May 2, 2008

Where are we going to get aggregates in the future?

Take just a minute before you read the rest of this article to reflect on all the uses of construction aggregates in your daily life. Some uses that might come to mind include the foundation under your home, the roads and bridges taken to get to your job, the foundation and parking areas at your work, and the foundations and play areas for the schools that your children attend.

Local sources of good-quality construction aggregates allow us to build all of our communities and infrastructure. Unfortunately, aggregate sources are not renewable. We cannot plant a new gravel pit today and expect to harvest it in 50 to 70 years.

To maintain our communities and infrastructure — and provide for the needs of generations to follow — new local sources of quality sand and gravel must constantly be located, permitted and brought on line to replace the sources that have been depleted.

Recently, a number of major sand and gravel sources in Steilacoom and Everett have closed due to a lack of reserves. New sources are not being developed to keep up with the sources that are closing.

Aggregates 101

There are two components to the cost of aggregates used for construction projects: the cost of the material and the cost for freight to get the material from the source to the site. Of the two, the freight component is the most variable.

With fuel costs at record highs, having an opportunity to buy aggregates from sources as close to the project site as possible becomes an economic advantage. In the Puget Sound area, we have the benefit of barge transportation for aggregates. While barge transportation is less expensive per ton than truck transportation for the same distance traveled, higher fuel costs have also increased barge costs significantly in recent years.

The need for local sand and gravel sources is generally recognized, but efforts to permit new sources are often met with vigorous opposition from local residents. A potential new source must comply with a number of local, state and federal permit requirements. Also, the complexities of navigating the legal and political processes in order to get the required permits are expensive and time consuming.

The cost of accessing new material sources is reflected in higher material prices to the consumer. Since a majority of projects using aggregates in this state are public, we all pay for these costs.

Concrete 101

A standard cubic yard of ready-mixed concrete contains approximately 1.5 tons of aggregates that meet specific size and quality standards. The balance of the cubic yard of concrete consists of cement and water.

A typical house requires 80 cubic yards of concrete made from 120 tons of aggregates. That amount of aggregate would be delivered in four truck and trailer loads. When a project gets bigger, a school for example, the total could go up to 3,500 cubic yards of concrete and 5,250 tons of aggregates in 175 truckloads. A mega-project such as the Tacoma Narrows Bridge required 250,500 tons of aggregates delivered in 8,350 truckloads to produce the 167,000 cubic yards of concrete needed for the project.

Aggregate prices per cubic yard of concrete vary somewhat within the Puget Sound region mostly due to transportation costs. They vary even more up and down the West Coast due primarily to transportation costs and supply options.

As an example, the aggregates to make the concrete for a house in the Puget Sound area would cost $1,080, based on October 2007 pricing. The aggregates for that same house would cost $1,760 in San Francisco, $2,160 in Vancouver, B.C., and $2,640 in Los Angeles. If those figures were extrapolated for the Tacoma Narrows Bridge, the cost of aggregates to make the concrete would be $2.25 million here, $3.67 million in San Francisco, $4.51 million in Vancouver, B.C., and $5.51 million in Los Angeles.

Aggregate resources are woven into our daily lives and make an important contribution to our quality of life, much like clean water and energy. If we are to maintain our quality of life, we will need to be aware of our need for quality aggregates and plan ahead to ensure that there is access to these materials in the future.

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