Minnesota Administrative Rules

7053.0215 REQUIREMENTS FOR POINT SOURCE DISCHARGES OF SEWAGE.

Subpart 1.

Minimum secondary treatment for municipal point source and other point source dischargers of sewage.

The agency shall require secondary treatment as a minimum for all municipal point source dischargers and other point source dischargers of sewage. For purposes of this part, "municipal" has the adjective meaning of municipality as defined in part 7001.1020, subpart 18. "Secondary treatment facilities" means works that will provide effective sedimentation, biochemical oxidation, and disinfection, or the equivalent, including effluents conforming to the following:

Characteristic or Pollutant	Limiting Concentration or Range*
Five-day carbonaceous biochemical oxygen demand*	25 mg/L
Fecal coliform group organisms **	200 organisms per 100 milliliters
Total suspended solids*	30 mg/L
Oil	Essentially free of visible oil
Phosphorus	See part 7053.0255
pH range	6.0 - 9.0
Toxic or corrosive pollutants	Concentrations of toxic or corrosive pollutants shall not cause acute toxicity to humans or other animals or plant life or directly damage real property or exceed the final acute value unless the effluent satisfies the whole effluent toxicity test. If a whole effluent toxicity test performed on the effluent results in less than 50 percent mortality of the test organisms, the effluent must not be considered acutely toxic unless the commissioner finds that the test species do not represent sensitive organisms in the affected surface water body or the whole effluent test was performed on a sample not representative of the effluent quality. The final acute value and whole effluent toxicity test are defined in part 7050.0218, subpart 3, items Y and AAA, respectively.

*The arithmetic mean for concentrations of five-day carbonaceous biochemical oxygen demand and total suspended solids shall not exceed the stated values in any calendar month. In any calendar week, the arithmetic mean for concentrations of five-day carbonaceous biochemical oxygen demand shall not exceed 40 milligrams per liter and total suspended solids shall not exceed 45 milligrams per liter.

**Disinfection of wastewater effluents to reduce the levels of fecal coliform organisms to the stated value is required from April 1 through October 31 for Class 2 waters and May 1 through October 31 for Class 7 waters, except that where the effluent is discharged 25 miles or less upstream of a water intake supplying a potable water system, the reduction to the stated value is required all year. The stated value is not to be exceeded in any calendar month as determined by the geometric mean of all the samples collected in a given calendar month. The application of the fecal coliform group organism limit is limited to sewage or other effluents containing admixtures of sewage and do not apply to industrial wastes, except when the presence of sewage, fecal coliform organisms, or viable pathogenic organisms in such wastes is known or reasonably certain. Analysis of samples for fecal coliform group organisms by either the multiple tube fermentation or the membrane filter techniques is acceptable.

Subp. 2.

Exception for existing trickling filter facilities.

A.

The secondary treatment effluent limits in subpart 1, for five-day carbonaceous biochemical oxygen demand and total suspended solids, do not apply to municipal point source dischargers and other point source dischargers of sewage that meet all of the following conditions:

(1)

the treatment facility was in operation on January 1, 1987;

(2)

the treatment facility uses a trickling filter as the principal method of biologically treating the wastewater; and

(3)

the discharger has been incapable of consistently meeting the effluent limits for five-day carbonaceous biochemical oxygen demand or total suspended solids contained in subpart 1.

B.

For those municipal point source dischargers and other point source dischargers of sewage that meet the conditions of item A, the following effluent limits for five-day carbonaceous biochemical oxygen demand and total suspended solids apply as the arithmetic mean of all samples collected during a calendar month.

Five-day carbonaceous biochemical oxygen demand	40 mg/L*
Total suspended solids	45 mg/L**

*In any calendar week, the arithmetic mean for five-day carbonaceous biochemical oxygen demand shall not exceed 60 milligrams per liter.

**The arithmetic mean for any calendar week shall not exceed 65 milligrams per liter for total suspended solids.

C.

The other effluent limits in subpart 1 apply to those municipal point source dischargers and other point source dischargers of sewage whose limits for five-day carbonaceous biochemical oxygen demand and total suspended solids are established by this subpart.

Subp. 3.

Exception for pond facilities.

A.

The secondary treatment effluent limits in subpart 1 for total suspended solids do not apply to municipal point source dischargers and other point source dischargers of sewage that operate stabilization ponds or aerated ponds as the principal method of biologically treating the wastewater.

B.

For such treatment works, the effluent limit for total suspended solids for a discharge from the pond is as follows:

Total suspended solids

45 mg/L* (arithmetic mean of all samples collected during any calendar month)

*The arithmetic mean for any calendar week shall not exceed 65 milligrams per liter for total suspended solids.

C.

The other effluent limits in subpart 1 apply to those municipal point source dischargers and other point source dischargers of sewage whose limits for total suspended solids are established by this subpart.

Statutory Authority:

MS s 115.03; 115.44

History:

32 SR 1699

Published Electronically:

November 20, 2017