Rocky Flats Site Tour

Legacy Management

Rocky Flats,

Colorado,

Site Tour

The Rocky Flats area, located 16 miles northwest of Denver, was once inhabited by Native Americans and then homesteaders and was used for grazing and mining.

Rocky Flats later became a critical part of the U.S. nuclear weapons complex during the Cold War. After World War II, the U.S. Atomic Energy Commission established facilities around the country to assist in the large-scale production of nuclear weapons, and in 1951, Rocky Flats was identified as one of these locations. From 1952 to 1994, Rocky Flats produced nuclear and nonnuclear weapons components for the nation’s arsenal.

In 1989, nuclear operations were suspended when the Federal Bureau of Investigation and the U.S. Environmental Protection Agency raided Rocky Flats to investigate reports of environmental violations. With the end of the Cold War, the site’s weapons-related mission ended in 1994.

The new mission of the site was cleanup and closure. The U.S. Department of Energy (DOE) and its contractor completed a $7 billion cleanup in December 2005. More than 800 structures were demolished and removed from Rocky Flats. Radioactive waste and other materials were also removed from the site.

DOE’s Office of Legacy Management assumed responsibility for the remediated site in October 2005. In 2007, Rocky Flats was divided into two areas. Over 4,500 acres of the former plant’s security buffer zone was released for unlimited use and unrestricted exposure, which means that long-term surveillance and maintenance is not required. It became the Rocky Flats National Wildlife Refuge, which is managed by the U.S. Fish and Wildlife Service. DOE retains responsibility for over 1,300 acres, known as the Rocky Flats Site or Central Operable Unit (COU), including the former industrial and production area. For more information on the Rocky Flats Site, visit the site’s main webpage.

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Legacy Management

Rocky Flats,

Colorado,

Site Tour

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The Rocky Flats area, located 16 miles northwest of Denver, was once inhabited by Native Americans and then homesteaders and was used for grazing and mining.

Rocky Flats later became a critical part of the U.S. nuclear weapons complex during the Cold War. After World War II, the U.S. Atomic Energy Commission established facilities around the country to assist in the large-scale production of nuclear weapons, and in 1951, Rocky Flats was identified as one of these locations. From 1952 to 1994, Rocky Flats produced nuclear and nonnuclear weapons components for the nation’s arsenal.

In 1989, nuclear operations were suspended when the Federal Bureau of Investigation and the U.S. Environmental Protection Agency raided Rocky Flats to investigate reports of environmental violations. With the end of the Cold War, the site’s weapons-related mission ended in 1994.

The new mission of the site was cleanup and closure. The U.S. Department of Energy (DOE) and its contractor completed a $7 billion cleanup in December 2005. More than 800 structures were demolished and removed from Rocky Flats. Radioactive waste and other materials were also removed from the site.

DOE’s Office of Legacy Management assumed responsibility for the remediated site in October 2005. In 2007, Rocky Flats was divided into two areas. Over 4,500 acres of the former plant’s security buffer zone was released for unlimited use and unrestricted exposure, which means that long-term surveillance and maintenance is not required. It became the Rocky Flats National Wildlife Refuge, which is managed by the U.S. Fish and Wildlife Service. DOE retains responsibility for over 1,300 acres, known as the Rocky Flats Site or Central Operable Unit (COU), including the former industrial and production area. For more information on the Rocky Flats Site, visit the site’s main webpage.
= BUILDING 551

