The Lowerline Site is a street in a residential area in the City of New Orleans (City). As recently as 2017, the Department of Energy (DOE) performed radiological sweeps of the area and identified a hot spot on Lowerline Street. Further investigation by Louisiana Department of Environmental Quality (LDEQ) better defined the hot spot as containing radium-226 (Ra-226). Activity measured at the surface indicated a potential source of 1 to 10 milli-Curies (mCi). At the time, the source was believed to be a discrete sealed source. The City worked with LDEQ and hired a contractor to excavate and remove the source.
The contractor excavated 36” x 36” laterally and 30” deep. The excavation did not reveal a sealed source but found contaminated soil below the original pavement level in the street. The contractor isolated, containerized, and shielded the contaminated soil in a drum. A subsequent radiation walking survey found five additional areas of subsurface contamination, which can be consolidated into three areas for reasonable excavation work. The consolidated areas are 5’x5’, 10’x20’ and 20’x40’. The survey extended the block and the intersecting street until the readings were not elevated. The contractor also surveyed the adjacent properties and did not find any contamination beyond the street.