NC0026441_Report_20231114

RECEIVED
Town of Siler City
NPDES #NC0026441
WWTP Nutrient Removal Optimization NCDEQ�0WR�NP®EJ
Quarterly Report: 3rd Quarter 2023 IV G 'V C
Introduction
In accordance with NPDES Permit requirements this report is provided to document implementation of
the optimization report and performance of the WWTP during the 3rd quarter of 2023. The primary
focus of this information is nutrient removal, however data on plant operations for other parameters
are included as they influence the nutrient removal performance.
Phosphorus (TP) removal is achieved with chemical precipitation and performance has been consistently
good with effluent TP averaging less than 0.2 mg/I during the 3rd quarter 2023. Therefore, no further
review of TP operation is included.
Optimization Report Recommendations
The optimization report was prepared in 2020 based on data from January to September of 2020.
Operating parameters at the time are shown in Table 1 below.
Table 1: Influent Wastewater during Optimization Study
Parameter
Daily
Average during
Optimization
2020
Daily Average
for 3rd Quarter
2023
Flow (mgd)
3.26
BOD (mg/1)
228
234
NH3 (mg/1)
19.5
28
TN (mg/1)
35.0
38.8
TKN (mg/L)
34.1
TSS (mg/1)
167
TP (mg/1)
3.34
2.8
The report recommends utilizing Simultaneous Nitrification/Denitrification (SNDN) to achieve nitrogen
reduction. The recommended parameters include maintaining dissolved oxygen (DO) in the oxidation
ditches between 0.8 to 1.2 mg/I and maintaining a FM ratio of 0.04 to 0.05 Ibs BOD/Lbs MLVSS with
MLVSS between a concentration of 3,400 to 4,200 mg/I.
Optimization Implementation
During the 3rd quarter of 2023 the overall performance of the Siler City WWTP has been very good with
average effluent BOD of 0.74 mg/I, and Ammonia of 0.07 mg/I. The influent BOD has been somewhat

lower than in previous quarters, which appears to be influenced from Mountaire's improved
performance in July and August. The September BOD is somewhat higher as Mountaire's BODs were
also higher at that time.
The TN concentration has been somewhat higher than desirable at an average of 25.54 mg/I for the
quarter. The MLVSS concentration averaged 2,825 mg/I which is just below the range recommended by
the optimization report. The dissolved oxygen concentration was somewhat variable and ditch 2 has
trended lower DO than ditch one as in previous quarters. Operations staff are monitoring DO and if DO
levels rise above 2 mg/I a blower is turned off keep the DO in an appropriate range for simultaneous
nitrification and denitrification.
The performance for TN is above the optimization report target of 15 mg/I and operators are continuing
to work on the manual DO control in the ditches. The relatively low flows over the summer at the WWTP
impact the mass of TN present in the discharge. The average mass TN discharged in Quarter 2 was
approximately 10,142 Ibs/month. In the 3'd quarter the average mass TN discharged was 15,322
Ibs/month. The total mass discharged in 2023 is approximately 99,593 Ibs through the first 3 quarters
leaving 46,534 Ibs remaining to meet the permit limit. This is an average of 15,511 Ibs/month and the
plant is therefore on track to maintain compliance but will need to closely monitor TN in the final
quarter.
Table 2: Nutrient Removal Performance for 3rd Quarter 2023.
Influent
Effluent
July
August
September
Average
July
August
September
Average
Flow
2.56
2.35
2.11
2.34
BOD
194
223
285
234
0.13
0.64
1.45
0.74
NH3
24
28
31
28
0.00
0.04
0.16
0.07
TN
33.7
34.5
48.1
38.8
22.58
31.42
22.63
25.54
TP
2.00
2.34
4.18
2.8
0.16
0.00
0.38
0.18
1. All concentrations reported in mg/I. Flow reported in MGD
Table 3: Operating Parameter Summary
April
May
June
Average
MLSS (mg/1)
3992
4607
4714
4437
MLVSS (mg/1)
2634
2853
2989
2825
Ditch 1 DO (mg/1)
2.26
2.66
2.37
2.43
Ditch 2 DO (mg/1)
0.80
1.43
1.60
1.28
Cnnrlusinn
Overall plant performance during the 3rd quarter of 2023 was very good and remains substantially
improved from before August of 2022. The plant is continuing to prioritize sludge handling and solids
levels in the basins are close to optimization report recommendations. The performance during this
period for nutrient removal is ok and on track for compliance, however the final quarter will be
important for meeting the 2023 limits.

