Hoover Dam, Metropolitan Water District Switchyard, U.S. Highway 93, Boulder City

Source document Quoted word for word from HAER NV-27-C. Not written, edited or summarised by this site.

U.S. Highway 93 Vicinity of Boulder City Clark County Nevada USGS Hoover Dam, Nevada-Arizona 7.5 Minute Provisional UTM Coordinates: l Date of Construction: Engineer: U.S. Bureau of Reclamation Builder: U.S. Bureau of Reclamation U.S. Highway 93 Vicinity of Boulder City Clark County Nevada USGS Hoover Dam, Nevada-Arizona 7.5 Minute Provisional UTM Coordinates: l Statement of

Source document Quoted word for word from HAER NV-27-C. Not written, edited or summarised by this site.

The Metropolitan Water District of Southern California Switchyard was the second- largest federal switchyard at Hoover Dam. The switchyard provided needed power for expansion of irrigation and municipal water supplies in California during and after World War II, but it also provided electricity to the Hoover-Basic Magnesium North and South transmission lines. Those lines provided high-voltage electricity that was essential for operation of Basic Magnesium, Inc.' s magnesium production plant to the south of Las Vegas during the war. Report Prepared by: Associated Cultural Resource Experts (ACRE) Sangre de Cristo Road, STE 202 Littleton, CO Date: April HOOVER DAM, METROPOLITAN WATER DISTRICT SWITCHYARD HAER NO.

(Page 2) HISTORIC AMERICAN ENGINEERNG RECORD HOOVER DAM, METRO POLIT AN WATER DISTRICT SWITCHYARD HAER NO. The Metropolitan Water District of Southern California Switchyard was the second-largest federal switchyard at Hoover Dam. The switchyard provided needed power for expansion of irrigation and municipal water supplies in California during and after World War II, but it also provided electricity to the Hoover-Basic Magnesium North and South transmission lines. Those lines provided high-voltage electricity that was essential for operation of Basic Magnesium, Inc.' s magnesium production plant to the south of Las Vegas during the war. Description: The Metropolitan Water District Switchyard is a x facility located between the Los Angeles Switchyard and U.S. Highway 93.

The 5-bay switchyard includes a massive steel bus structure supported by 24 lattice steel towers. Each bay included a symmetrical equipment configuration, from east to west, of two disconnecting switches, an oil circuit breaker, a line circuit selector switch, a second oil circuit breaker, and a disconnecting switch. The switchyard also included current transformers to provide appropriate current to equipment, carrier current equipment, and lightning arresters. Unlike other major federal switchyards at Hoover Dam, the Metropolitan Water District Switchyard did not include an oil or control house. The entire switchyard is on a single level, surrounded by a chain-link fence. History: The switchyard of the Metropolitan Water District of Southern California was built in two major episodes.

The location and general size of the switchyard were determined in along with the locations and size of the LA and Southern Sierras Switchyards. The original x Metropolitan Water District switchyard included two bays, although the switchyard was initially intended to serve only one transmission line.

Excavation for the control cable tunnel (extending from the LA Switchyard) and tower footings began on November 12, and concrete work in the switchyard was completed on March 23, Installation of cable trays in the control cable tunnel was started March I, and completed March 22, Erection of oil circuit breakers began on May 10, and the last circuit breaker was filled with oil on June 21, The relay board for the switchyard was set in position on April 11, and the control wiring was completed on June 1, Construction of the steel work in the switchyard began on May 2, and the structure was ready for stringing of the overhead bus on May 23, Disconnecting switches and buses were completed by the end of June Original equipment installed in included two 1,200-ampere, oil circuit breakers.

The circuit breakers were triple-pole, 60-cycle, single-throw, outdoor, electrically operated, non-oil- throwing, full-automatic type and were built by Westinghouse Electric and Manufacturing Company. Each oil circuit breaker had current transformers, auxiliary switches for control circuits, and other accessories. For isolating the switchyard oil circuit breakers, Pacific Electric Manufacturing Company disconnecting switches were installed. The disconnecting switches were outdoor, triple-pole, single-throw, motor-operated, 1,200-ampere, 60-cycle, type. HOOVER DAM, METROPOLITAN WATER DISTRICT SWITCHYARD HAER NO. (Page 3) The initial section of the switchyard was completed in July 193 8.

