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Manhattan Project NHP Site Preservation

Preserving historic Park sites in Los Alamos.
June 1, 2020
Concrete and earthen bunker at Gun Site.A visitor peers inside Pond Cabin.

Concrete and earthen bunker at Gun Site.


  • Manhattan Project NHP-Los Alamos Public Engagement Specialist
  • Jonathan Creel
  • (505) 667-6277
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Concrete has proven to be especially susceptible to the dozens of freeze-thaw cycles that often take place on a winter day in Los Alamos.—Jeremy Brunette

In Los Alamos, many of the sites constructed to support  the Manhattan Project were not designed to withstand the test of time. Researchers and military personnel hurriedly built structures for specific purposes in the race to win World War II  and many of those structures have since sat unused, exposed to the harsh Northern New Mexico environment. 

Two of these historic sites, the Concrete Bowl and Gun Site, recently underwent extensive preservation work in a collaborative effort by the Manhattan Project National Historic Park Team in order to preserve them and the stories they tell. 

The Concrete Bowl
The Concrete Bowl was built in 1944 as a possible “water recovery method” that might allow scientists to recover precious plutonium rather than losing it on a failed test. Though scientists quickly realized this method was not feasible for a full-scale nuclear test, the Concrete Bowl remains in place—a tangible testament to the wartime Laboratory’s practice of testing multiple solutions to solve complex problems. 

In the 75 years since the bowl’s construction, weeds and trees moved in and local fauna discovered it as a reliable watering hole on the arid Pajarito Plateau. The introduction of creeping vegetation and constant exposure to the elements soon began to take their toll on the concrete used to construct the bowl and it began to decay and crumble.

To restore the Concrete Bowl and protect it from further deterioration, the Lab’s Historic Buildings team worked with Vital Consulting Group from Albuquerque to remove the encroaching vegetation and grade the soil away from the bowl to lessen the accumulation of water inside the bowl. While the deer and elk may need to find a new watering hole, these efforts will preserve this historic site for years to come.

The Concrete Bowl before and after restoration. 
Gun Site
During Project Y, Los Alamos researchers also developed the Gun Site, known in 1943 as Anchor Ranch Proving Ground, to design and test nuclear weapon prototypes. At this site, scientists, engineers, and ordinance experts conducted experiments on the inner workings of a “gun-type” atomic bomb design, hence the site’s name.

Built to protect researchers during the  numerous “gun-assembly” tests, this site’s concrete and earthen bunkers were constructed in a natural drainage, which placed the tests above the bunkers and lessened the hazards of these experiments for the staff performing them.

The bunkers at Gun Site underwent extensive concrete repairs in 2012, including reconstruction of the concrete parapet wall and the addition of a concrete cap to drain water from the top. However, the concrete cap failed and allowed further degradation. To address this, and prevent further damage to the structures, workers removed the crumbling concrete from the 2012 project.

 Concrete work at Gun Site.

These two sites are notable examples of the Lab’s long-standing history of bringing people together to solve difficult, often overwhelming, scientific and technological challenges, beginning with the Manhattan Project—an immense project that created new fields of science and forever shaped the world we live in today. 

In the collaborative spirit of its namesake, care for the Manhattan Project National Historical Park (MPNHP) is entrusted to a multi-organizational team dedicated to preserving these sites that represent an extraordinary moment in time. For updates on continuing MPNHP preservation work, please visit the Park’s website. 

About the Park
Formally established in November 2015 via a Memorandum of Agreement between the Department of Energy (DOE) and the National Park Service (NPS) to preserve portions of three World War II sites where the United States developed the first atomic weapons, the Park marks the history of the people, science, events, and controversy associated with the creation of the atomic bomb in the top-secret effort known as the Manhattan Project. Under the agreement, the NPS and DOE jointly manage and administer the park.