On Nov. 10, 2011 National Public Radio ran a story (http://www.npr.org/2011/11/10/142183546/epa-regulations-give-kilns-permission-to-pollute) by journalist Howard Berkes and associates about the Ash Grove cement kiln in Chanute, Kansas. They did a fine job of describing the pollution issues and the community conflict surrounding this facility that burns hazardous wastes. This article is intended to examine how these issues can be resolved to protect both the environment and public health.
The NPR story identified two areas of particular concern, emission of large amounts of mercury and a “higher than expected” level of hospitalizations of children with asthma. The KDHE & EPA are currently conducting a program of environmental testing at the site. USEPA Region 7 Administrator Karl Brooks stated in the NPR piece that he thought these new tests would allay the concerns in the community.
Probably not. The testing program fails to address the fundamental problem with the facility, ie. it is equipped with pollution controls that do not adequately control toxic gases, especially mercury and hydrochloric acid gas (HCL). The facility is equipped with a relatively new fabric filter/baghouse that should provide adequate capture of particulate matter if properly operated and maintained. It also has a fairly tall smoke stack (414 feet) that should reduce deposition onto the nearby central business district of Chanute.
The trouble is, mercury and HCL are vapors at the temperature in the baghouse and will go right through the fabric filters after exiting the combustion chamber. EPA’s technical support documents acknowledge that mercury is uncontrolled at this type of facility. The EPA documents also state that cement kilns burning hazardous wastes do not consistently control HCL and chlorine gas emissions. Indeed, the EPA’s Toxic Release Inventory shows that the Chanute facility was emitting about a 100 tons per year of HCL from 2004 to 2007, which is within the 2003 to 2008 period where KDHE’s screening study detected an excess of asthma hospitalizations. Much of the wastes burned at the site are solvents and other materials consisting of chlorinated compounds.
The meaning of the KDHE data is subject to debate, and the Ash Grove facility may or may not have something to do with the asthma cases. However, it is hard to ignore emissions of 100 tons per year of a highly reactive chemical like hydrochloric acid gas.
KDHE’s current site study consists of two principal elements: (1) hourly monitoring for particulates in the air, in and near the town, and (2) a set of tests for contaminants in Village Creek that runs though the facility. By monitoring only for particulate air emissions, KDHE is mainly scrutinizing the strongest component of Ash Grove’s pollution control system, not the weakest.
EPA has noted that HCL is “not consistently controlled.” Even though a substantial portion of the HCl may be routinely neutralized in the kiln combustion process, it is possible, indeed likely, that there are times when it is not. Asthma attacks may be triggered by such discrete, periodic pollution episodes. The only way to prove that the large emissions of HCL are not causing the asthma problem in the community is to install a continuous HCL monitor. Readily available for such an application, this monitor would need to be used over an extended period of time to include when cement production and waste burning are occurring at full capacity.
The Village Creek testing program includes some tests of fish tissue. Fish contamination is the pathway of highest health risk for mercury. However, KDHE’s program misses the mark entirely. First, the fish will be gathered within five miles of the plant. Mercury will fall that close to the plant or upstream only when it is raining. Otherwise, gaseous mercury typically travels hundreds of miles before being washed out by rain or falling as dry deposition after undergoing certain reactions in the atmosphere. Secondly, the highest concentrations by far are found in the fish at the top of the food chain like bass or walleye. It’s highly unlikely that KDHE will find any bass in Village Creek.
I asked KDHE why they didn’t take some fish samples from lakes in the area, and they cited their existing statewide monitoring program, noting it does not reach onto private property. The nearest large lake (Santa Fe Lake) was last sampled in 1996. A series of samples from the Mined Lake Wildlife Area did find some largemouth bass with a contamination level exceeding the threshold of concern. In general, however, there are far too few samples being obtained in SE Kansas to draw any definitive conclusions. It is not clear why KDHE doesn’t just ask permission from landowners who should be anxious to know if fish in their lakes are contaminated.
Regulators may say that such testing is unnecessary because they have conducted health risk assessments (HRAs) on the chemicals they are not regularly monitoring. HRAs are very complex computer models based on a chain of assumptions that may or may not be sufficiently valid. It is also very difficult to validate these models with actual measured results. Site specific application of these models for mercury emissions are generally a waste of time since mercury emissions are regional and national-scale pollutants. A 2009 EPA report testing fresh water top-predator fish found that 48% had levels in excess of the 0.3 ppm level of health concern. This means that mercury levels in fish in most of the country have already reached the threshold of harm.
Lakes and rivers are affected by hundreds of different sources, so the only logical approach is to tightly regulate all significant sources of mercury across the board. That is in fact what EPA has been doing, with the curious exception of cement kilns that burn hazardous waste. NPR was not able to get a straight answer from USEPA as to why they are not more tightly regulating cement kilns such as the Ash Grove unit in Chanute. When I inquired of USEPA headquarters, I was told that somebody from ORCR (staff that regulate hazardous waste) would get back to me. They never did.
Ash Grove and other cement manufacturing companies that burn hazardous wastes in their kilns have at least three options to significantly reduce their mercury emissions:
1. They can place tighter limits on mercury concentrations in the hazardous wastes they accept for disposal and on the amount of waste they burn. That would have the beneficial effect of forcing waste generators to use higher quality chemical inputs to their operations or substitute materials that do not contain as much mercury.
2. They can inject special adsorbents into the flue gas upstream of the baghouse. For example activated carbon powder is a proven process that readily captures gaseous mercury compounds.
3. They can add on a wet scrubber downstream of the baghouse. Wet scrubbers are very effective in removing soluble toxic gases like mercuric chloride and HCL.
Cement manufacturers may object that these changes will taint their product or interfere with their manufacturing process. For example, they typically recycle some of the dust captured in the baghouse or electrostatic precipitator back into the kiln process. Such an objection would merely confirm one of the main points in the NPR story, that cement kilns are designed to make cement, not burn hazardous waste. EPA technical support documents note that several cement kilns in the country, that do not burn hazardous waste, are equipped with wet scrubbers. Thus it must be a feasible alternative.
The industry may also object that these measures will raise their costs. We hear this all the time from industry. An HCL monitor wouldn’t be a big deal. Capturing mercury probably would involve a significant cost. But the costs are already out there in terms of impacts on health and environment. They just aren’t being incorporated into the product costs of the waste generators. It is time that they were.
By Craig Volland