Chloride
West Virginia has existing water quality standards for chloride (using those from a 1988 US EPA study)1 and its General Water Pollution Control Permit2 (hereafter called General Permit) for oil and gas waste disposal by landspraying has chloride concentration requirements.
Chlorides have a number of biological and non-biological effects. Chloride is persistent (chlorides take the form of sodium chloride, calcium chloride, magnesium chloride or potassium chloride) and doesn't degrade.3 Chloride ions pass readily through soil and will eventually enter surface water. Because chloride moves through soil at the same rate as water it shares the same hydrologic cycle as water. This means chloride deposited on soil's surface can also enter ground water.4
Chloride mobilizes heavy metals such as cadmium and can act as a transport helping to deliver these metals to surface or ground water. This is one of the two major non-biological effects of chloride (though these metals can have a profound biological effect).
Another effect of chloride is how it alters the density of water. This means that for lakes and ponds, when enough chloride is present, intermixing of water layers won't occur. Chloride concentrations can become quite high at the bottom layer and wetlands are most vulnerable.
When delivered to soil as sodium chloride serious negative effects to soil structure occur. These effects are persistent since the sodium ion will remain in the soil when the chloride ion leaves with water.
Sodium chloride is inhibiting to soil bacteria at about 50 mg/l. High concentrations of chloride will damage or kill leaves or buds when delivered as a spray. Concentrations first will affect sensitive vegetation and trees (such as beech). High enough concentrations will sterilize soil and prohibit any growth.
Adverse effects have been noted when sodium chloride is applied to roots at 280 mg/l or greater concentration. Vegetation will start to show the effects of sodium chloride spray at 1,000 mg/l. Pine mortality has a threshold of 13,000 ppm chloride. Our discussion below will focus on the state's program of landspraying liquid oil and gas well pit waste which can have very high chloride concentrations. While the intent is, by landspraying only on vegetation, to deal with chloride through plant uptake, it's hard to see how the program can be effective if the vegetation is killed. Sodium chloride is a registered herbicide.5
Chloride in water adversely affects some species of plankton at concentrations as low as 12 mg/l. The 1988 EPA study used chloride's toxic effects on three aquatic species (rainbow trout, cladoceran and flathead minnows) to develop criteria for water quality.6 The EPA determined that a chronic 4 day average concentration of not over 230 mg/l chloride once every 3 years is acceptable. An acute concentration of 860 mg/l chloride for a period of 1 hour average not more than once in 3 years is also acceptable. These are West Virginia's criteria. Other researchers have found that the EPA's acute concentration is possibly too high and 638 mg/l should be considered instead for water quality standards.7 The 1988 EPA criteria are perhaps not protective enough for aquatic vegetation and 200 mg/l has been suggested as a better chronic concentration (Siegel, 2007, page 14). Iowa Department of Natural Resources proposes a formula for acute and chronic concentrations of chloride.8 The formula includes hardness and sulfate concentrations since the harder the water is, the less toxic chloride will be. Sulfate has an inverse function (Iowa DNR, 2009, Table 2, page 5).
Chloride's mobilization and transport of heavy metals is especially troubling within an aquatic environment. Cadmium is toxic to rainbow trout at 1 part per billion. Chloride at 709 mg/l has been shown to release mercury from marine sediments. "Sodium chloride also enhances mercury mobilization from soils" (Environment Canada, 2001, page 80).
We've observed standing water at a well site with an elevated chloride concentration of 113 mg/l harboring tadpoles and frogs coexisting with insects and vegetation. We couldn't directly observe negative effects but some species are halophilic and we might not be noticing a shift of species to those that can withstand higher chloride. We've also seen standing water with much higher concentrations (over 650 mg/l chloride) with no signs of life or vegetation.
What we have noticed at well sites is where we find elevated concentrations of chloride (142 mg/l and higher) from brine or drilling waste there are numerous deer tracks.9 When the location is a closed drill waste pit with a large number of tracks and the concentration is over 650 mg/l chloride these animals are exposed to not just the chlorides which they seek out but also other chemicals, some extremely toxic. Sodium chloride can be toxic to animals at concentrations over 1,000 mg/l (Siegel, 2007, page 5).
