Section 410IAC6-10.1-90. Elevated sand mound on-site sewage systems: pressure distribution network

   (a) The effluent force main shall drain unless it is installed below the frost line, as listed in Table IX in section 84(d) of this rule, and designed so that no effluent remains in any portion of the effluent force main located above the frost line.

  (b) The effluent pump shall be sized, and its controls set, to deliver approximately one-fourth (1/4) of the DDF per dose.

  (c) The liquid holding capacity of the dosing tank shall be determined as follows:

(1) If the effluent force main and manifold do not drain to the dosing tank, the dosing tank volume shall be one-fourth (1/4) of the DDF.

(2) If the effluent force main and manifold drain to the dosing tank, the dosing tank volume shall be one-fourth (1/4) of the DDF plus the volume of the effluent force main.

(3) Additional dosing tank capacity must be provided to:

(A) keep the dosing tank effluent pump submerged at all times; and

(B) provide sufficient freeboard for a high water alarm.

  (d) The minimum inside diameter of the effluent force main shall be one and one-half (1 1/2) inches. The maximum inside diameter of the effluent force main shall be four (4) inches.

  (e) Tables X and XI in section 84(h) of this rule, or equivalent tables provided by the pipe manufacturer, shall be used in determining friction losses in the effluent force main and manifold when plastic pipe is used. The Hazen-Williams equation may also be used to determine friction loss in the effluent force main and manifold.

  (f) The design of the pressure distribution network shall meet the following requirements:

(1) The effluent force main shall approach the elevated sand mound as follows:

(A) On sites with slopes of one-half percent (1/2%) or less, from either end.

(B) On sites with slopes greater than one-half percent (1/2%) and less than or equal to six percent (6%), from the upslope side. If approach from the upslope side of the elevated sand mound is not possible due to site limitations, the effluent force main may approach from either end.

(2) The design (location) of the effluent force main shall provide for minimal disturbance of the basal area during installation.

  (g) Manifolds shall be installed between the effluent force main and the pressure distribution laterals as follows:

(1) The manifold shall be located in the aggregate bed.

(2) The manifold pipe shall:

(A) for on-site sewage systems with a DDF of seven hundred fifty (750) gallons per day or less, have a diameter of two (2) inches; or

(B) for on-site sewage systems with a DDF of greater than seven hundred fifty (750) gallons per day, have the same diameter as the effluent force main or a diameter of two (2) inches, whichever is greater, but no greater than four (4) inches.

  (h) The pressure distribution laterals shall meet the following requirements:

(1) Each pressure distribution lateral shall connect directly to the manifold.

(2) The length of each lateral shall be calculated as: Lateral length (L_Lat) = (AB_L- 3)/2

(3) No single pressure distribution lateral (from the manifold to the end cap) shall exceed fifty-five (55) feet in length.

(4) The diameter of the pressure distribution laterals shall be determined from Table XVII, as follows:

Table XVII - Pressure Distribution Lateral Diameter for Elevated Sand Mounds*
Lateral Length, L (ft.)	L ≤ 25 ft.	25 ft. < L ≤ 40 ft.	40 ft. < L ≤ 55 ft.
Diameter (in.)	1 in.	1 1/4 in.	1 1/2 in.
*Pressure distribution lateral diameters for one-quarter (1/4) in. holes spaced at three (3) ft. on centers.

(5) Pressure distribution laterals shall have one (1) row of holes with three (3) feet on center spacing.

(6) The holes in the pressure distribution laterals shall be one-quarter (1/4) inch in diameter.

(7) The number of holes per lateral, including the hole in the end cap, shall be calculated as:

Number of holes per lateral = (L_Lat – 1.50/3) + X;

where: X = 1 if R < 0.5; and X = 2 if R ≥ 0.5; and

R = the remainder from the mathematical equation.

(8) The first hole in each lateral shall be eighteen (18) inches from the center of the manifold.

(9) The last hole in the pressure distribution lateral before the end cap shall be at not less than eighteen (18) inches and not more than thirty-six (36) inches from the end cap.

(10) The end of each lateral shall be capped, and a one-fourth (1/4) inch hole shall be drilled in the upper half of the end cap.

(11) Burrs shall be removed from the edges of all holes and from the interiors of all laterals.

(12) All pressure distribution laterals shall be:

(A) at the same elevation; and

(B) level throughout their lengths.

(13) The pressure distribution laterals shall be placed in the aggregate bed with all holes, except the end cap holes, facing down.

  (i) Pressure distribution laterals shall be laid out as shown in Figure 2, as follows:

(1) The separation distance between pressure distribution laterals shall be not less than twenty-four (24) inches and not more than thirty-six (36) inches.

(2) Pressure distribution laterals shall be located not less than twelve (12) inches and not more than eighteen (18) inches from the sides of the aggregate bed along the length of the lateral.

(3) Pressure distribution laterals shall be attached to the manifold using nondirectional fittings designed to withstand the required pressures exerted on them.

(4) The end of each pressure distribution lateral with the hole in the end cap of the lateral shall be eighteen (18) inches from the end of the aggregate bed.

 

(5) All joints, including the end caps, shall withstand the pressures exerted on them.

  (j) Effluent pump selection for elevated sand mound on-site sewage systems shall be based on the manufacturer's pump curves for the required pump discharge rate at the total dynamic head imposed on the pump, as follows:

(1) The total discharge rate of the effluent pump shall be the total number of one-quarter (1/4) inch holes in all laterals (including the holes in the end caps) times one and twenty-eight hundredths (1.28) gallons per minute (gpm).

(2) The total dynamic head imposed on the pump shall be the sum of the following:

(A) The design head shall be three (3) feet.

(B) Plus friction loss in the effluent force main and manifold as determined by Tables X and XI in section 84(h) of this rule when plastic pipe is used.

(C) Plus the static head which is the difference in elevation from the effluent pump and the highest point in the effluent force main or the connection to the manifold, whichever is the highest elevation.

(Indiana State Department of Health; 410 IAC 6-10.1-90; filed Oct 19, 2012, 2:07 p.m.: 20121114-IR-410120157FRA)