Proposed Cleanup of
South Fork of Acid Canyon


Plutonium-239 has a half-life of 24,400 years and is an alpha emitter. The inhalation pathway is the most dangerous way for plutonium-239 to enter the body. Plutonium particles in soil can be resuspended in air and become mobile in sediments and water.

People downstream and downwind of Los Alamos National Laboratory (LANL) in general and the South Fork of Acid Canyon in particular are concerned that plutonium particles left in the environment could be resuspended by the winds and end up in our drinking water. Any quantity of plutonium in the environment presents a risk.

Plutonium Cleanup at Other DOE Facilities

1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA - Plutonium found in the soil at a Livermore park. The cleanup was regulated under CERCLA and the Federal Facilities Agreement. The soil was cleaned up to levels found in the EPA Region IX Preliminary Remediation Goal (PRG), which are 10 picoCuries/gram (pCi/gm) industrial scenario and 2.5 pCi/gm residential. The contamination was not averaged over the whole area, nor was it averaged over the core samples. For this cleanup, if plutonium is found above these levels, the site is cleaned up.

2. Mound Plant, Miamisburg, OH - In 1969, a pipe carrying seven types of radionuclides, including plutonium, and VOCs broke and flowed to a nearby canal that runs constantly. Contamination was found in the one-mile strip of the canal closest to the spill at levels between 3 and 5 Curies. The contamination had seeped 5 to 10 feet into the soil.

The U.S. EPA, Ohio EPA, City of Miamisburg, Neighbors in Need and Miamisburg Environmental Safety & Health (MESH) worked to establish cleanup standards for the site. The VOCs drove the cleanup. The first proposed cleanup level was 150 pCi/gm of plutonium in soil for a parkland use scenario; recreational standard use for four hours/day. In a community of 18,000, a cleanup level of 150 pCi/gm of plutonium meant that six people in 10,000 would die from exposure.

MESH added a child playing in the park scenario. The City and EPAs agreed on 75 pCi/gm. MESH asked for 25 pCi/gm and stepped aside on the 75 pCi/gm standard. The resulting cleanup was an average cleanup of 25 pCi/gm of plutonium in soil. During cleanup they found that the plutonium contamination was underestimated; they found 15 curies of plutonium-238 in the soil. Cleanup costs: $48 million.

3. Rocky Flats - In June 1995, the Rocky Flats Future Site use Working Group made the following consensus recommendation for Rocky Flats cleanup:

When the technology allows cleanup to average background levels for Colorado in a cost-effective and environmentally sensitive manner, then cleanup should be done to this level.

The average background level for plutonium in soil along the base of the Front Range in Colorado (eastern slope of the Rocky Mountains) is 0.04 pCi/g.

In October 1996, DOE, EPA and the Colorado Department of Public Health and Environment (CDPHE) adopted an "interim" Radionuclide Soil Action Levels (RSALs) for Rocky Flats at 651 pCi/g (sum-of-ratios calculation, assuming the presence of other radioactive material in soil). The public opposed the interim RSAL.

In 1998, DOE agreed to fund a citizen-directed independent scientific review of the Rocky Flats RSALs. An RSAL Oversight Panel was convened. The panel hired Risk Assessment Corporation (RAC) to conduct a detailed, peer-reviewed independent study. RAC recommended a cleanup level of 35 pCi/g of plutonium in soil (using sum-of-ratios approach).

4. Institute for Energy and Environmental Research (IEER) Recommendation - Cleanup to background when possible; otherwise 2 mrem ALARA (the British ALARA guideline), 10 mrem to a future maximally exposed individual for as long as the threat persists.

5. Proposed NMED risk of one in one hundred thousand for chemical carcinogens. This risk is also proposed for radionuclides.

6. EPA CERCLA (Superfund) Soil Screening Contaminant Levels (SSCLs) for Pu-239, Pu-238, Am-241, Cs-137, Sr-90 in pCi/g

Pathway Pu-239 Pu-238 Am-241 Cs-137 Sr-90
Ingestion of soil 2.88 2.92 3.66 18.3 5.51
Inhalation of soil/dust 545 540 646 1530000 161000
External rad exposure 558 1550 4.04 0.0438 5.69

Plutonium Cleanup at LANL

1. Hillside 140 (PRS 1-001[f]): Located just below the Timber Ridge Condo's, just west of the Los Alamos Inn. The 1996 LANL Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) Report results showed maximum values for:

U-234 873 pCi/g
U-235 38 pCi/g
U-238 820 pCi/g

The RESRAD computer model calculated dose using a trail user scenario best estimate for the hillside was 0.05 mrem/yr. The RESRAD reasonable maximum exposure (RME) dose using trail user scenario for the hillside was 4 mrem/yr. Prior to 1977, soil contamination was left in-place below Hillside 140, and it was fenced off to prevent public access. Hillside 140 is very accessible by the public.

LANL Action: In 1996, LANL conducted a VCA at this site (Hillside 140) as part of its best management practices. The VCA consisted of removing soils (15 cubic yards) with elevated concentrations of total uranium identified on upper and lower slope areas; all the contaminated soil was removed to MDA G.

2. Hillside 138 (PRS 1-001[d]): Located just below the Los Alamos Inn. The 1995 LANL RFI Report results showed maximum values for:

Hg (mercury) 1770 ppm
Cs-137 44.5 pCi/g
Pu-238 44 pCi/g
Pu-239 2500 pCi/g

The RESRAD calculated dose using trail user scenario best estimate for upper and lower hillside benches was 0.3 mrem/yr. The RESRAD calculated reasonable maximum exposure (RME) dose using a trail user scenario for upper and lower hillside benches was 15 mrem/yr and 9.7 mrem/yr respectively. Previously, the LANL ‚74-‚76 radiological survey found elevated levels of Cs-137 and Pu-239 on the upper and lower benches of Hillside 138

Pu-239 upper 3600 pCi/g
Pu-239 lower 8900 pCi/g

The hillside was remediated but the report has not been filed with the New Mexico Environment Department (NMED) DOE Oversight Bureau. Hillside 138 is very accessible by the public.

