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Concrete Solutions

To the Editors:

Douglas W. Larson's tongue-in-cheek title, "Reliably Safe" ( Macroscope, January-February), shows how the Army Corps of Engineers denies that its constructions sometimes exacerbate rather than correct problems it had intended to resolve. The Corps' refusal to concede that it may have used the wrong kind of concrete in building the Willow Creek dam in Oregon is analogous to cases on Long Island, New York, in which I was involved from 1970 to 1980.

The Corps, with approval of state, county, town, and village officials, and with taxpayer money provided by Congress, had over many decades built numerous large rock groins (long, narrow outcroppings, often made in groupings called groin fields) and jetties extending hundreds of feet out from beaches into the Atlantic Ocean. The work was done under an incorrect assumption that it would curtail erosion along the South Shore by the west-flowing littoral (shore) current. However, the current's natural tendency to deposit and erode roughly equal amounts of sand over time on the same beach was overridden by each rock structure, inasmuch as it caused more sand deposition on its up-current side and vastly more erosion on its down-current side.

The combined down-current erosion effect of the Corps' huge, 15-groin, Westhampton Beach groin field was so intense that many homes were washed away over the years as the beach and dunes disappeared beyond the last groin. There, the littoral current removed so much sand that ocean storm waves were able to erode openings through the barrier island that had to be quickly filled in at great expense to protect the valuable shellfish in the bay that ocean water's higher salinity would have killed.

The Corps' mission has changed very much since it was founded by George Washington more than two centuries ago.

Julian Kane
Great Neck, NY

To the Editor:

I found "Reliably Safe" to be very interesting, but I fail to come to the same conclusion as the author. Dr. Larson, as a scientist working on the project, raised a concern over the integrity of the Willow Creek dam due to leakage. His managers responded positively and authorized further scientific study on the leakage problem. The study reinforced these integrity concerns. A team of engineers was dispatched to evaluate the situation and came to the conclusion that the dam was not in danger of failure despite the leakage, and predicted the leakage would lessen with time.

Twenty years later, the dam is leaking less, as predicted, and has not failed. So where is the problem and lesson to be learned? Corps management was responsive to a concern raised by an employee on site, investigated further, dispatched its top experts and made a risk-based decision that appears to have been borne out with time. Yes, this process was a bit messy, but so is everything when the press stirs things up and elected officials get involved. And yes, you can always do more to investigate a problem. But I fail to see what "mistakes" occurred here.

John F. Tavolaro
Rahway, NJ

Dr. Larson responds:

Mr. Tavolaro paints an ideal picture of how the Corps of Engineers responded to the Willow Creek dam crisis. As an environmental scientist who spent six years clashing with Corps management over issues at Willow Creek, I witnessed a far different Corps response, which I described in my article.

Consider the team of engineers dispatched from Corps headquarters in Washington, D.C., to "evaluate the situation." While in Oregon, the engineer team spent only a few hours inspecting the dam and later examined the considerable quantity of data painstakingly gathered by the independent scientific team during the previous three years. After a few days of deliberation, the Corps engineers concluded that the scientific data did not support the argument that the dam's concrete was deteriorating, this despite the fact that much of the data was outside the engineers' area of expertise. The Corps then arbitrarily declared the dam "reliably safe."

Willow Creek dam—proclaimed by the Corps as "the world's first concrete gravity dam built completely by roller compaction methods"—was essentially an experimental project lacking the tried-and-true construction techniques used for conventional dams. As such, there were many unknowns. Luckily for the Corps and especially the 1,500 residents of Heppner, Oregon, the dam is still intact.



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