REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


will be just filled with dirty water. What class of material is it you expect to get here, Mr. Maltby?
 Mr. MALTBY. The material is nearly all clay. The material we are handling now is that material that has been deposited in a channel which has once been excavated. Are you speaking of Colon or Panama?
 Mr. HUNTER. Of Panama.
 Mr. MALTBY. The material on the Panama side varies very little. In places it is clay, not much sand in it; more sand on the La Boca side than on this side.
 Mr. HUNTER. Do you contemplate using cutters on your hydraulic dredge?
 Mr. MALTBY. Yes, sir.
 Mr. HUNTER. Are you acquainted with any place where that has been done successfully in scows?
 Mr. MALTBY. I suppose the best example of that would be all along the Atlantic coast. For handling into scows or into hoppers on board the dredge itself-self-contained dredges-New York Harbor is a splendid example of it, where they handled with two dredges 300,000 yards last month. It is a different material in New York Harbor than here; it has more sand.
 Mr. QUELLENNEC. Certainly, these old bucket dredges are not convenient; they are over twenty years old, and now we construct for the Suez Canal dredges of a different type. The solution of the question of economy of a dredging plant is to have the dredges as large as is possible under the circumstances, and I agree with the opinion of your engineer that at Colon and La Boca suction dredges with cutters should be used if possible. All kinds of cutters are not good; there are not many good ones. I know one or two suction dredges with cutters capable of dredging the clay of Mindi. I can say that the cost of material dredged at Suez by suction dredges and disposed through pipes costs less than 10 cents all together, and considering the large quantity to be removed in the sea-level parts of the Panama Canal I think the cost will approximate 10 cents. If it is possible to avoid the scows it is better to put the material into the pipes directly. It is more economical, and with the great width of the canal there should be no trouble from the passing of vessels during construction.
 Mr. PARSONS. You said you could dredge as far as Bohio from this side, I think?
 Mr. MALTBY. Roughly speaking.
 Mr. PARSONS. You spoke of the cost of 10 cents a yard for material put ashore; what portion of the material between here and Bohio would be of that nature?
 Mr. MALTBY. Fully nine-tenths of it. We have bored all the way to Bohio, and we find sand and mud. We get out of this indurated clay down here a little above Mindi. Later we bored at Gatun for a channel 45 feet deep, and we did not strike any of it there. There is nothing but sand and silt all the way until we strike the Bohio rock.
 Mr. PARSONS. Are you willing to hazard an estimate on the work of excavation-what it should be done for as far as Bohio; the cost per cubic yard?
 Mr. MALTBY. I am willing to let my opinion stand as for that class of material. I believe we can build a suction dredge with a cutter that will cut the indurated clay and put it ashore.
 Mr. PARSONS. At what cost would you think it would be safe, assuming for the cost of removing the indurated clay?
 Mr. MALTBY. Fifty cents a yard.
 Mr. HUNTER. Do you think it would be as much as that?
 Mr. MALTBY. I want to make my price big enough. We may have to shoot part of it; to shake it up and then cut it.
 Mr. HUNTER. To pump it over the dikes on each side, there would be no trouble?
 Mr. MALTBY. If we get it into the cutters we can handle it.
 The CHAIRMAN. The trouble is to get it into the cutter?
 Mr. MALTBY. We may have to shoot it. I believe we can build a cutter that will move the stuff.
 The CHAIRMAN. How about the coral rock?


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