40: 



PEPORT OF THE COMMISSIONERS OF 



PROFILE OF DAM. 



The section of the main wall of the dam at its greatest height is forty-seven feet 

 high, seven feet wide on top and thirty-three feet on the bottom ; the width being 

 gradually increased by batters on both faces. The top of the coping is seven feet 

 above the level of the spillway and the top of the embankment is two feet higher. 



GATE HOUSE AND DISCHARGE TUNNELS. 



To provide for the passage of water through the dam during construction, two 

 discharge tunnels, nine feet' in diameter, are built through the main wall at the west 

 side of the river channel. The arch and invert rings are of selected rubble work, 

 twenty inches deep. Three buttresses, one on each side and one between the openings, 

 compensate for the masonry taken from the section of the main wall by the discharge 

 tunnels. The gate house is situated on the upper side of the dam, opposite the 

 discharge tunnels, and consists of two wells eight feet square at the bottom and 12x14 

 feet at the top, with side walls eight feet thick at the bottom, battering to four feet at 

 the top. The object of the two discharge tunnels was to take care of any large floods 

 which might occur while the lower part of the dam was under construction, and thus 

 prevent the water from flowing over newly laid masonry. For the permanent 

 discharge from the reservoir, steel pipes, five feet in diameter and ten feet long, were 

 built in masonry inside the nine-foot discharge tunnels. It was the original intention 

 not to lay them in place until the main dam wall had been carried to a height above 

 all danger from possible floods. The contractors, however, wished to lay the pipes as 

 soon as the inverts of the tunnels were finished, and upon their agreeing to make good 

 all damages which might be received from floods, they were allowed to do so. 

 Fortunately no large floods occurred during the construction of the dam and the 

 leakage and overflow from the old wooden dam was easily carried by the two five-foot 

 openings. Single-disk flume gates made by Eddy Valve Co. are bolted to the pipes 

 by flanged connections and regulate the discharge from the reservoir. Each gate-well 

 is provided with two 3 x 5 -foot sluice openings, controlled by wooden slide gates and 

 protected by steel gratings. Owing to the difficulty of operating the slide 

 gates on account of the excessive friction under full head of water, provision is made 

 for filling the gate-wells by means of six-inch pipes built through the walls of each 

 well. A suitable superstructure with masonry side walls and shingle roof encloses 

 the operating mechanisms of all the gates, as well as the apparatus for indicating the 

 opening of the main gates. The maximum discharge through the two discharge pipes 

 with full reservoir is estimated at 1,400 cubic feet per second, although it is not 

 expected to discharge at a greater rate than about 1,000 cubic feet per second. 



