into Virginia waters, even if they exist only in trace elements, why not do it?
By contrast, John Craynon, director-environmental programs at Virginia Tech’s Center for Coal and Energy Research, says, “Our standards are very conservative. … I think the DEQ has proposed a standard that is protective and does not put an undue burden on all of us.” Just because we are capable of detecting the presence of heavy metals in parts per trillion does not mean we should regulate them at that level. Trace amounts of these elements exist in the environment and organisms have evolved to co-exist with them. Compelling industry to reduce levels even further is an exercise in diminishing returns. “Is it worth it? Some would say yes. I do a running cost-benefit analysis in my head.”
The federal Environmental Protection Agency sets the legal framework for administering the Clean Water Act, and DEQ operates within that framework. Based on the latest scientific knowledge, EPA continually updates federal water quality standards for some 130 different constituents including heavy metals, organic compounds and pesticides known to pose a threat to the health of humans and aquatic creatures. It is DEQ’s job to apply these standards to specific situations when writing permits.
DEQ determines a safe level for each constituent (measured either in micrograms per liter, or parts per billion) for three criteria: acute (short-term) impact on aquatic organisms, chronic (long-term) impact on aquatic organisms, and human health impact. In the first of many conservative safeguards, DEQ applies the most restrictive of the three numbers, even if that level provides more protection than is deemed essential for the other two.
Another conservative assumption DEQ builds into its permits is its “return interval” — the period of time over which a one-time, worst-case scenario is evaluated. The Water Quality Standards approved by EPA allow for instream standards to be exceeded once every three years. DEQ uses a ten-year interval when setting standards.
As translated into the permits for Bremo, DEQ’s discharge limits will protect the river water outside a mixing zone no larger than 16 feet wide and 2,000 feet long (about 1/3 of an acre) in the worst drought scenario predicted for a ten-year period. The vast majority of time, the area within the mixing zone where pollutants exceed Water Quality Standards will be much smaller — at times undetectable — although DEQ does not calculate how large it will be in any circumstance except the 10-year, worst-case scenario.
To determine the maximum level of pollutants in a discharge, DEQ uses a computer model into which it plugs a wide range of variables. These include temperature, pH, ammonia, river flow, discharge flow, and, perhaps most unappreciated by the public, “hardness,” or the availability of calcium carbonate, which buffers the impact of many heavy metals on aquatic life. DEQ sets Water Quality Standards to protect biological traits of the stretch of water in question: not just the presence of presence of aquatic species but of fish eggs, larvae, and other early-stage life forms. Permit writers crank in the river/stream water flow at various critical levels and the maximum volume of discharge to determine the effluent limits needed to protect the stream.
Another conservative assumption DEQ uses to set limits is that Dominion (or any other permit holder) will discharge water at the maximum permitted level, even though discharges typically vary. Similarly, DEQ assumes that the discharges will proceed into the indefinite future, even though Dominion has stated that it will take only nine months to a year to drain the coal ponds, at which point there will be no more water to discharge.
Perhaps the most conservative assumption in DEQ’s analysis is a statistically derived assumption used to set the Waste Load Allocation for each constituent. In that procedure, DEQ must conduct a “reasonable potential” analysis, which determines whether a certain level of discharge water has a reasonable potential to exceed the water quality limit in the river or stream. DEQ assumes that the effluent concentration exceeds the value only 3% of the time and is below the value 97% of the time.
Combining that 97% criteria with a 10-year low-flow assumption creates a huge safety margin, says Brockenbrough. “We’re assuming an extremely high pollutant concentration and an extremely low river flow to evaluate a worst case scenario. If the instream water quality standard is exceeded under that extreme combination of events (which occurs 1/333 years) then ‘reasonable potential’ is assumed to exist and a limit is placed on the discharge.”
Cobble on the other conservative assumptions, and the risk of exceeding safe levels for aquatic health become improbably remote — once in four or five life-times — and the risk for exceeding human safety levels too small to be meaningful.
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