Hanford Site National Environmental Policy Act (NEPA) - Pacific ...
Hanford Site National Environmental Policy Act (NEPA) - Pacific ...
Hanford Site National Environmental Policy Act (NEPA) - Pacific ...
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Contaminant, Units<br />
Table 4.4-1. Regulatory Drinking Water Standards for Groundwater<br />
Drinking<br />
Water<br />
Standard<br />
Contaminant, Units<br />
Drinking<br />
Water<br />
Standard<br />
arsenic (filtered), µg/L 10 gross beta, pCi/L 50<br />
cadmium (filtered), µg/L 5 iodine-129, pCi/L 1<br />
carbon tetrachloride, µg/L 5 nickel (filtered), µg/L 100<br />
carbon-14, pCi/L 2,000 nitrate, mg/L 45<br />
cesium-137, pCi/L 200 nitrite, mg/L 3.3<br />
chloroform, µg/L 100 plutonium-239/240, pCi/L not applicable<br />
chromium (dissolved), µg/L 100 strontium-90, pCi/L 8<br />
cis-1,2-dichloroethene, µg/L 70 technetium-99, pCi/L 900<br />
cobalt-60, pCi/L 100 trichloroethene, µg/L 5<br />
cyanide, µg/L 200 tritium, pCi/L 20,000<br />
fluoride, mg/L 4 uranium, µg/L 30<br />
gross alpha, pCi/L 15<br />
The highest strontium-90 concentration detected in riverbank springs during 2005 occurred at the<br />
100-K Area (2.7 ± 0.41 pCi/L [0.10 ± 0.015 Bq/L]). This value was 34 percent of the ambient<br />
surface-water quality criterion of 8 pCi/L (0.30 Bq/L). Samples from a spring at the 100-N Area have<br />
historically had the highest strontium-90 concentrations. However, because of decreased groundwater<br />
elevations, no flow has been observed at this spring since 1997 (Poston et al. 2006). Tritium<br />
concentrations in riverbank springs varied widely with location. The highest tritium concentration<br />
detected in riverbank springs during 2005 was 39,000 ± 2,800 pCi/L [1,400 ± 100 Bq/L]) at the<br />
<strong>Hanford</strong> townsite (Poston et al. 2006). During 2000 to 2004 the highest iodine-129 concentration of<br />
0.25 pCi/L (0.0093 Bq/L) was found in a <strong>Hanford</strong> townsite spring. Iodine-129 results were not yet<br />
available for 2005 (Poston et al. 2006).<br />
Non-radioactive contaminants of <strong>Hanford</strong>-origin continued to be detected in water from<br />
shoreline springs entering the Columbia River along the <strong>Hanford</strong> <strong>Site</strong> during 2005. Metals and<br />
anions (chloride, fluoride, nitrate, and sulfate) were detected in spring water. Concentrations of<br />
volatile organic compounds were near or below their detection limits in all samples. Trichloroethene<br />
was detected (1.4 µg/L) in one sample from the 300 Area and was the only analyte detected at all<br />
shoreline spring sampling locations. Trichloroethene has been consistently detected at low<br />
concentrations in 300 Area shoreline spring water (Poston et al. 2006).<br />
4.4.1.6 Runoff and Net Infiltration<br />
Total estimated precipitation over the Pasco Basin is about 9 x10 8 m 3 (3.2 x 10 10 ft 3 ) annually,<br />
calculated by multiplying the average annual precipitation averaged over the Pasco Basin by the<br />
4,900 km 2 (1,900 mi 2 ) basin area (DOE 1988). Precipitation varies both spatially and temporally with<br />
higher amounts generally falling at higher elevations. Annual precipitation measured at the HMS has<br />
varied from 7.6 cm (3 in.) to 31.3 cm (12.3 in.) since 1945. Most precipitation occurs during the late<br />
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