PERMIT RATIONALE FOR REISSUANCE
Crystal Springs POTW
Copiah County
Crystal Springs, Mississippi
Water NPDES No. MS0041874
June 2022

CLASSIFICATION

Municipal Minor Toxic

DESCRIPTION OF WASTEWATER

Domestic/ Municipal Wastewater

DESCRIPTION OF WASTEWATER TREATMENT  

Wastewater is collected and treated biologically by means of an aerated lagoon followed by disinfection before being land applied for overland flow via spray irrigation.  No increase in permitted or treatment flow is proposed within the application.

RECEIVING WATERS

Little Copiah Creek.  The receiving stream is located within the Pearl River Basin, and is classified as Fish and Wildlife. The receiving water does appear on the updated State of Mississippi 303(d) List of Impaired Waterbodies, nor does the discharge appear on the a Completed Total Maximum Daily Load (TMDL)

The instream wastewater concentration (IWC) 7Q10 at the point of discharge is determined by the following calculation:

Qw = Design flow Outfall 001 = 0.99 MGD or 1.5 cfs
Qr =  Receiving stream 7Q10 = 0.35 cfs
IWC = (Qw/ (Qw + Qr)) * 100 =  (1.5 / 1.5 + 0.35) * 100=  81.41%

APPLICABLE GUIDELINES 

I.	11 Mississippi Admin Code pt. 6, Commercial Facility Guidelines (Technology), State of Mississippi Water Quality Criteria (MSWQS), Waste Load Allocation (WLA)

SUMMARY OF LIMITATIONS –

Outfall 001
Parameters			Value					Basis
Flow				0.99 MGD				Design
BOD5				16 mg/l					WLA
BOD5 (Percent Removal)	85%				             

Technology
TSS				30 mg/l					Technology
TSS (Percent Removal)		85%					Technology
Phase I Ammonia Nitrogen	2.0 mg/l				WLA
Phase II Ammonia Nitrogen	1.6 mg/l				WLA
E. Coli 				126 Col./100 ml				WLA
Dissolved Oxygen		6.0 mg/l				WLA
PH				6.0 – 9.0 SU				MSWQS
Total Nitrogen			Report lbs. /day				WLA
Total Phosphorus		Report lbs. /day				WLA
Copper, Total Recoverable	0.0061 mg/l (Max Monthly Average)	 
				0.0086 mg/l (Max Weekly Avg)	 	WLA
Lead, Total Recoverable		0.0014 mg/l (Max Monthly Average)	
				0.0369 mg/l (Max Weekly Avg)	 	WLA
Chlorine, Total Recoverable	0.014 mg/l (Max Monthly Average)	
				0.023 mg/l (Max Weekly Avg)	 	WLA
	Ceriodaphnia dubia			81.41% Minimum			MSWQS
	Pimephale promelas			81.41% Minimum			MSWQS

The 24-hour total precipitation in inches shall be monitored 5 days/week with a rain gauge at the treatment site.

	See attached modeling data results attachment no. 1.

II.	CHANGES FROM PREVIOUS PERMIT –

Total Nitrogen and Total Phosphorus limitations have been added. Ammonia-Nitrogen limit has decreased from 2.0 mg/L to 1.6 mg/L.

The permittee shall achieve compliance with the effluent limitations specified for discharge in accordance with the following schedule:
Upon issuance of this permit, the permittee shall achieve compliance with the effluent limitations specified for the parameters without a phase designation and for the parameters noted as Phase I; Phase II limitations shall not apply at this time.

Beginning upon completion and start-up of improvements needed to comply with Phase II limitations or three (3) years after the issuance of the permit, whichever comes first, the permittee shall achieve compliance with the effluent limitations specified for the parameters without a phase designation and for the parameters noted as Phase II; Phase I limitations shall no longer apply at this time. 

The permittee shall notify our office orally at least 24 hours prior to start-up and in writing no later than 48 hours after start-up. [11 Miss. Admin. Code Pt. 6, R. 1.1.4.A(9).]

WHOLE EFFLEUNT TOXICITY AND CHEMICAL SPECIFIC EVALUATION

WHOLE EFFLEUNT TOXICITY EVALUATION

In accordance to 11 Mississippi Admin. Code pt. 6, a whole effluent toxicity evaluation was performed as part of the renewal application.  The applicant was to have tested in accordance with Short – Term Methods for estimating the Chronic toxicity of Effluents and Receiving Water to Freshwater organisms.  Short – term chronic WET test were performed on Ceriodaphnia dubia (invertebrate) and Pimephale promelas (vertebrate).  The results of the wet tests are as follows:

			August 2020
			Ceriodaphnia dubia		NOEL    	<10.18%
			Pimephales promelas		NOEL		100%
			
			October 2020
			Ceriodaphnia dubia		NOEL  		20.35%
			Pimephales promelas		NOEL   	N/A

			February 2021
			Ceriodaphnia dubia		NOEL    	10.18%
			Pimephales promelas		NOEL    	20.35%

April 2021
			Ceriodaphnia dubia		NOEL     	100%
			Pimephales promelas		NOEL     	100%

			August 2021
			Ceriodaphnia dubia		NOEL     	20.35%
			Pimephales promelas		NOEL     	100%

Not all of the inhibition concentrations were greater that the predicted IWC of 81.41%.  Based upon the results of the WET testing, chronic bioassay requirements will be placed within the permit.