The switchyard was supplied with power from generating Units N-5 and which came on-line in June and August respectively, and provided power to a transmission line to southern California, where the power was intended primarily for construction and operation of the Colorado River Aqueduct. In late an extension to the MWD Switchyard was begun that would nearly double the size of the switchyard by mirroring the existing bays and equipment. Enlargement of the MWD Switchyard was necessary to accommodate transmission lines to the Basic Magnesium plant then being built near Las Vegas, and to handle power from generator unit which was then under construction.

Excavations for the addition were started in late and completed in early Erection of steel structures for bays 3, 4, and 5 was started in April and completed by May 15, Installation of electrical equipment soon followed, and temporary service to the Basic Magnesium No. 2 line (Basic South) was established on August 30, By December 31, all necessary switchyard features, including five new sets of oil circuit breakers, were completed and in service, but work continued on the ground mat, fence and curb. On May 17, the MWD transmission line was moved from its original rack location and temporarily tied directly to the west bus. On August 14, the MWD line was moved to a location in the No. 4 bay of the switchyard.

The Basic Magnesium north line was tied into a permanent location at the former MWD line location, and after testing this line was energized on June 14, The Basic Magnesium south line was tied into the rack at the No. 3 bay on August 30, Installation of oil circuit breakers and controls continued until December and other equipment installation continued until September Basic Magnesium Corporation ceased production of magnesium by the end of but the Basic North and Basic South transmission lines remained in service for other markets. In February the Basic South line was relocated from the MWD Switchyard to the new A-N Switchyard. At the same time, the MWD transmission line was again relocated to Bay No. 1, and the Basic North line was relocated to Bay No. 4 in the MWD Switchyard.

The outgoing transmission line configuration remained unchanged until when MWD took delivery of all power from generating unit N-7 to feed its second transmission line to southern California. The new transmission line was installed in Bay No. 2 of the switchyard, which had been the initial location of the first MWD transmission line. Minor alterations were made to the steel bus structures in as part of the transfer of switching and control functions to the Mead Substation. Interconnection of the MWD Switchyard, the Southern California Edison (SCE) Switchyard, and the Arizona-Nevada Switchyard after allowed transfer of power between these systems during emergencies or planned outages. Work was started in on tie conductors between MWD west and SCE south, and MWD east and SCE north bays.

The latter tie was intended to be permanent, to be used in case of emergency. The CTI tie circuit between MWD and SCE switchyards was relocated from the east side to the west side of the MWD switchyard in to provide a more flexible operating arrangement for planned use of generating units by MWD and SCE. The new tie circuit eliminated an intermediate steel tower between the switchyards.

Relocation of the tie circuit included installation of a control panel in the LA relay house; installation of instrument transformers, disconnecting switches, and bus tie-downs in the southwest comer of the MWD Switchyard; relocation of the double gates at the southwest end of the switchyard; installation of new conduits between the control conduit tunnel and the new equipment, and extension of the ground mat. Construction and installation were accomplished during the last three months of

Source document Quoted word for word from HAER NV-27-C. Not written, edited or summarised by this site.

This documentation of features of Hoover Dam and associated structures was accomplished by Associated Cultural Resource Experts (ACRE). ACRE completed documentation of21 features in October Documentation on four linear features was extended and an additional 3 features were newly documented in February Both phases of documentation were conducted as part HOOVER DAM, METROPOLITAN WATER DISTRICT SWITCHYARD HAER NO.

(Page 4) of the historical/engineering recordation of Hoover Dam-prepared for the Department of Energy, Western Area Power Administration; Bureau of Reclamation; and Federal Highway Administration-that includes a narrative for the Addendum to Hoover Dam and individual documentation of 25 features located at the Hoover Dam facility, photo documentation, and documentation of existing historic photographs and site plans. The recordation confonns to the standards of the Historic American Engineering Record, U.S. Department of the Interior.

