Hoover Dam, Nevada Spoils Tunnel, Near the Lower Portal Tunnel Access Road, Boulder City

Source document Quoted word for word from HAER NV-27-X. 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: (start) (end) Date of Construction: Engineer: U.S. Bureau of Reclamation Builder: Six Companies, Inc. U.S. Highway 93 Vicinity of Boulder City Clark County Nevada USGS Hoover Dam, Nevada-Arizona 7.5 Minute Provisional UTM Coordinates: (start) (end) Statement of

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

The Nevada Spoils Tunnel was an important feature in the construction of Hoover Dam. The tunnel that was excavated to allow waste rock from Hoover Dam tunnels and other facilities to be deposited at the Nevada downstream waste tailings site Report Prepared by: Associated Cultural Resource Experts (ACRE) Sangre de Cristo Road, STE 202 Littleton, CO Date: April HISTORIC AMERICAN ENGINEERNG RECORD HOOVER DAM, NEV ADA SPOILS TUNNEL HAER NO. (Page 2) The Nevada Spoils Tunnel was an important feature in the construction of Hoover Dam. It tunnel that was excavated to allow waste rock from Hoover Dam tunnels and other facilities to be deposited at the Nevada downstream waste tailings site Description: The tunnel is about 380 feet long and 10 to 12 feet wide.

The south end of the tunnel has a post- and-lintel canopy that extrudes from the end of the tunnel to protect vehicles from falling rock. The canopy/curbing is upright beams bolted to the adjoining rock, with planks attached as wall and roof members. A era sign identifies the tunnel as a fallout shelter. Most of the tunnel has rough stone walls and ceiling, but about 45 meters feet) from the north end is an area of timbering of beams, beams, and smaller laterals, diagonal bracing, and roof members. The north end of the tunnel opens onto a wide hairpin turn area of the Lower Portal Tunnel Access Road The north end of the tunnel does not have timbering or curbing, but a steel pipe and woven wire gate restricts access to the tunnel. The tunnel has an earth floor.

History: One of the first features of the dam complex to be constructed, the Lower Portal Tunnel Access Road was built in to allow vehicular access to the bottom of Black Canyon downstream from the dam site, where a coffer dam was constructed and diversion tunnels were bored northward on the Nevada and Arizona sides of the river. To dispose of the tailings from the diversion tunnels and other excavations, a tunnel was driven through a mountain ridge to the southwest of the Nevada diversion tunnels, and waste rock and earth were hauled through the tunnel and deposited in a natural bowl adjacent to the river.

This tunnel was excavated in by Six Companies, Inc., general contractor for construction of Hoover Dam, to allow waste rock and other materials to be deposited in the Nevada downstream waste tailings area. The waste material was excavated from tunnels for diversion of the Colorado River around the dam construction site; from tunnels for penstocks, spillways, and access to the power plant; and from other features of the Hoover Dam complex downstream from the dam structure.

Source document Quoted word for word from HAER NV-27-X. 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 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 HOOVER DAM, NEVADA SPOILS TUNNEL HAER NO.

(Page 3) 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 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-X. 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 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.