Water quality monitoring for mining sites in Ontario

by David C. Richardson • May 29, 2018
Forester Daily News

The most dramatic and identifying characteristic of water is that it is always moving. Even so-called standing water is never completely static; it’s either being drawn by gravity to seep down into the earth or being agitated by warmth at the surface to rise into the air as a vapor. Water finds its way into every space available and into plants and animals, which help it move about across the land, sea, and into the air. It finds its way into the full gamut of human activities as well, sluicing off in various directions, carrying a complement of whatever impurities or enhancements might have been imparted by the people who used it. The complex cycle circulates from the clouds to the sea and back again in a never-ending circle. Along the way, various obstacles, impediments, and conveyances influence its movement and each, in its own way, can have a considerable effect on water quality. Understanding the dynamics of water as it moves across surfaces impacted by commerce, industry, and habitation becomes a powerful and necessary step in managing these effects.

An Information Gold Mine
Tom Killingbeck notes that water quality for mining sites in Ontario (ON), Canada, where BluMetric Environmental is headquartered, is heavily regulated. As a hydrogeologist for the firm, Killingbeck finds himself working on water-quality monitoring and management programs for more than 100 sites at any given time. “The big thing is the chemistry of the water,” he says. “Under regulations, the mining companies are required to make sure the chemistry of the water leaving their sites is as good as the environment. You have to release it cleaner than what it was when it came in.”

The province operates “a huge sampling program,” he says. “If they find any spots where water doesn’t meet standards, they’re required to collect all of that water and treat it.” However, he says regulators are equally concerned with hydrology in areas affected by mining activities. “They want to make sure that if you’re doing a lot of dewatering that you’re not drying out the entire area. They also want to make sure that you’re not adding extra water to the environment,” which occurs through the excess treated water used in mining processes.

BlueMetric Environmental plays a key role by “collecting volume data for discharges and providing monitoring for an area.” On some projects, rather than focusing on the level of contamination, it’s the precise level of the water flowing across, through, or from a site that becomes the target for in-depth analysis.

Killingbeck says he recently worked on an active diamond mining project, monitoring dewatering operations to evaluate potential impacts on nearby creeks and the local environment. Dewatering involves potential risks from inadvertently siphoning out the water table from below while pumping out excess water from the working face of the mine shaft.

In cases where the level of contamination is already well understood, he says, the question of how much affected water is flowing from the site becomes predominant. It’s a question that often arises when evaluating historic and legacy mining sites that have ceased active operations. He says many such sites can be found in the US and Canada.

Sometimes the land surrounding these mines has been impacted by ore residues or remnants of process chemicals and, if sufficiently mobilized by stormwater, they can eventually discharge into receiving waters, leading to environmental degradation. The question facing managers is how much of a risk they pose. Answering that question requires precise, high-quality data.

Killingbeck says he relies on ­Greyline Instruments’ Stingray Level-Velocity Loggers. “We’ve been using them since 2000. We’ve had good luck with them. I get data back at 0.1% accuracy,” he says.

“I worked on an open-pit mine that was discharging water that was high in iron. The government wanted data on the historic location, and they wanted to know how far away they were contaminating. They were looking for the volume, and then they could then run the contamination tables,” in order to evaluate which areas might be at environmental risk from the escaping ore.

Killingbeck says he typically deploys the loggers at strategic points on creek beds. “It gives you two readings together—the velocity and the depth. The only other requirement is to obtain a cross-section of the stream [at the site of the reading].” With that information, he can perform a simple calculation revealing water volume passing through the location at any point in time.

“It’s a relatively low-profile probe, measuring just 1 centimeter, so it doesn’t perturb the flow while taking a reading. When I mount that to the bottom of anything, it’s not interfering with the flow.” To further ensure comparable data across sites, when possible, Killingbeck prefers to situate the loggers within infrastructure with a known dimension and flat base. When no such structure exists at the measurement site, he often constructs a portable steel sluice to embed in the stream. After securing the logger to the base, he lowers it to the streambed, sandbagging the perimeter up to the streambank on both sides to ensure the full volume of water passes through the homemade culvert.

In areas where the stream is too wide and too deep to install a temporary sluice, says Killingbeck, he takes advantage of bridge pylons and trestles to provide a uniform base for taking velocity measurements. On rivers too large or unwieldy for any of these strategies, after taking a cross-section from aboard a small craft, he simply positions the boat mid-channel, mounts the logger to a steel plate, and lowers the assembly to the bottom, ready to transmit flow-volume data via cable to the data collection logger housed in a rugged case on shore.

“If I didn’t have the Stingrays, we’d have to manually go out with a flow meter and get a flow curve,” a prospect he says risks introducing various human errors into the raw data. With the Stingray, the only onsite staff needed is for making the initial placement of the device, periodic visits to download readings from the data logger, and performing basic maintenance such as battery replacement or modifying the data collection frequency. “I prefer to set them at 15-minute intervals,” he notes. “It has enough battery power, but to save battery power, I could set it to a different frequency.”

He adds, “Getting humans to mine sites is costly.” Compared to the limited number of periodic or seasonal readings that a human technician could provide, he says, “I get readings every 15 minutes—that’s the big difference.”

BluMetric Environmental has had such success with the Stingray model that the company has decided to augment its stable of velocity-level loggers to include Greyline’s new Manta Ray Portable Area-Velocity Flow Meter, which Killingbeck expects to begin deploying at future monitoring sites to provide wireless data collection capability.

The biggest problem he has encountered in the field, he says, “is that for some reason, people like to steal the Pelican case that houses the controls and the data loggers,” but overall he has had few problems with the product. “Greyline has always been very responsive. They have excellent technical support. If we have a problem and we can’t troubleshoot in the field, they send a replacement.”

Accurate readings, Killingbeck believes, will allow managers to predict where a plume might emerge, or whether the volume of water coming onto or going off a landscape represents an anomaly that requires closer inspection of mining operations in the watershed. “When you set up any monitoring situation, you need to make sure the quality of the data is good and that your initial setup is good.” He feels the diversity of situations encountered during water-quality monitoring projects—and having the tools that can handle them—are part of “what makes the work fun.”

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