Corps studying safety upgrades for Isabella Lake Dam
The U.S. Army Corps of Engineers began geotechnical studies in October 2011 as part of the Isabella Lake Dam Safety Modification Project.
Work, which was to run through March 2012, consists of trenching and boring at five locations around the lake. Results of these studies will help determine whether soil and rock near the lake is suitable for use in safety upgrades needed to the main and auxiliary dams.
All work will take place a minimum of 50 meters away from any known sensitive habitats or cultural sites. Once the geotechnical studies are complete, all study sites will be restored as nearly as practical to their present conditions.
An external peer review panel commissioned by the Corps confirmed in 2007 that Isabella Lake Dam has a high risk of failure. Built in 1953 as a flood control and water conservation structure, Isabella Lake Dam also controls flows released to Southern California Edison’s 12-MW Borel project.
The Corps said the Isabella Dam study is the highest priority in the nation for the Corps’ dam safety assurance program. Initial studies have found the project could be subjected to extreme ground motions under earthquake conditions, with potential to cause failure of earthen slopes and release of the reservoir.
Repairs to Red Willow Dam beginning soon
Repair work at Nebraska’s Red Willow Dam is ramping up, reports the Bureau of Reclamation.
SEMA Construction of Englewood, Colo., has moved equipment to the site and hauled and stockpiled materials. Excavation of the dam was expected to begin in February 2012.
The repairs were prompted after Reclamation discovered a sinkhole in the face of the dam in October 2009. Subsequent investigations revealed further cracking through the embankment, causing Reclamation to draw down Hugh Butler Lake, which is impounded by the dam.
The bureau accepted bids for the repair work after Congressional approval of the Safety of Dams plan in August and awarded the US$15.3 million contract to SEMA in October 2011.
The construction company is to excavate the embankment and toe drain, construct a filter/drainage blanket, place geonet composite on the excavated face of the embankment, construct a two-stage sand filter and coarse sand drain system, place geotextile on the coarse sand and gravel drain, construct a downstream stability berm and a two-stage filter drain in the channel and slopes downstream of the spillway and outlet works stilling basin, repair portions of the upstream dam face, and construct a toe drain system with monitoring wells.
Access to the construction site and travel across the dam will be off-limits to the public during the construction period. A small observation area at the southwest end of the dam will be constructed and accessible by county roads.
Construction is expected to be substantially complete by late 2012, with minor finishing work to continue through 2013.
Cutoff wall completed to control leakage at Clearwater Dam
Construction of the 4,100-foot-long underground cutoff wall for Clearwater Dam in Missouri was completed in December 2011. The wall extends as much as 195 feet deep, or 40 feet into solid rock.
This wall is the second phase of a three-phase, $248 million rehab project that was prompted by the 2003 discovery of a large sinkhole on the upstream face of the earthen portion of the dam. The sinkhole was 10 feet across and 8 to 10 feet deep.
The dam, owned by the U.S. Army Corps of Engineers, was given a Dam Safety Action Classification 1, meaning it would almost certainly fail under normal operations.
Seepage through the structure, on the Black River, was recorded as early as the 1950s. As a result, modifications were made over the years, including changes to the management of lake levels. In 1989, a seepage berm was constructed.
Phase I involved exploratory drilling and grouting. Phase III will involve construction of a hard-packed clay wall over the dam and work on an overflow spillway.
The rehab project is expected to be finished by 2014. Bencor-Recon Joint Venture of Dallas is the contractor for the work under a $93.3 million contract awarded in October 2008.
Canadian dam faces evaluation after heavy flooding
The Saskatchewan government will re-examine the safety of Alameda Dam after a period of unprecedented flooding in 2011, Canadian news sources report.
The province has contracted engineering firm Klohn Crippen Berger Ltd. “to conduct further investigations and analyses,” according to a release.
The 43-meter-tall Almeda Dam was constructed in 1995 and has a reservoir capacity of 105,000 decameters. It is owned by the Saskatchewan Watershed Authority and supplies water to both Saskatchewan and North Dakota.
