Aggregates 101

By: Bruce Chattin

Construction projects, required by our society, create large demands for non metallic aggregate resources. Every time a home is built, a roadway paved, or a building constructed, large quantities of bulk aggregates are used; most commonly in the form of sand, gravel & crushed rock. The demand for these products has resulted in the need for active mining operations of various sizes, throughout Washington State. Influences of past glaciations have provided Washington with a unique geologic environment, that contains a rich endowment of large, accessible, high quality sand & gravel deposits.

The vast majority of sand and gravel, mined in Washington, is the result of what is known as the "Fraser Glaciation." Our aggregate resources occurred from the advance of the glaciers and as outwash and flood deposits during their recession.

15,000 - 18,000 years ago, great continental sheets of ice extended down from the Polar Regions, forming alpine glaciers in the Cascades and covered the northern tier of the state and many have occurred and reoccured over 4 - 5 separate events.

A thick tongue, or lobe, of ice upwards of 6,000 feet thick reached into the Puget lowlands, carving out what we now call "Puget Sound" and extended as far south as Black Lake. When the glaciers and floods receded, they produced aggregate rich deltas, that spread from Friday Harbor, past Everett, east to Issaquah and to the Nisqually Delta.

Northeast of the Spokane valley, a lobe formed an ice dam, nearly 2,200 feet thick. A huge lake formed behind the dam, almost 1,000 feet deep and reached as far east as Missoula Montana.

When the ice dam broke, water reached speeds estimated at 65 miles per hour, flooded in the Columbia Plateau, to the Columbia River and moved westward through the Columbia Gorge. This incredible flood filled an area from Clark County to Eugene Oregon, before it made it's way to the Pacific Ocean. It is estimated that the Spokane Flood was equal to twenty times the combined flow of all of the rivers of the world that exist today.

Without the benefit of fancy marketing, or Madison Avenue advertising, Washington consumes nearly 80 million tons of sand, gravel and crushed rock products each year. That is nearly 15 tons per citizen in aggregates alone. Additionally, we require 1.3 cubic yards of ready mixed concrete and 1.25 tons of asphalt per person/per year.

So, where are all these resources used? Aggregates are required in large quantities every day, by our communities, for our homes, schools, shopping centers, offices, roads, parking lots, bridges, sewers and other underground infrastructure.

Fact: 15,000 - 18,000 years ago, great continental sheets of ice extended down from the Polar Regions, forming alpine glaciers in the Cascades and covered the northern tier of the state and many have occurred and reoccured over 4 - 5 separate events.

Fact: Nearly 15,000 tons are used to construct a typical elementary school or community hospital.

Fact: The Interstate-90 project, on Mercer Island, consumed nearly 1 million cubic yards of concrete alone.

Fact: While a typical four lane county road will use 85,000 tons of aggregates for a single mile.

It is these types of Public Works projects that make our local Governments and State Department of Transportation our single, largest customer. Their projects are built in response to the needs of the public, to maintain our roadways, and growing communities. No wonder sand and gravel are the most valuable production mineral commodities mined in Washington state.

Modern construction specifications require strong, durable, properly graded aggregates, that will hold up to millions of vehicle trips and to allow construction of high rises that will stand local seismic forces. Unfortunately, not all aggregates have the quality we require to meet our construction standards.

Most of all, aggregates must be economical. Unlike forests, that can be replanted, aggregate resources are finite, non renewable resources. Once consumed, we need to replace them with new sources of supply.

Like the Egyptians, that built pyramids next to the stone quarry, we can only get aggregates where nature has placed them. We cannot choose their location, or make them portable. Our aggregate resources need to be accessible to our communities and transportation system, because transportation accounts for almost 45% of the cost of bringing aggregates to our communities.

Proximity to the market place is critical for sand and gravel products. In Washington, well over 40% is transported by truck at a cost of 20-25 cents per mile. Some materials are barged, but our waterborne resources are limited and under developed. The further aggregates have to be transported, the more construction costs, and these costs are passed on to all of us.

Once a suitable resource has been located, the sand and gravel minerals will need to be processed. Today, sophisticated, efficient, high technology plants control production economics.

While transportation is expensive, processing and permitting costs are equally expensive. Especially in todays regulatory environment. To build a modern, long term production facility, in 1994, the cost may exceed 10 million dollars ($$), require as many as 56 state, federal and local permits, that govern air and water quality, noise, traffic and other social concerns, and may take up to five years in the permitting process, meeting with local government and community leaders, our neighbors and environmental groups.

While our region enjoys new growth throughout Washington State, built largely on the foundations of aggregates, our resources are diminishing. In the past decade, only an average of 3 new surface mining permits have been issued, while almost 700 facilities have been depleted or reclaimed since 1975.

Reclamation: The return of the land to a useful, productive, or natural condition.

Aggregate extraction is only an interim, temporary use of the land. Plans are carefully made, to assure depleted resource areas are reclaimed to a productive, desirable and often scenic use, in cooperation with local governments, citizens, neighborhood associations, and state agencies; well before the processing begins.

In Washington, segmental or progressive reclamation is the method of choice. Since 1971, over 8,000 acres or nearly 40% of mining lands have been reclaimed, and over 77 mining segments were reclaimed in 1994 alone.

Segmental reclamation is the restoration of mining segments once mining in that segment is completed. This process is repeated until the site has been fully developed and ready for it's intended future use. This keeps mining areas small, allows for ongoing reclamation, and reduces visual impacts to the environment and our neighboring communities.

With good planning and flexibility, our industries ability and expertise to reclaim mining sites is unlimited. For example, beautiful Buschart Gardens was once occupied by a sand, gravel and cement production facility!

Twin Lakes Park in Arlington, and the Kline Line Pond in Vancouver were once sand & gravel facilities, used in the construction of Interstate-5. Now they enjoyed as a community parks, beaches and swimming areas.

Now known as Ramsey Park, the former sand and gravel facility is an important part of this communities recreation and youth sports program, complete with baseball diamonds and soccer fields.

In Spokane, a facility is being reclaimed to construct a natural fish habitat and is stocked with trout.

Near Montesano, in cooperation with Trout Unlimited, an operator has recreated a natural stream setting and new spawning pools for salmon.

To ensure that funds are always available for future reclamation, for each ton of sand and gravel products extracted, monies are placed in a dedicated reclamation account. There will be nearly two hundred thousand dollars in the fund, when mining operations have been completed.

A Sand & Gravel Supplier, in partnership with the local community, neighborhood associations, local government leaders and environmental groups, this abandoned facility in Battleground, along the Lewis River will be reclaimed as a natural wild life habitat that will include lakes, reconstructed wetlands and protected lands. Shortly this area will be improved for the existing deer, blue heron and osprey populations that live there now.

Just as sand, gravel and rock is the foundation for our quality of life in Washington State. Environment, community and commitment is a part of the foundation of our industry, as environmental stewards of the land. With conservation, protection and wise use of our aggregate resources, combined with good planning, resource identification and communication, we will be able to maintain our partnership with our neighbors and communities. Together we can satisfy our vision for the future and meet the growing demand for aggregates, for the needs of Washington State, today and tomorrow.