PERMIT RATIONALE FOR REISSUANCE
Raymond POTW, East
Hinds County
Raymond, Mississippi
Water NPDES No. MS0025852
March 24, 2016

I.	CLASSIFICATION – Municipal Minor Toxic

II.	DESCRIPTION OF WASTEWATER – Municipal/ Domestic Wastewater

III.	DESCRIPTION OF WASTEWATER TREATMENT – Wastewater is collected and treated biologically by means of an aerated lagoon followed by disinfection with chlorination. No increase in flow is proposed within the application.

IV.	RECEIVING WATER – Snake Creek. The receiving water is located within the Big Black River Basin, and is classified as Fish and Wildlife.  Snake Creek is listed on the State of Mississippi 303(d) list of impaired waterbodies. It is listed as an impaired waterbody with monitoring date for aquatic life support due to biological impairment. The facility is listed in a completed TMDL for Pathogens.  

The instream wastewater concentration at the point of discharge is determined by the following calculation:

IWC = {(Qw) /(Qw + Qr)}*100

	Where:
	Qw = Design flow of the wastewater treatment facility, 0.93 cfs.
	Qr = Receiving stream 7Q10, 0.22 cfs.

IWC = {(0.93 cfs) / (0.93 cfs + 0.22 cfs)}*100 = 80.85 %

V.	APPLICABLE GUIDELINES – State of Mississippi Wastewater Regulations (WPC-1),  State of Mississippi Water Quality Criteria (WPC-2), Municipal Facility Guidelines

VI.	SUMMARY OF LIMITATIONS –

	Parameter						Value			Basis
	Flow						0.6 MGD			Design
	BOD5 						     8 mg/l (Max Monthly Avg)	TMDL
	BOD5 (Percent Removal)			    	85% Minimum			Technology
	TSS						     30 mg/l (Max Monthly Avg)	Technology
	TSS (Percent Removal)			          	85% Minimum			Technology
	NH3-N						     1 mg/l (Max Monthly Avg)	TMDL
	Dissolved Oxygen					     6.0 mg/l Minimum		TMDL
	Fecal Coliform					          200 Col./100 ml			TMDL	
	pH						     6.0 – 9.0 SU			WPC-2
	Chlorine, Total Residual			          	0.014 / 0.023 mg/l		WPC-2, IWC
	Copper, Total Recoverable		          	0.006 / 0.008 mg/l		CSA, WPC-2, IWC
	Cadmium						0.00019/0.00127 mg/l		CSA, WPC-2, IWC
	Chronic Ceriodaphnia					     80.85% Minimum		WET, IWC
	Chronic Pimephales					     80.85% Minimum		WET, IWC						
	Total Nitrogen 						     57.55 lbs/day (Max Monthly Avg)	TMDL
	Total Phosphorus					    	16.39 lbs/day (Max Monthly Avg)	TMDL

Wasteload Allocation (WLA), Best Professional Judgment (BPJ), Chemical Specific Analysis (CSA), Whole Effluent Toxicity (WET), Instream Waste Concentration (IWC), Mississippi Water Quality Criteria (WPC-2), Total Maximum Daily Load (TMDL)

The TMDL allocation is modeled for oxygen depletion in the receiving stream, and the toxicity limit determined for the parameters that are potentially acutely and chronically toxic. The more stringent of the modeled limit and the toxicity limit (for NH3-N) is what is given in the Wasteload Allocation, to meet Water Quality Based Effluent Limitations (WQBELs).

VII.	TOXICITY EVALUATION

Lead, Total Recoverable

There were no detectable values of Lead noted through the permit application data. We also reviewed the DMR/Historic Data from the previous two years. Lead did not exceed water quality standard for that time period and therefore was removed from the current draft permit.

Cyanide, Free-Amen. To Chlorination
     
There were no detectable values of Cyanide noted through the permit application data. Also, reviewing the DMR data indicate that there is no risk of Cyanide exceeding the water quality standard, therefore was removed from the draft permit. 

Copper

Copper exceeded the acute and chronic water quality criteria based on the data received through the permit application; therefore, we have placed the following limitation for Copper into the draft permit. 

Monthly Average					Monthly Maximum
0.006mg/l                                  0.008mg/l

Cadmium

Cadmium exceeded the acute and chronic water quality criteria based on the data received through the permit application; therefore, we have placed the following limitation for Cadmium into the draft permit. 

Monthly Average					Monthly Maximum
0.00019mg/l                                  0.00127mg/l

Whole Effluent Toxicity Evaluation

In accordance to State Regulation WPC-1 VI.B.2b., a whole effluent toxicity evaluation has to be 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).  

Based on the past three (3) years of results of whole effluent toxicity testing for Raymond POTW East, the discharge did not present a reasonable potential to violate water quality toxicity. Therefore, bioassay requirement will not be included in the reissuance. 

Chemical Specific Analysis

Chemical specific analysis has been performed in accordance with State Regulations WPC-1 V1.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 are tabulated in attachment No. 3.  The reported values 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. 2.  A column by column description of the calculations in attachment No. 2 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

For the City of Raymond the chemical specific data results submitted with the reapplication did indicate the reasonable potential for violation of the appropriate criteria in Table III of Appendix D of CFR 122 for Total Recoverable Copper and Total Recoverable Cadmium . See attached Chemical Specific Screening sheet and results. Therefore, chemical specific limits, divided by the IWC in order to account for the mass balance with the receiving waters, have been place in the permit for Total Recoverable Copper, Total Recoverable Cadmium.

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

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

For Volatile Organics, the facility had an average daily concentration of 0.005 mg/l for Chloroform. According to the 2002 National Recommended: Water Quality Criteria, the Human Health criteria for Chloroform is 0.470 mg/l, Organisms Only. The average concentration, multiplied by the power of 10 (0.05 mg/l), due to less than 12 samples, does not present a reasonable potential to violate Human Health Criteria.  

For Volatile Organics, the facility had an average daily concentration of 0.001 mg/l for Toluene. According to the 2002 National Recommended: Water Quality Criteria, the Human Health criteria for Toluene is 200 mg/l, Organisms Only. The average concentration, multiplied by the power of 10 (0.010 mg/l), due to less than 12 samples, does not present a reasonable potential to violate Human Health Criteria.  

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

Attachment 1

Attachment 2

Attachment3

Attachment 4