ASCE releases review of drilling, grouting for dam foundations
The American Society of Civil Engineers (ASCE) announces availability of a new book, Dam Foundation Grouting, Revised and Expanded. This second edition was written by Kenneth D. Weaver, a grouting consultant in California, and Donald A. Bruce, PhD, C.Eng., president of Geosystems L.P. Like the first edition, authored by Weaver, this book provides background information and guidance on design, construction, supervision, anal- ysis, and review of grouting programs.
This new edition has been revised to reflect contemporary grouting practice and has been enlarged to include coverage of geologic considerations and to address remedial grouting issues. In addition to providing extensive information on grouting technology, equipment, and procedures, the 504-page book provides guidance on specifications and contracts.
- – Geologic and geohydrologic considerations;
- – Conceptual design considerations;
- – Grouting materials;
- – Basics of particulate grout mix design, testing, and performance;
- – Grout injection pressure;
- – Miscellaneous factors affecting grouting effectiveness;
- – Drilling;
- – Grouting equipment;
- – Preparation for grouting;
- – Basic procedures for bedrock grouting;
- – Supervision and inspection;
- – Records (field and office, and progress reports);
- – Quality assurance, quality control, and verification;
- – Considerations for remedial foundation grouting; and
- – Specifications and contracts.
- – Dam Foundation Grouting, Revised and Expanded costs $105 for ASCE members and $140 for non-members. To order, visit the Internet: www. asce.org/bookstore/book.cfm?book =6981.
Geomembrane placed on dam over redwood planks
To return seepage levels at Sabrina Lake Dam on the Middle Fork of Bishop Creek to historical levels, owner Southern California Edison (SCE) chose to install a geomembrane system supplied by Carpi USA Inc. in Roanoke, Va. This installation was unique because Sabrina Lake Dam is a rockfill dam with a redwood timber upstream face that acts as a waterproofing membrane.
Over time, seepage through the dam was increasing, although still within acceptable levels structurally. The dam was completed in 1908, and SCE added a second layer of redwood in 1961. However, the timbers were becoming more expensive and difficult to find.
To determine if a geomembrane system could be installed at Sabrina Lake Dam, Carpi personnel visited the site and conducted anchor testing. They also developed a preliminary design to determine the feasibility of anchoring into the wood and covering it with a geomembrane.
Carpi began installation of the geomembrane system in late April 2006 and completed the installation in six weeks. The geomembrane system at Sabrina Lake Dam consists of:
- – A geotextile applied directly to the redwood face to act as a cushioning transition layer;
- – Stainless steel tensioning profiles to clamp the geomembrane and resist severe winds;
- – A polyvinylchloride (PVC) geocomposite as a waterproofing layer;
- – PVC geomembrane cap strips to cover the profile clamping system;
- – A stainless steel perimeter batten seal system to seal the geomembrane along the foundation; and
- – Construction of a shotcrete plinth for attachment of the perimeter seal system.
Since the geomembrane system was installed, seepage has been reduced dramatically. Before the installation, the downstream weirs would overtop. The weirs are now below 10 percent of capacity, indicating that seepage has been reduced by more than 90 percent, says John Stoessel, dam safety engineer with SCE.
ASCE calls for nominations for hydropower awards
The American Society of Civil Engineers’ Energy Division is accepting nominations through November 1, 2007, for its Rickey Medal and Phillip R. Hoffman Award.
The Rickey Medal, established in 1947, is named in honor of James W. Rickey and is awarded for a meritorious paper published by the society in the general field of hydroelectric engineering. It also can be given for service recognition of an individual or group that contributed to the science or progress of hydroelectric engineering.
The Hoffman Award, established in 1987, honors an engineer who contributed to the field of pumped storage. The contribution can be in the form of a published paper or performance in the field.
Award nomination forms are posted on ASCE’s Internet site, www.asce.org. Nominations can be submitted via e-mail to either [email protected] or [email protected] asce.org, or sent to: Jane Moran Alspach, Honors and Awards Program, ASCE, 1801 Alexander Bell Drive, Reston, VA 20191-4400. For more information, telephone (1) 800-548-2723.
Seminar on RCC dams includes study tours, debates
More than 60 people from 14 countries participated in the International RCC Dams Seminar and Study Tour (RCC 2007), March 18 to 23 in Atlanta.
At the seminar, 17 speakers from the U.S., Canada, Australia, Germany, and Spain presented lessons learned from past performance and state-of-the-art in the design and construction of roller-compacted concrete (RCC). RCC dams are being built as high as nearly 650 feet. Shear resistance and direct tensile strength at lift lines continue to be the major items to be solved in the design of high RCC dams.
More than 60 engineers from 14 countries took part in the International RCC Dams Seminar and Study Tour, which included visits to four roller-compacted concrete dams.
Seminar attendees visited several RCC projects, including:
- – Hickory Log Creek Dam, which is currently under construction to provide additional water supply for two Atlanta suburbs. At a final height of 188 feet, the gravity dam is the tallest RCC dam under construction in the U.S. Hickory Log Creek Dam is the only RCC dam in the U.S. with crest gates.
- – Big Haynes Dam, which was completed in 1995 to supply water to an Atlanta suburb. This dam used an exposed lean RCC mixture, and the spillway was constructed using precast concrete column sections anchored back into the RCC.
- – Two RCC overtopping protection projects on the Yellow River. For Y14, formed steps of exposed RCC were placed on the downstream slope of the embankment and adjacent to each abutment. For Y17, overlay RCC on all areas except the dam crest was covered with top soil and planted with grass. In the event of a flood, the grass cover could erode, leaving the RCC to protect the dam from failure.
The seminar was sponsored by Schnabel Engineering in conjunction with the Association of State Dam Safety Officials. The conference is held every other year.