Fourth Quarter 2005
INL Quarterly Site Environmental Report
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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 INL. Weekly precipitation samples are collected from the Experimental Field Station (EFS) on the INL. Surface and/or drinking water are sampled twice each year at 19 locations around the INL. This occurs during the second and fourth quarters. The results of the fourth quarter sampling are reported here.
Precipitation samples are gathered when sufficient precipitation occurs to allow for the collection of the minimum sample volume of approximately 20 mL. Samples are taken of monthly composites from Idaho Falls and CFA, and weekly from the EFS. Precipitation samples are analyzed for tritium. Storm events in the fourth quarter of 2005 produced sufficient precipitation to yield 12 samples – three from Idaho Falls and CFA, and six weekly samples from the EFS.
Tritium was measured above the 3s value in three of the samples collected during the fourth quarter 2005. Low levels of tritium exist in the environment at all times as a result of cosmic ray reactions with water molecules in the upper atmosphere. The EPA’s RadNet program collects precipitation samples from across the United States. From 1980 to 2005 tritium measured in samples from Region 10 (which includes Idaho) ranged from -200 to 7500 pCi/L (EPA 2006). Tritium measured in fourth quarter ESER samples were within this range, with a maximum of 306 ± 31 pCi/L at EFS. Data for all fourth quarter 2005 precipitation samples collected by the ESER Program are listed in Table C-6 (Appendix C).
Fourteen drinking water samples and one duplicate were collected from selected taps throughout southeast Idaho (Figure 11). Samples were analyzed for gross alpha, gross beta, and tritium (3H).
None of the samples exceeded the 3s value for gross alpha. Eleven samples exceeded their 3s value for gross beta (Table 2). The EPA Safe Drinking Water Act (SDWA) limits gross beta in drinking water based on an annual exposure of 4 mrem/yr. Since data are reported from the laboratory as a concentration (i.e., pCi/L), a screening concentration of 50 pCi/L is used to meet this level (Appendix B-1). The maximum concentration of gross beta detected was from Fort Hall and was lower than the SDWA screening value. Levels of gross beta observed in drinking water are not unusual given the basaltic terrain (Twinning and Rattray 2003). All values are similar to those recorded in previous years, and are well below the levels outlined for drinking water protection (Table B-1). All drinking water sample results may be found in Appendix C, Table C 7.
Tritium was detected in six of the samples collected. Detectable tritium concentrations ranged from 80 ± 27 pCi/L at Shoshone to 223 ± 31 pCi/L at Idaho Falls. Both values are well below the EPA limit of 20,000 pCi/L and the DOE DCG of 2.0 x 106 pCi/L. Tritium values were within historical data collected by the ESER and within EPA measurements made through the RadNet program in Region 10 (Alaska, Idaho, Oregon, and Washington), which ranged from -87 ± 37 pCi/L to 1402 ± 63 pCi/L in the period 2000-2005.
Figure 11. Drinking and surface water sampling locations.
Table 2. Drinking water results greater than (>) 3s.
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|
Sample Resultsa |
Limits for Comparisona |
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|
Location |
Result ± 1s |
SDWAb |
DOE DCGc |
|
|
Tritium |
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|
Carey |
130 ± 32 |
20,000 |
2 x 106 |
|
|
Fort Hall |
140 ± 30 |
20,000 |
2 x 106 |
|
|
Idaho Falls |
223 ± 31 |
20,000 |
2 x 106 |
|
|
Minidoka |
121 ± 30 |
20,000 |
2 x 106 |
|
|
Moreland |
121 ± 30 |
20,000 |
2 x 106 |
|
|
Shoshone |
80 ± 27 |
20,000 |
2 x 106 |
|
|
Gross Beta |
||||
|
Aberdeen |
4.79 ± 1.01 |
50 |
100 |
|
|
Atomic City |
3.57 ± 0.90 |
50 |
100 |
|
|
Carey |
2.73 ± 0.89 |
50 |
100 |
|
|
Fort Hall |
7.29 ± 1.05 |
50 |
100 |
|
|
Fort Hall (duplicate) |
8.57 ± 1.05 |
50 |
100 |
|
|
Idaho Falls |
2.80 ± 0.91 |
50 |
100 |
|
|
Monteview |
5.39 ± 0.97 |
50 |
100 |
|
|
Moreland |
3.57 ± 1.02 |
50 |
100 |
|
|
Mud Lake |
4.94 ± 0.91 |
50 |
100 |
|
|
Shoshone |
2.62 ± 0.86 |
50 |
100 |
|
|
Taber |
3.33 ± 0.92 |
50 |
100 |
|
|
a. All values shown are in picocuries per liter (pCi/L). b. SDWA = Safe Drinking Water Act. c. DCG – Derived Concentration Guide. |
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Five surface water samples and one duplicate sample were collected from
locations throughout southeast Idaho and were analyzed for tritium, gross alpha,
and gross beta. None of the samples had measurable gross alpha activity (all
results were less than 3s). Tritium was detected in two of the samples (Table
3), well below the SDWA screening value and the DCG (Table
B-1).
All six surface water samples were greater than their associated 3s values for
gross beta (Table 3). Even at reported levels, the gross beta values are lower
than the SDWA screening value of 50 pCi/L and the DCG values (Table
B-1).
Table 3. Surface water results greater than (>) 3s.
|
|
|
Limits for Comparisona |
|
|
Location |
Result ± 1s |
SDWA |
DOE DCG |
|
Tritium |
|||
|
Hagerman (duplicate) |
384 ± 33 |
20,000 |
2 x 106 |
|
Idaho Falls |
231 ± 31 |
20,000 |
2 x 106 |
|
Gross Beta |
|||
|
Bliss |
7.09 ± 0.96 |
50 |
100 |
|
Buhl |
4.82 ± 0.89 |
50 |
100 |
|
Hagerman |
3.88 ± 0.83 |
50 |
100 |
|
Hagerman (duplicate) |
4.76 ± 0.86 |
50 |
100 |
|
Idaho Falls |
3.70 ± 0.82 |
50 |
100 |
|
Twin Falls |
4.07 ± 1.13 |
50 |
100 |
|
a. All values shown are in picocuries per liter (pCi/L). |
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The presence of gross alpha and gross beta in surface water (particularly the springs) is typically related to dissolution of naturally occurring radionuclides (i.e., uranium, radium, potassium) by groundwater as it flows through the surrounding basalts (Twinning and Rattray 2003). Levels of gross alpha and gross beta in all samples are similar to results from recent years. All gross alpha, gross beta and tritium results can be found in Appendix C, Table C-7.