Section 410IAC6-10.1-68. Septic tanks: general requirements

   (a) Septic tanks shall be:

(1) watertight and constructed of durable material such as concrete, fiberglass, polyethylene, or polypropylene; and

(2) protected from corrosion.

  (b) Cast in place, concrete block, wood, or metal septic tanks are prohibited.

  (c) Every septic tank shall have a minimum capacity below the water line to provide at least forty-eight (48) hours detention time.

  (d) All septic tank effluent including effluent from tanks fitted with aeration units for aerobic digestion shall discharge into a soil absorption system or other treatment system as approved in accordance with section 49(h) of this rule.

  (e) Two-compartment tanks shall meet the following requirements:

(1) The liquid volume of the first compartment shall be between one-half (1/2) and two-thirds (2/3) of the total tank volume.

(2) The divider wall shall be:

(A) monolithically cast in the tank; or

(B) permanently secured within the tank body using noncorrosive fasteners or fittings.

(3) The transfer port or ports between the compartments shall consist of two (2) or more openings with a combined area of at least fifty (50) square inches. A continuous port across the width of the divider wall is also acceptable.

(4) The transfer port or ports shall be located in the middle twenty-five percent (25%) of the liquid depth.

(5) An access opening meeting the requirements of section 69(o) of this rule must be provided above each compartment, including a riser meeting the requirements of section 69(p) of this rule, for maintenance pumping above each compartment.

  (f) When multiple tanks are used in series, no single tank may be less than seven hundred fifty (750) gallons. The larger of the two (2) tanks must be upstream of the other.

  (g) When sewage is pumped into a septic tank using a grinder pump:

(1) a two-compartment tank must be used with the sewage pumped into the first compartment; or

(2) two (2) tanks in series must be used, with the sewage pumped into the first tank.

  (h) Tanks fitted with aeration units for aerobic digestion shall:

(1) conform to NSF/ANSI Standard 40-2010, Residential Wastewater Treatment Systems, for Class I plants or to standards of an equivalent third party product testing laboratory acceptable to the department that meet or exceed the NSF/ANSI standards;

(2) bear a current registered certification mark;

(3) provide a minimum aerobic treatment capacity to properly process the design daily flow;

(4) be preceded by a septic tank that meets all of the requirements of this section and sections 69 and 71 of this rule; and

(5) discharge into a soil absorption system or other treatment system as approved in accordance with section 49(h) of this rule.

  (i) Water softener backwash shall be discharged to:

(1) the building sewer;

(2) a secondary treatment device;

(3) the effluent sewer on the downstream side of either the septic tank or the secondary treatment device;

(4) the dosing tank serving the soil absorption system; or

(5) a separate soil absorption system constructed specifically for the water softener backwash.

(Indiana State Department of Health; 410 IAC 6-10.1-68; filed Oct 19, 2012, 2:07 p.m.: 20121114-IR-410120157FRA)