Second 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 second 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 second quarter of 2005 produced sufficient precipitation to yield 13 samples – two from Idaho Falls, three from CFA, and eight from the EFS.
Tritium was measured above the 3s value in eight of the samples collected during the second 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 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 x 106 pCi/L (-7.4 to 2.7 x 104 Bq/L) (EPA 2003). Tritium measured in second quarter ESER samples were within this range, with a maximum of 2.02 ± 0.32 x 103 pCi/L (7.47 ± 1.17 Bq/L) at CFA in May. Data for all second quarter 2005 precipitation samples collected by the ESER Program are listed in Table C-6 (Appendix C).
Thirteen 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, and two others for
tritium. 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 Fort Hall had a gross alpha concentration
of 7.84 ± 1.45 pCi/L which is below the EPA and DOE limits for tritium in
drinking water of 15 pCi/L (0.56 Bq/L) and 30 pCi/L (1.11 Bq/L), respectively.
Tritium concentrations ranged from 79 ± 25 pCi/L (2.91 ± 0.93 Bq/L) at Idaho
Falls to 170 ± 27 pCi/L (6.30 ± 1.01 Bq/L) at Carey. Both values are well below
the EPA limit of 20,000 pCi/L (740 Bq/L) and the DOE DCG of 2.0 x 106
pCi/L (74,074 Bq/L).
Of the fourteen drinking water samples collected, eight 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 Shoshone 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 2. Drinking water results greater than (>) 3s.
|
|
Sample Resultsa |
Limits for Comparisona |
||
|
Location |
Result ± 1s |
SDWAb |
DOE DCGc |
|
|
Gross Alpha |
||||
|
Fort Hall |
7.84 ± 1.45 |
8 |
30 |
|
|
Tritium |
||||
|
Carey |
170 ± 27 |
20,000 |
2 x 106 |
|
|
Idaho Falls |
79 ± 25 |
20,000 |
2 x 106 |
|
|
Gross Beta |
||||
|
Aberdeen |
4.89 ± 1.11 |
50 |
100 |
|
|
Carey |
3.18 ± 0.84 |
50 |
100 |
|
|
Fort Hall |
13.00 ± 1.16 |
50 |
100 |
|
|
Idaho Falls |
2.84 ± 0.88 |
50 |
100 |
|
|
Minidoka |
2.63 ± 0.86 |
50 |
100 |
|
|
Monteview |
4.68 ± 0.96 |
50 |
100 |
|
|
Shoshone |
13.50 ± 1.15 |
50 |
100 |
|
|
Taber |
3.53 ± 0.94 |
50 |
100 |
|
|
a. All values shown are in picocuries per liter (pCi/L). b. SDWA = Safe Drinking Water Act. c. DCG – Derived Concentration Guide. |
||||
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 tritium or gross alpha activity (all results were less than 3s).
Five of 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 gross beta results greater than (>) 3s.
|
|
|
Limits for Comparisona |
|
|
Location |
Result ± 1s |
SDWA |
DOE DCG |
|
Bliss |
3.70 ± 0.92 |
50 |
100 |
|
Duplicate |
5.54 ± 0.97 |
50 |
100 |
|
Buhl |
3.38 ± 0.94 |
50 |
100 |
|
Hagerman |
3.22 ± 0.90 |
50 |
100 |
|
Twin Falls |
6.23 ± 1.05 |
50 |
100 |
|
a. All values shown are in picocuries per liter (pCi/L). |
|||
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.