Aggregate extraction can pose a serious threat to the quantity and quality of surface water (creeks, rivers, streams, lakes, etc.) and ground water (aquifers, deep wells, etc.).
Sand, stone and gravel act as a natural filter between the surface and underlying waters. (Think of an aquarium with a bottom filter – contaminated water is drawn into the gravel, where debris is removed and the water leaves the filter crystal clear.) When the filter is removed, natural (land and water borne) and manmade (spills, fertilizers, etc.) contaminants can more easily contaminate surface water and groundwater. In below-water-table operations, extraction is, by definition, right into the groundwater.
Surface water impacts can be immediate and far-reaching, stretching many kilometres downstream. Groundwater impacts can be slower and very pervasive, as contaminants migrate through the aquifer from the source.
Hydrogeology can be an imprecise and unpredictable science. Recently, at a pit in Waterloo Region, the operator breached the water table when they were removing the overburden to create the berms – before they even began extraction and two metres above the water table established by the “experts”! In pits and quarries situated above fractured or karst bedrock, it is difficult if not impossible to predict the flow of water (and contaminants) through the rock.
Many gravel extraction operations require washing of the stone, using several million litres of water per year. Even when the washing is a “closed-loop” (water drawn for washing is returned to the ground), significant amounts of water can be left in the gravel or lost to evaporation. Significant down-draws in local water can impact wetlands, creeks and wells. Operatoins taking 50,000 litres per day or more from the environment are required to obtain a permit to take water from the Ministry of the Environment and Climate Change.
Where multiple pits and quarries operate or are proposed in proximity to each other, cumulative impacts should be considered.
Look not only at what’s in the reports; look at also at what’s not in the reports. Was testing done over a long enough period? Was testing done during periods of high rainfall, as well as periods of low rainfall? Were there enough test pits spread out throughout and well beyond the proposed extraction area? Are there anomalies in the data?