If initial lessons included in an interim status report on the cause of February’s failure of the main spillway at California’s Oroville Dam are heeded, hundreds of U.S. dams more than 50 years old may have to be re-examined and upgraded.

独立法医团队的9月5日报告将失败的责任归咎于1968年的大坝设计和建筑。一块40英尺宽的混凝土板进行了振奋和拆除，导致该国最高土壤水坝的斜槽中井下的“高风化岩石”井喷。失败导致紧急释放造成了近18.8万人和数百万美元的下游损失。

IFT的成员参观了该网站，采访了DWR员工，并检查了初始设计和施工记录。报告指出，失败的触发因素可以追溯到高速溢洪道流动，将水注入平板表面特征，例如开放的接头或未密封的裂缝。失败发生在大暴雨期间，导致每秒54,500立方英尺的流动通过封闭的溢洪道。1,700英尺长的溢洪道冠的排放量为250,000 cfs。该报告还表明，这些弱点中的一些可能先前已修复。调查人员排除了空穴，地下水的影响和地震损伤。

Although regular physical inspections of the facility were not adequate to reveal the weaknesses, inspectors applying current best practices might have been able to warn of the risks. IFT concluded that “comprehensive periodic reviews of original design and construction, taking into account comparison with the current state of the practice, are needed for all components of dam projects.” Such a review would have “connected the dots” before the damage was done. One possible missed indicator cited was excessive drain flow rates due to under-slab erosion.

The California Division of Dam Safety identified 93 dams in the state similar to Oroville in size, construction and age. The Dept. of Water Resources directed dam owners to complete a re-evaluation of their spillways, including a historical review back to the original design and construction, said Erin Mellon, spokeswoman for California DWR, owner of Oroville Dam and operator of hundreds of others around the state.

梅隆说：“正如我确定所有水坝的所有者一样，我们绝对是根据奥罗维尔（Oroville）重新评估我们的程序。”“整个大坝安全社区将从2月份的经历中学到很多东西。”

General contractor Kiewit Infrastructure West. Co. is scheduled to complete the first phase of a $500 million-plus repair, including emergency work before Kiewit was awarded the contract, to place 2,270 ft of reinforced, structural concrete on the main spillway by Nov. 1. This job includes 730 ft of the main spillway leading to the radial gates, which are being patched, reinforced and left in place this year but will be removed and reconstructed with structural concrete in 2018. It also includes more than 5,000 ft of underdrains in the structural-concrete sections, one of the problems called out in the independent report.

Water flows also eroded part of the emergency spillway in February, when it was used for the first time in the dam’s history and almost immediately began showing signs of headward erosion on the 1,450-ft earthen slope. Kiewit crews are building a secant pile cutoff wall in case the spillway is put to use once again.

梅隆说，一旦检测到侵蚀，DWR就设置了多个便携式摄像机来监视这两个溢洪道。紧急情况下，直升机和无人机中的摄像机补充了地面摄像头的监控。即使采用了所有这些技术，夜间连续监视也很困难，因为无人机没有配备红外摄像头，并且直升机受到空中空中的小时数的限制。梅隆指出，这些夜间工作的挑战和局限性并非紧急情况。