Experience of operating the outlets at the Kolyma hydroelectric station

detail here. Temporary Outlet (TO). The TO constructed on the right bank of the river was intended for passage of the diverted flow after damming the channel and discharges during temporary operation of the hydro development at a head up to 60 m. The design discharge of this outlet with a 0.5% probability is 10,700 m3/sec. The composition of the TO complex is shown in Fig. 2. The mechanical equipment of the outlet was designed with consideration of the operating conditions in the Far North. It should have been simple, cheap, and reliable during temporary operation for four years. The known layouts with crest radial gates required an expanded front for constructing the outlet and were rejected due to the difficult? of arrangement at the site of the hydro developent. Deep gates were taken as the basis. The design experience gained in this period (1977-1980) made it possible to develop deep vertical-lift gates with a span of 5-6 m and height up to 12 m for a head up to 50 m. In this case six openings would be required for passage of a discharge of 10,700 m3/sec, which would necessitate an additional rock excavation on the right canyon wall. Therefore, a variant, which at that time did not have analogues with respect to parameters, with four deep sliding gates with a span of 6.5 m and height of 16 m for a head of 60 m was developed. New unique 900-ton-capacity hydraulic hoists consisting of two successively arranged cylinders with a total stroke of 17 m were designed (the lower sections of the hydraulic cylinders were subsequently used on the permanent intake of the pressure power conduits of the hydrostation). Slides of a new antiffiction material -- maslyanite -- were used as the running gear. This mechanical equipment was relatively cheap to manufacture, and the simplicity of the design of the sliding gates and embedded parts made it possible to manufacture them at plants of the Trust for Installation of Hydromechanical Equipment (Gidromontazh) in a short time. Manufacture of the hydraulic drive did not cause difficulties. A substantial reduction of the front of the structure and rejection of the expensive and complex fixed-wheel gates with cast tracks usually used for permanent operation made it possible to make the water intake of the TO compact, economical, and sufficiently reliable for temporary operation. The presence at the object of a strong industrial base and team of builders and designers which could, if necessary, promptly solve problems arising during operation was taken into account. The intake headwall joined the 44-m-long transition section, on which water was delivered to a conduit with narrowing of the flow from a total width of 37 m at the start of this section to 22 m of the standard cross section of the conduit (Fig. 3). The entire transition section and transition itself with the conduit were made without smoothly streamlined surfaces and were equipped with a system of deflector-ledges providing the delivery of air for protecting the concrete from cavitation erosion. The same such deflectors and ski jump with a ledge were constructed at the exit from the bottom openings operating with complete opening of the gates in a pressure regime [3]. The 350-m-long conduit in the entire possible range of waste discharges operates, just as the transition section, in a free-flow regime with a maximum unit discharge of 486 m2/sec.