Hydraulic Impacts of Quarries and Gravel Pits

Hydraulic Impacts of Quarries and Gravel Pits

2005

Natural aggregate (crushed stone, sand, and gravel) is a vital part of our economic infrastructure in Minnesota. Aggregate is used for road and bridge construction and in a variety of building materials. In 2003, the value of construction sand and gravel and crushed stone in Minnesota was approximately $245,000,000. As Minnesota's economy continues to expand, the demand for aggregate will continue to grow. Sand and gravel pits are located in every county in Minnesota. In 1990, the Minnesota Department of Natural Resources, Division of Minerals (DNR Minerals), estimated the number of active and inactive operations at 1500 with the view that this number was likely too low (Dennis Martin, pers. comm.). Quarries for mining limestone, dolomite, sandstone, and hard rock (granite and quartzite) are found in 34 counties. A 1990 DNR Minerals inventory found 165 active operations, 88% of which were limestone quarries (Nelson and others, 1990). That same inventory counted 1,367 inactive operations, 70% of which were limestone quarries. Aggregate mining is an extractive use of resources: mining alters the landscape and its natural hydrologic system. When a new pit or quarry is proposed or when an existing operation needs to expand, local governments and citizens typically have many questions about the impacts mining might have. Local governments, which are responsible for reviewing these operations, rarely have the budgets to hire experts to evaluate potential impacts of quarry and gravel pit proposals. The Minnesota Legislature's Aggregate Resources Task Force identified that local government units (LGUs) often lack the expertise to assess ground-water models (Southwick and others, 2000). . Quarries and pits can affect ground-water and surface-water systems in various ways. This project focused on the following potential impacts: • lowering of local ground-water and surface-water levels from mining operations and mine dewatering, • changes in turbidity levels in ground water due to blasting and quarry operations, • interruption of ground-water conduit flow paths by rock removal, and • temperature change (thermal impacts) in springs and surface-water streams. This report is intended to help local officials, the public, and the mining industry understand the main issues surrounding mine establishment and to provide suggestions for monitoring and mitigation strategies to prevent significant impacts on water resource. The research at these sites (Figure 1) provides the first comprehensive assessment of aggregate mining impacts on groundwater systems in Minnesota. This information can be used for siting of new aggregate mines and for more accurately assessing their impacts on local ground-water resources. It can also be used for planning purposes at the state and local level.

Green, J.A.
Pavlish, J.A.
Merritt, R.G.
Leete, J.L.

DNR
DNR
DNR
DNR

Minnesota Department of Natural Resources
Environment and Natural Resources Trust Fund

139

Surface Water
Water Use & Availability
Water Restoration & Protection

water level
water levels
water-level
water-levels
groundwater level
groundwater levels
ground water level
ground-water level
ground water levels
ground-water levels
hydraulics
hydraulic
gravel
hydraulic impact
quarries
gravel pits

2000-2009

No

Public Domain

Minnesota Water Research Digital Library