Roxboro BTV GW Response to comments_20170816

TECHNICAL MEMORANDUM
Date: August 16, 2017 File: 1026.107
To: Kimberlee Witt
Cc: Kathy Webb
From: Craig Eady (1��
Subject: Response to Comments -Roxboro Background Groundwater Datasets
(Comments provided via electronic mail by NCDEQ (Eric Rice) on August
10, 2017)
Roxboro Steam Electric Plant (Semora, NCS
Samples for BG -01 (transition zone dataset) collected on 07/12/2016 and 09/08/2016 are less
than the minimum 60 (sixty) days between sample events per the guidance document.
Indicate which event will be utilized for the dataset.
RESPONSE: Sample results for 7/1212016 were included in statistical
determinations. Results for 910812016 were identified as autocorrelated and not
included in statistical determinations. Corrections have been made to Table 1
indicating sample results for 9108/2016 as autocorrelated.
2. Page 3 of the technical memorandum indicates that a revised background dataset for
bedrock that accounts for the removal of MW-13BR, MW-16BR and MW-17BR and updated
outliers is presented in Table 2. Table 2 (the revised bedrock background dataset) was not
located in the August 4, 2017 submittal document. Please submit the revised dataset and include
a copy of the dataset in excel format.
RESPONSE: The specified reference to Table 2 on Page 3 of the memorandum was in
error. The text has been revised to indicate "Table 1".
3. Well 13G -01D was not a monitoring well included in the previously reviewed background
well set for the transition zone. Sample BG -01D collected on 01/27/2017 is present in the
dataset and so appears to have been utilized in the calculation of the BTVs. If this well
sample was used in the calculation of BTVs please provide a justification for the inclusion of
this sample event from well BG -01D in the dataset. Also, be aware the well was not listed in
the footnote for transition zone background wells utilized in Table 2.
P:\Duke Energy Progress. 1026\Statistics—CAMA\Background Determinations for NCDEQ July 72017\BTV TECH
MEMO\ Roxboro\ Groundwater\ Roxboro Tech Memo Response to DEQ RRO Comments BG GW Datasets 15Aug2017.docx

Response to Comments — Roxboro and Mayo Background Groundwater Datasets August 14, 2017
Mayo Steam Electric Plant and Roxboro Steam Electric Plant Page 2 of 2
RESPONSE: Results from BG -01D should not have been included in Table 1 and have
been removed. Initial statistical determinations did not include BG -01D data.
4. For radionuclides the dataset list analytical results for the requested analytes by species
(Radium 226, 228 and Uranium 233, 234, 236, 238) per the guidance document. However in
Table 2 "Groundwater Threshold Values" the Background Threshold Values (BTVs) are
reported as Radium (Total) and Uranium (Total). Please explain why radionuclides were
reported as totals and the method/s used to calculate the values.
RESPONSE: NCDEQ, including representatives from the Central Office and Raleigh
Regional Office, met with Duke Energy and SynTerra on October 7, 2015 in Raleigh, NC
to discuss NCDEQ comments pertaining to the CSA report (SynTerra, September 2015).
Review comments were presented in three categories: general comments applicable to
CSA reports regardless of site; site-specific comments applicable to a specific site (in
this case, Roxboro Plant); and editorial or fact errors.
"NCDEQ General Comment No. 13 - Include analysis for total uranium, radium -226, and
radium -228 in background, below ash basin, immediate downgradient, and other
downgradient locations. Use Federal MCL for standard for Ra 226, Ra 228, and U."
Therefore, although analytical results are reported by the analytical laboratory as
individual species, for comparison with the Federal MCLS and for comparison to
background concentrations, total Uranium and combined Ra226 + Ra228 values are used.
5. If your actions to address item #'s 1-4 above result in the removal or addition of sampling
events or data from a particular dataset/s, it will be necessary to recalculate the background
threshold value/s and submit updated BTVs to the Department.
RESPONSE: BTVs have been recalculated, as necessary, in response to comments #1, #2,
and #3 and the new values are included as revised and updated Technical Memorandum
- Background Threshold Values for Groundwater (Roxboro Steam Electric Plant) which
is attached as a separate document.
P: \Duke Energy Progress. 1026\Statistics—CAMA\Background Determinations for NCDEQ July 7 2017\BTV TECH
MEMO\ Roxboro\ Groundwater\ Roxboro Tech Memo Response to DEQ RRO Comments BG GW Datasets 15Aug2017.docx