best that the lower stretches of the canal should be over rather than under sized. The canal banks from Laguna Dam to Pilot Knob have been designed to give a 6-foot freeboard, in order that ample capacity may be provided to carry all possible storm waters without endangering the canal. 7. STRUCTURES. (a) All the structures along the line of canal are planned to be of concrete and steel. The approximate location of the several structures is shown on the map attached to this report. The cost of the structures is given under the heading "Estimates of Cost." Pencil sketches of the several types of structures have been prepared as a basis for estimates and are on file in the Yuma office. A brief statement of the type of structure is as follows: (b) Laguna Dam and Sluiceway Improvements.--It is contemplated to raise the crest of Laguna Dam 2 feet, if after a thorough study of the conditions this is deemed safe and advisable. The grades and sections of the canals are based upon the assumption that it is practicable to make this addition to the dam. The sluiceway and regulating gates are to be of the same type as those now in use, but are to be enlarged to handle 10,600 cubic feet. It is contemplated to add another Stoney gate of the same size as the three now in use. (c) Waste gates.-At a point about 7,000 feet below Laguna Dam, near Araz and at Pilot Knob, waste gates of the Stoney type are planned, of sufficient capacity to drain the canal and to give a sluicing velocity. Wasteways are also provided for at the Alamo and New Rivers. (d) Checks.-Checks are provided below all the principal turnouts of the flashboard type. (e) Turnouts.-All the turnouts from the main canal are planned of concrete with steel gates and appropriate lifting devices. (f) Drops. The location and height of drops are shown both on the map and the profile. These are of the inclined chute type. At two of the larger drops on the Mesa, plans are made for power development and designated as Mesa Power Plants Nos. 1 and 2. The small drop above Mesa Power Plant No. 1 may in the future be added to the drop at the power plant by raising the banks of the canal and the structures at Power Plant No. 1. No provision, however, has been made for this future work in the estimates. 8. UNIT COSTS. In arriving at unit costs for this work in consultation with the board of engineers it was decided that costs should be based upon what this class of work could be done for under present conditions with standard equipment now in use upon work of like magnitude. The unit prices adopted and used are as follows: Earth excavation--Laguna Dam to Pilot Knob Rock excavation__.. Concrete (massive). Concrete (formed) Concrete (Alamo and New River flumes) Reinforced steel (in place). Right of way $0.20 .25 18-.20 .50 75 --per cubic yar__ __do___. _do do. do. 15.00 Power plants__ Engineering and contingencies 9. ESTIMATES OF COST. (a) Estimates have been prepared and given below upon the basis, first: Of providing for the diversion of 10,600 cubic feet of water at Laguna Dam, to serve the Yuma project, the present Imperial Irrigation District and the available new land which it is possible to irrigate. (b) Second. For the diversion of 7,600 cubic feet of water at Laguna Dam, to serve the Yuma project and the Imperial Irrigation District. In this latter 1 Does not include penstocks, by-pass tail race, or excavation for the buildings. estimate, all structures are estimated of a size and capacity sufficient for the larger development. Only such structures as are required solely for the purpose of placing water on the new land are omitted. The division of costs between the Reclamation Service (for the Yuma project) and the Imperial Irrigation District for the enlargement of the canal from Laguna Dam to Siphon Drop and the construction of a new canal from this point to the proposed power plant near Araz is fixed by the contract of October 23, 1918, between the Secretary of the Interior and the directors of the Imperial Irrigation District. This division of costs is taken into account in the final analysis. No division of costs has been attempted as between the Imperial Irrigation District lands and the Mesa lands. (c) Table of estimates of costs. (See accompanying sheets.) Estimates-All-American canal of capacity to serve Imperial irrigation district and additional Mesa lands. Laguna Dam to Siphon Drop (canal capacity 10,600 second-feet): Pilot Knob to East Side Mesa Canal (No. 1 Sta. 1525) (9,000 second-feet canal): Excavation Earth-45,935,684 cubic yards, at 25c.. Rock-312,307 cubic yards, at 75c-- Total 15 per cent contingency-. Structures East Mesa Canal, No. 1 Turnout. Drop and Check 26 miles telephone line-- Total 15 per cent contingency. Total Mesa Canal No. 1 Sta. 1525 to Mesa Canal No. 2 Sta. $11, 496, 421 353, 948 234, 230 12, 084, 599 1,812, 690 490, 676 2,496, 290 13, 897, 289 24, 000 52, 000 5, 850 81, 850 12, 277 94, 127 13, 991, 416 $422, 020 485, 323 240, 000 10,000 1, 125 251, 125 37, 668 288, 793 774, 116 $1,230, 552 184, 583 1, 415, 135 300,000 14,000 11, 000 28, 000 Sheet No. 12-Laguna Dam to Siphon Drop_. Sheet No. 13-Siphon Drop to Araz_. Sheet No. 14-Araz to Pilot Knob Sheet No. 15-Pilot Knob to East Side Mesa Canal No. 1. Grand total____ 3, 473, 379 4, 905, 447 1,091, 954 2,496, 290 13, 991, 416 774, 116 3, 473, 379 26, 732, 602 The estimated cost from Laguna Dam to Araz is $5,997,401, of which $1,900,000 will be the amount paid to the Government for a connection with Laguna Dam under the contract of October 23, 1918, between the Secretary of the Interior and the directors of the Imperial irrigation district. This leaves the cost of enlargement and construction $4,097,401, of which the Government will pay for two-ninths (for the Yuma project) under the above-mentioned contract, or $910,534, leaving a total net cost to the irrigation district and new land $25,822,068. Estimates.-All-American canal of capacity to serve Imperial irrigation district lands. Laguna Dam to Siphon Drop (7.600 second-feet canal): |