Issue identification module: introduction | social issues | historical issues | aesthetic issues | economic issues | legal and land-use issues | engineering issues | fish, wildlife, and environmental issues | summary | appendixes

Engineering issues

Site-specific factors, such as the floodplain of a river, the physical characteristics of a watershed, and national and statewide regulations, control the safety of dams and should be considered when making a decision about a dam.

Dam safety and hazard classification

Checklist questions

• What is a dam safety inspection? How often does the dam owner need to perform it?
• What is the size, type, age, and safety condition of the dam?
• What is the land-use classification of the land downstream of the dam? (that is, are there towns over a certain size? campgrounds in the area?)
• What is the level of development at and below the dam site? Would there be liability concerns during dam repair or removal? Who would be the responsible party?
• What is the Wisconsin Department of Natural Resources hazard ranking of the dam? (that is, how much potential damage could be caused if the dam were to fail?)
• What is the National Dam Safety Program Act prepared by the Federal Emergency Management Agency? Does it affect the dam in your community?

Toolbox

• The Wisconsin Administrative Code NR 333.06 provides standards for land use and hazard ranking classifications.
• The Wisconsin Department of Natural Resources hosts a web page with basic information on how to perform a dam safety inspection: http://www.dnr.state.wi.us/org/water/wm/dsfm/dams/checklist.html
• Wisconsin Department of Natural Resources Dam Safety Bureau. Contact the Dam Engineer in your county or contact the State Dam Safety Engineer; web site: http://www.dnr.state.wi.us/org/water/wm/dsfm/dams/staff.html
• Training Aids for Dam Safety. One of Federal Emergency Management Agency's most successful training initiatives is the Training Aids for Dam Safety (TADS) program, which uses an array of modern training materials. The TADS program consists of three parts: (1) the inspection component, in which state regulators are taught how to conduct a dam safety inspection; (2) the awareness component, which emphasizes dam safety mitigation; and (3) the analysis component, in which state regulators are taught how to analyze dam safety data. Two TADS modules are in the process of being updated: the inspection embankment dams module and the module on evaluation of seepage conditions. For additional information on TADS or to order TADS materials, call 303/236-4308. Or check the dam safety inspection module: Brown, Thomas A., Dalton, Robert H., McCleskey, Timothy, Pawlikowski, Witold J., Ryker, Norman L., “Training Aids for Dam Safety: Preparing to Conduct a Dam Safety Inspection,” United States Government Printing Office, Denver, Colorado, 1988.
• Wisconsin Department of Natural Resources safety inspection checklist: Appendix D of this module.
• The Federal Emergency Management Agency hosts a web page explaining the National Dam Safety Program Act; web site: http://www.fema.gov/mit/damsafe/ndspact.htm
• Association of State Dam Safety Officials, a nonprofit group dealing specifically with dam safety; web site: www.damsafety.org

Flood studies

Checklist questions

• Does the dam provide flood protection?
• Does the dam meet necessary flood standards?
• What is the flood passage capacity of the dam?
• Are there other dams in the river system that could be physically affected by this dam’s removal?
• Have floodplain studies been administered previously in your watershed? Is one necessary for this specific site?

Toolbox

• The Wisconsin Administrative Code NR 333.04 (4) states the standards a dam must be in compliance with for possible flood damage. Also, the Wis. Admin. Code NR 116 provides further floodplain regulations.
• To learn more information on federal and state governments working on floodplain management and flood insurance programs, check the web site hosted by the Wisconsin Department of Natural Resources: http://www.dnr.state.wi.us/org/water/wm/dsfm/flood/links.htm
• The Wisconsin Department of Natural Resources Dam Safety, Floodplain, Shoreland Specialist: John Hagengruber, 608/267-7571.

 

Structure assessment and analysis

Checklist questions

• Would the dam survive maximum headwater conditions (impoundment filled to the top)? Is it possible to see sliding, overturning, or foundation failure (such as, cracks, holes, crumbled sections, and so forth)?
• Would there be a need for design or construction of alternative water intakes, storm sewer outfalls, or ramps if the dam were removed?
• Is there a millrace or canal associated with the dam? How would that be addressed if the dam were removed?
• Is there easy access to both sides of the dam for the necessary construction equipment?
• If the dam were to be removed, are there alternatives that should be taken into consideration (such as saving part of the pond adjacent to the free-flowing river, creating artificial wetlands next to stream, creating artificial riffles or a small waterfall area if they are desired or would not exist naturally following the dam’s removal)?
• Is there adequate current knowledge of a removal method that would work for the specific site (that is, what are the uncertainty issues associated with removal methods)? If not, can that information be obtained?

