SAN TAN VALLEY — The Arizona Department of Environmental Quality has begun investigating the Johnson Utilities plant off Hunt Highway in response to a high volume of complaints of odors coming from the plant.
ADEQ visited the area on three occasions since Jan. 20. In a letter to residents who filed complaints, ADEQ said that although odor was noted and the wastewater treatment plant was “out of compliance,” that “based on the current data, no adverse health effects (i.e. decreased respiratory function) are expected among the exposed population. Some people may smell unpleasant odor and feel discomfort at the detected levels.”
Discomfort, in this instance, means physical symptoms such as headache and nausea caused by hydrogen sulfide effects on the body, beyond the discomfort induced by the sensation of a foul stench.
“You may feel discomfort? That’s a health issue,” said Matt O’Connell, who lives near the plant and has organized a group of concerned residents called The United Citizens, Clean Air Clean Water.
O’Connell said that symptoms of physical discomfort caused by the odor and the presence of hydrogen sulfide are a cause for concern that is not being adequately addressed given the symptoms being reported by residents.
An Arizona Department of Health Services toxicologist analyzed data provided to ADEQ by the Pinal County Air Quality Department and determined that based on that data, the residents should not experience adverse health effects.
However, according to the table of human health effects used by ADEQ, exposure to hydrogen sulfide at the level between 0.01 and 0.6 ppm can cause “increased eye symptoms, increased nausea, increased headache, mental symptoms, diseases of the nervous system and sense organs.”
On Jan. 14, hydrogen sulfide levels exceeded county regulations (0.03ppm) and the California EPA regulations, which are set to protect against odor nuisance and physical symptoms, at 0.063 ppm for an hour average. ADHS reports concluded that therefore “some people may smell the odor of H2S (hydrogen sulfide) and experience some physical symptoms such as headache and/or nausea. Hydrogen sulfide odor is readily detectable by humans at very low concentrations.
“Yet, direct health impacts such as decreased respiratory function was not likely to occur among the exposed residents because none of the 24-hour average concentrations exceeded (the Agency for Toxic Substances and Disease Registry minimal risk levels).”
However, levels have been recorded by the county as high as 0.23 ppm (July 16, 2016) and given the limitations of the county’s monitoring system and the properties of hydrogen sulfide gas, it is possible some residents have experienced higher levels of hydrogen sulfide than have been recorded.
During inspections on Jan. 24 and 25, ADEQ staff also observed violations of the requirements in the Johnson Utilities Section 11 aquifer protection permit, including overflowing and full basins, disposal of effluent in an unpermitted fashion and failure to keep required documentation on site. Treated water, not sewage, is overflowing out of the facility, but it still constitutes a violation. Staff observed evidence such as erosion in soil and plants grown that show the overflows had been occurring for an extended period of time.
ADEQ could not comment on what actions might be taken in response to the violations as the investigation is ongoing. They will be reviewing additional data collected by Pinal County’s recently added additional hydrogen sulfide monitors in the coming weeks.