COMMENTS ON ENGINEERING WORK OF AUTHORITY

Colonel PARKER. Now I should like to introduce certain exhibits to illustrate the way really in which our work is carried on. I think that it will illustrate also several other things. It will illustrate the character of the work, and also the way in which our construction costs are controlled and handled, and analyzed.

I first would like to introduce a few exhibits indicating the way the different departments, an example of the way they handle the work. I have already shown one exhibit, showing the flood area in Chattanooga.

The chart marked "No. 4" in this folder, that shows the character of the lower Mississippi Valley, and I rather hesitate to introduce this because we don't want to get involved in a detailed discussion of the lower Mississippi Valley. I simply show it to indicate that we have given some thought to this and to the prevalence and character of the floods down there and to various areas involved.

We have had an engineer make a report on the effect of our flood regulation on the lower Mississippi.

Mr. BIDDLE. The top of that is Cairo, and how near to Cairo does the Tennessee Valley come into the river?

Colonel PARKER. Our Gilbertsville Dam is located right here near the mouth of the Tennessee, which I believe is something less than 50 miles from Cairo, and that, by the way, is less than 1 day's journey by water, that is the flow of the river, the water in the river requires only a day to pass from the site of Gilbertsville Dam to the mouth of the Ohio.

Mr. BIDDLE. And the bottom of the chart is New Orleans, I take it. Colonel PARKER. New Orleans is here.

Mr. BIDDLE. Do you know how long the navigation takes from New Orleans to Cairo? I meant boat travel; I didn't mean water flow.

Colonel PARKER. About a week.

Representative JENKINS. Let me ask a question about that, Colonel. You don't claim that anything that is done or will be done on the Tennessee River, by T. V. A., will have any appreciable influence on the floodwaters of the Mississippi River?

Colonel PARKER. We estimate that the regulation afforded by our proposed Gilbertsville Reservoir will lower flood crests at Cairo by at least 2 feet, from 2 to 21⁄2 feet, those flood heights on the Ohio and Mississippi at that point.

Representative JENKINS. I have here before me-do you know the name of the gentleman, the river expert, representing the Mississippi River Association, that testified in these trials?

Colonel PARKER. Major Putnam?

Representative JENKINS. No; not Major Putnam.

Mr. BIDDLE. Mr. Kurtz?

Representative JENKINS. No; I think he is president of the Mississippi River Association, or something like that. He was a witness and testified-I would like to have permission to furnish his testimony, a few lines in the record, at this point, and I can't find it here, but I can find it.

Chairman DONAHEY. You may proceed.

Colonel PARKER. Shall I proceed with chart No. 6, indicated here?

The next exhibit is labeled No. 5, in my records, and is the report on the Chickamauga project, which was compiled by our planning department, preliminary to the development of that site. It is offered as an example of this character of work; it is an example of the investigation carried on prior to the actual authorization of construction.

Mr. BIDDLE. Would you mark that, please, as "Exhibit 497?" (The document above referred to was received in evidence and marked "Exhibit No. 497.")

Mir. BIDDLE. Describe that very briefly.

Colonel PARKER. It is the result-it shows the results of the investigation which was made by the planning department to determine the proper site for this development. The general character of it, the height of the dam, amount of power to be installed, and general characteristics of the construction.

Those depend or result from a good deal of basic data acquired in the way of surveys, borings at the site, stream flow gages, and calculations of various kinds, which has to be extremely thorough in order to insure a project of this magnitude being carried out in the proper

way.

There is also a great advantage in setting up such results in this form where it affords a permanent record of our work, and a means of ready reference from all those interested in the project. It does not necessarily contain the exact dimensions of the structures as finally built; it is a guide; after approval by the Authority, by the board of directors, and authorization of the project, such a report is passed to our design department, and serves as a guide for them in developing the detailed and practical designs for the dam.

Mr. BIDDLE. Would that be a guide of estimated costs?

Colonel PARKER. It accompanies and includes an estimate of the cost of the project and in that way forms a basis for the request for authorization and for funds which we make to Congress.

