Section R18-9-E315. 4.15 General Permit: Aerobic System Less Than 3000 Gallons Per Day Design Flow

A.      A 4.15 General Permit allows for the construction and use of an aerobic system that uses aeration for treatment.

1.        Definition. For purposes of this Section, an “aerobic sys- tem” means a treatment unit consisting of components that:

a.         Mechanically introduce oxygen to wastewater,

b.        Typically provide clarification of the wastewater after aeration, and

c.         Convey the treated wastewater by pressure or grav- ity distribution to the disposal works.

2.        An applicant may use an aerobic system if:

a.         Enhanced biological processing is needed to treat wastewater with high organic content,

b.        A soil or site condition is not adequate for installa- tion of a standard septic tank and disposal works under R18-9-E302,

c.         A highly treated wastewater amenable to disinfec- tion is needed, or

d.        Nitrogen removal from the wastewater is needed and removal performance of the system is documented according to subsection (C)(6).

B.       Performance.

1.        An applicant shall ensure that the aerobic system is designed so that the treated wastewater released to the native soil meets the following criteria:

a.         TSS of 30 milligrams per liter, 30-day arithmetic mean;

b.        BOD5 of 30 milligrams per liter, 30-day arithmetic mean;

c.         Total nitrogen (as nitrogen) of 53 milligrams per liter, five-month arithmetic mean, or as low as 15 milligrams, five-month arithmetic mean per liter if documented under subsection (C)(6); and

d.        Total coliform level of 300,000 (Log10 5.5) colony forming units per 100 milliliters, 95th percentile.

2.        An applicant may use an aerobic system that meets the following less stringent performance criteria if the aero- bic technology is listed by the Department under R18-9- A309(E) and the Department bases its review and listing on the technology being less costly and simpler to operate when compared to other aerobic technologies:

a.         TSS of 60 milligrams per liter, 30-day arithmetic mean;

b.        BOD5 of 60 milligrams per liter, 30-day arithmetic mean;

c.         Total nitrogen (as nitrogen) of 53 milligrams per liter, five-month arithmetic mean, or as low as 15 milligrams, five month arithmetic mean per liter, if documented under subsection (C)(6); and

d.        Total coliform level of 1,000,000 (Log10 7) colony forming units per 100 milliliters, 95th percentile.

C.      Notice of Intent to Discharge. In addition to the Notice of Intent to Discharge requirements specified in R18-9-A301(B) and R18-9-A309(B), an applicant shall submit:

1.        The name and address of the aerobic system manufac- turer;

2.        The model number of the aerobic system;

3.        Evidence of performance specified in subsection (B)(1) or (B)(2), as applicable;

4.        A list of pretreatment components needed to meet perfor- mance requirements;

5.        A copy of the manufacturer’s warranty and operation and maintenance recommendations to achieve performance over a 20-year operational life; and

6.        If the aerobic system will be used for nitrogen removal from the wastewater, either:

a.         Evidence of a valid product listing under R18-9- E309(E) indicating nitrogen removal performance, or

b.        Specifications and third party test data corroborating nitrogen reduction to the intended level.

D.      Design requirements. In addition to the applicable require- ments in R18-9-A312, an applicant shall ensure that:

1.        The wastewater is delivered to the aerobic treatment unit by gravity flow either directly or by a lift pump;

2.        An interceptor or other pretreatment device is incorpo- rated if necessary to meet the performance criteria speci- fied in subsection (B)(1) or (2), or if recommended by the manufacturer for pretreatment if a garbage disposal appli- ance is used;

3.        A clarifier is provided after aeration for any treatment technology that achieves performance that is equal to or better than the performance criteria specified in subsec- tion (B)(1); and

4.        Ports for inspection and monitoring are provided to verify performance.

E.       Installation requirements. In addition to the applicable require- ments in R18-9-A313(A), an applicant shall ensure that:

1.        The installation of the aerobic treatment components con- forms to manufacturer’s specifications that do not con- flict with Articles 1 and 3 of this Chapter and to the design documents specified in the Construction Authori- zation issued under R18-9-A301(D)(1)(c); and

2.        Excavation and foundation work, and backfill placement is performed to prevent differential settling and adverse drainage conditions.

F.       Operation and maintenance requirements. The permittee shall:

1.        Follow the applicable requirements in R18-9-A313(B), and

2.        Ensure that filters are cleaned and replaced as necessary.

G.      Reference design.

1.        An applicant may use an aerobic system that achieves the applicable performance requirements by following a ref- erence design on file with the Department.

2.        An applicant using a reference design shall submit, with the Notice of Intent to Discharge, supplemental informa- tion specific to the proposed installation on a form approved by the Department.

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).