This was correspondence written in response to a discussion where a legislative body wanted to ban the spread of natural gas brine of roads.
This issue needs to be looked at objectively as with any other decision making process regarding the management of wastewater. It means looking at permit limits or standards; in this case, specifically the role of standards for human health protection. Standardized values remove emotional subjectivity from the decision making processes and rely on scientific values. As with any issues that rely on science, there have been too many decisions are being made on emotion and not facts.
Impacts to Health are the Reason that the use of brine is questioned
As with any decision regarding chemical exposure and human health the principles of risk assessment need to be applied; in this case a simple exposure assessment should be included in the discussion. This part of the discussion has been largely ignored by people opposed to the spreading of brines.
An risk or an exposure assessment would seek to answer question posed by most people – What will be the impact of the brines on my health? In a more toxicological mind frame the question would be “what is concentration of the chemicals of concern at the point of ingestion? - And at concentration would there be an impact to health? The answer to this question should guide the conversation, instead on the abstract discussion on the “innate” toxicity of the produced water.
Travelling through the environment changes chemicals
If the brine is spread on the roads then the concentration should calculated after a fate and transport model is run to determine what the concentration of the chemicals would be at the point of ingestion (in this case a drinking water well). From the general discussion on this topic that has been prevelant at the informational forums, there is an erroneous assumption that the chemical concentrations of brine would NOT change from that in the produced water (average values can be found in various literature sources). This is categorically not true. This assumption completely negates the natural processes and the science behind environmental distribution, biodegradation, soil adsorption, volatilization and all the other physical and chemical reactions that these assumed “toxic” chemicals would have to go through before they enter into the groundwater and travel the distance(long or short) to someone’s water well where there is a potential of for consumption.
Common conclusions about gas brines ignore facts
Other issues not taken into account are,
- Dilution factor associated with the precipitation (snow) or ice. In some cases it can be as high as 500 to 1. This does not assume that dilution is a solution but a diluted solution has a better chance for the body to metabolize and eliminate efficiently.
- Biodegradation of some of the components that have the potential to be found in the produced water; for example the biocides and some of hydrocarbons (biodegradation natural or by ambient micro-organisms). Incidentally the same biocides are used in cooling towers and then ultimately discharged into surface waters.
- Volatilization of the dilute concentrations of some of hydrocarbons off the road surface.
If we used the kind of decision making process and thinking that is currently occurring with the misinformation circulating, then it would wrong for any type of permitted industry or manufacturing plant to release any type of chemical compounds to surface water because of the innate “toxic” nature of some of the chemicals contained in certain industrial wastewater streams. It would also be unacceptable for anyone to drink coffee considering how innately toxic caffeine is with a LD50 of about 200 mg/kg while the biocide DBNPA (used in hydraulic fracturing) has an LD50 of 290 mg/kg
If the question is the concentrations of the chemicals in the brine, then that would vary from source to source. How about using the worst case scenario to determine the potential health impact? Take the concentration of the most potent chemical of concern, its dilution off the road surface, biodegradation etc. and a person’s water well, 10 feet off the roadside and calculate the potential impact to get a better understanding of what really happens to these brine and road salt once it is spread on the roads.
Some interesting reports
This one titled: An Investigation of Naturally Occurring Radioactive Materials (NORM) in Oil and Gas Wells in New York State April 1999 and revised in 2004.
“While NORM-contaminated equipment has been a concern in North Sea oil well drilling, the results of this investigation show that NORM contamination of New York State equipment is insignificant. New York State well drilling equipment and wastes do not constitute a health risk for the State’s residents nor present a potential degradation of the State’s environment.”
Granted this report did not address shale brines but it looked natural gas brines in New York State. It used (7.4 pCi/g) resulting 3 mR/year as the worst case scenario and found it to below the 10mR/year standard in from the TAGM.
Information on the Quantity, Quality and Management of Water Produced during Gas Production
“The quality of produced water from oil and gas production is generally poor, and in most situations, it cannot be readily used for other purposes without prior treatment.”
Does not discount uses but recommends prior treatment. This Committee discounts all use.
Has some interesting facts on brine usage in Michigan albeit it old information
This correspondence does not agree with or disagree with the use of brines on the county’s road, all it does is present some of the logical thought that goes into determining whether a chemical (brine or road salt) would have an impact on human health of not.