= BUILDING 776

= BUILDING 771

= 903 Pad

= CENTRAL AVENUE

= COU ENTRANCE

= EAST SHED

= EAST TRENCHES PLUME TREATMENT SYSTEM

= INTERCEPTOR TRENCH SYSTEM

= LADY BIRD JOHNSON MEMORIAL FOREST

= MOUND SITE PLUME COLLECTION SYSTEM

= NOTCH

= ORIGINAL LANDFILL

= PRESENT LANDFILL

= PRESENT LANDFILL TREATMENT SYSTEM

= SOLAR PONDS

= SOLAR PONDS PLUME TREATMENT SYSTEM

= WEST GATE

= WALNUT CREEK POINT OF COMPLIANCE

= WOMAN CREEK POINT OF COMPLIANCE

LEGEND

Central Avenue

Once the bustling “main street” of the Rocky Flats Plant and later the Rocky Flats Environmental Technology Site, Central Avenue ran from east to west. Today, it serves as the primary gravel road for post-closure operations. This vital thoroughfare connected many facilities, including the B551 warehouse, a cafeteria, a laboratory, the dosimetry department, the paint shop, and the essential services of the fire department, gas station, and garage. It also provided access to the medical facility and the main administrative building. Notably, one of the three access points to the Protected Area was situated along Central Avenue.east to west. Today, it serves as the primary gravel road for post-closure operations. This vital thoroughfare connected many facilities, including the B551 warehouse, a cafeteria, a laboratory, the dosimetry department, the paint shop, and the essential services of the fire department, gas station, and garage. It also provided access to the medical facility and the main administrative building. Notably, one of the three access points to the Protected Area was situated along Central Avenue.

Historic
photos

903 pad

The 903 Pad was an area of open-air bare ground that was used from summer 1958 to January 1967 for storing drums containing machining lubricants and chlorinated solvents contaminated with plutonium. Hundreds of the drums leaked, causing environmental contamination. The area of windblown contamination from the 903 Pad became known as the 903 Lip.

Cleanup of the 903 Pad required the removal and off-site disposal of soil from a surface area of about an acre. Cleanup of the 903 Lip required the removal of soil over an area several times as large. In all, approximately 38 acres of 903 Pad-related contamination required remediation.

historic
photos

Central Avenue

Once the bustling “main street” of the Rocky Flats Plant and later the Rocky Flats Environmental Technology Site, Central Avenue ran from east to west. Today, it serves as the primary gravel road for post-closure operations. This vital thoroughfare connected many facilities, including the B551 warehouse, a cafeteria, a laboratory, the dosimetry department, the paint shop, and the essential services of the fire department, gas station, and garage. It also provided access to the medical facility and the main administrative building. Notably, one of the three access points to the Protected Area was situated along Central Avenue.

site
photos

Central Operable
Unit Entrance

The main entrance to the U.S. Department of Energy Office of Legacy Management’s Rocky Flats Site, Colorado, also called the Central Operable Unit, is at the western edge of the site. This restricted area is secured by a locked solar-and-battery powered gate connected to a fence with “no trespassing” signs that surrounds the site. A sign listing institutional controls and use restrictions is posted at this gate and at other access points to the site.

A boulder with a brass plaque honoring former Rocky Flats Plant workers also sits at the entrance gate. Small shrubs past the entrance are the remains of landscaping for the access road to the former B130/131 building and 130 trailers.

ADDITIONAL RESOURCES

East Trenches Plume Treatment System

The East Trenches Plume Treatment System (ETPTS) was built in 1999 to treat groundwater contaminated with volatile organic compounds (VOCs) before it reaches South Walnut Creek. It has since been significantly updated and improved, and now uses a simple, eco-friendly, solar and battery-powered air stripper to remove VOCs from the water. Since 2016, the ETPTS has also been treating groundwater from the nearby Mound Site Plume Collection System, which was built in 1998. The treated water meets all applicable Rocky Flats Legacy Management Agreement standards.

The site received the GreenGov Presidential Award and the DOE Sustainability Award for the ETPTS improvements.

ADDITIONAL RESOURCES

The Notch

From this vantage point, you can see South Walnut Creek, the Mound Site Plume Collection System, and the East Trenches Plume Treatment System (ETPTS) facilities. To the west is the former industrial area, which has been converted to grasslands. You can also see the breached dams of what once held Ponds B-1, B-2, and B-3.

