ML24052A360
| ML24052A360 | |
| Person / Time | |
|---|---|
| Site: | 07000925 |
| Issue date: | 02/21/2024 |
| From: | Lux J Environmental Properties Management |
| To: | James Smith Office of Nuclear Material Safety and Safeguards, Document Control Desk |
| References | |
| Download: ML24052A360 (1) | |
Text
February 21, 2024
Mr. James Smith U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738
Re: Docket No. 07000925; License No. SNM-928 Cimarron Environmental Response Trust Response to NRC Concerns Regarding Potential Seepage in Burial Area #1
Dear Recipients:
In a letter dated October 2, 2023, the U. S. Nuclear Regulatory Commission (NRC) issued requests for additional information (RAIs) resulting from the NRCs technical review of Facility Decommissioning Plan - Rev 3 (the D-Plan, accession number ML22287A079). Solely as Trustee for the Cimarron Environmental Response Trust (CERT), Environmental Properties Management LLC (EPM) submitted responses to those RAIs in a letter dated December 8, 2023.
Subsequent communications with the NRC identif ied a need for clarification or additional information (addressed herein as a concern) related to those responses. The NRC documented their concerns in a February 12, 2024, email (accession number ML24043A156). This letter provides a summary of the NRCs concern and information that is believed to address it.
NRC Concern: EPMs RAI response indicated that Transition Zone monitoring wells 02W20 and 02W26 will be included in the in-process mon itoring wells for evaluation of uranium plume migration within groundwater and possibly to the vicinity of the ephemeral stream east of the site. These wells are located far enough to the northeast Injection Trench GWI-BA1-01 that they are not well situated to evaluate potential seepage east of the injection trench. NRC staff is concerned about potential seepage on the eastern slope or in the stream channel resulting from the injection.
EPM Response: During discussions about NRCs concern, EPM agreed that 02W20 and 02W26 are not optimally located to evaluate the impact of the mounding created by injection of treated groundwater. It is EPMs understanding of the NRCs concern is that significant mounding may be created by the injection of treated groundwater. Significant mounding of injected water could result in seepage to the ground surface or discharge into a drainage channel located approximately 150 feet east of the injection trench.
In this response, EPM attempts to summari ze conclusions that EPM reached following discussions with the NRC.
Page 1 February 21, 2024 Response to NRC Concern Regarding Potential Seepage in Burial Area #1 Safety-Related Impact from Injection of Treated Water presents an excerpt from Figure GWRM-3-2, attached to EPMs December 8, 2023, response to RAIs (accession number ML23346A262) related to the safety evaluation review of D-Plan. Attachment 1 shows the locations of monitor wells located in the southeastern portion of Burial Area #1 (BA1). Injection Trench GWI-BA1-01 is shown as a green dashed line.
The area of concern is east of the injection tren ch, where blue dashed arrows indicate potential flow paths for groundwater (and treated water) during remediation activities. The locations of monitor wells north and east of the eastern end of GWI-BA1-01 are shown, along with the groundwater elevation in each monitor well.
As was discussed in the response to RAIs related to the Safety Evaluation Report, the concentrations of uranium in groundwater in the southern portion of BA1 have been declining as the uranium plume migrates to the north. Uran ium concentrations shown in red font in confirm that uranium concentrations in groundwater in the area now not only comply with the NRC Criterion of 180 picocuries per liter (pCi/L) but are significantly below the State Criterion of 30 micrograms per liter (µg/L). presents tabulated uranium concentrations for the last five groundwater sampling events for each monitor well. If groundwater samples were collected from a well less than five times, all of the results for that location are tabulated.
The decline in uranium concentration is best shown in the groundwater data for Monitor Wells 02W26 and 1409. Groundwater samples from both wells have not yielded uranium concentrations above the State Criterion. Groundwater samples from neither Monitor Well 02W50 nor 02W52 have yielded a uranium concentration above 5 pCi/L since 2002.
Groundwater samples from Monitor Wells TR-07, TMW-20, and 02W20 have not yielded uranium concentrations above the State Criterion; however, each monitor well has only been sampled once (for TMW-20, over 20 years ago). In the southeastern portion of BA1, only TMW-25 has yielded a uranium concentration exceeding the NRC Criterion, and that was during a groundwater sampling event that occurred over 20 years ago, the only time the well was sampled.