Toolbox

• Wis. Admin. Code NR 333.05 (2) states the requirement for structure stability analyses.
• Wis. Admin. Code NR 333.05 (2) states the requirement for structure stability analyses.
• For guidelines, contact the Wisconsin Department of Natural Resources Dam Safety Engineer in your county and also check the guidelines provided at the web site: http://www.dnr.state.wi.us/org/water/wm/dsfm/dams/checklist.html
• For term definitions visit the Wisconsin Department of Natural Resources web page: http://www.dnr.state.wi.us/org/water/wm/dsfm/dams/definitions.html

Emergency Action Plan

Checklist questions

• If an Emergency Action Plan (EAP) applies to your community, how do you create one?
• Does one need to be completed for this dam?
• How does it work?
• How much does it cost?

Toolbox

• The Federal Emergency Management Agency provides training products for preparing an Emergency Action Plan targeted to dam owners and operators, dam safety officials, emergency managers, and the public. For a videotape, contact the Federal Emergency Management Agency at 800/480-2520. For further questions, contact Rita Henry at rita.henry@fema.gov.

• The Wisconsin Department of Natural Resources web site has a sample Emergency Action Plan and a sample Operation and Maintenance Plan: http://www.dnr.state.wi.us/org/water/wm/dsfm/dams/sample.html.

Sediment management

Checklist questions

• How much sediment is built up behind the dam? How was the estimate determined?
• What type of sediment has accumulated behind the dam (determined, for example, from core samples of sediment)? Is it contaminated? If so, can the contaminants be cleaned up and/or disposed of easily and effectively? Who are the responsible parties?
• How often does the pond need to be dredged? Does a sediment disposal site exist nearby?
• How does dredging affect fish/wildlife habitat? (Please also check the Fish, wildlife, and environment section of this module.)
• If the dam were removed, how will the sediment built up behind it be handled? (Please also check the Fish, wildlife, and environment section of this module.)
• Is there someone who could make use of uncontaminated sediment (for example farmers)?
• How much sediment would potentially be released downstream with dam removal? How would that sediment impact the stream? Depending on the watershed, where will the sediment end up? If it would seriously impact the stream and/or watershed, what are the alternative sediment-management options?

Toolbox

• The Wisconsin Department of Natural Resources hosts a web page where the details on how to collect, prepare, preserve and package sediment samples are explained. This web site also provides the necessary contact information for sending the samples to the Wisconsin State Laboratory of Hygiene for the analysis: http://www.dnr.state.wi.us/org/water/wm/wqs/sediment/sampling/701_5.HTM
• The University of Wisconsin Soil and Plant Analysis Laboratory analyzes sediments for total minerals and heavy metals under the environmental tests classification. See their web site:  http://uwlab.soils.wisc.edu/fees.htm. For additional information about the lab, go to http://uwlab.soils.wisc.edu/.
• The U.S. Environmental Protection Agency (EPA) has a publication entitled Contaminated Sediment Management Strategy, available from the National Center for Environmental Publications and Information, P.O. Box 42419, Cincinnati, Ohio 45242. Copies may be ordered by phone at 800/490-9198; by fax at 513/489-8695; or at their web site:  http://www.epa.gov/ncepihom/orderpub.html. Questions concerning the publication may be directed to EPA's Office of Science and Technology at 202/260-8897. See also the EPA web page for a copy online: http://www.epa.gov/OST/cs/manage/stratndx.html.
• The U.S. Army Corps of Engineers, Great Lakes Region, has information available on different sediment management strategies, including beneficial uses, open water placement, and confined disposal. Also available is information on mechanisms that initiate sediment control. Check this information at http://www.lrd.usace.army.mil/gl/sediment.htm.

• Strategic Dam Planning: Chequamegon National Forest. 1994. Put together by lead engineer, Art Johnson.
• Private consultants have experience in the fields of dam safety inspection, sediment analyses, sediment-transportation modeling, structure assessment, and Emergency Action Plan preparation. Find an engineering firm or a contractor from this list assembled by Wisconsin Department of Natural Resources staff; web site: http://www.dnr.state.wi.us/org/water/wm/dsfm/dams/consultant.html#consultants
• Trout Unlimited study on Engineering and Dam Removal (in production) – “Removing Small Dams: A Practical Guide to Engineering and Other Scientific Considerations.” For more information, contact Trout Unlimited Watershed Restoration Coordinator Brian Graber at 608/255-0361 or bgraber@tu.org

 

Next section: Fish, wildlife, and environmental issues

URL: http://www.ies.wisc.edu/research/wrm00/issueeng.htm