LANL Action: LANL conducted a voluntary corrective action (VCA) on this hillside and remediated it in part (all Pu-239 and Hg hot spots were removed) during 1996-97 and erosion controls were put in place by the Surface Water Action Team (SWAT).

3. Old Catholic Church Septic Tank (PRS 0-030[g]): This tank was situated on mesa-side private property above Acid Canyon. LANL Environmental Restoration Project (ER) found the tank to contain metals, mostly

Hg at elevated ppm levels
Pu-239 maximum value at 35.116 pCi/g

No RESRAD calculated dose or risk to human health and the environment was given. Very accessible by the public.

LANL Action: In 1993, this septic tank was removed during a marathon "round the clock" remediation effort and quickly became LANL's first million-dollar cleanup.

4. Old Catholic Church Septic Tank Outfall Drainage---0-030(g) Drainage: A drainage from the 0-030(g) Septic Tank outfall on the mesa top to Acid Canyon, roughly 850 feet in length. As a follow up to the 1993 Septic Tank RFI, this drainage, only located a couple hundred yards west of South Fork Acid Canyon, was jointly sampled in 1999 by LANL ER and NMED Oversight Bureau for full-suites of chemical carcinogens and radionuclides. The results showed elevated levels of PCBs, arsenic, pesticides and radionuclides. A risk assessment on the chemical concentrations showed the risk to both children and adults to be within the one in ten thousand to one in one million cancer range, thus no action was proposed for chemical cleanup at the site. The maximum values for radionuclides in the drainage showed:

Pu-239 82.5 pCi/g
Am-241 7.6 pCi/g
U-235 2.1 pCi/g
U-234 28.3 pCi/g
U-238 15.7 pCi/g

These radionuclides resulted in a total potential dose ranging from 2.0 to 6.9 mrem/yr for the child and 2.0 to 7.2 mrem/yr for the adult; both these dose levels were well below the 15 mrem/yr dose level used to determine if exposure is potentially unacceptable to the public.

LANL Action: No proposed cleanup for Old Catholic Church Septic Tank Outfall Drainage 0-030(g) based on chemical and radionuclide risk results.

5. 0-11k Outfall at TA-21 (PRS 21-011[k]): This rather hot outfall drainage on LANL property underwent several remediation actions in the past 20 years, lots of contaminated soil has been removed. The LANL RFI Report results showed maximum values for:

Cs-137 51.8 pCi/g
Sr-90 1800 pCi/g
Pu-239 46000 pCi/g
Am-241 2600 pCi/g

No RESRAD calculated dose or human health and the environment risk was given. There is little or no public access to this site.

LANL Action: In 1995 LANL ER decided to post and fence all areas of the 21-011[k] drainage that showed gamma radiation contamination readings greater than 50 uR/hr, based on a 10 mrem/yr maximum dose.

6. Outfall 024u at TA-21 (PRS 21-024[u]): Discovered by LANL ER on LANL property to be about the most alpha contaminated outfall at TA-21. The initial LANL RFI results showed maximum values for:

Gross alpha 1113 cpm
H-3 (tritium) up to 13000 pCi/g

No RESRAD calculated dose or human health and the environment risk was given. There is little or no public access to this site!

LANL Action: The small outfall area at the very edge of the mesa was posted and fenced off sometime between late 1995 and 1997.

7. ESH Experimental Garden in Los Alamos Canyon: Was located near and downstream from the confluence of LA and DP Canyons. The garden consisted of posted and fenced (steel cages) plots of plants growing in soils that were rather contaminated with Cs-137 and lesser plutonium. No RESRAD dose or risk to human health and the environment were given. There was only limited public access to this site.

LANL Action: Tens of cubic yards of contaminated soil in the area, including the plots, were removed by LANL ER during the summer of 2000 in response to erosion concerns resulting from the Cerro Grande fire.

CCNS Recommendations

1. The County of Los Alamos should appoint a Task Force to investigate the proposed South Fork of Acid Canyon Cleanup and request a recommendation from the Task Force. Use the Rocky Flats Cleanup Agreement Stakeholder Focus Group as a model. Request that DOE/LANL recalculate the exposures based on actual exposures, not averaging the contamination through the length of the South Fork.

2. Put up contamination signage around the South Fork of Acid Canyon NOW.

3. In the alternative, close the area to public access.


1. Adapted from How Clean is Clean? A Look at Radionuclide Soil Action Levels for Rocky Flats, by LeRoy Moore, Ph.D., Rocky Mountain Peace and Justice Center.
2. Personal communications with Marylia Kelly (Livermore), Sharon Cowdrey (Mound), and my attendance at the 1/31/01 Rocky Flats Cleanup Agreement Stakeholder Focus Group.
3. Id. An RSAL specifies the quantity of radioactive material that may remain in the environment after "cleanup" without exceeding a legally permitted exposure level. If radiation in the soil exceeds the established standard, remedial action to remove the danger or to isolate it is triggered.
4. Science for Democratic Action, "Cleaning Up the Cold War Mess," p. 20.
5. LANL RCRA Facility Investigation (RFI) Reports.


Joni Arends
Waste Programs Director
Concerned Citizens for Nuclear Safety