Dunlap
Wastewater
System

 

NPDES PERMIT No. TN0021946


REPRESENTATIVE: Sammy Hixson
LOCATION: Dunlap, Sequatchie County, Tennessee
PHONE NUMBER: 423.949.3801
WATERSHED: Sequatchie                 HUC: 60020004
WASTEWATER:
                              Discharge number: 001
                              Average Design Flow: 0.934 MGD
                              Industrial Flow: 4%
PRESENT TREATMENT: Extended aeration activated sludge plant with
                                               chlorination/dechlorination followed by land
                                               application of sludge

PERMIT: Issued     October 1, 1999
                  Expires     September 30, 2000

RECEIVING WATERS

STREAM: Sequatchie River at mile 43.9
LOW FLOW: 3Q20 = 9MGD  (14 CFS)
ESTABLISHED FROM: USGS Water-Resources Investigation Report
                                            95-4293 Station #03570835
CLASSIFICATION: Domestic and industrial water supply, fish and aquatic life,
                                    recreation, irrigation, livestock watering, and wildlife
WATER QUALITY STATUS: The Sequatchie River at mile 43.9 is considered
             fully supportive of its designated use classifications (per the 303 (d) List
             June 1998 edition).
Tier Designation: Not evaluated at this time.

 

PLANT LIMITS:

PARAMETERS MONTHLY AVERAGE CONCENTRATION MAXIMUM CONCENTRATION RATIONALE
CBOD5   mg/l 25 40 D.O. protection
Total Suspended Solids  mg/l 30 45 T.C.A. 1200-4-5-.03
NH3-N mg/l 10 20 Ammonia Toxicity
Dissolved Oxygen mg/l 1.0 (daily minimum) Report D.O. protection
Total Chlorine Residual mg/l Report 0.2 (instantaneous) Aquatic Protection
Fecal Coliform (colonies/100ml) 200 1000 T.C.A. 122-4-3-.03
Settleable Solids (ml/l) Report 1.0 T.C.A. 122-4-3-.03
PH (standard units) 6.0 - 9.0 9.0 T.C.A. 122-4-3-.03
Flow      
Influent  MGD Report Report Used to quantify pollutant load
Effluent  MGD Report Report Used to quantify pollutant load
Whole Effulent Toxicity      
IC25 > 9.4% per sample see serial dilutions Aquatic Protection

DARK INHIBITION CONCENTRATION

IC25% =         Design flow           *  100>        0.934       *  100        >   9.4%  (PL)
               Low flow + Design flow                     9 + 0.934

   Where:
                9.0        =   3Q20
                0.934    =   Designed Capacity (MGD)
                IC25       =   Concentration causing 25% reduction in survival,
                                  reproduction and growth of test organisms

Serial Dilutions for Whole Effulent Toxicity (WET) Testing

4 x PL 2 X PL Permit Limit
(PL)		 0.50 x PL 0.25 x PL Control
37.6 18.8 9.4 4.7 2.35 0

% Effluent

CHLORINATION

The residual chlorine limit is derived using the mass balance formula and the EPA instream protection value of 0.019 mg/l for fish and aquatic life. Applying this formula yields the following calucation:

        0.019  (Qd  + Qs)     =  Limit (mg/l)  =      0.019   (0.934  + 9)     =  0.2 mg/l
                 Qd                                                               0.934

Where:
                0.019    =   instream protection value (acute)
                0.934    =   design flow of STP (MGD)
                9.0          =    3Q20 flow of receiving stream (MGD)