Aggregates
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What is Aggregate?
 Aggregate is sand, gravel and crushed stone in their natural or processed state. In Minnesota, aggregate companies mine glacial sand and gravel deposits and quarry limestone, quartzite, granite and other igneous rock formations.
Aggregate is fundamental to nearly every construction project. The Aggregate & Ready Mix Association of Minnesota estimates that a new home uses 120 tons of aggregate material and a 4-lane highway uses 20,000 tons of aggregate per mile. While used primarily in construction, aggregate also has environmental, agricultural, landscaping and industrial uses.
The Minnesota aggregate industry is also an important contributor to state and local economies. Minnesota aggregate companies empoy approximately 3,500 people and generate revenues of $250 million per year.
Choosing a Mine Site
Aggregate companies consider a number of factors when choosing a mine site:
Geology – Factors such as the quantity and quality of the deposits depend on the geologic history of an area.
Proximity to Market – Transportation costs are a major factor in the viability of a site. A deposit needs to be near the area in which the product will be used, or near rail or water transport routes. The greater the distance the aggregate travels, the more expensive the construction project will be along with the need for more trucks hauling the products, adding to traffic congestion.
Permits – Mining cannot begin without the proper permitting from local, state and federal agencies. Aggregate companies must be able to meet stringent environmental standards and comply with zoning ordinances before being granted permits.
 Mine Reclamation
As part of the process of obtaining a mining permit, an aggregate company must submit a plan for the reclamation of the property after the aggregate has been removed. As a result, depleted quarries and mines often become valuable assets to the community. If a mining site is developed prematurely, the aggregate resources that are present can no longer be extracted. Community planning plays an important role in allowing sites to be mined before being developed, so the aggregate resources can be utilized. After a site is mined, the land can be restored for a variety of uses, including parks, lakes and commercial or residential developments.
Minnesota’s Aggregate Dilemma
According to the Minnesota Aggregate Task Force, approximately 1.7 billion tons of available aggregate materials lie underneath the Twin Cities metro area. However, due to spreading urbanization, 600 million tons of aggregate, or 35%, will become inaccessible over the next 40 years. At the same time, demand for aggregate products will increase from the current level of 27 million tons per year to between 41 and 58 million tons per year. Because of these factors, the metro area’s supply of aggregate could be exhausted as soon as 2028. Because the price of transporting aggregate doubles approximately every 19 miles, importing aggregate from outside the metro area would greatly increase the cost of urban development.
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