Section R18-9-D302. 3.02 General Permit: Process Water Discharges from Water Treatment Facilities

A.      A 3.02 General Permit allows filtration backwash and dis- charges obtained from sedimentation and coagulation in the water treatment process from facilities that treat water for industrial process or potable uses. The permittee shall ensure that:

1.        Liquid fraction. The discharge meets:

a.         All numeric Aquifer Water Quality Standards for inorganic chemicals, organic chemicals, and pesti- cides established in R18-11-406(B) through (D);

b.        The discharge meets one of the following criteria for microbiological contaminants:

i.         Either the concentration of fecal coliform organisms is not more than 2/100 ml or the con- centration of E. coli bacteria is not more than 1/ 100 ml, or

ii.        Either the concentration of fecal coliform organisms is less than 200/100 ml or the con- centration of E. coli bacteria is less than 126/ 100 ml if the average daily flow processed by the water treatment facility is less than 250,000 gallons; and

2.        Solid Fraction. The solid material in the discharge quali- fies as inert material, as defined in A.R.S. § 49-201(19).

B.       Notice of Intent to Discharge. In addition to the Notice of Intent to Discharge requirements specified in R18-9-A301(B), an applicant shall submit:

1.        A characterization of the discharge, including a represen- tative chemical and biological analysis of expected dis- charges and all source waters; and

2.        The design capacity of any impoundment covered by this general permit.

C.      Impoundment design and siting requirements. An applicant shall:

1.        Ensure that the depth to the static groundwater table is greater than 20 feet;

2.        Not locate the area of discharge immediately above karstic or fractured bedrock, unless the discharge meets the microbial limits specified in subsection (A)(1)(b)(i);

3.        Maintain a minimum horizontal setback of 100 feet between the facility and any water supply well;

4.        Design and construct an impoundment to maintain, using design volume or mechanical systems, normal operating volumes and any inflow from the 100-year, 24-hour storm event. The applicant shall:

a.         Divert any surface water run-on from the 100-year, 24-hour storm event around the facility if not intended for capture by facility design; and

b.        Design the facility to maintain 2 feet of freeboard or an alternative level of freeboard that the applicant demonstrates is reasonable, considering meteorolog- ical factors, the size of the impoundment, and other site-specific factors; or

c.         Discharge to surface water under the conditions of an AZPDES permit; and

5.        Manage off-site disposal of sludge according to A.R.S. Title 49, Chapter 4.

D.      Operational requirements.

1.        Inorganic chemical, organic chemical, and pesticide mon- itoring.

a.         The permittee shall monitor any discharge annually to determine compliance with the requirements of subsection (A).

b.        If the concentration of any pollutant exceeds the numeric Aquifer Water Quality Standard, the per- mittee shall submit a report to the Department with a proposal for mitigation and shall increase monitor- ing frequency for that pollutant to quarterly.

c.         If, in the quarterly sampling, the condition in subsec- tion (D)(1)(b) continues for two consecutive quar- ters, the permittee shall submit an application for an individual permit.

2.        Microbiological contaminant monitoring.

a.         The permittee shall monitor any discharge annually to determine compliance with the requirements of subsection (A)(1)(b).

b.        If the concentration of any pollutant exceeds the lim- its established in subsection (A)(1)(b), the permittee shall submit a report to the Department with a pro- posal for mitigation and increase monitoring fre- quency for that pollutant to monthly.

c.         If, in the monthly sampling, the condition in subsec- tion (D)(2)(b) continues for three consecutive months, the permittee shall submit an application for an individual permit.

E.       Recordkeeping. A permittee shall maintain at the site, the fol- lowing information, if applicable for the disposal method, for at least 10 years, and make it available to the Department upon request:

1.        Construction drawings and as-built plans, if available;

2.        A log book or similar documentation to record inspection results, repair and maintenance activities, monitoring results, and facility closure;

3.        Water quality data collected under subsection (D);

4.        Standard operating procedures; and

5.        Records of any discharge other than those identified under subsection (B).

F.       Reporting requirements. The permittee shall:

1.        Report unauthorized flows into the impoundment to the Department within five days of discovery, and

2.        Submit the report required in subsections (D)(1)(b) or (2)(b) within 30 days of receiving the analytical results.

Historical Note

New Section adopted by final rulemaking at 7 A.A.R. 235, effective January 1, 2001 (Supp. 00-4). Amended by final rulemaking at 11 A.A.R. 4544, effective November 12, 2005 (05-3).