NC0080853_Report_20210309

AECOM
March 8, 2021
AECOM
1600 Perimeter Park Drive, Suite 400
Morrisville, North Carolina 27560
NCDEQ / Division of Water Resources
NPDES Permitting
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
919-461-1100 phone
919-461-1415 fax
Subject: Corrective Action Plan Update
Salem Business Park Remediation Site #NC0080853
Nokia of America Corporation
3370 Lexington Road, Winston-Salem, Forsyth County, North Carolina
Dear Mr. Coco:
On behalf of Nokia of America Corporation (Nokia), AECOM Technical Services of North Carolina
Inc. (AECOM) is submitting the following Corrective Action Plan (CAP) Update to fulfill the
requirements of Condition A.(2.) of National Pollutant Discharge Elimination System (NPDES)
Permit #NC0080853 for the groundwater treatment system located at the former Nokia facility,
now known as the Salem Business Park Remediation Site, in Winston-Salem, Forsyth County,
North Carolina.
Background
A groundwater treatment system operates at the Site to remediate groundwater impacted with
volatile organic compounds (VOCs). The primary treatment unit is a shallow -tray air stripper. As part
of the NPDES permit monitoring requirements, effluent samples are collected from a flume (FE-151)
located approximately 100 feet downstream of the air stripper. Between 2015 and 2018, the
tetrachloroethene (PCE) concentration in effluent samples collected from flume FE-151 ranged from
<0.5 micrograms per liter (pg/L) to 5.6 pg/L (Figure 1), with an average concentration of
approximately 2.5 pg/L ± 1.8 pg/L. These concentrations have been consistently below the
historical permit limit of 17 pg/L.
On August 29, 2018, Nokia received notification from the North Carolina Department of
Environmental Quality (NCDEQ) Division of Water Resources (DWR) that the facility would
receive a new NPDES permit that would include a concentration limit of 6.1 pg/L for PCE at the
permitted effluent sample point (FE-151). While the concentrations of PCE at the permitted
effluent sample point have not historically exceeded the new limit, the average factor of safety will
be reduced from nearly ten -fold to approximately three -fold. Based on the substantial change in
permit -required treatment, Nokia requested a compliance schedule for meeting the new discharge
concentration limit. The compliance schedule was included as Condition A.(2.) of the NPDES
permit that became effective on February 1, 2019. The new PCE discharge limit also became
effective on February 1, 2019, along with a requirement to increase the frequency of PCE
sampling from FE-151 from quarterly to monthly. The compliance schedule provides an additional
two years (February 2021) for Nokia to achieve compliance with the new PCE limit. AECOM
submitted a CAP on behalf of Nokia to NCDEQ DWR on August 1, 2019, outlining proactive
corrective action activities implemented prior to the CAP submittal, along with proposed additional
corrective actions to ensure permit compliance by February 2021 (AECOM, 2019).

AECOM 2
Completed Corrective Action Activities
In May 2019, Nokia proactively began corrective action activities to improve air stripper
performance and ensure consistent compliance with the new PCE discharge limit. Between April
2019 and June 2019, AECOM conducted multiple tests and compliance activities, including:
• Instrumentation upgrades for improved data collection;
• Air stripper air -to -water flow ratio optimization; and
• Increased sample QA/QC.
Activities completed between April 2019 and June 2019 are detailed in the CAP submitted on
August 1, 2019 (AECOM, 2019). Additional corrective actions were conducted between July 2019
and January 2020 and detailed in the CAP Update submitted on January 20, 2020 (AECOM,
2020). These actions included:
• Continued evaluation of sample QA/QC;
• Additional air stripper air -to -water flow ratio testing (all extraction wells operating);
• Treatment testing with artificially high influent concentrations (only extraction wells EW-16
and EW-17 operating); and
• Air stripper air -to -water ratio testing with artificially high influent concentrations (only
extraction wells EW-16 and EW-17 operating).
Conclusions
The primary conclusion from the testing conducted between May 2019 and January 2020 is that a
relationship among the air stripper operational parameters has not been identified that would
further optimize PCE removal. All samples collected during normal system operation (all extraction
wells operating), at various air -to water flow ratios were consistently in compliance with the
NPDES permit limit, and only inducing an artificially high influent concentration (simulated by only
operating extraction wells with PCE concentrations greater than 1,000 tag/L) could result in
inadequate treatment and result in a permit exceedance. No additional corrective actions occurred
between January 2020 and February 2021. Despite the lack of an apparent optimization model, all
samples collected from FE-151 during the compliance schedule between February 2019 and
February 2021 have been in compliance with the new PCE limit of 6.1 tag/L (Figure 1).
Results from the corrective action period indicate the groundwater treatment system is capable of
consistently reducing PCE concentrations below the new limit and achieve permit compliance.
Nokia will continue to conduct permit -required sampling and monitor the air stripper performance
to ensure effluent PCE concentrations remain below the permitted limit.
If you have any questions or require additional information, please contact Erin Stewart at
919-461-1323.
Sincerely,
AECOM
John Moran, E.I.
Staff Engineer
ChristoSher Brownfield, P.E. Erin Stewart, P.G.
Project Engineer
cc: NCDEQ / Division of Water Resources - WSRO
Project Manager

AECOM 3
References
AECOM, 2019. Corrective Action Plan, Salem Business Park Remediation Site #NC0080853.
Former North Carolina Works, Lexington Road Plant, Winston-Salem, NC. August 2019.
AECOM, 2020. Corrective Action Plan Update, Salem Business Park Remediation Site
#NC0080853. Former North Carolina Works, Lexington Road Plant, Winston-Salem, NC.
January 2020.

PCE Concentration (ug/L)
6
5
1
0
Figure 1
Outfall (FE-151) PCE Concentrations
J)
12/1/2014 12/1/2015 12/1/2016 12/1/2017
12/1/2018
1
1
I
1
1
1
i
12/1/2020