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Planning a dam

things to consider

Environmental concerns
Relocation & other issues

who is doing the considering

Local government
State government
Federal government
Enginneering firm
People being affected
Safety officials
Labor officials
Environmental groups
Quality officials
You'll notice that there are more people making decisions as there are things to decide. These lists are not comprehensive; they are just to give you an idea of how much goes into a large-scale project like building a dam.

Here you'll have a chance to consider each thing yourself and make a comment on the bulletin board about it. Any of the POST buttons will open the bulletin board for you; post your message under Planning Scenarios.


First question: why is the dam necessary?
Is there more than one reason for the dam?
Do the reasons outweigh the disadvantages?
These are very important questions to ask about each dam. An even more important question is, how do you decide?

The Edwards Dam on the Kennebec River in Maine had one purpose: to provide hydroelectric power, power that does not pollute the environment. The Edwards Dam has also blocked the passage of several species of fish, causing a decline in their numbers. The dam is being taken down this year, 1999, because the power it provided was not enough to justify the fish it killed.

There are many dams that provide just one service; there are many more dams that have several purposes. How many purposes do you think justify a dam's existence? What else does it depend on?

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The cost of the project will be highly influenced by what type of dam it is. For instance, a gravity dam uses much, much more concrete than an arch dam and, consequently, gravity dams are more expensive than arch dams. But arch dams are not always appropriate. The type of dam must be determined based on a number of different issues: cost, materials, location (foundation type). Once the type is decided on, an engineer or an engineering firm is called on to design the dam; another engineer or firm will double check the work. Often several designs might be presented for the same dam and a decision must be made based on structural reliability and efficiency, among other things.

Civil engineers are often involved in the design of dams.

The St. Francis Dam failed in 1928 in California. It was designed by really just one person, William Mulholland. Some feel that the dam failed because no one checked his work.

How many people should check dam designs? What other types of designs should be checked? Bridges, buildings, cars?


Location is important because the foundation of a dam must be laid down in a stable location. Strong, impermeable bedrock provides a solid base for foundations. Porous stone, such as limestone, will not work for dams because reservoir water will seep out through the stone. Also, dams should not be constructed on fault lines for obvious reasons -- if an earthquake ever occured there, that would be the end of that dam. The width of the river or gorge also determines what type of dam can be built there.

Civil engineers may investigate the foundation for a dam.

Another thing to consider is what is surrounding the potential dam site. How many people will have to move? Will forests have to be cut down? Where will the employess live?

Malpasset Dam failed because of problems with its foundation. Some argue that these problems were not forseeable at the time of construction.

Who is responsible for the damages caused by the failure in that case?


The court case Bayne v. Everham makes engineers responsible for both what they do and what they say. It is both their legal and moral responsibility to protect people. If a cost-cutting technique is used in the construction process, an engineer must consider all possible risks before granting his approval.

Sometimes government or other authorities have enough power to make decisions without consulting anyone else. The local government near the El Atazar Dam tried to convince everyone that there was no crack in the dam when there definitely was. Construction on the Teton Dam, which failed in 1976, was allowed to begin before the final studies and design were finished.

Who has the right to contest government or authority decisions?

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Environmental Concerns

The construction of a dam can seriously affect the surrounding environment. Frequently, the land around rivers is very fertile. However, when a dam creates an artificial lake, the water table (underground water level) of the land around the lake will often be raised. This causes the land to become infertile due to inadequate soil drainage. Also, increased erosion and river pollution must be considered. Some researchers also believe that the creation of reservoirs can lead to climate changes and increased chances for earthquakes. Fish are also an important consideration, the cause of opposition to dams all over America.

The US Army Corps of Engineers has been researching what would happen to fish in the Lower Snake River if four dams are removed. They have determined that fish survival would likely increase. Do you think this is a good reason to take the dams out?


There are two major costs of dams. These are the cost of construction as well as the costs of operation and maintenence. These costs can total millions of dollars. The Tennessee Valley Authority, for instance reported that by 1971, the total cost for their series of dams in the Tennessee Valley was $281 million. However, without these dams, it is estimated that by 1971, over $392 million worth of flood damage was averted. But often the costs of construction can be grossly underestimated, as in the case of the Three Gorges Dam being built in China. The estimates to finish the dam are now three times what they originally were.

There are also costs associated with relocating people, loss of ancestral grounds, and loss of archaelogical artifacts. Some of these things can't be put in terms of money.

What things do you think the Tennessee Valley Authority estimated in the cost to build their dams? What things should be included in a cost analysis?

Relocation & other issues

The costs of relocation, lost environmental habitat, and lost artifacts must be considered as mentioned above. The Three Gorges Dam in China will cover an estimated 120,000 people had to be relocated for the Aswan High Dam in India; an estimated 1-2 million people will have to move because of the Three Gorges Dam being built in China presently. There are often problems with relocation.

Where do the people go? Who pays for their move or their new land? What if they don't want to go? What if the people are moved near other people they do not get along with? This happened because of the Volta River project in Ghana.

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It is important to have the entire dam project planned out. Scheduling delays due to poor planning of resource allocation (including labor and capital) can cost contractors upto $50,000 a day. The increased estimates in the costs of the Three Gorges Dam have left authorities unsure about where the needed money will come from. Check out a recent headline about the costs of the Three Gorges Dam in Dam News: money -- they don't have enough!

Who should be responsible for time and money lost due to scheduling problems?


Typically the dam owner will hire construction engineers and a contractor to assemble a construction group. Usually hundreds (and sometimes even thousands) of workers are required for the construction of a dam. The Fontana Dam on the Little Tennessee River in North Carolina used 5,000 workers. These workers will also need a place to live. In cases like the Hoover Dam and the Grand Coulee Dam, whole towns were born to house the employees of the dam project. Sometimes the workers showed up before the towns were ready -- there was no drinking water or electricity for them yet.

Although this is unlikely to happen again in the United States, it could happen in other countries that are just beginning large dam projects. What kinds of scheduling and provisions need to be made for the employees of the project?

You probably noticed how intertwined the things to consider are. Making a decision about a dam, either to build it or take it down, involves teamwork and trade-offs. What are the most important things to consider in your opinion?

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Goldsmith and Hildyard

Scenarios Dam construction