ML20261H528

E-Mail Dated July 29, 2020, from John Hickman, NRC, to William Barley, Pg&E, Forwarding a Request for Additional Information on the Humboldt Bay Caisson Final Status Survey Report

ML20261H528
Person / Time
Site:	Humboldt Bay
Issue date:	07/29/2020
From:	John Hickman Division of Decommissioning, Uranium Recovery and Waste Programs
To:	Barley W Pacific Gas & Electric Co
Hickman J
References
Download: ML20261H528 (2)

Text

From: Hickman, John To: Barley, William

Subject:

FSSR items Date: Wednesday, July 29, 2020 10:22:00 AM

Bill, I really dont want to make our reviews of your FSSRs difficult for either of us, but we need to have reports we can use to demonstrate compliance with the criteria we review against.

Regarding the Caisson FSSR, your responses to our RAIs were generally fine but we still have an issue with residual activity in the groundwater. Our issue is that the LTP states:

5.4.3.7 Groundwater Assessments of any residual activity in groundwater at HBPP will be via groundwater monitoring wells. The monitoring wells installed at the site will monitor groundwater at both deep and shallow depths. Section 2.2.2 describes the groundwater monitoring conducted.

The data collected from the monitoring wells will be used to ensure that the concentration of well water available, based upon the well supply requirements assumed in Section 6 for the resident farmer (i.e. resident farmer's well), is below the U.S. Environmental Protection Agency (EPA) maximum contaminant levels (MCLs) (e.g., 20,000 pCi/I for H-3). This will ensure that the dose contribution from groundwater is a small fraction of the limit in 10 CFR 20.1402.

We understand that there was no specific monitoring of the groundwater in the caisson after backfilling, but is there any way you can provide some estimate of the concentrations of contaminants that remained in the groundwater?

Regarding the Trailer City FSSR, the issues are similar to the Caisson survey:

1. No discussion is present regarding residual radioactivity in the groundwater media, please provide residual radioactivity concentrations.

2. Not all radionuclides of concern in Table 6.4 of the LTP are addressed in the surveys. Usually, only Cs-137 is addressed directly while many ROCs are deselected and otherwise accounted for. This leaves 6-7 ROCs not accounted for in the surveys. Please provide data for these ROCs.

3. Please clarify why the deselection listing of ROCs is different in NOL09-08 vs the other survey units.

4. Provide the depth of backfill in each of the survey units. Also, clarify whether, in each case, the last few feet of backfill originated from off-site after the surveys were performed.

5. If the backfill exceeded a depth of 1 meter, provide information regarding the non-surface volume of backfill and how it was shown to meet the release criteria for all ROCs.

Please let me know if you want to discuss any of these items with the reviewers. Also, for the Trailer City issues, do you want me to send a formal RAI or do you just want to supplement to address the items.

Thanks, John