A recent inspection of the inflatable rubber dams installed seven years ago atop the spillways for Lake Altoona and the Impounding Dam near Horseshoe Curve showed the rubber dams are in fundamentally good condition and could last another 25 or 30 years, according to authority General Manager Mark Perry.

That “good news” assuages authority fears that the rubber dams would need replaced far sooner than would normally be expected, due to recent cracking and leakage of air, as reported at a meeting in May.

The cracking of the rubber atop the Impounding Dam, however, is only superficial, and doesn’t affect the integrity of the bladder, which is good — although a patch will be needed, according to a preliminary report on the inspection by M2i of Montreal, Perry said.

“That was a relief that we were not faced with (potentially) millions” in expenses for premature replacement, Perry told the board Thursday.

The current rubber dams were manufactured in China and replaced a pair of rubber dams that had been manufactured in Japan — and that had lasted 30 to 35 years, officials said last month.

By the time the authority replaced those prior rubber dams seven years ago, the Japanese manufacturer no longer made rubber dams, officials have said.

By that time, the Chinese version was one of only two choices, according to a retired authority engineer who contacted the Mirror several weeks ago.

Nevertheless, more than 1,500 of those rubber dams from China had been installed around the world by then, according to that retired engineer.

The rubber dams from China met the International Organization for Standardization’s quality assurance measures and met the specifications the authority had listed, which mirrored those that applied to the Japanese version, according to the engineer.

Moreover, the American company offering the Chinese version was the lowest qualified bidder for the rubber dams, Perry stated several weeks ago in a letter to the Mirror, before the recent optimistic inspection results were known.

In Pennsylvania, public agencies are generally required to award contracts to the lowest responsible and responsive bidder, according to online sources.

It can be “difficult for engineers to write specifications that rule out every possibility of a deficiency in a product or project, while attempting to maintain a broad audience for qualified bidders,” Perry wrote.

Thus, red flags that may be raised by uncertainty about the quality of a product may need to be ignored, according to Perry.

A longer warranty period might help alleviate some of those kinds of concerns, Perry stated in the letter.

The 134-foot-long rubber dam at Lake Altoona raises the spillway top by four feet, adding 116 million gallons of capacity, Perry said.

The 117-foot-long rubber dam at the Impounding Dam raises the spillway top by five feet, adding 65 million gallons of capacity, he said.

The additional capacity the rubber dams provide is important to the authority, especially in times of drought, and is an inexpensive way to obtain such capacity, according to Perry and Glenn.

There have been rubber dams on the spillways of Lake Altoona and the Impounding Dam since the 1960s, according to authority consulting engineer Mark Glenn of Gwin Dobson and Foreman.

Mirror Staff Writer William Kibler is at 814-949-7038.