Brine – Alton Channel and the Shubenacadie River
During construction of the caverns, brine will be released into a constructed channel connected to the Shubenacadie River where it will mix with the tidal (brackish) river water to maximize dilution.
The requirements of our monitoring program with the Nova Scotia Environment, Environment Canada and the Department of Fisheries and Oceans will ensure that the related brine will not impact the ecosystem of the Shubenacadie River.
The flow of tidal water at the mouth of the Shubenacadie River is approximately 55 million m3 with each tide. During peak production, the release of brine on each tide will be approximately 5,000 m3. All organisms living in a tidal river are accustomed to a range and quick changes in salinity. The diluted brine that will be released into the tidal river will be within the range of salinities normally experienced in the river.
There will be a slight increase in salinity levels at the discharge site, but within a few meters of the discharge site the salinity of the river will return to natural levels. Environmental studies have shown that the slight increase in salinity is insignificant in terms of the natural fluctuation of salinity, which the river's biological community is subject to on each turn of the tidal cycle. The amount of actual salt released into the Shubenacadie River will represent only 0.095% of the total salt in the river – a small fraction of its total salt concentration.
Several alternatives for discharging the brine were considered, including underground injection of the brine, selling brine to salt producers, supplying brine for winter maintenance of roads and producing salt. Following discussions with several third parties, including salt producers and Nova Scotia Department of Transportation and Infrastructure Renewal, these commercial options were not found to be feasible as a brine disposal option. As part of Alton's hydrocarbon storage-area lease with the Province of Nova Scotia, we are currently not permitted to trade, sell or give away the salt. We are willing to work with the provincial government should a feasible alternative use for the brine be identified.
The underground salt formations that will be diluted to construct the gas storage caverns are essentially pure sodium chloride (salt). The formation was created by ocean water evaporation approximately 330 million years ago and there are very few other elements found in the salt formation. For more detailed information on the element levels in the brine discharge and in the tidal Shubenacadie River water see Table 1.
Table 1. Element levels (ug/L) detected in a sample of the salt core dissolved in distilled water to 26ppt compared to those detected in the Shubenacadie tidal river water. Canadian water quality guideline limits for the protection of aquatic life are included.
|Salt Core dissolved in distilled water||Shubenacadie Tidal River Water||Canadian Water Quality Guidelines|
|Elements||Units (ug/L)||Detected Levels||Detected Levels||(Freshwater/Marine) Limits|
|Total Aluminum (Al)||ug/L||ND||40,700||5-100/NA|
|Total Arsenic (As)||ug/L||ND||18||5-12.5|
|Total Antimony (Sb)||ug/L||ND||ND||160a|
|Total Barium (Ba)||ug/L||ND||258||4a|
|Total Beryllium (Be)||ug/L||ND||3||0.53a|
|Total Bismuth (Bi)||ug/L||ND||ND||NA|
|Total Boron (B)||ug/L||ND||860||750a|
|Total Cadmium (Cd)||ug/L||ND||0.2||0.017/0.12|
|Total Chromium (Cr)||ug/L||ND||22||8.9/56|
|Total Cobalt (Co)||ug/L||ND||13||23a|
|Total Copper (Cu)||ug/L||ND||14||2-4/NA|
|Total Iron (Fe)||ug/L||ND||55,200||300/NA|
|Total Lead (Pb)||ug/L||ND||36.4||1-7/NA|
|Total Manganese (Mn)||ug/L||ND||3,180||120a|
|Total Molybdenum (Mo)||ug/L||ND||ND||73/NA|
|Total Nickel (Ni)||ug/L||ND||25||25-150|
|Total Selenium (Se)||ug/L||ND||29||0.1/NA|
|Total Strontium (Sr)||ug/L||180||1,050||1,500a|
|Total Thallium (Tl)||ug/L||ND||NA||0.8/NA|
|Total Tin (Sn)||ug/L||ND||NA||73a|
|Total Titanium (Ti)||ug/L||ND||513||NA|
|Total Uranium (U)||ug/L||ND||1.6||26a|
|Total Vanadium (V)||ug/L||ND||35||20a|
|Total Zinc (Zn)||ug/L||ND||58||300/NA|
ND: Not detected, i.e., levels below detection level
NA: No level stipulated by the Canadian Council of Ministers of the Environment (CCME) or Environmental Restoration Division (ERD).
a: Toxicity Reference Value stipulated by the Environmental Restoration Division (ERD) of the US Environmental Protection Agency, used when no CCME guidelines exist.