PART 133—SECONDARY TREATMENT REGULATION Authority: Secs. 301(b)(1)(B), 304(d)(1), 304(d)(4), 308, and 501 of the Federal Water Pollution Control Act as amended by the Federal Water Pollution Control Act Amendments of 1972, the Clean Water Act of 1977, and the Municipal Wastewater Treatment Construction Grant Amendments of 1981; 33 U.S.C. 1311(b)(1)(B), 1314(d) (1) and (4), 1318, and 1361; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; 95 Stat. 1623, Pub. L. 97-117. Source: 49 FR 37006, Sept. 20, 1984, unless otherwise noted. § 133.100 Purpose. This part provides information on the level of effluent quality attainable through the application of secondary or equivalent treatment. § 133.101 Definitions. Terms used in this part are defined as follows: (a) 7-day average. (b) 30-day average. (c) Act. et seq., (d) BOD. (e) CBOD 5 5 (f) Effluent concentrations consistently achievable through proper operation and maintenance. (g) Facilities eligible for treatment equivalent to secondary treatment. (1) The BOD 5 (2) A trickling filter or waste stabilization pond is used as the principal process, and (3) The treatment works provide significant biological treatment of municipal wastewater. (h) mg/l. (i) NPDES. (j) Percent removal. (k) Significant biological treatment. 5 (l) SS. (m) Significantly more stringent limitation 5 5 (n) State Director [49 FR 37006, Sept. 20, 1984; 49 FR 40405, Oct. 16, 1984, as amended at 50 FR 23387, June 3, 1985] § 133.102 Secondary treatment. The following paragraphs describe the minimum level of effluent quality attainable by secondary treatment in terms of the parameters—BOD 5 (a) BOD 5 (1) The 30-day average shall not exceed 30 mg/l. (2) The 7-day average shall not exceed 45 mg/l. (3) The 30-day average percent removal shall not be less than 85 percent. (4) At the option of the NPDES permitting authority, in lieu of the parameter BOD 5 5 5 (i) The 30-day average shall not exceed 25 mg/l. (ii) The 7-day average shall not exceed 40 mg/l. (iii) The 30-day average percent removal shall not be less than 85 percent. (b) SS. (2) The 7-day average shall not exceed 45 mg/l. (3) The 30-day average percent removal shall not be less than 85 percent. (c) pH. [49 FR 37006, Sept. 20, 1984; 49 FR 40405, Oct. 16, 1984] § 133.103 Special considerations. (a) Combined sewers. i.e., (b) Industrial wastes. 5 5 5 (c) Waste stabilization ponds. 5 (d) Less concentrated influent wastewater for separate sewers. (e) Less concentrated influent wastewater for combined sewers during dry weather. The Regional Administrator or, if appropriate, the State Director is authorized to substitute either a lower percent removal requirement or a mass loading limit for the percent removal requirements set forth in §§ 133.102(a)(3), 133.102(a)(4)(iii), 133.102(b)(3), 133.105(a)(3), 133.105(b)(3) and 133.105(e)(1)(iii) provided that the permittee satisfactorily demonstrates that: (1) The treatment works is consistently meeting, or will consistently meet, its permit effluent concentration limits, but the percent removal requirements cannot be met due to less concentrated influent wastewater; (2) to meet the percent removal requirements, the treatment works would have to achieve significantly more stringent effluent concentrations than would otherwise be required by the concentration-based standards; and (3) the less concentrated influent wastewater does not result from either excessive infiltration or clear water industrial discharges during dry weather periods. The determination of whether the less concentrated wastewater results from excessive infiltration is discussed in 40 CFR 35.2005(b)(28), plus the additional criterion that either 40 gallons per capita per day (gpcd) or 1500 gallons per inch diameter per mile of sewer (gpdim) may be used as the threshold value for that portion of the dry weather base flow attributed to infiltration. If the less concentrated influent wastewater is the result of clear water industrial discharges, then the treatment works must control such discharges pursuant to 40 CFR part 403. [49 FR 37006, Sept. 20, 1984, as amended at 50 FR 23387, June 3, 1985; 50 FR 36880, Sept. 10, 1985; 54 FR 4228, Jan. 27, 1989] § 133.104 Sampling and test procedures. (a) Sampling and test procedures for pollutants listed in this part shall be in accordance with guidelines promulgated by the Administrator in 40 CFR part 136. (b) Chemical oxygen demand (COD) or total organic carbon (TOC) may be substituted for BOD 5 § 133.105 Treatment equivalent to secondary treatment. This section describes the minimum level of effluent quality attainable by facilities eligible for treatment equivalent to secondary treatment (§ 133.101(g)) in terms of the parameters—BOD 5 (a) BOD 5 (2) The 7-day average shall not exceed 65 mg/l. (3) The 30-day average percent removal shall not be less than 65 percent. (b) SS. (1) The 30-day average shall not exceed 45 mg/l. (2) The 7-day average shall not exceed 65 mg/l. (3) The 30-day average percent removal shall not be less than 65 percent. (c) pH. (d) Alternative State requirements. 5 (The information collection requirements contained in this rule have been approved by OMB and assigned control number 2040-0051) (e) CBOD 5 (1) Where data are available to establish CBOD 5 5 5 5 (i) The 30-day average shall not exceed 40 mg/l. (ii) The 7-days average shall not exceed 60 mg/l. (iii) The 30-day average percent removal shall not be less than 65 percent. (2) Where data are available, the parameter CBOD 5 (f) Permit adjustments. 5 (2) For new facilities, the permitting authority determines that the 30-day average and 7-day average BOD 5 [49 FR 37006, Sept. 20, 1984; 49 FR 40405, Oct. 16, 1984]