4101_Guilford_CityHighPoint_Riverdale_MSWLF_Seaboard_Comments_FID1821452_20231117

SEABOARD GROUP II AND THE CITY OF HIGH POINT
November 17, 2023
Eric B. Aufderhaar, P.G., Environmental Program Consultant
North Carolina Department of Environmental Quality
Division of Waste Management
1646 Mail Service Center
Raleigh, North Carolina 27699-1646
Re: Response to Comments on TM-11 Fourth Quarter and Final Summary Report
Former Seaboard Chemical and Riverdale Drive Landfill Site
Jamestown, Guilford County, North Carolina
EPA ID No. NCD071574164/ Solid Waste Permit No. 4101-MSWLF-1979
Dear Mr. Aufderhaar:
In response to NC DEQ email comments received on the TM -II Fourth Quarter and Final
Summary Report dated November 3, 2023, the Seaboard Group/City of High Point (Parties)
provide the following response:
Comment: On Figure 2 for the Pond 3 area spikes in total VOC concentrations are shown
for samples from OW-SF1 for Q1 and Q3. In the SIS Basin part of the report, Section
3.2, you indicated that the spikes in concentration were attributed to inefficiencies in
operation of the RW-SIS7 pump in that the pump and discharge line were susceptible to
iron fouling which limited the extraction rate. Have the pump and discharge line in OW -
SF 1 also had iron fouling problems?
Response: We do have iron fouling at OW -SF I, the pump and discharge line in this
extraction well have required cleaning. We have recently replaced the pump and
discharge line in this well with a higher capacity pump and discharge line with a larger
diameter to help with fouling and improve the extraction rate. However, the iron fouling
at the Pond 3 Area is minor compared to the SIS Basin Area, likely due to the presence of
inorganics in the groundwater at the SIS Basin Area.
The flow rate in all of the extraction wells is monitored weekly, if a drop-off is noted in
the pumping rate the cause is investigated and addressed.
2. Comment: In Section 3.2 and in Section 5 (Conclusions and Recommendations), you
indicated that the expanded groundwater capture zone at the SIS basin appears to have
improved Surface Water Quality at the SW-4 monitoring location and the graph for 1,4-
dioxane is shown on Page 7. Did the laboratory test samples of SW-4 for VOCs during
one or more of the four quarters, and if yes, did VOC concentrations trend downward?

Response: A comparison of the historical total VOCs and 1,4-dioxane in the surface
water samples in the SIS drainage basin during the Extraction System Evaluation is
provided below:
Total VOCs ug/I
300
250
200
OD 150
3
100
50
0
W of y0
SW-3 SW-4 SW-5
1,4-Dioxane ug/I
80
60
own 40
3
20
0
SW-3 SW-4 SW-5
As shown on the graphs, total VOCs exhibited decreasing concentration trends similar to
decreasing trends observed for 1,4-dioxane.
3. Comment: The surface water locations for SW-3 and SW-5 are not shown on the
Figures. Please revise one of the first three figures to show their locations. The SW-4
location is shown on Figure 4.
Response: The locations of SW-4 and SW-5 have been added to Figure 1 - Pond 3
Potentiometric Map (attached).

4. Comment: We concur with the recommended quarterly program indicated on page 12.
Response: We plan to begin the quarterly monitoring effective the 4th quarter of 2023.
Please contact us if there are any questions or comments regarding this correspondence.
Respectfully,
Seaboard Group II and City of High Point
Mr. Gary D. Babb, P.G.
Babb & Associates, P.A.
Attachment
cc: Jackie Drummond - NCDEQ Division of Solid Waste

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ih
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`t 704.56
" W-18 713.89
Processing Area ;. W-30 726.26
MW-7A D i 5 rY
_ =*MW-7B 694.26
*� *F 'i �•�' ' — - - - y W-SF1 687.63
J : ` Pre -pumping water levels PW-41 694.87
* 684.21
r shown in yellow RW-SF1 681.59
AC
4-*" • f -t bservation Well
y.•� - ' ';, xtraction Well
February 2019 :Lira -,' — -; �_ { �. ontour Interval = 5'
Photographyti

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ih
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Cn t
rteC�\ttent Stye od` �. - � •� . .,,. ;� r _ .. - _, :,
kern\
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1 •. 1
goo
1
;.. ♦ , 11 , '♦ ,I aft,
41
`��,,���•'•o
100
40#,,, ; ••W Elevations
+_ r, R frFr ' `� �, "� W-5 714.32
W-8A 695.88
���-• ,�.�� � W-12A Dry
' Former Seaboard W-30 W-14
`t 704.56
" W-18 713.89
Processing Area ;. W-30 726.26
MW-7A D i 5 rY
_ =*MW-7B 694.26
*� *F 'i �•�' ' — - - - y W-SF1 687.63
J : ` Pre -pumping water levels PW-41 694.87
* 684.21
r shown in yellow RW-SF1 681.59
AC
4-*" • f -t bservation Well
y.•� - ' ';, xtraction Well
February 2019 :Lira -,' — -; �_ { �. ontour Interval = 5'
Photographyti