Treated water containing uranium at concentrations below the State Criterion will be injected into GWI-BA1-01. Because the injected water that will be flushing groundwater to the east, and the existing groundwater will both comply with NRC and State criteria, the injection of treated water presents no adverse impact from a safety perspective.
The one groundwater sample yielding a uranium concentration exceeding the NRC Criterion in the area of interest was collected from TMW-25 over 20 years ago. Based on uranium groundwater concentration trends observed for other monitor wells in the area, the uranium
Page 2 February 21, 2024 Response to NRC Concern Regarding Potential Seepage in Burial Area #1 concentration in TMW-25 has likely declined well below the NRC Criterion since the sample was collected.
EPM proposes to add the collection of a groundwater sample from TMW-25 for analysis of mass concentration for U-235 and U-238 (by EPA Method 200.8) during the 2024 annual environmental monitoring sampling event.
Environmental Impact from Injection of Treated Water Injection Trench GWI-BA1-01 was constructed and tested during the 2017 pilot test. During the test, the injection of water into GWI-BA1-01 caused the groundwater elevation to rise as high as 14 to 15 feet above static groundwater elevations. Rather than repeat the word approximately multiple times, all of the following elevations and measurements should be understood to be approximate.
During the pilot test, the water elevation within Injection Trench GWI-BA1-01 was maintained near 953 feet above mean sea level (AMSL), with an average injection rate of 10 gallons per minute (gpm).
From 2017 through 2023, the elevation of groundwater in TR-07 (located at eastern end of GWI-BA1-01) averaged 941 feet AMSL. The ground surface elevation at this well location is 957.4 feet AMSL. Fifteen feet of groundwater mounding (resulting from treated water injection) would raise the groundwater elevation at the TR-07 location to 956 feet AMSL, only slightly below existing grade. The elevation of the top of the bank of the drainage channel located 150 feet to the east is 940 feet AMSL; therefore, during injection, the gradient between the injection trench GWI-BA1-01 and the drainage channel would be increased significantly. The injection of treated water into GWI-BA1-01 may result in either surface water seepage between the injection trench and the drainage channel, or continuous discharge of water to the currently-ephemeral stream.
EPM does not believe that either the creation of a surface water seep or the subsurface discharge of clean water to the drainage channel repres ents an adverse environmental impact; however, NRC concerns regarding seepage or discharge to the drainage channel are understandable.
An Environmental/RP Technician conducts a routine monthly radiological survey at the site.
This survey is typically conducted during the first week of each month. There is sufficient time within each day to conduct both the routine radiological survey and a visual inspection of the area east of GWI-BA1-01.
EPM proposes to generate a standard operating procedure (SOP) to conduct a routine, monthly visual inspection of the area of potential seepage. The technician would document in a field logbook: 1) the preceding weather conditions (i.e., rainfall for the previous weeks), 2) the relative elevation of water in the eastern pond, 3) whether surface water is flowing in the drainage channel, and 4) the locations (or absence) of any seepage at the ground surface or
Page 3 February 21, 2024 Response to NRC Concern Regarding Potential Seepage in Burial Area #1 water seeps into the drainage channel. The monthly inspections would produce baseline observations to which observations made during remediation system operations would be compared. During remediation operations, should seepage or discharge to the stream channel be identified, a path forward would be developed for further evaluation or other action.
Should the NRC or the DEQ desire additional clarification or information, EPM will be pleased to respond as soon as practical.
