Hoover Dam, Explosives Magazines, About 75 feet west of Lower Portal Tunnel Access Road, Boulder City

Source document Quoted word for word from HAER NV-27-V. 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: 1 Date of Construction: ca. 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: 1 Statement of

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

These two explosives magazines were constructed for storage of dynamite used in the early phases of construction of Hoover Dam, possibly as early as for blasting the route of the Lower Portal Tunnel Access Road and the diversion tunnels on the Nevada and Arizona sides of the Colorado River. Report Prepared by: Associated Cultural Resource Experts (ACRE) Sangre de Cristo Road, STE 202 Littleton, CO Date: April HISTORIC AMERICAN ENGINEERNG RECORD HOOVER DAM, EXPLOSIVE MAGAZINES HAER NO. (Page 2) These two explosives magazines were constructed for storage of dynamite used in early phases of construction of Hoover Dam, possibly as early as for blasting the Lower Portal Tunnel Access Road and diversion tunnels on the Nevada and Arizona sides of the Colorado River.

Description: This site consists of two poured/cast concrete explosives magazines located about 75 feet west of the Lower Portal Tunnel Access Road. The magazines are located in a turn-out, at least the western portion of which appears to have been excavated into a rocky hillside. The magazine structures are recessed into a nearly vertical rock face, so that most of the explosives storage areas are shielded on sides, rear, and top by natural or deposited rock. The entry to each magazine is a rectangular structure with walls, floor, and roof of poured or cast concrete. Magazine 1 has an entry structure that about 2.5 meters square, and about 3 meters high. A hook-shaped metal vent pipe extrudes from the roof, and a padlocked steel door restricts access.

The entry structure for Magazine 2 is larger than that of Magazine 1, about 4.5 meters wide, and about 3 meters high. Dry-laid stone curbing flanks the concrete entry structure, and two hook-shaped vents extrude from the roof. A padlocked steel door restricts access. The buildings appear to be in good condition, although the interiors were not examined. Evidence of recent use was not observed, and the tum-out did not exhibit evidence ofrecent activity. History: Probably designed and built by either Six Companies, Inc. or the Bureau of Reclamation, the explosives magazines were built as early as and probably used for storing the dynamite needed to blast the route of the Lower Portal Tunnel Access Road, as well as the diversion tunnels on the Nevada and Arizona sides of the Colorado River.

One of the first features of the dam complex to be constructed, the Lower Portal Tunnel Access Road was built 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 southwest of the Nevada diversion tunnels, and waste rock and earth were hauled through the tunnel and deposited in a natural bowl adjacent the river. As the dam was nearing completion, a 1,900-foot-long tunnel was driven through rock on the Nevada side of the river to provide vehicular access to the power plant.

The road became known as the Lower Portal Tunnel Access Road. No construction or demolition project in the vicinity would have required large amounts of explosives after the dam was completed in

Source document Quoted word for word from HAER NV-27-V. 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 24 features located at the Hoover Dam facility, photo documentation, and documentation of existing historic photographs and site plans.

The recordation conforms to the HOOVER DAM, EXPLOSIVE MAGAZINES HAER NO. (Page 3) 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 25 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-V. 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 HOOVER DAM, EXPLOSIVE MAGAZINES HAER NO. (Page 4) switchyards at Hoover Dam, an evaluation of the Hoover Dam construction railroads, a National Register nomination for Hoover Dam, and other documents.