Mr. BIDDLE. All right. Thank you.

Colonel PARKER. The next exhibit is labeled No. 9 in our list, chart No. 6.

Mr. BIDDLE. That is found in the exhibit which the committee already have, 494.

Colonel PARKER. This is an example of the work of our design department, to indicate in a general way what the structures look like in cross section. This figure on the left is the cross section through the Hiwassee Dam and is typical of the high dam type of project.

You will see that it shows an operating deck up here, for regulating overflow and sluiceways down here to permit the discharge of the waters which are below this crest in the event that we wish to lower the reservoir level in anticipation of flood in order to provide sufficient volume up here.

You will notice this extensive apron, so-called, plunge basin, which is devised to use up the energy of the falling water so that it won't tear away the rock below the dam and undermine the dam structure. The shape of this thing is developed in our hydraulic laboratory very carefully on models.

This diagram bere shows a typical main river dam which as you see is very different from the high dam on tributaries. It consists. of a lower block of concrete with an apron to absorb the energy and high piers, which are in the case of most of our dams, about 40 feet apart, the space between these piers is occupied by large steel gates, which are ordinarily about 40 feet high, and 40 feet wide, made in two sections, which can be raised by suitable arrangement on the operating deck so that in time of floods all that is left of this structure is the sill and the piers, that you see is necessary because the volume of water which we have to contend with in the main river is so much greater than it is on the tributaries. In addition

Representative JENKINS. One question there. That doesn't mean that you let down all--you don't let down the gates; all of the gates in the dam, or you wouldn't have any left for power.

Colonel PARKER. The normal procedure is to raise enough of the gates to permit passage of the amount of water which is flowing or desired to pass and maintaining this water level at the desired elevation. We are able to control the flow entirely in this manner.

This depth of gate-they are very large, this is a very large structure.

Representative JENKINS. The water would go over the top; it did go over the top of Chickamauga about 8 feet once?

Colonel PARKER. Over the sill, but that was this point here; that is only up to the elevation of the framework.

Representative JENKINS. Am I mistaken about this, that the last flood that you had in the Chickamauga section down there went clear over the top of some of the construction?

Colonel PARKER. We had certain floods which overflowed our cofferdams, but our cofferdams are merely temporary structures which are used to unwater only, and they bear no relation to the height of the permanent dam.

These gates have this unusual depth largely for the purpose also of being able to draw these reservoirs down in anticipation of a flood, We might have designed a longer spillway, with a higher crest and shallower gates, but that would not permit the reservoir to be down in anticipation of a flood. It requires that additional depth so that as the water rises, it doesn't rise up to a flood height and fill the floodcontrol storage.

Mr. BIDDLE. All right, the next one.

Colonel PARKER. Next is chart No. 7, which is shown merely as an illustration of what design work really is. Of course, for any particular project, something like 800 or 1,000 drawings are made of all sorts of details. Now, one of such drawings is this cross-section through a powerhouse, taken in this instance through the generating unit, which is here, and the headwork structure is here, and here is the water wheel and generator and this is a photograph taken of the actual water wheel which is down here, just to indicate the character of thing that we have to make drawings of, and I am not sure that we are all familiar with just what such drawings really constitute.

Over here is a general drawing of a dam, a spillway, with a crosssection shown here, and here is a photograph showing the downstream face of this power house, and this spillway over here. That is simply to indicate what these structures really are when you cut them in two and look at them like that.

Representative JENKINS. Colonel, there was a question that I asked you awhile ago about the Chickamauga Dam. Here is what I had in mind. I was a little bit at fault, but we will see if this is right. It is taken from the testimony in the Eighteen Power Co. case.

The Chickamauga Dam is completely flooded out with the top of its gates under 7 to 9 feet of water, by the maximum flood to be expected at Chattanooga.

Colonel PARKER. That doesn't have reference to anything that has happened; that is a prediction that such would take place.

Representative JENKINS. But isn't it the fact that this indicates that the maximum flood to be expected in Chattanooga will be 7 or 9 feet over all of the dam structure?