Studies have shown chlorides, when ingested in significant quantities can be deadly to some birds (notably members of the finch family). For both birds and animals like deer that seek out chloride and the minerals associated with it, chloride can have a stupefying effect, altering behavior around vehicles and people.10
Footnotes:
1Environmental Protection Agency, 1988, Ambient Water Quality Criteria for Chloride -- 1988. Fuller bibliographic information and URLs appear under Sources.
2West Virginia Office of Oil and Gas, General Water Pollution Control Permit. GP-WV-1-88.
3We've tried to be precise in our language. Chloride refers specifically to the chloride ion; chlorides are chemicals made up of 2 ions, one of which is chloride. Sodium chloride is the commonest form found in wellfield waste. When sodium chloride concentrations are given, about 60% is the chloride ion. This means 1000 mg sodium chloride/l is roughly equivalent to 600 mg chloride/l.
4Much of the description of chloride and its action, which appears below, is from Environment Canada, 2001, Priority Substances List Assessment Report, Road Salts.
5Lori Siegel, 2007, Hazard Identification for Human and Ecological Effects of Sodium Chloride Road Salt, page 10.
6The EPA study used sodium chloride. Potassium, magnesium or calcium chlorides can be more toxic (page 2).
7Iowa Department of Natural Resources, 2007, Draft Ambient Aquatic Life Criteria for Chloride, pages 6-7.
8Iowa Department of Natural Resources, 2009, Water Quality Standards Review: Chloride, Sulfate and Total Dissolved Solids, page 62
9George Monk and Molly Schaffnit, 2009, Environmental Assessment for 47-039-02026, Raymond City #6, in Kanawha County, West Virginia. See also Campbell, Tyler A., et al, 2004, "Unusual white-tailed deer movements to a gas well in the central Appalachians." Wildlife Society Bulletin 32(3), pages 983-986.
10Environment Canada, 2001, page 116. See also Don Bleitz, 1958, "Attraction of Birds to Salt Licks Placed for Mammals," The Wilson Bulletin, March 1958, 7(1), page 92.
Sources:
Bleitz, Don. 1958. "Attraction of Birds to Salt Licks Placed for Mammals," The Wilson Bulletin, March 1958, 7(1).
Campbell, Tyler A., et al. 2004. "Unusual white-tailed deer movements to a gas well in the central Appalachians." Wildlife Society Bulletin 32(3), pages 983-986.
Environment Canada. 2001. Priority Substances List Assessment Report, Road Salts. Environment Canada, Health Canada.
Environmental Protection Agency. 1988. Ambient Water Quality Criteria for Chloride -- 1988. Environmental Protection Agency, Office of Water, Regulations and Standards, Criteria and Standards Division, EPA 440/5-88-001.
Iowa Department of Natural Resources. 2009. Water Quality Standards Review: Chloride, Sulfate and Total Dissolved Solids.
Iowa Department of Natural Resources. 2007. Draft Ambient Aquatic Life Criteria for Chloride.
Monk, George and Schaffnit, Molly. 2009. Environmental Assessment for 47-039-02026, Raymond City #6, Kanawha County, West Virginia.
Siegel, Lori. 2007. Hazard Identification for Human and Ecological Effects of Sodium Chloride Road Salt. New Hampshire Department of Environmental Services, Water Division, Watershed Management Bureau.
West Virginia Office of Oil and Gas. General Water Pollution Control Permit. GP-WV-1-88.
What Happened at Fernow
Landspraying
Fernow Experimental Forest
Discharge Monitoring Report
Chloride Load
SAR
Liming the Pit
A Short History of Fracturing
Fracturing Chemicals
What Happened at Fernow
Recommendations & Sources
Gas Well Study is the examination of natural gas wells in West Virginia.
Underground Injection Control Class 2 Wells
These wells are used either for the disposal of oil and gas liquid waste or for the enhanced recovery of oil or natural gas.
Gas Well Study Site Visits
Annual reports, environmental assessments, and individual well information.
YouTube Videos
Select videos from the Gas Well Study YouTube channel.
What Happened at Fernow
An investigation into what caused the vegetation death in the land application area after landspraying hydraulic fracture flowback waste.
The Spill at Buckeye Creek
An investigation into a spill from a Marcellus well site into Buckeye Creek in Doddridge county.
The Details
Plunger Lift Technology on Gas Wells
Fluids Brought to the Surface during Production
Plugging a Well
How To Read a Lab Report
Information the Completion Report Provides
Casing and Cementing