NCG030486_AO Smith - Tier III Response Letter_20231206

A.O.Smith Water Systems
CoSmith hart Raleigh Street
Charlotte,NC 28213
Innovation has a name. [phone]
December 06, 2023,
Mr.Jerry Eplin, PE
Assistant Regional Engineer
North Carolina Department of Environmental Quality
Division of Energy, Mineral, and Land Resources (Mooresville Regional Office)
610 E. Center Ave. Suite 301
Mooresville, NC 28115
Re: Tier Three Action Plan for Zinc and Copper Benchmark Exceedances
A.O.Smith Water Systems(4302 Raleigh Street,Charlotte,NC 28213)
Stormwater Certificate of Coverage NCG030486
Dear Mr. Eplin:
A.O. Smith Water Systems ("A.O. Smith") owns and operates the hot water system manufacturing facility("The
Facility") located at 4302 Raleigh Street, Charlotte, NC 28213.A.O. Smith is authorized to discharge stormwater
associated with industrial activities via their Certificate of Coverage#NCG030486("The Permit"). The Permit is
effective July 01, 2021.
The Facility has two Outfalls that are sampled (Outfalls 002 and 003). Four exceedances above the benchmark
values within a single permit term were noted for Zinc at Outfall 002 and Copper at Outfall 002,triggering the
Tier Three response status per Section E-7 of The Permit. Figure 1, below,shows the outfall placement and
general facility layout.
Figure 1: Layout and Outfall Placement at Facility
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A.O.Smith Water Systems
• Smith 4302 Raleigh Street
Charlotte,NC 28213
Innovation has a name. [phone]
This letter shall serve as The Facility's Action Plan and a summary of the Tier Three Response.
Element 1: Documentation of Benchmark Exceedances
Four benchmark exceedances were found for Zinc at Outfall 002,and Copper at Outfall 002 within the permit
term to date.The exceedances have been documented in The Facility SWPPP in accordance with Section E-5(b)
in The Permit (NCG030000).The exceedances have been summarized in Table 1 below for reference.
Table 1:Summary of Exceedances
Zinc(Outfall 002) Copper(Outfall 002)
Benchmark=0.126 mg/1 Benchmark=0.010 mg/1
Sample Date Sample Value Sample Date Sample Value
February 2022 0.455ug/I September2021 0.0192mg/I
October 2022 0.457 ug/I February 2022 0.0225 mg/I
January 2023 0.571 ug/I October 2022 0.0277 mg/I
August 2023 202 ug/1 August 2023 0.0210 mg/I
Element 2: NCDEQ Notification
Following receipt of the laboratory results indicating benchmark exceedances,The Facility provided the
Stormwater Discharge Outfall Monitoring Report to the regional NCDEQ Office in Mooresville, NC and notifying
the office of the quarter's exceedance dates, pollutants,and values.
Element 3:Stormwater Management Inspection and Identification of Feasible Actions
Prior to the Stormwater sampling event on August 03,2023,The Facility,accompanied by their stormwater
consultants Ms. Kimberly Seddon, PE and Mr. Mark Van Auken, PE at Arcadis, Inc., had conducted their Annual
Inspection on 1/09/2023.The inspection identified a priority list of corrective action items. Subsequent periodic
inspections have occurred and been documented on a monthly basis.
Historically,the facility had filter mats installed at Outfalls 002 and 003 to assist with general pollutant
reduction.Although it was noted during the January inspection that the mats had been removed by previous
staff,filters were replaced in Q2 2023. More samples are needed post-filter in order to determine their overall
effectiveness.
Although several corrective action items were identified early in 2023 for the overall reduction of pollutant
discharge from The Facility, a more robust Action Plan is needed to identify the source of the pollutants
upstream of the inlet filters.A facility inspection occurred on August 25,2023 to assess drainage areas and
potential pollutant sources.The plan Is further detailed below. Please see the Stormwater Investigation Source
Sampling Plan enclosed under separate cover with this letter. Please note that the plan is subject to variability
'depending on in-field conditions or new information received by the project team.The team may opt to revise,
add, or remove sample locations as reasonably required to achieve the plan objective.

A.O.Smith Water Systems
CoSmulth Charlotte,
Raleigh Street
Charlotte,NC 28213
Innovation has a name. [phone]
The staff at A.O. Smith has made a strong commitment to compliance and are eager to bring The Facility into
conformance with The Permit requirements.
If you have any questions related to this notification, please contact me at [phone] x202 or
([e-mail].
d Regards,
c
aura Viers
JAA*nO Smith, Charlotte Water Systems
Plant Manager