PERMIT RATIONALE FOR REISSUANCE
MSARNG, Camp Shelby
Forrest County
Camp Shelby, Mississippi
Water NPDES No. MS0059838
November 2016

I.	CLASSIFICATION – NPDES Major

II.	DESCRIPTION OF WASTEWATER – Domestic Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Domestic wastewater collected by the permittee will be treated biologically by an aerated lagoon followed by disinfection.  The treatment capacity for the aerated lagoon treatment system is 1.0 MGD with no increase in treatment capacity proposed.    

IV.	RECEIVING WATERS – Leaf River.  The receiving stream is located within the Pascagoula River Basin and is classified as Fish and Wildlife.  See attachment no. 1 for the discharge location.  At the point of discharge the receiving stream does not appear on the most recent State of Mississippi 303(d) list of evaluated or impaired waterbodies.  The discharge is listed in the Total Maximum Daily Load (TMDL) for Biological Impairment/Low Dissolved Oxygen and Nutrient in the Leaf River (June 2005) and the TMDL for Fecal Coliform (December 2004).  
		The 7 – day, 10 year minimum flow, 7Q10, for Leaf River at the point of discharge is 374 	cfs.  The instream wastewater concentration (IWC) at the point of discharge can be determined using 	the following calculation:

IWC = {(Qw)/(Qw + QR)} * 100
	
	Where:
	Qw = Design flow of the wastewater treatment facility, 1.0 MGD or 1.55 cfs.
	QR = Receiving stream 7Q10 or 374 cfs

IWC = {(1.55 cfs)/(1.55 cfs + 374 cfs)} * 100 = 0.41 %

V.	APPLICABLE GUIDELINES – 11 Mississippi Administrative Code pt. 6, WLA, TMDL

VI.	SUMMARY OF LIMITATIONS –
	Parameter				Value					Basis
	Flow					1.0 MGD				Design
	BOD5					25 mg/l (Monthly Avg.)			Modeled
	TSS					60 mg/l (Monthly Avg.)			Technology
	Ammonia-Nitrogen (NH3-N)		Report mg/l (Monthly Avg.)		Admin Code
	Dissolved Oxygen 			> 6.0 mg/l (Monthly Avg.)			Admin Code
	Fecal Coliform
	May – October				200 Col./100 ml				Admin Code
	November – April			2000 Col./100 ml				Admin Code
	Chlorine, Total Residual			0.011 mg/l 				Admin Code
	pH					6.0 – 9.0 SU				Admin Code
	Nitrogen (Total)				Report lbs/day				TMDL
Phosphorus (Total) (Phase I)		Report lbs/day				TMDL
Phosphorus (Total) (Phase II)		43.3 lbs/day				TMDL
	
	See attached modeling data results (attachment no. 2).

	
	WHOLE EFFLUENT TOXICITY AND CHEMICAL SPECIFIC EVALUATION

BIOASSAY

		Municipal major dischargers are required to perform Whole Effluent Toxicity (WET) tests as part 	of their application reissuance and shall conduct four (4) WET tests in the year preceding filing of the 	application.  These tests are to be performed seasonally (hot-dray and cold-wet) on vertebrate and 	invertebrate aquatic species.  The applicant shall test in accordance with Methods for Measuring the Acute 	Toxicity of Effluents to Freshwater and Marine Organisms.  The acute WET tests shall be performed on 	Pimephale promelas and Ceriodaphnia dubia.  
	The Mississippi Army National Guard, Camp Shelby in the WET testing used a dilution ratio of 0.41 %.  The WET tests on the species were performed in April 2012, November 2013, March 2014, and October 2015.  

	April 2012

	 Species				IC50 Results

	Ceriodaphnia dubia			>100 %
Pimephale promelas			>100 %

November 2013

	Species				IC50 Results

	Ceriodaphnia dubia			>100 %
Pimephale promelas			>100 %

March 2014

	Species				IC50 Results

	Ceriodaphnia dubia			>100 %
Pimephale promelas			>100 %

October 2015

	Species				IC50 Results

	Ceriodaphnia dubia			>100 %
Pimephale promelas			>100 %

All of the inhibition concentrations were greater than the predicted IWC of 0.41 % for all species in all tests; it appears the effluent is not toxic to aquatic species.  

Chemical Specific Analysis

	Chemical specific analysis has been performed in accordance with State Regulation 11 MS Admin Code, pt. 6, VI.B1.  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 of this analysis are tabulated as attachment no. 3.  The tabulated results are then analyzed and compared to water quality criteria to determine any possible toxic effect to the receiving waters.  A synopsis of these calculations is listed in attachment no. 4.  

A column by column description of the calculations in attachment no. 4 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 Results

	Major Municipalities shall determine the toxic characteristics of their wastewater by analyzing for toxic pollutants listed in Table III 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).
	For the Mississippi Army National Guard, Camp Shelby the chemical specific data results submitted with the reapplication did not indicate the reasonable potential for violation of the appropriate criteria in Table III of Appendix D of 40 CFR 122.  See attached chemical specific screening sheet (attachment no. 4) and calculations (attachment no. 5).

Chemical Specific Analysis for Volatile Organic 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 and Dichlorobromomethane

Average Daily Concentrations
Chloroform				0.00823 mg/l
Chlorodibromomethane			0.00186 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				0.47 mg/l
Chlorodibromomethane			0.013 mg/l

Multiplying the average concentrations above by 10 (due to a less than 12 sample data set) and the IWC of 0.41 % determines the reasonable potential of the compound’s concentration to violate the Human Health Criteria

IWC = 0.41 % (0.0041)

Chloroform
[(0.00823 mg/l)*(0.0041)] = 0.00823 mg/L*10= 0.0823mg/l < 0.47 mg/l

Chlorodibromomethane
[(0.00186 mg/l)*(0.0041)] = 0.000007626 mg/l *10= 0.00007626 mg/l < 0.017 mg/l 

The above results demonstrate that the average concentrations for both compounds do 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 Discharge Location Map
Attachment 2 Waste Load Allocation
Attachment 3 Chemical Specific Tabulated Results
Attachment 4 Chemical Specific Calculations

Attachment 1: Discharge Location Map

Attachment 2: Waste Load Allocation (WLA)

Attachment 3: Chemical Specific Tabulated Results

	

Attachment 4: Chemical Specific Calculations