Hoover Dam, Nevada State Switchyard, U.S. Highway 93, Boulder City

Source document Quoted word for word from HAER NV-27-D. 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: 1 Statement of

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

The Nevada State Switchyard (also initially called the Pioche Switchyard) was the smallest of the six major federal switchyards at Hoover Dam. This switchyard was constructed to be the principal point at which Nevada's allocation of power from Hoover Dam could be delivered to utility companies serving the state. Power from the switchyard initially helped expand the mining industry of the state, and later it provided electricity to the growing gaming, residential, and military economy of the Las Vegas Valley. Report Prepared by: Associated Cultural Resource Experts (ACRE) Sangre de Cristo Road, STE 202 Littleton, CO Date: April HISTORIC AMERICAN ENGINEERNG RECORD HOOVER DAM, NEVADA STATE SWITCHYARD HAER NO.

(Page 2) The Nevada State Switchyard (also initially called the Pioche Switchyard) was the smallest of the six major federal switchyards at Hoover Dam. This switchyard was constructed to be the principal point at which Nevada's allocation of power from Hoover Dam could be delivered to utility companies serving the state. Power from the switchyard initially helped expand the mining industry of the state, and later it provided electricity to the growing gaming, residential, and military economy of the Las Vegas Valley. Description: The Nevada State Switchyard is a x facility located to the northwest of the Southern California Edison Switchyard. The switchyard includes two connected but distinctly different areas.

The northern or original area of the switchyard includes a variety of current and metering transformers, disconnect switches, oil and other circuit breakers, capacitor banks, lightning arresters, and control and metering systems. The southern area includes banks of larger oil circuit breakers and disconnecting switches that appear to be newer than the equipment in the northern section. The entire switchyard is enclosed with a 7'-high, woven-wire fence. The switchyard does not have an oil house. A large hole at the south end of the switchyard area reflects removal of a large oil tank and oil-contaminated earth beneath the tank base.

History: The Nevada State Switchyard was built in a series of episodes from to The initial portion of the switchyard was constructed to provide power to the Lincoln County Power District No. 1 for their transmission line to Pioche and other mining and residential sites in Nevada. Construction of what was called the Pioche Switchyard began in September with excavation of a control conduit trench from the end of the conduit tunnel at the north end of the LA Switchyard.

General excavation for the x switchyard began in October and concrete work was finished on January 11, Construction of the steel bus structure began on January 19 and was competed on January 24, Installation of the oil circuit breakers and disconnecting switches was completed on February 4, Laying of ground cables for the switchyard began on February 1 and was completed in June Erection of power transformers was completed in April The Pioche Switchyard consisted of two banks of three oil circuit breakers, five disconnecting switches, a current metering set, and take-off structures. This switchyard did not require a building to house the substantial oil storage and control equipment that was necessary for the larger Hoover Dam switchyards. All seven steel towers for Circuit No.

13, which would bring power to the switchyard from the Bank Y transformers connected by transfer bus to generating units N-1 and were completed on March 11, The switchyard began providing power to the Pioche transmission line in July Additions within the switchyard began almost immediately. In the Needles Gas and Electric Company installed its own equipment in vacant space in the Pioche/Nevada State Switchyard to provide current to a transmission line serving Searchlight and Nelson, Nevada, and Needles, California. By this company had become part of the California Pacific Utilities Company, but the transmission line and switchyard connection generally were identified as the "Needles" HOOVER DAM, NEVADA STATE SWITCHYARD HAER NO. (Page 3) facilities.

In the Southern Nevada Power Company constructed a transmission line from Las Vegas to the Pioche/Nevada State Switchyard. To accommodate this line, pole structures, switching equipment, metering equipment, and additional control conduits were installed in the switchyard in late and early Additional potential and current transformers and metering equipment were installed in the Pioche Switchyard in January and February Installation of this equipment required extensive modification of the rack structures to rearrange instrument transformers and coupling capacitors and to allow installation of Thyrite lightning arresters. Reclamation expanded the switchyard again in to accommodate a new transmission line to Boulder City.

Extensive backfilling and excavating for the Boulder City extension was begun in September In October additional control conduit, breaker footings, and the oil circuit breaker were installed. By February 15, the lightning arresters, the oil circuit breaker bypass and isolating disconnecting switches, and the extension and connection of the jack-bus were installed. The equipment was first tested on February 16, and placed in service on February 19, Metering and relay equipment was installed and ready for service by April 30, and at that time the switchyard extension was complete. Installation of generating unit A-9 required construction of a extension to the Nevada State Switchyard in to accommodate one incoming transformer circuit (Circuit No.

1) and two outgoing transmission lines of the Southern Nevada Power Company. Extension of the switchyard included installation of three 600-ampere oil circuit breakers; 27 600-ampere, single-pole disconnecting switches; two 600-ampere, three-pole disconnecting switches; three lightning arresters; 12 instrument transformers; two metering and relaying cabinets; one 440-volt to 115-volt station transformer; one 440-volt power distribution cabinet, one 115-volt lightning distribution cabinet; of 4/0 ground wire for ground mat; 373 linear feet of cyclone fencing; 50 tons of galvanized structural steel for bus and equipment support; and of duct bank, consisting of 12 2-inch, non-metallic conduits. Substantial changes were made in the switchyard to accommodate the new circuit and lines.

The original Lincoln County Power District Pioche take-off station was relocated from the old section of the switchyard to the new section, to become the take-off point for the Southern Nevada Power Company No. 1 transmission line (the two lines would be interchanged at a Southern Nevada switchyard several miles to the northwest). Three lightning arresters were relocated from the first pole of the old Pioche line west of the switchyard, to the steel structure in the new section of the switchyard. Three coupling capacitors and two carrier current equipment units together with their steel support structures were moved from the original Pioche line position to the new Pioche line take-off position, which was the position formerly occupied by the Southern Nevada No.

1 transmission line in the old section of the switchyard. Five wood poles with cross arms and hardware were erected in the original Pioche circuit position in the old section of the switchyard to provide a jack bus and oil circuit breaker bypass connection for the new incoming circuit from the power plant. Other changes included removal of transformers and disconnecting switches in the old section, installation of steel work and disconnecting switches for the new incoming circuit, removal of a disconnecting switch, and relocation and updating of metering and relaying equipment for the Needles and Pioche transmission lines.

The Nevada State Switchyard contains some circuit breakers and other equipment from the early years of construction, and much of the remaining equipment dates from the extensive changes made in Some electrical equipment and steel and wood structures have been removed from the southern part of the switchyard, and a depression in the southwest comer of the HOOVER DAM, NEV ADA STATE SWITCHYARD HAER NO. (Page 4) switchyard is the result of removal of contaminated soil from a leaking metering unit. Switching and other functions of the Nevada State Switchyard were assumed by the Mead Substation about and most of the transmission lines that originated at the Nevada State Switchyard now originate at Mead Substation. Transformer Circuit No.

1 is no longer connected to the Nevada State Switchyard, and it is no longer energized. The western end of Transformer Circuit 13 was slightly relocated around the southern end of the switchyard to form a direct connection with a Southern Nevada Power Company line; this combined line provides service to the Citizens Utility Company's Kingman Switchyard on the Arizona side of the dam.

Source document Quoted word for word from HAER NV-27-D. 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 of2I 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 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 conforms 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-D. 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. FHW A 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 HOOVER DAM, NEV ADA STATE SWITCHYARD HAER NO. (Page 5) 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 Westem, 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 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 Western switchyards at Hoover Dam, an evaluation of the Hoover Dam construction railroads, a National Register nomination for Hoover Dam, and other documents.