A U.S. special inspector released a report October 30, faulting quality control of an emergency grouting program at Iraq’s 750-MW Mosul Dam and warning that failure of the structure could flood the city of Mosul to a depth of more than 20 meters.
The Special Inspector General for Iraq Reconstruction (SIGIR), Stuart Bowen Jr., presented a U.S. House subcommittee his quarterly report on Iraq reconstruction efforts October 30. He also issued a separate report, “Relief and Reconstruction Funded Work at Mosul Dam,” containing additional detail on the dam problem.
The report said Mosul Dam, the largest dam in Iraq, was completed in 1984 on a soluble foundation of gypsum, anhydrite, and karstic limestone. To save construction time, foundation grouting was not completed ahead of time. It began seeping immediately upon filling of the reservoir in 1985, on the Tigris River in Ninewah Province. Iraq has carried out a major grouting program continuously since that time.
Upon the overthrow of Iraqi President Saddam Hussein, the U.S. Army undertook a program to supply an advance injection grouting system as a short-term solution to stay ahead of the seepage problem. (HNN 5/11/06) As a permanent solution, the United States has urged the Iraq government to complete the partly built 170-MW Badush Dam downstream as a backup structure in the event of Mosul’s failure.
The report found that although US$19.4 million of equipment and materials has been delivered over two years to the dam site under the US$27 million grouting initiative, none of it has been of benefit to Iraq’s Ministry of Water Resources. SIGIR blamed lack of quality control, allowing deficient drawings, inadequate construction, incorrectly delivered equipment and materials, and failure to track completion.
Although it said the U.S. Embassy has developed mitigation measures to correct the problems with the grouting program, the SIGIR report highlighted Mosul Dam as “a serious concern.” Incorporating strong warnings from the U.S. Army Corps of Engineers (USACE), the report spurred headlines in national and international news media.
Corps: “The most dangerous dam in the world”
“The USACE concluded in September 2006 that ‘in terms of internal erosion potential of the foundation, Mosul Dam is the most dangerous dam in the world… If a small problem at Mosul Dam occurs, failure is likely,'” the SIGIR report said.
The report said the Corps concluded in December 2006 that the current probability of Mosul’s failure is exceptionally high. It attached a warning letter to Iraqi Prime Minister Nouri al-Maliki from U.S. Ambassador Ryan Crocker and Commanding General David Petraeus.
“A catastrophic failure of Mosul Dam would result in flooding along the Tigris River all the way to Baghdad,” the U.S. officials wrote. “However, the most severe impact of a dam failure would be to the city of Mosul, located 50 kilometers downstream of the dam with a population of 1.7 million. Assuming a worst case scenario, an instantaneous failure of Mosul Dam filled to maximum operating level could result in a flood wave 20 meters deep at the city of Mosul, which would result in significant loss of life and property.”
The reservoir has been lowered somewhat from its maximum level. The officials also recommended developing a dam break warning and evacuation program and urged action by the Iraqi government on a permanent solution, notably the proposed Badush Dam.
Reports indicated Iraq’s government is not convinced Mosul is the extreme hazard cited by the U.S. The U.S. Embassy noted in September the Ministry of Water Resources met with international firms to consider installation of a positive cut-off wall at Mosul Dam. The embassy noted that solution was evaluated in 2005 and found not to be feasible.
At the same time, the Iraq Transition Assistance Office (ITAO), a U.S. agency appointed to support agencies in concluding large infrastructure projects, urged the SIGIR to moderate its report on Mosul Dam.
In comments attached to the SIGIR report, ITAO said the description of Mosul as “‘the most dangerous dam in the world’ is inflammatory and almost certainly disprovable.” ITAO recommended the original Corps report containing that comment be provided to ITAO for review and referral to Iraq’s Ministry of Water Resources.