Town of Siler City-Siler City WWTP
EMC SOC WQ S22-033
Quarterly SOC Progress Report
3rd Quarter 2023
Please accept this submittal as a quarterly progress report for the work and activities of the Town of
Siler City under the Special Order By Consent.
Scheduled Activities paragraph 2(a)
Quarterly Reports
Quarterly Nutrient Optimization Report and Quarterly SOC Report were submitted on July 30,
2023
Collection System Permit WQCS00056
Permit for Main Interceptor Replacement Project was Submitted on February 28, 2023, Sewer
Extension Permit was issued on April 19, 2023.
ARPA Sewer Rehabilitation Project Engineering Report was submitted on May 1, 2023, (not a
formal activity), ER review is pending with NCDEQ however Survey work is complete, and design
is underway for this project. Permit submittals are expected to be completed on schedule by
November 30.
All other Activities are scheduled for future quarters and are currently expected to be on
schedule.
NPDES Permit NCO026441
IUP Permits were issued to Mountaire Farms, Brookwood Farms, and the Siler City Water
Treatment Plant on May 19, 2023. Mountaire Farms requested an adjudicatory hearing for their
permit which was held on July 21. Mountaire is currently appealing the results of the hearing.
Supplemental Aeration Equipment has been installed in the oxidation ditch basins. The
installation was complete on May 26, 2023, with initial email notification on May 30 and a
formal letter on June 29, 2023, notifying NCDEQ of completion.
All other Activities are scheduled for future quarters and are currently expected to be on
schedule.
Water Treatment Plant
IUP Permit was issued to the Siler City Water Treatment Plant on May 19, 2023
Construction of the WTP Pretreatment Improvements is still underway. During a meeting on
October 27, 2023, the Contract indicated that there are 3 outstanding items to be ready to put
the system into operation. A flow meter which was shipped with the wrong connection type,

delivery of sand and polymer (scheduled for October 31, 2023) and wiring of a torque switch.
They expect the equipment could be ready to startup by November 3 d however resolution to
these issues must be completed.
McGill Associates has been retained to provide Engineering services for the WTP Solids Handling
Improvements and is currently preparing an Engineering Report evaluating alternative
configurations.
Action Items under Paragraph 4(a)
Phase 1
All Action Items associated with Phase 1 have been completed.
Phase 2
Town is working to obtain all permits and funding required to begin construction for the WWTP.
Approval of the State budget begins the process with NCDEQ DWI. The Town expects to submit plans
and specifications to DWI for review and approval in November 2023 and will work to advertise for Bids
as soon as DWI approval is available.
As noted above, supplemental aeration equipment installation was completed on May 26, 2023.
As noted above, the Town is issued updated IUPs on May 19, 2023
Phase 3
No overflows from the Town's WTP have occurred from date of execution of the SOC.
As noted above, the WTP pretreatment system improvements schedule has been delayed and is
expected to be complete in mid -November.
Phase 4
Activities are scheduled for future quarters.
Additional Wastewater Flow Pursuant to Paragraph 4
Issuance of flow has been given to:
Brookwood Farms 25,000 GPD
Jersey Mike's 520 GPD
Ingle Street Subdivision 1080 GPD @ 120 gallons will be reduced to 675 GPD @ 75 gallons, when HB600
goes into effect.
Wolfspeed construction 40,000 GPD
Project Ice 4000 GPD
Deliverance Church 1195 GPD