NC0026441_Study Plan_20230505

RECEt JED
MAY 0 6 2023
April 28,2023 NCDEQIDWRINPDES
TOWN of SILER CITY WWTP NPDES PERMT NC0026441 STUDY PLAN
1.0 INTRODUCTION
As a condition of the Siler City WWTP NC0026441 permit issued by the NC Department of Environmental Quality
(DEQ)Division of Water Resources(DWR),an annual instream biological integrity assessment was added based on
the current status of the facility.The September 28,2022,renewal permit[Section A.(4.}]states the following:
A.(4.)INSTREAM ASSESSMENT OF BIOLOGICAL INTEGRITY(Annual)
[1SA NCAC 02B.0200 et seq.]
a. By April 30,2023(180 days after the permit effective date),the Permittee shall submit a study plan to annually
assess biological integrity in the receiving water via benthic macroinvertebrate(benthos)sampling and analysis.
The study plan shall include methodologies consistent with DWR-approved assessment methodologies 1 and
propose an annual assessment schedule and sampling location(s).The study plan shall be submitted to the Division
at the address listed under(d.)of this section.Once DWR-NPDES approves the study plan, it shall be used for all
assessments unless a study plan modification is approved/recommended by the Division.Instream biological
integrity assessments shall be conducted by a laboratory or entity that is NC-certified for the procedure.
b. By November 1, 2023(one year from the permit effective date)and November 1 of every subsequent year until
permit expiration,the Permittee shall conduct an instream benthos assessment annually.
c.With each planned assessment,the Permittee shall provide the Division sufficient notice of sampling so that
Division personnel may attend and share samples collected.
d.The Permittee shall submit instream biological integrity assessment reports within 60 days of completion.All
reports shall include the owner's name,NPDES permit number and Permittee contact person, and shall be
submitted to:
(1) NCDEQ/Division of Water Resources
NPDES Permitting—Municipal Branch
1617 Mail Service Center
Raleigh,NC 27699-1617
(2) NCDEQ/Division of Water Resources
Raleigh Regional Office-WQRO
3800 Barrett Drive
Raleigh,NC 27604
e. If it is determined by the Division that the permitted discharge from the facility is not causing stream
degradation resulting in water quality standards violations,including narrative standards,the Permittee may
request that the instream assessments be terminated.
f.The addition of instream biological integrity assessment requirement does not preclude the Division from taking
any action necessary to resolve any ongoing compliance activity or effluent violations.
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In order to facilitate these requirements,Slier City proposes to conduct BMI monitoring at the four designated
monitoring locations;one each upstream and downstream of the discharge in Loves Creek and the Rocky River
(LCU, LCD, RRU, RRD),Table 1.
The methods proposed utilize DEQ standards to update existing baseline data for benthic macroinvertebrate and
allow for repeatable monitoring. Field crews will consist of personnel experienced in DEQ protocols with NCDEQ
certified laboratory conducting laboratory identification and analysis.
Table 1.BMI Sampling Stations
Station Description
ID
LCU Loves Creek Upstream Sampling Point
LCD Loves Creek Downstream Sampling Point
RRU Rocky River Upstream Sampling Point •
RRD Rocky River Downstream Sampling Point
2.0 FIELD DATA COLLECTION
2.1 Benthic Macroinvertebrate Community Sampling
Stations will be sampled utilizing methodology described in the NCDEQ's Standard Operating Procedures(SOP)for
Collection and Analysis of Benthic Macroinvertebrates, Version 5.0 February 2016.Per the SOP,sites will be sampled
utilizing the full scale method due to the site locations,and waterbody conditions.Qualitative collections of aquatic
macroinvertebrates will be made with appropriate equipment according to the SOP.A multiple habitat approach will
be used,where specimens from all available habitats(stream margins,leaf packs,aquatic vegetation,detritus,woody
debris and logs,etc.)are collected.Certified Laboratory will perform the required identification.
Techniques utilized will allow for identification of taxa to species level(where feasible)and calculation of taxa
richness, EPT taxa richness,EPT abundance, Biotic Index,and Biotic Index rating.The primary output for this
sampling method is a taxa list with an indication of relative abundance(Rare,Corn mon,Abundant)for each taxon.
Baseline stream chemistry(temperature,conductivity, pH,and dissolved oxygen)will be conducted in conjunction
with benthic sampling.
2.2 BMI Habitat Assessment
Piedmont/Mountain Stream Habitat Assessment Forms located in Appendix A of the SOP will be completed to
characterize habitat at each site along with digital photographs.These visual-based habitat evaluation scores
consist of seven parameters that rate channel modification,in-stream habitat,bottom substrate,pool
variety, bank stability and vegetation, light penetration and riparian vegetation zone width for each
monitoring station.A numerical score is used to rate each parameter and the total score gives a relative
measure of overall habitat quality.
2.0 REPORTING and COORDINATION
Sampling efforts will be scheduled during appropriate flow and conditions in coordination with DWR prior to
November 1,2023.The results of the surveys and analysis will be provided to NCDEQ in accordance with the
permit.
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