To be conservative, they typically overestimate the rate of groundwater movement for their analyses. They estimated that contaminated groundwater from Rocky Flats would take from 30 to 300 years to travel through various geologic pathways eastward to Indiana Street. The data from all Rocky Flats groundwater monitoring wells including six wells along the plant's eastern boundary at Indiana Street are regularly checked and are routinely reported to the public. From 1992-1994, scientists detected plutonium levels exceeding the state standard for groundwater in samples from one shallow groundwater well next to Walnut Creek at Indiana Street near the northeast corner of the site. When sediment in the well was cleaned out in 1994, the levels of plutonium dropped below the standard and have remained so to date.
Scientists believe that heavy rains caused the contaminated sediment to enter the well.
Summary Scientists concluded that it is unlikely that groundwater contaminants released from the plant in the past could have reached any wells used by the public today. Sampling of plant-wide wells has confirmed these conclusions. Monitoring data available to date indicate that contaminated groundwater from the Rocky Flats Environmental Technology Site has not migrated to the plant's eastern boundary. Nor have groundwater contaminants released from the plant in the past reached any private or municipal wells east of the site. However, monitoring of the groundwater at Rocky Flats will continue, and the data will be available to the public.