As is well known, pyritic slate (acid generating rock) is common to the area and has been an on-going problem in Halifax and throughout Nova Scotia, causing major recent projects to halt and cost millions of dollars more than projected costs. “Acid rock drainage, once it appears, is virtually impossible to reverse and with the current technology, its treatment can cost millions of dollars and go on for centuries (Feasby and Tremblay 1995; Jennings et al. 2008).” The site, as per the proponent and scientific mapping, contains Goldenville Formation.
The proposed site is also near the border of the Halifax Formation, the highest-risk acid-generating rock, and is possibly in an area called the Goldenville-Halifax Transition (GHT) zone, which has not had as much study except to find that this is a distinct area with abundant sulphides and high concentration of metals. The transition zone has only been mapped in SouthWest Nova Scotia, and not in the Halifax area. However, in all mapped areas of transition zones, the risk is moderate of acid-producing potential. Recent articles have shown the GHT zone is 800m in one area studied in Southwest Nova Scotia, and that previous maps of the boundary between the Goldenville and Halifax formations were inaccurate by 500-1000m. Other researchers found that the “boundary between the Goldenville and Halifax formations [was located] at the highest exposed bed of quartzite in the Goldenville.” The transition zone is thought to be up to half a mile wide.
Because of the damage caused by acid rock drainage, Nova Scotia developed regulations, some portions of which are quoted below.
6 (1) Where a developer of any proposed development knows or ought to know that the proposed development will involve the physical disturbance or disposition of aggregate in a measure greater than 500 m3 in situ or 1300 tonnes and which contains a sulphide bearing material, the developer shall immediately notify an Administrator of the proposed development.
(2) The developer identified in subsection (1) shall supply an Administrator with a map number and grid reference (1:50 000 map series) that identifies the location of the proposed development.
7 (1) Unless exempted under Section 5, a developer shall
(b) take two samples that are representative of the lands to be developed for each hectare or part thereof to be developed;
(2) A sample provided under subsection (1) may be taken by
(a) the test pit method at 0.5 m intervals for the first 2 m depth of sulphide bearing material and thereafter at 1 m intervals to the depth of the proposed excavation site;
(b) the core method with the sample being split along its axis half and the core analyzed along its entire length; or
(c) the trenching method with the sample being analyzed along its entire length.
One test result was included in the application. One. It was from outside the proposed footprint. When the footprint moved and changed shapes between applications, the sample analysis didn’t change. It does not say how deep the sample was taken. The regulations state TWO samples that are REPRESENTATIVE for each HECTARE. For a 3.9ha quarry, that’s 8 samples. In several places in the application the word “samples” with an “s” is used, samples, the plural of sample. But only one test result was given. Does not inspire confidence in us that the proposed quarry site does not contain acid-generating rock. The solution Scotian Materials provides for if/when they come across the slate of the Halifax Formation? Toss it aside.
Consider the following quote from a scientific article, regarding land adjacent to the proponent’s property:
One of the earliest and most extensively studied sites associated with ARD [acid rock drainage] in HRM involved the construction and subsequent expansion(s) of the Robert Stanfield International Airport (previously referred to as the Halifax International Airport). Here a direct correlation was demonstrated between construction activity in the Halifax Group and significant fish kills in the nearby Shubenacadie River between 1960 and 1976 (Pasava et al. 1995; Worgan 1987). Remediation and treatment costs have averaged one million dollars annually at the airport, and treatment of surface waters continues (Hicks 2003).
This type of rock is such a concern to Nova Scotia that it has been included in provincial legislation, with specific regulations required for its disposal. Nova Scotia Environment employees must insist the proponent follow ALL Nova Scotia Environment regulations for rock-testing for acid-generating potential. Note also that the proponent refused to provide the scientific names of rocks found on the site when requested by legal counsel for our community group. This could be an attempt to conceal the fact that there is slate on the property, which is an indication of rock with acid-generating potential.
The Environment & Sustainability Standing Committee of Halifax directed that rather than test the rock itself for sulphide sulphur percentage when extracting within the Halifax Formation, which can be inaccurate, “the prudent approach… is to assume the rock is acid generating, unless extensive testing at the time of construction is able to demonstrate otherwise.” Wouldn’t that be a prudent approach considering the sensitive area and the moderate-risk potential of acid-rock drainage in the transition zone?
From the Scotian Materials website, the proponent concludes the site will not produce acidic water because one of the nearby neighbourhoods can drink well water:
“The groundwater resources in the area were previously studied by T. Lay and Nolan, White & Associates (1979). This study reports that groundwater from the Goldenville Formation is generally considered good drinking water quality but, may contain elevated concentrations of iron, manganese and arsenic and may have low pH. Therefore, it is assumed that the water quality of the domestic wells at Miller Lake West is generally of acceptable quality and meets the Nova Scotia Department of Environment potable water standards as well as the Canadian Drinking Water Quality Guidelines with potential treatment requirements for hardness, iron, manganese and arsenic.”
Wait a minute, the Goldenville Formation produces groundwater with low pH? That was supposed to be a cue to Scotian Materials to follow the regulations, and Nova Scotia Environment to ensure they were followed. Employees at Nova Scotia Environment should ask why the proponent is assuming anything after citing a source that states the rock type produces acid,
The Environment Act of Nova Scotia makes clear that Nova Scotia Environment is the lead agency to define contaminants and regulate wastes and acid-generating rock. From the Nova Scotia Environment website: “Environmental Assessment Regulations under the Environment Act require that undertakings which disrupt a total of two or more hectares of any wetland must undergo an environmental assessment… High priority sites will include those in watersheds and regions where wetland loss has been high and ecosystem services or functions are below thresholds necessary to maintain watershed health.”
Even if the rock on the proposed site is found to be not acid-generating, the acid-rock drainage and acidity levels of nearby watercourses are still at issue. The Halifax Airport site continues to degrade the water nearby. According to Fox, Robinson and Zentilli (1997), in the headwater region for the Salmon River watershed just south of HSIA, acid rock drainage is treated with lime but only about 50% gets treated, and “untreated ARD bypasses the treatment facility through a stormwater interceptor drain and through groundwater leakage… Lund et al. (1987) estimated approximately 16,000 kg/year Al and 250,000kg/year acidity by-pass the treatment facility and discharge directly into McDowell Brook.” One of the remediation efforts near the airport has been to install an artificial wetland vegetated system. It stands to reason, then, that given the proximity to the airport, the Halifax Formation, and its location in a watershed, the proposed site should be studied to determine what effects the wetlands in this area may have on improving the quality of water that drains from the HSIA site or other nearby areas of the Halifax Formation and into this area. In addition, Arnold (2004), found that rock in the GHT zone, while falling below the threshold for being considered acid-generating, and while being of neutral pH itself, still had potential to lower the pH of freshwater to as low as 3.9, a level at which fish are killed and undesirable species of plankton and mosses begin to grow. As stated previously, we did water testing ourselves and Holland Brook is already at a dangerously low 4.5pH. It will not survive further lowering of the pH.
Member of the Nova Scotia Road Builder’s Association Robert MacPherson. Scotian Materials Limited. Rob MacPherson. Contact. Address: 100 Venture Run, Suite 103. Dartmouth. #scotianmaterials scotianmaterials.com scotianmaterials.info scotianmaterials.ca Halifax quarry quarries aggregate gravel #noFRquarry Scotian Materials Ltd.