Apache Nitrogen Products

The company was incorporated June 11, 1920. It was formed as a cooperative venture by several large mines located throughout the Southwestern United States and northern Mexico. It was led by Charles E. Mills, a Harvard-educated mining engineer who moved to Bisbee, Arizona in 1888 where he worked for the Copper Queen Mine. Mills found great success in Arizona and was later the president of Arizona's Valley Bank. The dry climate of southern Arizona "was considered beneficial to the production of high grade powder". Another benefit of the location was hilly terrain that provided natural protection from explosion for the buildings used in production.[7] The owners were primarily interesting obtaining cheaper explosives by self-manufacturing and reducing the transportation costs by producing locally.[8]

Construction of the plant took about ten months, finishing in June 1921.[9] The first shipment of dynamite occurred in 1922. Production was running at one million pounds of powder per month in 1923. In the late 20s production began to shift to nitroglycerine-based explosives. The company was the only producer of these explosives in the Southwestern United States, producing 41 million pounds in 1956.[3] It supplied explosives to mines in Arizona, New Mexico, northern Mexico, and the surrounding areas.[7] The complex grew to around 140 buildings spread out around more than 700 acres (280 ha). Employment was in the hundreds, even through the great depression.[7] The plant eventually became the largest single location for the production of dynamite in the country.[8]

In response to changes in mining technology, the product line expanded to include blasting agents based on ammonium nitrate and nitric acid in the 1940s.[7] Ammonium nitrate was produced from anhydrous ammonia and air (the DuPont process) beginning in the 1950s.[7] The original nitroglycerine-based products were phased-out by 1983.[2] In the 1990s the company was also producing detonating cord and ammonium nitrate solution for agricultural fertilizer. Fertilizer was being sold to alfalfa, asparagus, cotton, citrus, lettuce, pecan, and wheat farmers in Arizona, California, New Mexico, and Mexico.[7] Three quarters of sales were to the mining industry, however.[7] One of the original buildings at the site, a red brick structure known as the Powderhouse (built c. 1922), was still in use as of 2012. It contains boilers that produce steam which turn turbines to make the plant's electricity.[2]

As of the mid-1980s, the company was owned jointly by Phelps Dodge, Magma Copper, Cyprus Copper, Southwest Energy, and the heirs of Charles Mills. Its land had expanded to 1,040 acres (420 ha).[7]

The plant operated a narrow-gauge railroad to move material around the complex. The length of track was 1.857 mi (2.989 km) in 1922.[10] It was a three-foot gauge railway. Because of the risk of sparks causing an explosion in a dynamite manufacturing plant, freight was initially pulled by mules. The mules were later replaced with fireless locomotives manufactured by H.K. Porter Company.[8][11] Apache Powder purchased seven of these locomotives, which could run for an hour on 400 °F (204 °C) steam after being charged at a boiler located a safe distance away from the working areas of the complex.[12]

The company was connected to the national rail network by a 1.3 mi (2.1 km) long spur to the nearby El Paso and Southwestern Railroad.[8]

Present location of six of the Porter 0-4-0 locomotives:[13][14]

In 1923, an explosion killed four workers and injured another. It was the first disaster since the plant opened. Five small buildings and a warehouse were destroyed.[15]

In 1927, 3,000 lb (1,400 kg) of nitroglycerine exploded at the place destroying several buildings. The explosion was heard for miles but caused no injuries. An operator noticed a problem and initiated a warning system; he and other workers were able to run to safety before the explosion.[16]

The United States Environmental Protection Agency (EPA) has designated the site as a as Superfund site due to pollution of hazardous material contaminations requiring a long-term response to clean up. The site includes approximately 9 sq mi (23 km²) or 945 acres (382 ha)[17] and contains groundwater contaminated with arsenic, fluoride, nitrate, and perchlorate. In addition, soil is contaminated with arsenic, antimony, barium, beryllium, chromium, lead, manganese, nitrate, 2,4-DNT, 2,6-DNT, lead, vanadium pentoxide, paraffins, and TNT from the commercial production of chemicals.[18][19][20]

The EPA finalized a treatment plan in 1994 which called for contaminated water to be pumped out and evaporated, as well as some treatment via wetlands and aquifer recharge. Contaminated soils were either contained on-site and capped or excavated and removed to off-site disposal. All construction work was completed in 2008[21] and the area was classified as "Ready for Reuse and Redevelopment" in 2010.[22]

Apache Powder Historic Residential District
U.S. National Register of Historic Places
143 W. 6th St
Location in Arizona Show map of Arizona Location in United States Show map of the United States
Location	100 & 200 Blocks, W. 6th St., Benson, Arizona
Coordinates	31.9667°N 110.2997°W / 31.9667; -110.2997
Area	4 acres (1.6 ha)
Built	1925 (1925)
Architectural style	Mission/Spanish Revival, Bungalow/Craftsman, Spanish Eclectic
MPS	Benson MPS
NRHP reference No.	94000078[23]
Added to NRHP	March 11, 1994

The company purchased land in 1925, to provide housing for company management, from the Benson School District on West 6th Street in Benson, about 8 mi (13 km) north of the plant. Eight individual lots were sold to company officials, who had houses built (by unknown contractors). After a disagreement, the company purchased the lots back and then rented them to the employees at subsidized rates. Apache also build an "evacuation hospital" at 209 West 6th St. The company owned the properties for many decades, eventually selling them in the 1970s and 80s. A 1.75 acres (0.71 ha) parcel on the north side of the street was used as a park and legally transferred in the 1960s by the company to the City of Benson.[7]

The eight houses, the hospital building, and the park were designated as the Apache Powder Historic Residential District and listed on the National Register of Historic Places in 1994. Seven of the houses are in the Craftsman Bungalow architectural style, the dominate style of the district. The style was popular in the Benson area in the mid-1920s. All but one are stuccoed with wood-sided gable ends. One is entirely wood-sided. All have detached garages opening to an alley, hardwood flooring, and were built on redwood piers over a crawl space. One other house is Spanish Colonial Revival and Mission Revival style with stucco, stepped parapets, and an articulated porch, and originally served as an hospital for the company. The final building in the historic district is Spanish Eclectic with influences of Moorish, Byzantine, Gothic, and Renaissance architecture.[7]

The district is considered "architecturally significant" for representing popular architectural styles at the time of Apache Powder's early history and association with the company, which is a significant part of Benson's history. The company brought important employment and economic stimulus to Benson.[7]

• Porter locomotive on display