The historic growth of the groundwater monitoring network at the Site reflects the increasing DOE, regulatory, and public emphasis on identifying areas of groundwater contamination and preventing contaminant releases to the environment. The first three monitoring wells were installed in 1954 in the Solar Ponds area. A total of 1,382 wells and piezometers were installed at the Site from 1971 to present of which 290 have been abandoned. The groundwater monitoring well map part 1 | part 2 shows all the wells that have been installed at the Site.

How Often Are Wells Sampled?

Wells in the groundwater monitoring network were sampled annually until 1974, twice a year until 1980, and three times a year during 1981. From 1982 to 1995, designated monitoring wells were sampled quarterly. Beginning in 1995, designated wells were sampled either quarterly or semiannually, depending on regulatory requirements. The wells to be sampled are determined by the types of wells (e.g., RFCA project specific), and the areas being monitored. Currently, Rocky Flats 167 wells are sampled on an annual or semiannual basis to support a variety of technical programs and regulatory requirements.

What Chemicals Are Investigated?

Groundwater has been monitored for radionuclides since the first wells were installed in 1954; other chemicals of interest were added in 1974, 1979, 1981, 1985, and 1994. Beginning in 1985, the wells were sampled and analyzed for volatile organic compounds (VOCs), metals, and major anions. Limited analyses for pesticides have also been performed. Results of groundwater analyses from 1986 to present are compiled in the Soil Water Database (SWD), which is used by Site personnel to prepare required documents and analyses. Recent groundwater data are provided quarterly in the RFCA Quarterly Groundwater Report.

How Many Wells Are Sampled?

Based on a wealth of historical data, the well-monitoring program was reevaluated in 1994 and the number of wells routinely monitored dropped from 460 wells to 350 wells, but those wells in or near contaminant plumes were retained. In 1995, based on updated groundwater plume analyses, the number of wells monitored was reduced from 350 wells to 150 wells, and the sample frequency and chemical list were amended. In 1996, utilizing a data quality objectives process, the number of wells monitored was decreased by 44% to the current program. The wells currently monitored are shown in the groundwater monitoring well map part 1 | part 2.

More detailed information on Rocky Flats' groundwater monitoring programs and thier relationship to other Site programs and the Closure Mission is in the Integrated Monitoring Plan Executive Summary.