Chemical Specific Analysis

Chemical specific analysis has been performed in accordance with 11 Mississippi Admin. Code pt. 6.  Municipalities shall determine the toxic characteristics of their wastewater by analyzing for the toxic pollutant listed in Table III of appendix D of 40 CFR 122.  The results are tabulated in attachment No. 2.  The reported values are then analyzed and compared to water quality criteria (attachment No. 4) to determine any possible toxic effect to the receiving waters.  A synopsis of these calculations is listed in attachment No. 3.  A column by column description of the calculations in attachment No. 3 is hereby provided:

Column No. 1 – Maximum concentration.  The highest effluent reading of the parameter

Column No. 2 – The maximum concentration mixed with the receiving water IWC.  This     is calculated by the following equation:

{Maximum Concentration (Column 1) * IWC %} / 100

Column No. 3 – Acute allowable – Chemical Specific State Water Quality Criteria                                   
	Column No. 4 – Pass or Fail. If column 2 > column 3 water quality criteria is exceeded                              and failure occurs.

Column No. 5 – Long term average (LTA) of all tests.  The summation of the 12 samples divided by 12.

Column No. 6 – The long term average concentration mixed with the receiving water                                  IWC.  This is calculated by the following equation:

{LTA Concentration (Column 5) * IWC%} / 100

Column No. 7 – Chronic allowable – Chemical Specific State Water Quality Criteria                                   
Column No. 8 – Pass or Fail. If column 6 > column 7 water quality criteria is exceeded                                and failure occurs.

Column No. 9 – Human health determination.  Long term average (Column 5) is mixed                with the mean annual flow IWCMA .  This is calculated by the following                            equation:

{LTA Concentration (Column 5) * IWCMA %} / 100

Column No. 10 – Human health allowable – State Water Quality Criteria   Note: Organisms only column is used if receiving waters are not drinking water supply. 

	Column No. 11 – Pass or Fail.  If column 9 > column 10 water quality criteria is exceeded                        and failure occurs.

Chemical Specific Analysis for Metals and Results

Municipalities shall determine the toxic characteristics of their wastewater by analyzing for toxic pollutants listed in Table II of Appendix D of 40 CFR 122.  Metal analysis shall be for total recoverable metals.  Municipalities shall submit twelve influent and effluent samples collected.  Chemical specific limits shall be placed in a permittee’s permit if any of the parameters evaluated in the toxic screening procedure indicate the reasonable potential for violation of the appropriate criteria (acute, chronic, and human health).
	
The chemical specific data results submitted for last permit issuance did indicate the reasonable potential for violation of the appropriate criteria in Table III of Appendix D of CFR 122 for Total Recoverable Copper, Total Recoverable Lead. Total Recoverable Copper and Total Recoverable Lead parameters will be kept in permit due to violations from DMR data history from the past two years.

Chemical specific analysis for Volatile Organics Compounds, Acid-Extractable Compounds, and Base-Neutral Compounds and Results

For Volatile Organics, the permittee had an average daily concentration for the following compounds: Chloroform 

Average Daily Concentrations
Chloroform				0.00102 mg/l

According to the National Recommended Water Quality Criteria, the Human Health criteria for these compounds are shown below (organisms only):

Human Health Criteria for Organism Only
Chloroform				2 mg/l

Multiplying the average concentrations above by 10 (due to a less than 12 sample data set) and the IWC of 81.41 % determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria

IWC = 81.41 % (0.8141)

Chloroform
[(0.00102 mg/l)*(0.8141)] = 0.00083 mg/L*10= 0.0083mg/l < 2 mg/l

The above result demonstrates that the average concentrations for Chloroform does not present a reasonable potential to violate Human Health Criteria.

The chemical specific data results submitted had no detects for Acid-Extractable Compounds or Base-Neutral Compounds.

Attachments
Attachment 1	Waste Load Application 
Attachment 2	Tabulated Metals Results 
Attachment 3	Synopsis of Metals Results 
Attachment 4 	Water Quality Criteria

Attachment 1

Attachment 2

Attachment 3

Attachment 4