NC0026441_Permit Modification Request_20150402

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SILER CITY, NORTH CAROLINA 27344-0769
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PO BOX 769e PHONE[phone]
311 N SECOND AVENUE 2 ti FAX[phone]
March 25, 2015
RECEIVED/DENR/DWR
NC Department of Environment and Natural Resources APR - 2 2015
Division of Water Quality/NPDES Unit Water Quality
ATTN: Mr.John Hennessy
Permitting Section
1617 Mail Service Center
Raleigh, NC 27699-1617
Subject: NPDES Permit Modification Request
Sampling Reduction Request
Town of Slier City
NPDES Permit#NC0026441
Chatham County
Dear Mr. Hennessy:
The Town of Slier City is requesting a minor permit modification of NPDES Permit NC0026441 for a
reduction in sampling. We request that monitoring for BODS, TSS, Ammonia Nitrogen and Fecal
Coliform be reduced under the "exceptionally performing facilities" criteria to two times per week. The
attached data (summarized in the following table) indicates that the WWTP effluent has exceeded the
minimum criteria for reduced monitoring. The most restrictive summer limit was used for calculating all
BODS and Ammonia Nitrogen removal rates. In addition to the test results, the Siler City WWTP is in
compliance with all other criteria listed in Section B Approval Criteria of the October 22, 2012 guidance
document regarding reduction of monitoring frequencies. The date used for this analysis was for the
period of January 2012—February 2015.
Analysis of testing results for the past three years:
Percent of Monthly Average Limit
Parameter Monthly Limit 3-Year Average %of Limit
BODS 5.0 mg/I 1.5 mg/I 30%
TSS 30.0 mg/L 0.7 mg/L 2.5%
NH3 1.0 mg/I 0.21 mg/I 21%

Fecal Coliform 200/100 ml 5.5 colonies/100 ml 3 %
Number of Samples Over 200% of Monthly Average Limit
Parameter 200% of Monthly Limit Number of Samples Over
BODS 10 mg/1 2
TSS 60 mg/L 0
NH3 2 mg/1 4
One(1)Fecal Coliform sample exceeded 200%of the weekly average limit
The Town appreciates the Division's effort to reduce the regulatory and monetary burden on
systems that strive consistently to provide exceptional wastewater treatment. We thank you for
your consideration in these matters. If you have any additional questions or comments, please
call Chris McCorquodale at 919/742-4581.
Sincerely
Bryan Thompson, Town Manager
Town of Siler City

Three Year Data Summary-Slier City NPDES#0026441
2012 BOD Ave 30D Ma TSS Ave TSS Max FC Ave FC Max NH3 Ave NH3 Max
January 1.0 6.3 0.0 <2.5 1 2 1.2 3.5
February 0.0 2.0 0.0 <2.5 1 1 0.0 <0.5
March 0.0 2.0 0.0 <2.5 1 1 0.0 <0.5
April 1.7 4.2 0.0 <2.5 1 3 0.0 <0.5
May 2.5 4.1 0.0 <2.5 2 295 0.0 <0.5
June 2.4 3.8 0.0 <2.5 3 9 0.0 <0.5
July 4.1 5.7 0.0 <2.5 5 57 0.1 0.8
August 2.1 4.2 0.1 <2.5 4 16 0.0 <0.5
September 1.3 4.1 0.1 <2.5 10 32 0.0 <0.5
October 0.8 2.9 0.0 <2.5 4 14 0.0 <0.5
November 0.8 3.9 0.0 <2.5 2 6 0.0 <0.5
December 0.5 2.3 0 <2.5 1 1 0.1 <0.5
2013 BOD Ave 30D Mai TSS Ave TSS Max FC Ave FC Max NH3 Ave NH3 Max
January 1.4 5.5 0.3 3.3 1.2 4 0.5 3.0
February 2.0 4.4 2.1 7.3 1 2 0.4 3.7
March 2.9 8.9 3.6 7.5 1 1 1.0 4.0
April 1.5 3.6 0.0 <2.5 2 11 0.0 <0.5
May 2.1 4.1 0.3 1.0 14 200 0.0 <0.5
June 1.4 4.0 0.1 <2.5 18 45 0.1 2.0
July 1.9 8.6 0.3 3.6 39 265 0.5 5.4
August 0.9 4.6 0.0 <2.5 40 133 0.0 <0.5
September 1.1 5.0 0.0 <2.5 29 56 0.0 <0.5
October 0.6 4.4 0.0 <2.5 20 43 0.1 <0.5
November 1.4 7.1 0.0 <2.5 22 1900 0.1 <0.5
December 2.1 15.1 0.0 <2.5 2 11 0.0 <0.5
2014 BOD Ave 3OD Ma TSS Ave TSS Max FC Ave FC Max NH3 Ave NH3 Max
January 0.6 4.6 0.2 4.2 2 535 0.1 2.3
February 1.3 3.9 0.5 3.9 1 4 1.3 6.2
March 4.1 25.5 3.8 44.0 2 3 1.3 8.3
April 2.7 3.9 0.0 <2.5 4 16 0.0 <0.5
May 2.8 6.7 0.9 8.9 44 760 0.1 0.9
June 1.3 4.0 0.0 <2.5 43 230 0.0 <0.5
July 1.6 5.6 0.2 <2.5 26 59 0.1 0.8
August 0.7 4.8 0.4 4.7 23 420 0.5 5.2
September 0.6 4.0 0.0 <2.5 38 57 0.0 <0.5
October 0.7 3.6 0.0 <2.5 27 48 0.0 <0.5
November 1.3 3.5 4.5 13.0 30 381 0.0 <0.5
December 1.1 3.1 3.4 10.2 6 23 0.0 <0.5
2015 BOD Ave 100 Ma TSS Ave TSS Max FC Ave FC Max NH3 Ave NH3 Max
January 2.3 5.2 3.7 10.3 4 240 0.0 0.5
February 1.1 5.7 2.2 7.3 2 14 0.1 1.4
3-Year Arithmetic Average 1.5 0.7 f` 0.21
3-Year Geometric Mean Average 5.5
Permit Limit 5.0 30.0 200 1.0
% of Limit 30% 2.5% 3% 21%