Colonel PARKER. Now, may I explain what that really means again? I don't wish to go too far into Professor Woodward's territory, but I think that I can clear that up.

That might I don't know whether it is or not, but if such a flood reached Chickamauga Dam, such a statement might perhaps be true in part, but with adequate flood-control reservoirs upstream, which will constitute probably 80 or 90 percent of the flood-control storage provided, 80 or 90 percent of the amount of such flood-control storage provided would be retained in those reservoirs, and this maximum flood would never reach the Chickamauga, so that the water which reached Chickamauga would be readily regulated by it.

Representative JENKINS. If you got water in Norris like the last flood, you didn't know whether there was going to be a flood, then you wouldn't help Chattanooga.

Colonel PARKER. I don't recognize that allusion; that instance, as you describe it.

Representative JENKINS. Well, it is a fact that you had a flood that went over the top of Norris last year, didn't you?

Colonel PARKER. Well, my recollection is that we used Norris quite effectively during the last floods to aid in the flood control both at Chattanooga, and to a minor extent down the river.

Representative JENKINS. If when a flood does go over the top of a dam, at that time, that dam is clear out of commission as far as flood control or navigation is concerned, isn't it?

Colonel PARKER. I don't recall that the water passed over the top of Norris Dam.

Representative JENKINS. I am asking you of the case when the water goes over the dam, then its efficiency for navigation or flood control are both gone?

Colonel PARKER. That I think is too general a statement.

Representative JENKINS. Now, isn't it a fact-is a dam when the water is going over it, is it of any value for flood control?

Colonel PARKER. It depends upon how much water is going over it, and whether you are allowing for it.

Representative JENKINS. Just the minute that the water goes over any dam its utility for flood control is gone, isn't that true, for navigation, too, it is gone?

Colonel PARKER.

You might be releasing on purpose an entirely minor amount of the water behind it.

Representative JENKINS. You have released all that, and there is more than you can release, and it is running over the dam, that is what I am talking about.

Colonel PARKER. I don't recall that anything like that happened. Representative JENKINS. I am asking you a question now, if and when water goes freely over a dam, that dam is useless at that time, either for navigation or flood control?

Colonel PARKER. I wouldn't agree, in general; no.

Representative JENKINS. Let me ask you this, then, and I know myself the answer to that question that I asked you; I know as well as you do; but here is one thing that I don't know, that I will ask you about. What about the efficiency of any of these dams for power when the water goes over the top of the dam? Is it still efficient for power?

Colonel PARKER. If enough goes over the top, so that the water level below rises faster than the water level above the head is reduced, in accordance with that, and the power output is reduced, but how much it is reduced is dependent upon how much is passing by, and what the characteristics of the particular plant are.

Representative JENKINS. Of course, but generally speaking, the flood comes from above the dam and goes over the dam, generally, I judge, from the looks of Norris, that it wouldn't have any serious effect as far as the power is concerned, would it?

Colonel PARKER. No, it wouldn't; but I think that in the first place, Norris, the control of the water was not lost at Norris, as far as I recall, since it has been built, is that right?

Mr. WOODWARD. Yes, sir.

Colonel PARKER. We have always maintained regulation there and there has been no instance such as you describe.

So far as Chickamauga being drowned out by a maximum flood, I think that I explained that a maximum flood would not reach the Chickamauga Dam. A great portion of it would be stopped in the upstream reservoirs, and Chickamauga Dam is perfectly competent to handle and regulate moderate floods. Is that clear?

Representative JENKINS. I disagree with you on this, if in the management of Norris Dam, if you had anticipated correctly the oncoming of a flood, and would let out your dead storage, let that all out, and let the surface down to the minimum storage, necessary for power production, of course, you would have a great opportunity there to hold back lots of water, there is no question about that, and I don't want you to think that I am holding out that you had no value in that respect.

Colonel PARKER. The next exhibit is No. 8, and is a collection of drawings showing the general features of the Pickwick Landing project. I won't annoy you gentlemen by going into the details of it, but I think you may be interested just to leaf it through, and get an idea of what these drawings look like.

115943-39-pt. 11-15