Outlet Works. The outlet works consist of a submerged intake structure with a hydraulically-operated slide gate, a 36-inch diameter, 481-foot long cast-in-place concrete outlet pipe with a steel liner under the dam, and a concrete outlet structure housing the control valves. The outlet is controlled downstream with a 30-inch butterfly valve operated from the outlet structure. The outlet pipe is connected to the Almaden Valley Pipeline downstream of the outlet structure at the Xxxxxx Valve Yard, about 700 feet downstream of the dam. Planning studies have indicated that the outlet works is corroded, does not meet DSOD emergency drawdown capacity criteria, and is not designed to current structural standards. The planning studies recommend replacement of the outlet works with a carrier pipe in oversized tunnel, and new sloping intake structure.
Outlet Works. Up to ten (10) vertical borings will be drilled to depths of about 30 to 120 feet (about 20 feet below the proposed invert depth of the tunnel, sloping intake, and outlet works). Up to four (4) of the borings will be drilled from a barge-mounted rig in the reservoir, including two (2) borings at the site of the xxxxxx dam. Samples of reservoir silt, shallow surficial soils, and bedrock will obtained for testing. Up to seven (7) Packer tests will be performed within the rock. Downhole televiewer surveys will be conducted in up to five (5) borings. Up to four (4) borings will be converted to open standpipe piezometers. Groundwater grab samples will be obtained from the piezometers for environmental testing. Consultant shall perform seismic refraction surveys in the vicinity of the sloping intake, tunnel alignment, and outlet works.
Outlet Works. Consultant shall evaluate the proposed outlet works to confirm, select, and refine the proposed outlet works as necessary to support detailed design. The outlet works shall be capable of meeting all established operational, regulatory and District requirements. Consultant shall provide the size, horizontal and vertical layout, hydraulic, structural and geotechnical design details as well as control and operational requirements for the District. The TM shall summarize basis of design for the outlet works.
Outlet Works. The outlet works is the feature that drains the EDB in specified quantities and periods of time. The outlet works is typically constructed of reinforced concrete into the embankment of the EDB. The concrete structure typically has steel orifice plates anchored/embedded into it to control stormwater release rates. The larger openings (flood control) on the outlet structure typically have trash racks over them to prevent clogging. The water quality orifice plate (smaller diameter holes) will typically have a well screen covering it to prevent smaller materials from clogging it. The outlet structure is the single most important feature in the EDB operation. Proper inspection and maintenance of the outlet works is essential in ensuring the long-term operation of the EDB. The typical maintenance items found with the outlet works are as follows:
Outlet Works. Where SFBs do not have a detention component the outlet works may take the place of the splitter box. If this is the case the outlet works includes an overflow. The overflow outlet works allows runoff amounts exceeding the WQCV to exit the SFB to the detention facility. When the SFB does have a detention component the outlet works is typically constructed of reinforced concrete into the embankment of the SFB. The concrete structure typically has steel orifice plates anchored/embedded into it to control stormwater release rates. The larger openings (flood control) on the outlet structure typically have trash racks over them to prevent clogging. Proper inspection and maintenance of the outlet works is essential in ensuring the long-term operation of the SFB. The typical maintenance activities required for the overflow outlet works are as follows:
