Media Contacts:
Dr. Michael Kimberley, 919/515-7831 or kimberley@ncsu.edu
Greg Thomas, News Services, 919/515-3470 or greg_thomas@ncsu.edu

March 23, 2000

NC State Expert Says Rock Quarries Could Prevent Flooding

FOR IMMEDIATE RELEASE

Hurricane Floyd and its floods killed 51 people in North Carolina, and made life miserable for tens of thousands of others. But a professor at North Carolina State University says the effects of flooding could be lessened in many areas if rock quarries were used for flood control -- a controversial idea that often pits neighbors, businesses and politicians against one other.

Dr. Michael Kimberley, an associate professor of geochemistry at NC State, has been studying the feasibility of using quarries for flood control, and says one quarry in Raleigh is ideally suited to prevent future flooding. He’ll present a case study at 9 a.m. Friday, March 24, at the Geological Society of America (GSA) Southeastern Section’s 49th Annual Meeting in Charleston, S.C.

Kimberley says a quarry operated by Hanson Aggregates Carolina Inc. on Duraleigh Road in Raleigh is in a unique position to control flooding on Crabtree Creek, a waterway that regularly spills its banks after heavy rains, threatening scores of businesses and homes. The quarry is located just upstream from the city, and Kimberley says the pit could hold flood waters that would otherwise cause havoc farther downstream. He says to use the quarry for flood control could prevent all future flooding of Crabtree Creek.

A similarly sized quarry near Rocky Mount saved portions of that city from more extensive flooding during Hurricane Floyd.

"Most people want to completely forget about floods until they’re in the middle of one, and we, as geologists, have to remind them it’s going to happen. It may not happen this year, it may be next year, but it’s going to happen, so it’s logical to take some precautions," Kimberley says.

The NC State professor says there also is an environmental benefit to the idea of using quarries for flood control -- cleaner water. Sediments would settle out to the bottom of the quarry before the water continued on downstream, reducing suspended solids that degrade water quality.

The idea of using the quarry in Raleigh for flood control has been mired in controversy for several years. The quarry’s operator says the company will give up the pit for flood control use if it is allowed to mine on an adjacent piece of property, a plot of land for which it holds a state mining permit. Neighbors and city officials oppose the idea of new mining, and say city zoning regulations prohibit a new quarry.

In 1991, the U.S. Department of Agriculture estimated the cost of preparing the Crabtree quarry for flood control at approximately $20 million. Kimberley says policy makers need to decide if the benefits outweigh the cost. "For example, will this project save $20 million (in potential losses), or is it going to only save $5 million?" Kimberley isn’t taking a side in the dispute. He just wants all interested parties to discuss the options and develop a plan before another devastating flood arrives. "Not very many people are talking about this idea," he says, "but many, many people would be affected. It needs to be discussed."

-thomas- NOTE TO EDITORS: The abstract from Dr. Kimberley’s GSA presentation follows.

"Quarry Pits as Flood Reservoirs: Accidental and Intentional"

Author: Michael Kimberley, North Carolina State University.
Presented: March 24, 2000 at The Geological Society of America Southeastern Section Annual Meeting.

Abstract: Ten years ago, the chief geologist of the Crabtree quarry in NW Raleigh (Jim Sprinkle) proposed that the quarry be used as a flood reservoir for Crabtree Creek, the main stream across North Carolina’s capital. The quarry owner offered to exchange the old quarry for Raleigh’s agreement to allow a new one on contiguous, state-permitted property. If acted upon, that would have saved several million dollars in flood damage and insurance premiums through the past decade. Instead, this has become a classic battle of local versus regional interests. Local property owners are latecomers because the state quarry permit preceded their subdivision by >20 years. Several government agencies have become involved. Indeed, government has more to lose from flooding in Raleigh than anyone else, given self-insurance of their buildings. If Floyd had affected Raleigh as it did nearby Rocky Mount, the governments’ cost would have been astronomical. Would the public have accepted the resulting tax hike upon learning that a quarry had offered a free solution? Feasibility of the quarry-reservoir project has been verified by the Army Corp. of Engineers and the Natural Resource Conservation Services. More dramatically, Floyd demonstrated quarry filling at another Hanson Aggregates site in Rocky Mount. This site resembles the Crabtree quarry (500 x 300 m and 100 m deep) and lies along the Tar River. During Floyd, the Tar filled the pit. Uncontrolled quarry filling like this is more dangerous to adjacent property that controlled filling, as demonstrated by the Rocky Mount site, where mass-wasting has affected the quarry rim due to soaking of the soil and saprolite. Eastern Rocky Mount was largely saved by this quarry filling.

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