The Mound Site Plume and East Trenches Plume source areas are located to the south. Groundwater flowing through them toward South Walnut Creek gets contaminated with volatile organic compounds (VOCs). This groundwater is intercepted by collection trenches that route the contaminated water to the ETPTS for treatment. This process is a fundamental part of the Rocky Flats remediation strategy: the shallow groundwater reaches surface water before that water leaves the U.S. Department of Energy’s Central Operable Unit, and where that groundwater is contaminated and might impact the surface water quality, it is collected and treated before it reaches surface water.

ADDITIONAL RESOURCES

Solar Ponds Plume Treatment System (SPPTS)

The Solar Ponds Plume Treatment System (SPPTS) was installed in 1999 to collect and treat groundwater contaminated with nitrate and uranium flowing from the former Solar Evaporation Ponds toward North Walnut Creek. The SPPTS intercepts and collects this flow, treats the water, and discharges it underground to reduce the impact on surface water quality.

Nitrate is the primary contaminant and uranium is the secondary contaminant. Since 2016, nitrate has been consistently treated to well below its applicable standard, and an improved uranium treatment component was installed in 2025 to reduce uranium to concentrations below its standard.

ADDITIONAL RESOURCES

Walnut Creek Point of Compliance

The Walnut Creek Point of Compliance (WALPOC) is one of two surface water Points of Compliance at the Rocky Flats Site. These Points of Compliance monitor water quality where surface water leaves the site. The Points of Compliance are therefore key monitoring locations for determining if long-term stewardship of the Rocky Flats Site remains effective.

At WALPOC, concentrations of plutonium, americium, uranium, and nitrate are analyzed. Samples are collected as flow-paced composites or, in the case of nitrate, as grab samples. Flows from No Name Gulch, North Walnut Creek, and South Walnut Creek join just upstream of WALPOC. This Point of Compliance operates at various flow conditions.

historic
photos

West gate

The West Gate served as the original entrance to the Rocky Flats Plant. A second entrance provided access from Indiana Street on the east side of the property. The West Gate road was several lanes wide and each incoming lane had a booth with an armed guard who would check badges before allowing anyone to enter the site. Individuals without a badge were not allowed entry.

ADDITIONAL RESOURCES

Woman Creek Point of Compliance

The Woman Creek Point of Compliance (WOMPOC) is one of two surface water Points of Compliance at the Rocky Flats Site. These Points of Compliance monitor water quality where surface water leaves the site. The Points of Compliance are therefore key monitoring locations for determining if long-term stewardship of the Rocky Flats Site remains effective.

At WOMPOC, concentrations of plutonium, americium, and uranium are analyzed. Samples are collected as flow-paced composites and monitor water from Woman Creek and Pond C-2, which is fed by the South Interceptor Ditch. This Point of Compliance operates at various flow conditions.

= BUILDING 551

= BUILDING 776

= BUILDING 771

= 903 Pad

= CENTRAL AVENUE

= COU ENTRANCE

= EAST SHED

= EAST TRENCHES PLUME TREATMENT SYSTEM

= INTERCEPTOR TRENCH SYSTEM

= LADY BIRD JOHNSON MEMORIAL FOREST

= MOUND SITE PLUME COLLECTION SYSTEM

= NOTCH

= ORIGINAL LANDFILL

= PRESENT LANDFILL

= PRESENT LANDFILL TREATMENT SYSTEM

= SOLAR PONDS

= SOLAR PONDS PLUME TREATMENT SYSTEM

= WALNUT CREEK POINT OF COMPLIANCE

= WOMAN CREEK POINT OF COMPLIANCE

LEGEND

903 pad

The 903 Pad was an area of open-air bare ground that was used from summer 1958 to January 1967 for storing drums containing machining lubricants and chlorinated solvents contaminated with plutonium. Hundreds of the drums leaked, causing environmental contamination. The area of windblown contamination from the 903 Pad became known as the 903 Lip.

