St. Louis Airport Storage Site 

(SLAPS)

Special Exposure Cohort

LaVon B. Rutherford, CHP

Division of Compensation Analysis and Support

January 6, 2015

 
Facility Designation

 St. Louis Airport Storage Site (SLAPS) 

 Department of Energy site in St. Louis, 

MO

 January 3, 1947–73, 1984–98 covered 

time period
Site History

 From 1940s Manhattan Engineer District (MED) 

used 21.7-acre site north of the St. Louis 

International Airport to store residues from the 

processing of uranium ore

 Mallinckrodt Chemical Works sent residues to 

SLAPS from 1946–1953 and continued to store 

residues at SLAPS until production at 

Mallinckrodt stopped in 1966

 Most stored materials were removed from 

SLAPS from 1966–1969 
Site History (cont.)

 St. Louis Airport Authority

• Removed residues, above-ground structures

• Added clean fill over remaining buried materials 

• Most work completed in 1969, completed final 

survey for turnover November 3, 1971

 City took over area in 1973

 DOE started managing property in 1984 

under the Formerly Utilized Sites Remedial 

Action Program (FUSRAP)

 1998 DOE transferred site to Army Corps of 

Engineers 
Background

 Evaluation Report (ER) Rev.0 April 13, 2010

• NIOSH recommended add class for January 3, 1947–

November 2, 1971; Board agreed

• NIOSH found dose reconstruction feasible 

• Remaining covered period, November 3, 1971 –

December 31, 1973 

• January 1, 1984 – December 31, 1998 

• Board action postponed for further consideration

 Presented ER May 20, 2010 in Niagara Falls, NY

 Advisory Board voted to recommend class
Dose Reconstructions

NIOSH Claims Tracking System 

(December 23, 2014)

 Submitted to NIOSH 3

 Within the SEC period (1947–1971) 2

 DRs completed outside SEC period 1

 Containing internal dosimetry 1

 External dosimetry 2
Potential Exposures

 Site stagnant 1971–1973 with 1–3 feet of clean fill 

on the surface

• Internal exposure only from radon from the clean fill.

• External exposure from gamma emissions through 

clean fill

 1984–1998 activities mostly environmental 

monitoring with some site maintenance

• Potential internal/external exposure potential only 

from contaminated debris, residual source material 

from maintenance 
Personal and Area Monitoring Data

 Internal monitoring data from November 3, 

1971 – December 31, 1973

• Before November 3, 1971 all buildings and 

source material removed from the site with 1 to 

3 ft. clean fill dirt put over area

• No personnel monitoring and air sampling data
Personal and Area Monitoring Data 

(cont.)

 Internal monitoring January 1, 1984 –

December 31, 1998

• From 1984–1998 urine samples taken from 

workers involved in characterization and remedial 

action activities 

• Urine samples analyzed for thorium-230, thorium- 232 and radium-226, as well as thorium-228 during 

some periods

• Air sampling included breathing-zone

• 1991 analysis to determine isotopic ratios of SLAPS 

soils
Personal and Area Monitoring Data 

(cont.)

 External monitoring data November 3, 1971 –

December 31, 1973

• Before November 3, 1971 all buildings and source 

material removed site, 1 to 3 ft. clean-fill soil used 

to cover area

• No personnel external monitoring data

• Verification survey completed November 3, 1971 

verifying no area at SLAPS exceeded 1 mrad/hr
Personal and Area Monitoring Data

(cont.)

 External monitoring data January 1, 1984 –

December 31, 1998

• From 1984–1998 workers involved were 

monitored for external radiation 

• Workers issued TLDs for 1985, 1987, 1988, and 

1990 (Not all of the results for these years 

obtained)

• 1986 summary report estimated worker exposure 

less than 20 mrem/yr
1971–1973 approach

 Only internal dose from radon applied using highest 

radon concentration from site remedial investigation

 External dose based on highest rate from the 1971 

site survey, found highest external dose rate 1 mr/hr

Dose Reconstruction
1984–1998 approach

 Use (when available) internal, external personal 

monitoring data 

 If no personal internal monitoring data available for 

individuals, determine period internal exposure 

• Based on re-suspension of contaminated soil (OTIB-0070)

• Develop co-worker model, if applicable

 If no personal external monitoring data available for 

individuals, determine period external exposure based on 

area monitoring or develop co-worker model 

Dose Reconstruction (cont.)
Questions?