Could the lead, cadmium, arsenic, and other heavy metals in H-POWER ash ever reach such high levels that the ash is regulated as hazardous waste?
Absolutely, positively not.
That’s not to say the levels could not be high enough to justify concern over use of the ash in such applications as roadbeds, masonry, and landfill cover.
Nor is it to say that the metal content in the ash is always going to fall below the threshold of regulatory concern set in federal and state laws.
It is to say, however, that by definition, state regulations exempt H-POWER ash from being considered as hazardous waste, no matter how high the concentrations of such metals in either the ash itself or in the leachate produced when the ash is bathed with a mildly acidic wash, such as occurs in the standard Toxicity Characteristic Leaching Procedure (TCLP) test. (The acidity level of the TCLP wash is intended to be about the same as is found in landfills generally.)
According to Grace Simmons, head of the state Department of Health Hazardous Waste Section, the state regulations exempting H-POWER ash from consideration as hazardous waste have been in place since 1994. Simmons says the state regulations mirror federal Environmental Protection Agency language concerning ash from operations such as H-POWER, referred to in regulatory language as “resource recovery” facilities.
The EPA regulations were triggered following a U.S. Supreme Court decision in the spring of 1994. The case at issue involved ash from a Chicago trash-to-energy plant that flunked the TCLP test for lead, with one sample exceeding the EPA’s recommended action level for lead in drinking water (0.015 milligrams of lead per liter of water) by 100-fold.
For non-exempt materials, if a TCLP test shows lead concentrations in the leachate of at least 5 parts per million (more than 333 times the EPA action level for drinking water), the material is to be regulated as hazardous waste.
Low Standards?
The hazardous-waste standard of 5 ppm lead in leachate, even though it does not apply to H-POWER, has itself been criticized as overly lenient to polluters. As Peter Montague writes in Rachel’s Envirnment & Health Weekly of August 18, 1994, the TCLP test “does not identify the actual pollutants contained in the ash; it only identifies those pollutants that leach out under certain specific conditions. Since, sooner or later, all of the ash will be released into the environment (even ash that is monofilled), it is the total pollutant content that will affect communities, not merely what leaches out under TCLP conditions. Therefore, the TCLP test gives a misleading estimate of the ash hazard.” (Monofilling refers to the practice of placing ash in lined landfill cells intended to receive only ash. H-POWER’s ash is monofilled at the Waimanalo Gulch landfill.)
H-POWER is not required to measure the total lead content in its as a condition of its permit to operate. However, such tests have been done, most recently in connection with the desire of the City and County of Honolulu and H-POWER’s operator to see the ash re-used as landfill cover, building material, or in road construction. Under a contract issued by the federal Department of Energy’s National Renewable Energy Laboratory, H-POWER ash was analyzed for a number of different elements and compounds. One sample of combined bottom ash and fly ash found lead concentrations as high as 15,809 parts per million — in other words, the ash was 1.5 percent lead. For purposes of comparison, ash samples from a sister trash-to-energy plant in Connecticut, which were used as a control in the NREL study, had on average just 37 ppm lead. (The clean-up targets for lead in soils at Superfund sites are, by contrast, 400 ppm for residential areas and 1,000 ppm for industrial or commercial areas.)
Process Residue
In addition to ash, H-POWER produces what it calls process residue. This residue consists of glass, dirt, metal pieces, and other heavy materials, saturated with solvents and other wet wastes, that fall through a 2-inch screen intended to remove non-combustible items from the waste stream. A spokeswoman for Ogden Environmental and Energy, which operates the plant, told Environment Hawai`i that typically, 12 to 13 percent of the solid waste received by H-POWER falls out as process residue. Thus, on a day when 2,000 tons of waste are delivered to H-POWER’s front door, about 250 tons of process residue (in addition to 400 tons of ash) are taken out the back.
Much of this waste ends up being used to augment the daily cover at the Waimanalo Gulch landfill. Joe Hernandez, environmental manager for WMI, described how the residue is used: “Sometimes there are gaps and holes on the active face of the fill. When we have a homogeneous waste like this, it is used to fill the gaps in the daily face. Then after the face is smoothed out, we apply six inches of daily cover.” (Hernandez mentioned that “auto fluff” — the cushions, upholstery, and plastics removed from cars by metal recyclers — is also sometimes used to augment the daily cover.)
Under terms of H-POWER’s solid waste permit, the process residue must be tested periodically. Chemical analyses done in 1998 showed lead levels averaging 224.6 parts per million, with one sample showing concentrations as high as 650 ppm.
But once more, no matter how high the concentration of lead or other contaminant may be in process residue, it is exempted by state rules from regulation as hazardous waste.
— Patricia Tummons
Volume 9, Number 10 April 1999