Is housing construction affected by contamination from Rocky Flats?

During and since closure, new houses have been constructed in the vicinity of Rocky Flats. Many potential new residents have asked if it is safe to live so close to a former weapons plant. The simple answer is that all offsite areas around the Rocky Flats site, as well as the refuge itself, have been determined to be safe for any use. A huge number of surface and sub-surface soil samples were collected across the Rocky Flats site and offsite. Offsite levels of plutonium are generally at or near background. A study of the offsite areas called Operable Unit 3 shows that the highest offsite levels sampled were from an open space area just east of the site’s former east entrance on Indiana Street – about seven picocuries (trillionths of a Curie) per gram. Even if that level were widespread, it would equate to a risk that is at the bottom end of the EPA’s range of acceptable risk for a hypothetical resident (a less than three in a million additional risk for a resident to contract cancer). Several other sampling efforts have produced similar results – for instance the soil and sediment sampling study produced by the Citizens’ Environmental Sampling Committee in 1996. 
The average concentration of plutonium in the 77 samples collected within a mile south of the refuge’s boundary is 0.05 picocuries (trillionths of a curie) per gram (pCi/g). That amount is in the range of background levels along the Front Range. The background levels are due to world-side atmospheric testing of nuclear weapons back in the 1950s and early 1960s. These minute soil concentrations, whether from weapons testing or from Rocky Flats’ sources, are in the upper couple of centimeters of surface soil. Any construction or digging would mix this uppermost soil with deeper clean soils so that resulting soil concentrations would be well below background.
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