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Water Sampling
The ESER program samples precipitation, surface water, and drinking water. Monthly composite precipitation samples are collected from Idaho Falls and the Central Facilities Area (CFA) on the INEEL. Weekly precipitation samples are collected from the Experimental Field Station (EFS) on the INEEL. Surface and/or drinking water are sampled twice each year at 19 locations around the INEEL. This occurs during the second and fourth quarters. Precipitation Sampling
When
adequate precipitation occurred, samples were taken of a monthly
composite from Idaho Falls and CFA, and weekly from the EFS.
A minimum sample volume of approximately 20 mL is needed for a
single sample.
Precipitation samples are analyzed for tritium.
For the fourth quarter of 2001, there was enough precipitation
for a total of twelve samples – three from Idaho Falls, three from
CFA, and six from the EFS. Tritium
was detected in nine samples: two from Idaho Falls in November and
December; three from CFA in October, November, and December; and four
from the EFS in October, November, and December.
While there is no regulatory limit for tritium in precipitation,
the DOE DCG and maximum contaminant level set by EPA for tritium in
drinking water can be used as a measure.
The highest tritium concentration, 269.5 ±
65.8 pCi/L (10.0 ±
2.4 Bq/L), was measured in a sample collected from the EFS on October
31. This
value is many times lower than the DCG value and the Safe Drinking Water
Act Limit for tritium in drinking water. Due to cosmic ray reactions in the upper atmosphere, low levels of tritium exist in the environment at all times. Tritium measured in fourth quarter ESER samples were within the range of values measured elsewhere. The EPA’s ERAMS program collects precipitation samples from across the United States. From 1978 to 2001 tritium measured in those samples ranged from -2.00 to 7.38 ´ 106 pCi/L (-7.4 to 2.7 ´ 106 Bq/L) (EPA 2002). Data for all precipitation samples collected by the ESER Program, fourth quarter, 2001, are listed in Table C-6 (Appendix C). A drinking water sample was collected from tap water at each of fourteen locations throughout southeast Idaho. One duplicate drinking water sample was also collected from the Minidoka sampling location. All samples were analyzed for gross alpha, gross beta, and tritium (3H). Three
drinking water samples had gross alpha results greater than their
respective 2s values. Eleven
of 14 drinking water samples had gross beta results greater than their
associated 2s values. The
DCG values for gross alpha and gross beta in water are 30 and 100 pCi/L,
respectively. The EPA limits for gross alpha and gross beta in water are 15
and 50 pCi/L, respectively (Safe Drinking Water Act, 40 CFR 141).
The maximum gross alpha concentration in the drinking water, from
Monteview, was 1.9 ±
1.5 pCi/L (0.07 ±
0.06 Bq/L) and was lower than the DCG value and the EPA limit.
The maximum gross beta concentration of 11.1 ±
2.5 pCi/L (0.4 ±
0.09 Bq/L), measured at Monteview, was also lower than the DCG value and
the Safe Drinking Water Act limit. Gross
alpha and beta concentrations measured in fourth quarter drinking water
samples were within the range of values observed in the past. Gross
alpha and beta activity is a function of amount of alpha and beta
emitting radionuclides present in the sample.
The majority of gross alpha and beta activity in water is
primarily from naturally occurring uranium, thorium, radium, and their
decay products. Gross alpha
and beta concentrations were not higher at locations “down stream”
from the INEEL, indicating no INEEL contributions to gross alpha or beta
concentrations measured in drinking water. Tritium analyses showed seven drinking water samples with tritium results greater than their associated 2s values. The highest value of 144.3 ± 64.6 pCi/L (5.3 ± 2.4 Bq/L) was measured in a sample collected at Shoshone. The DCG value for tritium in drinking water is 80,000 pCi/L (2,960 Bq/L). The Safe Drinking Water Act sets a limit of 20,000 pCi/L (740 Bq/L) for tritium. The level of tritium measured in the sample from Shoshone was many times lower than the DCG value and the Safe Drinking Water Act limit. The EPA’s ERAMS program collects drinking water samples from across the United States. From October 1996 through September 1997 tritium measured in 304 samples ranged from -83 to 560 pCi/L (-3.1 to 20.7 Bq/L) (EPA 1996, EPA 1997a, EPA 1997b, EPA 1997c). Table C-7 of Appendix C lists all drinking water sample results.
Surface
water samples, and a duplicate, were collected from five locations along
the Snake River in the area where the Snake River Plain Aquifer
discharges. One sample was
collected from an upstream location at Idaho Falls.
Samples were analyzed for the same constituents as drinking
water. Gross alpha activity was not detected in any of the surface water samples. All surface water samples had detectable levels of gross beta activity. One of the surface water samples collected at Hagerman exceeded the 2s value for tritium. The maximum result for gross beta of 8.1 ± 2.1 pCi/L, or 0.3 ± 0.08 Bq/L) is less than the DCG and the SDWA limit. Levels of gross beta activity in all samples are within the range of results observed from recent years. The presence of gross alpha and gross beta in surface water (particularly the springs) is related to dissolution of naturally occurring radionuclides (i.e., uranium and radium) by groundwater as it flows through the surrounding basalts. The tritium result [73.4 ± 64.5 pCi/L (2.7 ± 2.4 Bq/L)] is far less than the DCG and the SDWA limit for tritium in drinking water and well within results measured in the past. Surface water results were similar to drinking water results. Table C-7 of Appendix C lists all data for the surface water samples. |
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