Other reports in the HAER collection completed for these projects are a narrative for the Addendum to Hoover Dam and 24 short forms for individual structures: Hoover Dam, Los Angeles Switchyard (NV-27-A); Hoover Dam, Southern Sierras/CEP/Southern California Edison Switchyard Hoover Dam, Metropolitan Water District Switchyard Hoover Dam, State of Nevada Switchyard Hoover Dam, Southern California Edison Switchyard (NV-27-E); Hoover Dam, Arizona-Nevada Switchyard Hoover Dam, Static Towers and Lines Hoover Dam, Los Angeles Relay Control Building Hoover Dam, Switchyard Fire House (NV-27-I); Hoover Dam, Promontory Water Tank Hoover Dam, Control Cable Hoist House Hoover Dam, Transformer Circuits Hoover Dam, Los Angeles BPL Lines 1-3 Hoover Dam, Southern California Edison North and South Lines Hoover Dam, Hoover-Basic Magnesium North and South Lines Hoover Dam, Metropolitan Water District Line 1 Hoover Dam, United States Construction Railroad Hoover Dam, U.S.

Highway 93 Nevada Segment Hoover Dam, Lower Portal Access Road Hoover Dam, Kingman Switchyard Hoover Dam, U.S. Highway 93 Arizona Segment (NV-27-U); Hoover Dam, Explosives Magazines Hoover Dam, Nevada Downstream Waste Tailings and Hoover Dam, Nevada Spoils Tunnel Hoover Dam, Henderson-Mead Transmission Line 2

Source document Quoted word for word from HAER NV-27-C. Not written, edited or summarised by this site.

This documentation was prepared for three federal agencies: U.S. Department of Transportation, Federal Highway Administration (FHWA), Central Federal Lands Highway Division, Lakewood, CO; U.S. Department of Energy, Western Area Power Administration (Western), Desert Southwest Customer Support Region, Phoenix, AZ; and U.S. Department of Interior, Bureau of Reclamation (Reclamation), Lower Colorado Region, Boulder City, NV. This documentation records certain transportation and electrical features associated with Hoover Dam before planned removal or alteration of some structures. FHWA plans to construct a bridge over the Black Canyon of the Colorado River about downstream from Hoover Dam. The Hoover Dam Bypass Project would include realignment of U.S.

Highway 93 on the Nevada and Arizona sides of Black Canyon. The project would include demolition, relocation, or substantial visual impact to a segment of U.S. Highway 93 on the Nevada approach to Hoover Dam, a segment of a former alignment of U.S. Highway 93 in Arizona, electrical transformer circuits in Arizona and Nevada, two electrical switchyards, a segment of the grade of the U.S. Construction Railroad, a stone gate structure for a dam construction and operations road, and six historic transmission lines. This documentation also records certain structures not directly affected by FHWA's Hoover Dam Bypass Project. Electrical transmission facilities at Hoover Dam are administered by Western, but these facilities are within a federal reservation administered by Reclamation.

Documentation of electrical structures is intended to partially fulfill responsibilities of Western and Reclamation under Section 110 of the National Historic Preservation Act (As amended). Some electrical structures addressed by Western and Reclamation would be directly affected by FHWA's Hoover Dam Bypass Project, and all structures addressed by Western and Reclamation are functionally related and geographically near structures addressed by FHWA. Project Manager and historian for the recordation was Kurt P. Schweigert of Associated Cultural Resource Experts. The photographers were Deborah Dobson-Brown and Douglas M. Edwards of Associated Cultural Resource Experts.

This documentation was prepared on the basis of research conducted at Reclamation archives in Denver, CO, and Boulder City, NV; Western archives and HOOVER DAM, METROPOLITAN WATER DISTRICT SWITCHYARD HAER NO. (Page 5) files in Denver and Phoenix, AZ; the National Archives and Records Administration in Denver; libraries of the University of Nevada-Las Vegas; and the Western History Collection of the Denver Public Library. This documentation includes information contained in survey reports for the Hoover Dam Bypass Project Environmental Impact Statement, an evaluation of the W estem switchyards at Hoover Dam, an evaluation of the Hoover Dam construction railroads, a National Register nomination for Hoover Dam, and other documents.