Questions about the dam’s condition were first addressed in a study conducted by the authority in October 2011. This review will be used to develop a 10-year infrastructure renewal plan for the province’s water-management structures.
“Creating a 10-year infrastructure renewal plan will not only ensure that we have reliable water supplies and effective flood protection long into the future, it will give Saskatchewan a more effective planning process for rehabilitation of our dams and water-management structures,” says Dustin Duncan, minister of the Saskatchewan Watershed Authority.
Duncan also asked the authority to inspect all dams affected by high water levels and high water flows in 2011. These special inspections were designed to identify any immediate actions needed as a result of unprecedented runoff and rainfall.
Although the review noted minor damage related to 2011 flooding at several dams, the overall conclusion was that Saskatchewan’s water-management infrastructure performed well under challenging circumstances in 2011. The government provided the authority C$1.9 million (US$1.87 million) in 2011 for urgent repairs that were identified.
Overall, the review found no substantive reduction in the safety of the authority’s dams occurred as a direct result of the flooding in 2011. However, the review does suggest that upgrades are required over the long term to ensure water-management infrastructure remains safe and effective for decades into the future.
The review also included a request to examine operations at Saskatchewan’s major dams (Gardiner, Rafferty, Alameda and Boundary).
CDA releases book on dams and public safety
The Canadian Dam Association announces availability of a new publication, called Public Safety Around Dams.
Construction and operation of dams and hydroelectric plants presents unique challenges for management of public safety, CDA says. This document provides guidance on implementing a managed system approach to these challenges at dams and associated facilities.
The publication includes several documents under one cover:
- Guidelines for Public Safety Around Dams, a 44-page document that outlines a managed system approach, discussion of the public safety hazards associated with dams, step-by-step risk assessment methodology and templates, and description of typical risk treatment or control measures;
- Technical Bulletin: Signage for Public Safety Around Dams, a 20-page document of technical recommendations for signage and dozens of sample signs, intended to help dam owners plan and purchase appropriate signage;
- Technical Bulletin: Booms and Buoys for Public Safety Around Dams, 12 pages of technical guidance and an outline of regulatory requirements for booms and buoys in Canada; and
- Technical Bulletin: Audible and Visual Signals for Public Safety Around Dams, 4 pages of guidance and references for use of audible and visual signals.
Washington state agency weighs increase in dam safety fees
The Washington Department of Ecology proposes to increase fees for state dam inspection, as well as charges to review new dam construction plans.
In 2011, the Washington Legislature ordered Ecology to increase dam safety fees to offset more of the costs of dam inspections and review of construction plans from dam owners. The department helps ensure the safety of more than 1,000 state-regulated dams.
The legislation authorizes Ecology to propose a rule that would add $256 to $352 to existing inspection fees for more than 380 dams and reservoirs that would pose a high or significant hazard to human health and safety if they were to fail. Inspections are required every five years. The legislation also would increase fees for construction plan reviews by $3,510 for dams of less than 15 feet in height, ,940 for dams between 15 and 50 feet tall, and $14,284 for dams exceeding 50 feet.
“Current inspection and permit fees cover only about 18% of the costs of our dam safety program, which has helped prevent dam failures in Washington,” Dam Safety Supervisor Ben Bonkowski says. “The fee increases will allow the state to recover 26 percent of the costs of the program from dam owners who benefit from Ecology’s regulations that help ensure that their structures are safe and, in turn, reduce their liability.”
The department says failures are extremely rare among the dams that it permits, with none resulting in loss of life or significant property damage. However, dams built without the required permits and oversight have failed.
ASDSO names officers, presents awards
The Association of State Dam Safety Officials announced new officers and presented awards during a banquet held at its annual conference in September 2011 in National Harbor, Md.
Zahir (Bo) Bolourchi, P.E., of Louisiana is president. Bolourchi took office during the 2011 annual meeting, succeeding John H. Moyle, P.E., of New Jersey, now immediate past president.
Also serving as 2011-2012 ASDSO officers are Jason Campbell of Illinois (president-elect), James W. Gallagher, P.E., of New Hampshire (treasurer) and Tom Woosley, P.E., of Georgia (secretary).
Bolourchi is director of dams, levees (non-coastal), reservoir development and water resources programs for the Louisiana Department of Transportation & Development, Division of Public Works and Water Resources. Campbell is a dam safety/floodway permitting engineer with the Illinois Department of Natural Resources. Gallagher is chief of the dam bureau of the New Hampshire Department of Environmental Services. Woosley is program manager for Georgia’s Safe Dams Program. Moyle is manager of the New Jersey Department of Environmental Protection Bureau of Dam Safety and Flood Control.
Rehabilitation project of the year
ASDSO selected the seismic rehabilitation and spillway modification work at Big Tujunga Dam as its 2011 rehabilitation project of the year. Big Tujunga, owned and operated by the Los Angeles County Department of Public Works, is a 244-foot-high, 830-foot-long variable radius thin arch dam in the San Gabriel Mountains. It was built from 1930 to 1932 and impounds a reservoir with an area of 5,750 acre-feet.
Several improvements to the abutment and foundation have taken place, including stabilizing the downstream abutments with shotcrete and grouting. In early 2005, spillway discharge undercut the left canyon rock slope and initiated a localized rockfall. Additionally, past hydrologic and seismic studies had concluded spillway capacity was inadequate to pass the probable maximum flood and the dam was unable to adequately resist seismic loading with a full reservoir. Consequently, the reservoir was restricted to 75% storage.
MWH Americas re-analyzed seismic and hydraulic issues to confirm these deficiencies and considered a number of alternatives. LA County Public Works chose to incorporate a complete rehabilitation of the dam into the final design, including geotechnical, structural, hydraulic, mechanical and electrical rehabilitation. Construction began in early 2008, and the last mass concrete block was completed in January 2011.
Awards of merit
This year’s National Award of Merit was presented to Perry J. Hensley, senior advisor for design, estimating and construction oversight and dam safety officer for the Bureau of Reclamation. He manages a program to conduct internal quality assurance reviews of Reclamation’s major design and construction projects, serves as responsible official for value engineering and advises the Commissioner on the performance of Department of Interior dam safety programs.
Several regional awards of merit also were presented at the banquet.
Consultant Carl Montana received the Northeast Regional Award of Merit. He serves on the executive committee of ASDSO’s New Jersey/Pennsylvania Counsel for Safe Dams and on ASDSO’s affiliate advisory, scholarship and peer review committees. Montana has participated in reviews of state dam safety programs in Pennsylvania, Massachusetts, Kansas, Utah, Kentucky and Mississippi and developed and taught several ASDSO dam owner workshops.
Brian Long with the West Virginia Dam Safety Program received the Southeast Regional Award of Merit. He has spent more than 35 years working in dam safety on a state, regional and national level. Long has served on the ASDSO board for 15 years and as president from 1997 to 1998, and he is an ASDSO representative on the National Dam Safety Review Board.
George E. Mills, P.E., received the Midwest Regional Award of Merit for his work in the field for the Ohio Department of Natural Resources in the Dam Safety Section for more than 28 years and as a consultant for more than 13 years. Mills served as ASDSO president from 1995 to 1996 and on ASDSO’s executive committee and board of directors from 1993 to 1997 and 1991 to 1997, respectively.
Patrick J. Regan, regional engineer in the Portland Regional Office of the Federal Energy Regulatory Commission, received the West Regional Award of Merit. He has been instrumental in helping lead efforts to evaluate dams based on potential failure mode analysis procedures. In the Pacific Northwest, this procedure soon will become FERC’s standard to classify dams and rank each project’s potential failure modes, determine their effects on operations and institute actions to mitigate the most likely failure sequence.
The President’s Award was given to Dan Mahoney, former director of the Division of Dam Safety and Inspections for FERC. Under his leadership, FERC carried out many initiatives to improve dam safety, including supplementing ASDSO’s training program by bringing technical courses to state dam safety offices.
ASDSO presented several student awards, including a scholarship and the winners of a student paper competition.
