Hydropower, Storage

Dam Safety & Security

Issue 5 and Volume 26.

Homeland Security completes dams sector protection plan

The U.S. Department of Homeland Security (DHS) completed a dams sector-specific protection plan in support of its National Infrastructure Protection Plan (NIPP).

Work on the NIPP began following the terrorist attacks of Sept. 11, 2001, which raised awareness of the potential vulnerabilities of critical infrastructure.

The NIPP defines critical infrastructure protection roles for government, industry, and non-governmental organizations. It also called for development of 17 sector-specific plans – including one on dams – addressing unique characteristics and risk landscapes.

The NIPP and the sector-specific plans were developed through a collaborative process involving federal agencies, private sector owners and operators, state, local, and tribal entities, and other security partners.

For the dams sector, two councils established by DHS – the Dams Sector Coordinating Council and Dams Government Coordinating Council – worked with the department to prepare the dams plan.

While the dams sector plan is restricted and classified “for official use only,” the federal government agency said each sector-specific plan defines roles and responsibilities, catalogs security authorities, institutionalizes existing security partnerships, and establishes strategic objectives.

DHS said it seeks to balance the information needs of its security partners while ensuring sensitive information is protected. By designating some of the sector-specific plans “for official use only,” the department said it allows for distribution on a need-to-know basis. That designation also is intended to discourage what it considers to be inappropriate sharing of sensitive security information.

DHS said representatives of the dams sector who want access to the dams sector-specific plan should contact the NIPP program office by e-mail at [email protected]

FERC finalizing new plan for dam safety monitoring

The Federal Energy Regulatory Commission (FERC) is finalizing its new Dam Safety Surveillance Monitoring Plan.

FERC says the plan – referred to as the SMP – explains how a dam owner is to monitor and evaluate the performance of a dam or project structure.

FERC said the need for the SMP grew out of a meeting with several licensees in the commission’s Chicago Regional Office. Members of the National Hydropower Association’s Hydraulic Power Committee contributed to the development of the plan, FERC said.

One requirement outlined in the new plan is for dam owners to submit, periodically, a Surveillance and Monitoring Report. FERC staff in the Office of Energy Projects’ Division of Dam Safety and Inspections says the purpose of the report is to present, evaluate, and provide findings on overall dam performance.

The plan also provides information on an operator surveillance program, an instrumentation monitoring program, discussion of potential failure modes, and procedures for processing and evaluating data.

Flood control district awards contract for dam safety work

The Flood Control District of Maricopa County, Ariz., awarded AMEC a contract to provide up to $500,000 in on-call dam safety geotechnical services over the next two years.

The contract covers a broad range of engineering services that might be needed for the assessment, repair, or rehabilitation of dams, AMEC said.

The district foresees a need for field investigations such as borings, material sampling, and material testing. Additional technical services could include surveying, hydrology and hydraulics, geology, geomorphology, structural engineering, aerial mapping, biological sciences, archeology, landscape architecture, and public involvement.

AMEC, a project management and services company, said contracted services could apply to any of the district’s 22 earthen flood-control dams. However, it considers the Saddleback Flood Retention Structure in Maricopa County and Cave Buttes Dam east of Phoenix as the most likely candidates.

UPPCO chooses to rebuild failed Silver Lake dam

Upper Peninsula Power Co. (UPPCO) announced it will rebuild the failed Silver Lake Dam, part of the utility’s 11.2-MW Dead River hydroelectric project.

“It’s been four years of studies, reviews, and discussions,” UPPCO Vice President Keith Moyle said. “In the meanwhile, construction costs are escalating, and we’re losing the benefit of a renewable resource in our generation mix.”

The Dead River project features two powerhouses below the Silver Lake storage basin, where the dam failed in May 2003. An investigation by the Federal Energy Regulatory Commission (FERC) concluded a fuse plug foundation and emergency spillway channel were inadequate and had eroded more than expected, leading to the dam’s failure.

With the decision made, Moyle said UPPCO is eager to begin rebuilding the dam. UPPCO will restart the design process for the new dam with FERC. The utility is developing a timeline for project work. However, its early estimates call for some of the work to begin later this year, and for all work to be completed in late 2008.

