NCG030034_Tier II_20220425

00 17- 1
April 21, 2022 NC DepaFtment-f
EnvironRe ental
ceivedQuai�ty
DEQ Winston-Salem Regional Office APR 2 5 2G,^,,2
Attn: DEMLR Stormwater Program Winston
450 West Hanes Mill Road �'w ism
Regional O7ee
Suite 300
Winston-Salem,NC 27105
RE: Tier II Notification Letter
Isometrics,Inc. Plant 2
7537 Highway 87 North, Reidsville,
North Carolina,27320
EI Project No.: ENM0220011.00
Dear,
EI is writing this letter to notify the DEQ Winston-Salem Regional Office of the Tier II response for a second
benchmark exceedance at the above-mentioned facility,Isometrics,Inc. Plant 2. Isometrics,Inc. is a covered
under COC number NCG030034 as a metal fabrication facility. The exceedance occurred for copper
(threshold of 0.01) at Outfall 002, and zinc (threshold of 0.126) at Outfall 002 and 004. As specified by the
general permit, samples were collected during a quarterly monitoring event and the laboratory analytical
results are summarized below.
Sample Outfall Total Suspended pH Copper,total Lead,total Zinc,total Chemical Oxygen Non-Polar Oil&
Date Number Solids(mg/L) recoverable(mg/L) recoverable(mg/L) recoverable(mg/L) Demand(mg/L) Grease(mg/L)
Benchmark - 100 6.0-9.0 0.01 0.075 0.126 120 15
2/23/2022 002 52.4 8.2 0.0114 0.00618 1 1.05 32.9 0.89 J
2/23/2022 004 25.1 7.9 0.00763 0.0029 J 1.04 <11.7 1.0 J
Inspection Observations
As specified by the general permit, an inspection was conducted by Parker Alvis, EI, who is a certified
SCM Inspector. This visual inspection of the BMPs and stormwater systems revealed opportunities to
improve housekeeping and storage,well as uses for heavy metal absorbent socks in the drainage areas and
stormwater systems. Overall cleanliness is always noted and suggested during quarterly inspection reports
but installing absorbent socks and properly maintaining them should have an impact on reducing the levels
of copper and zinc at this facility. Outside sources of run on that contains copper and zinc are not ruled
out from potential causes for an exceedance.
2101 Gateway Centre Boulevard Suite 200 Morrisville,NC 27560 Tel:[phone] Fax:[phone]

Recommendations
Good housekeeping is always encouraged during site visits and inspections. The SWPPP requires regular
housekeeping and preventative maintenance to reduce the risk of pollution in stormwater runoff. Good
housing keeping along with installing heavy metal absorbent socks should have an impact in reducing the
amount of copper in both outfalls. Proper installation and maintenance of a heavy metal absorbent sock is
recommended at the storm drain inlets, as well as incorporating them into the SCMs to remove pollutants
before discharge. Removal of excess scraps or exposed metals is also recommended as an ongoing effort.
Conclusions
Within two months of receiving sampling results, the above-mentioned recommendations shall be
implemented at this facility and monthly monitoring will begin. Monthly monitoring reports will be
completed and submitted to the DEQ Winston-Salem Regional Office until three consecutive sampling
events occur with no exceedance for all parameters.No flow DMRs will be submitted for months without
a representative event or an event that occurs outside of normal operating hours.
Regards,
The El Group, Inc.
Parker Alvis Josh Dunbar,PE
Environmental Scientist II Vice President,Engineering&Environmental
2101 Gateway Centre Boulevard Suite 200 Morrisville,NC 27560 Tel:[phone] Fax:[phone]