NCS000158_Tier Relief Approval_20210322

ROY COOPER
Governor
DIONNE DELLI-GATTI
Secretary
BRIAN WRENN
Director
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NORTH CAROLINA
Environmental Quality
March 22, 2021
Cascade -Die Casting Group, Inc. - Atlantic Division
ATTN: Ken Savage, VP of Human Resources
1800 Albertson Road
High Point, NC 27261
RE: NPDES Stormwater Permit: Request for Regulatory Relief
Cascade Die Casting Group, Inc. - Atlantic Division
Individual Permit No: NCS000158
Guilford County
Dear. Mr. Savage,
A Request for Regulatory Relief for the subject facility was submitted by Cascade Die Casting
Group, Inc. - Atlantic Division to the staff of the Division of Energy, Mineral & Land Resources
on January 4, 2021. The request and November 3, 2020 inspection conducted by this office show
that the facility has been following the tiered response actions for aluminum at Outfall #2 and that
the sampling limitations associated with the outfall have likely contributed to the concentration of
aluminum in the samples.
Tier Three response actions were initiated following four exceedances of aluminum benchmarks
for Outfall #2. Please keep in mind that benchmark exceedances are NOT limit violations or
violations of permit conditions; however, you are obligated to follow the tiered response actions
outlined in your permit. The relief request shows that the subject facility has been following the
tiered response actions and therefore is in compliance with the NCG030000 permit.
Based on your lack of apparent exceedances associated with Outfall 41, the drainage area of which
covers the majority of the industrial activity on the site, and the apparent sampling issues associated
with Outfall #2, we are granting regulatory tier relief from the Tier Three response requirements
of the permit. Upon receipt of this letter, Cascade Die Casting Group, Inc. — Atlantic Division may
resume the permit -specified semiannual analytical monitoring. A subsequent benchmark
exceedance of these or any other parameter listed in your permit will trigger tiered response
actions as described in the general permit. To avoid this, it is recommended that you update
your Stormwater Pollution Prevention Plan (SWPPP) to address sampling at Outfall #2 and/or seek
representative outfall status for Outfall # 1.
You must notify this office in writing, within five business days, if you become aware of any
significant source of aluminum at your facility that has the potential to be exposed to stormwater.
North Carolina Department of Environmental Quality I Division of Energy, Mineral and Land Resources
D. E Winston-Salem Regional Office 1 450 Hanes Mill Road, Suite 3001 Winston-Salem, North Carolina 27103

Cascade Die Casting Group. Inc. - Atlantic Division
March 221, 2021
Page 2 of 2
The relief granted in this letter is contingent upon the current industrial practices at Cascade Die
Casting Group, Inc - Atlantic Division. If industrial practices change and aluminum does become
a significant stormwater exposure risk, then this office reserves the right to withdraw this decision
and reinstate the Tier Three status for Outfall #2, which includes monitoring and reporting on a
monthly basis.
Please retain and append this letter to your Stormwater Pollution Prevention Plan (SWPPP) or
permit. If you have any questions or comments concerning this letter, please contact Levi Hiatt or
me at [phone].
Sincerely,
lx
Tamera EP lin PE
Regional Engtjaieer
Land Quality Section
cc: Bethany Georgoulias, NC DEQ Stormwater Program