Groundwater - Operable Unit 5
Before discussion of contamination in groundwater, it is important to remember that no one at Lowry is drinking groundwater that underlies Denver. Lowry's drinking water, as well as the rest of the Metro Denver area, comes from surface water reservoirs replenished annually by high mountain snowmelt. For more information about Denver drinking water, visit Denver Water or call 303.628.6510.
As discussed in Site History, the activities that occurred at the former Lowry AFB were similar to other communities at that time. However, there were some contaminant releases to the environment as a result of these activities. Groundwater contaminants were initially released into the environment at several locations on the Lowry AFB. The primary origin of contaminant release was into the storm sewers from several on-base facilities including an auto hobby shop. Other likely sources of contamination included accidental spills or leaks of solvents around firing range facilities, disposal of solvents into septic systems at the firing range, leakage from a storm sewer in the Headquarters area, accidental spills or leaks at the fuel storage area in the vicinity of Uinta Street, releases related to fire training activities, and leakage from fuel tanks at the Yosemite Street Gate Site. The specific hydrogeology at Lowry AFB strongly affected the infiltration and movement of the contaminant releases to the groundwater. Infiltration of solvents and fuels from these source areas transported contaminants through the vadose (unsaturated) zone, into the alluvial water-bearing zone, and in some cases, the underlying bedrock water-bearing zone.
To facilitate the investigation and evaluation of remediation alternatives for the groundwater contamination, all of the impacted groundwater was grouped into one unit identified as Operable Unit 5 (OU5). OU5 is defined as all areas within and adjacent to Lowry AFB where groundwater has been impacted by past Air Force activities. The OU5 groundwater contamination occurs in five distinct, mapable contaminant plumes. These include:
Yosemite Street Gate Plume was closed in May 2007 and is discussed in more detail as part of the NFA sites.