Round Valley Ensphere
Front of the dome with main entrance
|Location||Eagar, Arizona, USA|
|Owner||Round Valley High School/Round Valley Unified School District|
|Capacity||Volleyball, basketball: 9,000
American football: 5,500
|Field size||189,000 ft.² Diameter 440 feet / 134 m|
|Opened||October 11, 1991|
($19.8 million in 2017 dollars)
|Architect||Rossman Schneider Gadbery Shay|
|General contractor||Sletten Construction Company|
The Round Valley Ensphere is a wooden-dome stadium in Eagar, Arizona, USA. It is owned by Round Valley High School and the Round Valley Unified School District. It is the only domed high school football stadium in the United States. Opened in 1991–92 at a cost of US$11 million, the venue seats 5,500 persons for American football and 9,000 for basketball and volleyball. The dome encloses a floor area of 189,000 square feet (17,600 m2).
In 1987, a $12 million bond for the dome and repairs was floated and passed after it was found that Tucson Electric Power, which operates a generating station in the area, would have to pay for $11 million of it. (Since the utility generates 90% of the property values in the area, it pays 90% of the property taxes.) TEP, at the time facing financial issues, sued to block construction, but trial and appellate courts rejected the lawsuit.
Construction began in the summer of 1990. It was forced to stop for three months for reinspection when two workers were hit by wooden beams and fell 75 feet to their deaths.
The venue was closed in 2015 due to water damage and remained closed for nearly a year. The water damage was caused when heavy rains brought water into the building through the exterior doors. The damage to the synthetic turf in the facility produced elevated levels of mercury vapor, which required the facility to undergo professional remediation. After playing outside for the 2015 season, the Round Valley team returned to the dome for football games in 2016.
The Ensphere encloses 8,000,000 cubic feet (230,000 m3) of space and was the first fully day-lighted dome of its kind, allowing light and heat to enter.
In addition to football, the facility is used for basketball and track and field.
The dome is also used for nonschool events, such as a car show (). In 2002, as a result of the Rodeo-Chediski fire, the second-largest in Arizona history, the dome was used as a shelter. It took in 9,800 evacuees, tripling Eagar's population overnight, and President George W. Bush visited the shelter. The absorption of so many people almost caused the town's sewage system to be overloaded.
In 2016, the Cedar Fire prompted evacuations in Pinetop, for which the Round Valley Dome was made available as an evacuation site.
- Walkup Skydome – another wooden dome in Arizona, built in 1977 for athletics and other uses
- Tacoma Dome, 1983 ensphere-design arena built for a much larger capacity
- Federal Reserve Bank of Minneapolis Community Development Project. "Consumer Price Index (estimate) 1800–". Federal Reserve Bank of Minneapolis. Retrieved January 2, 2018.
- "High school gets its own dome", Houston Chronicle (AP), August 11, 1991
- Miner, Carrie. Off the Beaten Path Arizona: A Guide to Unique Places. p79. Google Books: 
- "Indoor Stadiums of the World". Ballparks.com. Archived from the original on May 6, 2011. Retrieved June 5, 2011.
- Bordow, Scott (January 22, 2011). "Round Valley High School fears elimination of sports teams". The Arizona Republic. Archived from the original on May 6, 2011. Retrieved June 5, 2011.
- Leiby, Mike. "Round Valley Dome closes due to water damage". White Mountain Independent. Retrieved 2015-08-29.
- "Cougars win opener 34-7". White Mountain Independent. 2015-08-28. Retrieved 2015-08-29.
- RVUSD letter
- Round Valley Ensphere: Eagar
- "Arizona Communities: Eagar: "The Home of the Dome" Was a Late Bloomer". Arizona 1912 – 2012. January 22, 2010. Archived from the original on May 6, 2011. Retrieved June 5, 2011.
- "Mitigation Project Spotlight". Mitigation Outlook. Archived from the original (PDF) on May 6, 2011. Retrieved June 5, 2011.
- "Cedar Fire grows to 40,000+ acres on Monday". ABC15. June 21, 2016. Retrieved August 19, 2016.