Cleanup of the 903 Pad required the removal and off-site disposal of soil from a surface area of about an acre. Cleanup of the 903 Lip required the removal of soil over an area several times as large. In all, approximately 38 acres of 903 Pad-related contamination required remediation.

HISTORIC PHOTOS

Central Avenue

Once the bustling “main street” of the Rocky Flats Plant and later the Rocky Flats Environmental Technology Site, Central Avenue ran from east to west. Today, it serves as the primary gravel road for post-closure operations. This vital thoroughfare connected many facilities, including the B551 warehouse, a cafeteria, a laboratory, the dosimetry department, the paint shop, and the essential services of the fire department, gas station, and garage. It also provided access to the medical facility and the main administrative building. Notably, one of the three access points to the Protected Area was situated along Central Avenue.

HISTORIC PHOTOS

East Trenches Plume Treatment System

The East Trenches Plume Treatment System (ETPTS) was built in 1999 to treat groundwater contaminated with volatile organic compounds (VOCs) before it reaches South Walnut Creek. It has since been significantly updated and improved, and now uses a simple, eco-friendly, solar and battery-powered air stripper to remove VOCs from the water. Since 2016, the ETPTS has also been treating groundwater from the nearby Mound Site Plume Collection System, which was built in 1998. The treated water meets all applicable Rocky Flats Legacy Management Agreement standards.

Additional Resources

The Notch

From this vantage point, you can see South Walnut Creek, the Mound Site Plume Collection System, and the East Trenches Plume Treatment System (ETPTS) facilities. To the west is the former industrial area, which has been converted to grasslands. You can also see the breached dams of what once held Ponds B-1, B-2, and B-3.

The Mound Site Plume and East Trenches Plume source areas are located to the south. Groundwater flowing through them toward South Walnut Creek gets contaminated with volatile organic compounds (VOCs). This groundwater is intercepted by collection trenches that route the contaminated water to the ETPTS for treatment. This process is a fundamental part of the Rocky Flats remediation strategy: the shallow groundwater reaches surface water before that water leaves the U.S. Department of Energy’s Central Operable Unit, and where that groundwater is contaminated and might impact the surface water quality, it is collected and treated before it reaches surface water.

Additional Resources

Solar Ponds Plume Treatment System (SPPTS)

The Solar Ponds Plume Treatment System (SPPTS) was installed in 1999 to collect and treat groundwater contaminated with nitrate and uranium flowing from the former Solar Evaporation Ponds toward North Walnut Creek. The SPPTS intercepts and collects this flow, treats the water, and discharges it underground to reduce the impact on surface water quality.

Additional Resources

Walnut Creek Point of Compliance

The Walnut Creek Point of Compliance (WALPOC) is one of two surface water Points of Compliance at the Rocky Flats Site. These Points of Compliance monitor water quality where surface water leaves the site. The Points of Compliance are therefore key monitoring locations for determining if long-term stewardship of the Rocky Flats Site remains effective.

At WALPOC, concentrations of plutonium, americium, uranium, and nitrate are analyzed. Samples are collected as flow-paced composites or, in the case of nitrate, as grab samples. Flows from No Name Gulch, North Walnut Creek, and South Walnut Creek join just upstream of WALPOC. This Point of Compliance operates at various flow conditions.

Additional Resources

Woman Creek Point of Compliance

The Woman Creek Point of Compliance (WOMPOC) is one of two surface water Points of Compliance at the Rocky Flats Site. These Points of Compliance monitor water quality where surface water leaves the site. The Points of Compliance are therefore key monitoring locations for determining if long-term stewardship of the Rocky Flats Site remains effective.

At WOMPOC, concentrations of plutonium, americium, and uranium are analyzed. Samples are collected as flow-paced composites and monitor water from Woman Creek and Pond C-2, which is fed by the South Interceptor Ditch. This Point of Compliance operates at various flow conditions.

Additional Resources