Alexander McCaskill, a senior at the University of Missouri-Kansas City majoring in civil engineering, received a $10,000 Senior Undergraduate Scholarship. He is vice president for the UMKC student chapter of the Missouri Society of Professional Engineers and is a member of ASDSO, American Society of Civil Engineers, American Institute of Steel Construction and Association of Engineering Geologists. After graduation, he intends to pursue a graduate degree in geotechnical engineering.
ASDSO’s Committee on Education Outreach chose three winners for its Student Paper Competition: Mahdi Khalilzad of North Carolina State University; Mishelle Shriro and Diego Cobos-Roa of the University of California, Berkeley; and Christopher D. Sandt of the University of North Carolina, Chapel Hill. The winners presented their papers at the conference and received a $500 prize.
NRCS names five companies to repair nine Tennessee dams
In contracts exceeding $1.2 million, the Natural Resources Conservation Service (NRCS) has named five small businesses to repair storm damage to nine dams in Tennessee.
- Elk Mountain Construction Co. Inc. of Cookeville, Tenn., received two contracts. First was a $218,020 contract to repair spillway outlet channels of Jennings Creek Dam No. 3 in Jackson County that were severely damaged during a May 2010 flood. The primary portion of the work is to install two grouted rock riprap chutes in the spillway outlet channels to stabilize the auxiliary spillways. Second was a $241,725 contract for debris removal and repair of damaged spillways of Jennings Creek Dams No. 6 and 10 in Jackson County.
- Adams Contracting Co. of Robbinsville, N.C., also received two contracts. One was a $147,527 contract for debris removal and repair of damaged spillways of Jennings Creek Dams No. 13 and 18 in Jackson County. The primary portion of the work is to install a grouted rock riprap chute in the spillway outlet channel to stabilize the auxiliary spillway. The second was a $266,109 contract for debris removal and repair of damaged areas of Jennings Creek Dam No. 15 in Jackson County.
- Precision Point Contracting Inc. of Shell Knob, Mo., received a $109,271 contract for debris removal and repair of damaged spillways of Jennings Creek Dam No. 17 in Macon County.
- Fuel Tank Maintenance Co. LLC of Cookeville, Tenn., received a $201,882 contract for debris removal and repair of damaged areas of Hurricane Creek Dam No. 9 in Humphreys County. The dam has three areas of work: the emergency spillway and berm drains, impact drain, and access road.
- Three Rivers Contracting Inc. of Dixon Springs, Tenn., received a $49,063 contract for debris removal and repair of damaged spillways of Line Creek Dam No. 3B in Clay County.
Oregon firm to maintain, repair California dams
The U.S. Army Corps of Engineers has awarded a maximum $5 million contract to M.J. Hughes Construction Inc. of Gresham, Ore., to maintain and repair more than a dozen dams in the Corps’ Sacramento District of California.
M.J. Hughes received a five-year indefinite delivery indefinite quantity contract for dam maintenance and repairs. In addition, the company received five task orders for actual work totaling $1.2 million. The task orders are for work at 2.65-MW New Hogan Dam; 6.2-MW Black Butte Dam; Buchanan Dam (Eastman Lake); Hidden Dam (Hensley Lake); and Martis Creek Dam.
Work under this new contract can include, but is not limited to: emergency, service, low-flow, tainter radial and bulkhead gates; conduit liners; penstocks; breast walls; trashracks; all facets of painting, paint removal, and concrete repair; spillways; intakes; plumbing, electrical, hydraulic, and pump systems; wing walls, drain holes; vertical drains; conduits; and gate seals.
The list of other prospective work under the contract includes 11.95-MW Lake Isabella Dam on the Kern River, which is being studied for remedial actions to prevent possible failure during earthquakes.
Other projects on the list include: 1.4-MW Success Lake Dam; Lake Kaweah Dam, site of the 17-MW Terminus project; 165-MW Pine Flat Dam; Englebright Dam, site of the 12-MW Narrows project and a portion of the 395-MW Yuba River project; and the Merced Stream Group (Burns, Bear, Owens, and Mariposa dams).More HR Current Issue Articles
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