Second Quarter 2006
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 Site. Weekly precipitation samples are collected from the Experimental Field Station (EFS) on the INL Site. Surface and/or drinking water are sampled twice each year at 19 locations around the INL Site. This occurs during the second and fourth quarters.
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 second quarter of 2006 produced sufficient precipitation to yield 10 samples –two from Idaho Falls, three from CFA, and five weekly samples from the EFS.
Tritium was measured above the 3s value in only one of the 10 samples collected during the second quarter of 2006. 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 all second quarter ESER samples were within this range, with a maximum of 274.0 ± 33.9 pCi/L at CFA. Data for all second quarter 2006 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).
Figure 11. Drinking and Surface Water Sampling locations.
One of the samples exceeded the 3s value for gross alpha. Tritium was not detected in any sample. It is not unusual to detect these constituents in water of the Snake River Plain. They tend to be related to natural production from the basalts that make up the aquifer. The sample from Howe had a gross alpha concentration of 1.58 ± 0.41 pCi/L which is below the EPA and DOE limits for gross alpha in drinking water of 15 pCi/L and 30 pCi/L, respectively.
Of the fifteen drinking water samples (including the duplicate) collected, all samples but three 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 Moreland and was lower than the SDWA screening value. Levels of gross beta observed in drinking water are not unusual given the basaltic terrain (USGS 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.
Table 1. Drinking water results greater than (>) 3s.
|
|
Sample Resultsa |
Limits for Comparisona |
||
|
Location |
Result ± 1s |
SDWAb |
DOE DCGc |
|
|
Gross Alpha |
||||
|
Howe |
1.58 ± 0.41 |
8 |
30 |
|
|
Gross Beta |
||||
|
Aberdeen |
4.79 ± 0.58 |
50 |
100 |
|
|
Atomic City |
4.87 ± 0.55 |
50 |
100 |
|
|
Fort Hall |
7.83 ± 0.64 |
50 |
100 |
|
|
Howe |
2.45 ± 0.49 |
50 |
100 |
|
|
Idaho Falls |
2.45 ± 0.49 |
50 |
100 |
|
|
Minidoka |
3.12 ± 0.55 |
50 |
100 |
|
|
Monteview |
3.31 ± 0.56 |
50 |
100 |
|
|
Moreland |
5.07 ± 0.61 |
50 |
100 |
|
|
Mud Lake |
3.83 ± 0.55 |
50 |
100 |
|
|
Roberts |
2.73 ± 0.54 |
50 |
100 |
|
|
Shoshone |
2.51 ± 0.53 |
50 |
100 |
|
|
Taber |
3.34 ± 0.53 |
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. One of samples had measurable gross alpha activity greater than 3s. None of the samples had measurable tritium activity (all results were less than 3s).
Five of six surface water samples were
greater than their associated 3s values for gross beta activity (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 gross beta results greater than (>) 3s.
|
|
|
Limits for Comparisona |
|
|
Location |
Result ± 1s |
SDWA |
DOE DCG |
|
Bliss |
4.80 ± 0.53 |
50 |
100 |
|
Buhl |
3.95 ± 0.53 |
50 |
100 |
|
EFS |
8.82 ± 0.57 |
50 |
100 |
|
Hagerman |
2.12 ± 0.48 |
50 |
100 |
|
Idaho Falls |
1.64 ± 0.52 |
50 |
100 |
|
Twin Falls |
6.89 ± 0.60 |
50 |
100 |
|
Twin Falls duplicate |
6.14 ± 0.60 |
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 and gross beta results can be found in Appendix C, Table C-7.