AEGON dam, protecting Kirkwood Estates, overdue for inspection

Nearly a year overdue for inspection, Linn County's only high-hazard dam sits atop a hill in southwest Cedar Rapids, holding back a six-acre pond circled by office workers on their lunch hour.

Listed as the “AEGON dam” on the state's dam inventory, the earthen structure is one of 101 Iowa dams classified as high-hazard. But the classification doesn't refer to the dam's condition or chance of failure.

“It's a classification based on the downstream risk,” said  Jon Garton, Department of Natural Resources dam safety engineer.

In the case of the AEGON dam, that's Kirkwood Estates, the manufactured housing park at the base of the hill.  Cheryl Wheeler, property manager of the park, said the dam's presence isn't an issue for its residents.

Only 12 of the state's 101 high-hazard dams have filed an emergency action plan with the DNR and local emergency officials. The AEGON dam is among those without a plan. AEGON spokeswoman Cheryl Nordoft said no one has contacted the company about it.

“The DNR inspects it every two years,” she said. “They tell us if there's anything we need to do.”

Actually, the AEGON dam was last inspected in October 2007. Garton said it will be checked this year.

“That one wasn't completed last year on schedule, so we have it on this year's schedule,” Garton said.

Dams rated less than high-hazard are inspected every five years.

An inspection of a relatively new earthen dam like takes “usually an hour or two,” Garton said. “It's mostly visual, walking the embankment looking for signs of erosion, looking for seepage.”

A visit this week turned up no such signs. About 30 feet wide on top and maybe four times as wide at its base, the dam is made of bentonite, a heavy clay, planted with prairie grasses. It's 26 feet long and 2,660 feet wide, holding back 124 acre-feet (enough to cover 124 acres a foot deep) when  the pond is full, according to the DNR.

Emergency plans are encouraged but not required, said Garton. In the wake of the July 24 Lake Delhi dam failure, the agency is urging dam owners to file plans with the agency.

“We're working with all our high-hazard owners,” Garton said.

The AEGON dam was built in 1997, part of what was then McLeod Technology Park at 6400 C St. SW. The site became AEGON Financial Park when that firm took over the office park from the troubled telecom.

The dam impounds a six-acre pond fed by draining the 169-acre property. It's encircled by a broad sidewalk and equipped with a fishing pier open to AEGON employees and their families and guests.