Sincerely,
Jeff Lux Project Manager
cc: (electronic copies only)
Stephanie Anderson and Linda Gersey, NRC Region IV Rachel Miller, Paul Davis, Keisha Cornelius, Pam Dizikes, David Cates, and Jon Reid, DEQ NRC Public Document Room vcpsubmittals@deq.ok.gov
Page 4 February 21, 2024 Response to NRC Concern Regarding Potential Seepage in Burial Area #1
ATTACHMENT 1 SOUTHEASTERN AREA OF BA1
February 21, 2024 Response to NRC Concern Regarding Potential Seepage in Burial Area #1
ATTACHMENT 2 URANIUM CONCENTRATION DATA ATTACHMENT 2 Prepared by: Jeff Lux-Date: 2/12/2024 Uranium Concentration Data Reviewed by: Jim Feild - Date: 2/16/2024
Location Date Analyte Result Total Uranium Uncertainty Unit Qual
Uranium-234 2.8 0.714 2002-08-26 Uranium-235 0.189 0.1645.0pci/L Uranium-238 2.03 0.583 Uranium-234 2.12 0.362 2004-09-08 Uranium-235 0.121 0.08973.5pci/L Uranium-238 1.26 0.279 02W50 Uranium 3.99 4.0 ug/L 2013-05-21 Uranium-233/234 2.38 0.9 Uranium-235/236 0.0997 0.28 U3.5pci/L Uranium-238 1.01 0.595 Uranium 3.7 3.7 ug/L 2015-03-25 Uranium-233/234 1.99 0.813 Uranium-235/236 -0.0191 0.165 U2.7pci/L Uranium-238 0.759 0.548 Uranium-234 2.24 0.674 2002-08-26 Uranium-235 0.16 U3.8pci/L Uranium-238 1.58 0.543 Uranium-234 1.13 0.272 2004-09-08 Uranium-235 0.148 0.09951.9pci/L Uranium-238 0.668 0.209 02W52 Uranium 2.06 2.1 ug/L 2013-05-21 Uranium-233/234 1.51 0.872 Uranium-235/236 0.0733 0.407 U2.0pci/L Uranium-238 0.456 0.503 Uranium 2.49 2.5 ug/L 2015-03-25 Uranium-233/234 1.37 0.642 Uranium-235/236 0.0556 0.209 U2.0pci/L Uranium-238 0.622 0.456 TR-07 2018-08-24 Uranium-235 0.264 0.013622.3ug/L Uranium-238 22 1.1 Uranium-234 4.84 0.529 TMW-20 2001-06-29 Uranium-235 0.309 0.07019.2pci/L Uranium-238 4.09 0.456
Page 1 of 2 ATTACHMENT 2 Prepared by: Jeff Lux-Date: 2/12/2024 Uranium Concentration Data Reviewed by: Jim Feild - Date: 2/16/2024
Location Date Analyte Result Total Uranium Uncertainty Unit Qual
2022-01-19 Uranium-235 0.01 0.00337 J1.4ug/L Uranium-238 1.36 0.0718 2022-04-20 Uranium-235 0.01 0.00335 U0.8ug/L Uranium-238 0.83 0.0471 02W20 2022-07-08 Uranium-235 0.01 0.00334 U0.4ug/L Uranium-238 0.355 0.0285 2022-10-20 Uranium-235 0.01 0.00334 U0.5ug/L Uranium-238 0.493 0.0333 2023-07-21 Uranium-235 0.01 0.00334 U0.6ug/L Uranium-238 0.551 0.0355 Uranium-234 8.24 1.6 2002-08-26 Uranium-235 0.187 U12.4pci/L Uranium-238 4.2 0.984 Uranium-234 1.36 0.36 2004-09-07 Uranium-235 0.107 U2.1pci/L Uranium-238 0.71 0.261 Uranium 7.1 7.1 ug/L 02W26 2013-05-21 Uranium-233/234 3.49 1.17 Uranium-235/236 0.153 0.421 U5.6pci/L Uranium-238 1.93 0.87 Uranium 2.26 2.3 ug/L 2015-03-25 Uranium-233/234 0.966 0.592 Uranium-235/236 0.0771 0.217 U1.4pci/L Uranium-238 0.385 0.371 2017-04-25 Uranium-235 0.0263 J2.8ug/L Uranium-238 2.74 2017-12-04 Uranium-235 0.517 0.026150.9ug/L 1409 Uranium-238 50.4 2.52 2018-08-24 Uranium-235 0.191 0.010118.5ug/L Uranium-238 18.3 0.913 Uranium-234 157 18.1 TMW-25 2001-06-29 Uranium-235 8.19 1.08254.0pci/L Uranium-238 88.8 10.3
Notes: Calculated results are shown in red bold font.
Mass concentration results are shown in blue font.
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