NCG030033_Tier II_20220425

NC Depaarne it cf
Environmental QuuJ;t
Received
APR 2 5 2022
Winston-.`--ilem
Regional Office
April 21,2022
DEQ Winston-Salem Regional Office
Attn: DEMLR Stormwater Program
450 West Hanes Mill Road
Suite 300
Winston-Salem,NC 27105
RE: Tier I1 Notification Letter
Isometrics,Inc. Plant 1
1266 North Scales Street, 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 1.Isometrics,Inc. is a covered
under COC number NCG030033 as a metal fabrication facility. The exceedance occurred for copper
(threshold of 0.01)at Outfall 002 for a second consecutive time.As specified by the general permit,a sample
was collected during a quarterly monitoring event and the laboratory analytical results are summarized below.
The exceedance occurred in Outfall 002, but both sets of data are shown for a comparison of levels.
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
2/3/20221 001 1 58.8 7.8 1 0.00603 J 0.00509 0.0069 <11.7
2/3/20221 002 1 25.1 8.2 0.011 0.0049 J 0.0401 J <11.7 1.78 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 faulty absorbent
socks around the storm drains located within the drainage areas for Outfall 002. Overall cleanliness is
always noted and suggested during quarterly inspection reports but replacing the absorbent socks and
properly maintaining them should reduce their copper levels. Outside sources of run on that contains
copper is 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 replacing the absorbent socks should have an impact in reducing the amount
of copper in Outfall 002. 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.
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]