Gas plant image from Energy & Utilities Board documents filed by NB Power
The proposed 500 MW gas/diesel generating plant on the Chignecto Isthmus would not pose a threat to human health, according to a consultant’s report commissioned by the U.S. company PROENERGY.
“Basically what we found was that during the electricity generation mode, the project will emit some common air pollutants, but the levels that we’re predicting are below the levels associated with the health effects identified by the World Health Organization,” said Tania Noble, a risk assessor for the consulting company Stantec.
She was speaking Tuesday during a 90-minute, question and answer session organized by PROENERGY, the company that would build and operate the gas/diesel plant over 25 years.
The online meeting also heard from Stantec’s Jennifer McPhail that test wells showed there is enough groundwater to supply the gas plant’s needs, but that the water would have to be managed carefully, especially during peak winter months.
“What our study found was that there is enough water for the project on an annual basis,” McPhail said, adding however, that operational measures would be needed during peak periods to avoid the need to pump more water than the aquifer could sustain.
“What this means is that during periods when the plant is not operating, water could be pumped from the well and put into storage so that it’s available when it’s needed during those peak periods,” she said.
Health study
Tania Noble. Photo: Stantec
During her detailed presentation on health risks, Tania Noble explained that Stantec considered air emissions to be the main concern because there would be no hazardous wastewater from power generation and any solid wastes would be removed from the site for safe disposal.
She said the plant would emit nitrogen oxides, particulate matter, carbon monoxide, sulphur dioxide and ammonia only when it is burning gas or diesel to generate electricity, not during 85% of the time when its turbines would be spinning without burning fuel to provide stability to the power grid.
“For electricity generation, the base case or the expected case is a little over 500 hours per year,” she said. “So a very small percentage of the time.”
She added that the Stantec health study used about 2,700 hours per year in its modelling to build in an even greater margin of safety.
While she acknowledged that the modelling showed levels of particulate matter above World Health Organization guidelines, she said existing air quality conditions in the area are already above the WHO guidelines and the gas plant would add only a small incremental amount.
Noble said Stantec was recommending routine, air-emissions monitoring to ensure actual emissions match the study’s modelling predictions.
She also said a comprehensive groundwater monitoring plan is under development to protect residential well users, with commitments to address any effects on their water supplies.
When PROENERGY Canada President John MacIsaac was asked about a letter signed by about 130 scientists and academics opposing the gas/diesel plant partly on health grounds, he said the company commissioned the study assessing health risks even though it was not required under the regulations.
He noted that Stantec’s health impact assessment used a worst case scenario.
“It [the study] clearly articulates that there’s negligible to no human health impact, so the results actually in the report speak for themselves,” MacIsaac said.
Water study
Jennifer McPhail. Photo: Stantec
In presenting Stantec’s water study, Jennifer McPhail maintained it was designed to determine how much groundwater could be pumped from deep underground without affecting other users.
She said Stantec concluded that the aquifer could sustain withdrawals of about 416 litres per minute or up to 435 litres per minute for periods shorter than 30 days.
However, she acknowledged that during the cold months of January and February when the gas plant may need to meet peak electricity demand, it could require about 852 litres per minute or about double the sustainable level, but she said that on-site water storage tanks filled during periods of low demand could fill the gap.
The Stantec water study says that during “constant-rate pumping tests,” groundwater levels recovered gradually after the pumping stopped.
“The prolonged recovery response suggests that the aquifer does not rebound immediately following sustained pumping and that residual drawdown may persist for an extended period after shutdown,” the study adds on page 15.
“This response was considered in the interpretation of wellfield performance and supports the need to evaluate operational pumping rates, pumping duration, and recovery periods when assessing long-term wellfield sustainability.”
When McPhail was asked about the aquifer’s slow recovery, she said the answer would be more complicated than she could provide during the online Q&A, promising to post a written response later on the RIGS website.
Rte 940
John MacIsaac. Photo: PROENERGY
One question, addressed to John MacIsaac referred to the “poor quality of Rte. 940,” the road that leads to the proposed site of the gas/diesel plant:
“What actions will be taken to bring this highway up to a condition that will allow the heavy trucking that will occur during the construction phase?”
MacIsaac’s response:
“Our commitment to the local residents and to the local municipal unit and to the department of transportation is based on the fact that we recognize the condition of the road. We’ve done a baseline assessment of the road conditions. We’ve done a detailed video recording the condition of the road before any activity was commenced and we’ll take into consideration the condition of the road and the route that we select to travel the heavier loads,” he said.
“The heavier loads will use special equipment to move the heavier pieces across the road so that we mitigate and minimize the risk for road damage and our commitment to the local residents and to the department of transportation is to leave the road in as good a condition as we found it, if not better,” MacIsaac added.
“We’ll be specific on the route that we travel with pieces of gear and and we’re more than likely on the larger pieces to come in from the Shemogue end to minimize the amount of traffic through the community.”
Wildfire risk
When MacIsaac was asked whether PROENERGY had assessed the risks of wildfires that could affect the plant, he replied:
“What we’ve agreed with the provincial fire authority is that we would have the ability to connect to the tanks…and prioritise firefighting ahead of water storage. So there will be the ability to leverage two very large tanks for the unfortunate event or unplanned event of fire in the local area. So it will help support the local fire department in addressing water needs for localized firefighting.”
To read the Stantec human health risk assessment, click here.
To read Stantec’s water supply report, click here.