UPPCO abandons plan to file license amendment

In announcing the decision to rebuild Silver Lake, UPPCO also said it no longer would pursue a license amendment that would have allowed it to operate the project with lower water levels.

UPPCO previously concluded it must amend its license for operating the Dead River project to make rebuilding Silver Lake Dam more economically feasible than abandoning it. However, based on information obtained during initial consultation on the proposed amendment, UPPCO said, several new costs and environmental certainties were brought to light. Those factors made the alternative to rebuild according to current license conditions the most cost-effective option, it added.

UPPCO is a subsidiary of Integrys Energy Group. It owns nine hydropower plants.

Government chooses spillway as part of Folsom upgrade

The Bureau of Reclamation said it will construct a new auxiliary spillway and wing dams at California’s 198.72-MW Folsom Dam as part of a larger plan designed to increase flood protection for Sacramento and to improve dam safety.

Reclamation, the U.S. Army Corps of Engineers, and other agencies recommended increasing the height of the dam 3.5 feet and building the auxiliary spillway as the preferred alternative in a final environmental impact statement (EIS).

Before reaching that decision, Reclamation, the Corps, state agencies, and a local agency studied five scenarios to address flood damage reduction, dam safety, and security issues. The agencies found that none of the other alternatives they looked at would achieve the project’s purpose and need.

The preferred alternative includes construction to increase dam height and replacement of three emergency spillway gates to reduce flood damage. It includes construction of the auxiliary spillway and control structure with six submerged tainter gates, concrete-lined chute, stilling basin, and approach channel.

It also calls for jet-grouting of the Mormon Island Auxiliary Dam foundation for seismic stability; and toe drains and filters at the Left and Right Wing dams, Mormon Island Auxiliary Dam, and Dikes 4, 5, and 6 to address static risks.

The Corps is responsible for implementing measures to reduce flood damage. Reclamation is responsible for implementing dam safety and security issues. Both agencies are partners in the construction of the new auxiliary spillway, known as the Joint Federal Project auxiliary spillway.

EIS stems from 2006 revision of dam upgrade plan

The EIS is based on a revised plan for Folsom, issued in 2006, which estimated it would cost $1.357 billion to add the auxiliary spillway and possibly increase the height of the dam, with completion by 2014.

A previous plan, costing $2 billion, included building an auxiliary spillway, enlarging and adding outlets, and raising the height of the dam 7 feet, with completion by 2023.

Reclamation was lead federal agency for the EIS, with the Corps serving as a cooperating agency. Other partners included the California Department of Water Resources, California Reclamation Board, and Sacramento Area Flood Control Agency.

Corps scales back scope of work for Tuttle Creek Dam

The U.S. Army Corps of Engineers says work required at its 157-foot-tall Tuttle Creek Dam to ensure seismic structural stability is not as extensive as originally thought.

The Corps is modifying the 7,500-foot-long rolled earth and rockfill embankment dam to meet current safety standards. Without improvements, the Corps said, a 5.7 to 6.6 magnitude earthquake could inflict significant damage to the structure. Thirteen thousand people live downstream of the dam, located on the Big Blue River in Riley and Pottawatomie counties in northeast Kansas.

The original plan called for injecting a cement-and-water mix under high pressure beneath the dam’s upstream slope to form a wall and columns to support the dam. (See “Dam Safety & Security,” November 2005.)

However, a computer model used to represent the soils at the site and to evaluate an earthquake at the dam determined sands beneath the embankment are not as vulnerable to earthquake shaking as original models showed.

Based on results from the new model, the Corps said it would eliminate the planned work beneath the upstream slope and instead re-grade the upstream face to protect against wave action. However, it said construction to stabilize the downstream side of the dam still is necessary.

Corps to replace spillway gates

In a separate development, the Corps said it planned to name a contractor for work on spillway gates at the project. A 2002 report of an evaluation of the dam determined the gates did not meet current structural design criteria for trunnion friction and wave loading.

The government said it would name a contractor to make structural modifications to the gates, including removing and replacing pins and bushings; adding additional struts, braces, and plates; removing lead-based paint, and repainting.

The work is expected to cost $10 million.