Ind. Admin. Code tit. 410, r. 6-8.3-76 – Subsurface trench flood dosed on-site sewage systems: design and construction requirements

Sec. 76. (a) Subsurface trench flood dosed on-site sewage systems shall meet all of the requirements of:

(1) sections 74 and 75 of this rule; and
(2) this section.

(b) When a subsurface trench flood dosed soil absorption system is used, the dosing effluent pump shall be sized, and its controls set to deliver the DDF to the soil absorption field in each dose. Effluent pump selection shall be based on manufacturer's pump curves for the required discharge rate from Table VII, as follows, at the total head imposed on the pump:

Table VII – Required Effluent Pump Discharge Rates for Subsurface Trench Flood Dosed On-Site Sewage Systems
Number of Bedrooms	Discharge Rate in Gallons per Minute
1	30-35
2	30-35
3	30-45
4	30-60
5	38-75
6	45-90

(c) The total head for a subsurface trench flood dosed soil absorption system shall be the elevation difference between the effluent pump off and the highest point in the force main or the outlet of the effluent force main in the distribution box, whichever is the highest elevation, in addition to the friction loss in the effluent force main expressed in feet.

(d) The effluent force main shall drain unless it is installed below the frost line, as listed in Table VIII, as follows, and designed so that no effluent remains in any portion of the effluent force main located above the frost line:

Table VIII – Frost Penetrations in Indiana (in inches)
Adams	60	Franklin	48	Lawrence	48	Rush	54
Allen	60	Fulton	60	Madison	60	St. Joseph	60
Bartholomew	48	Gibson	42	Marion	54	Scott	36
Benton	60	Grant	54	Marshall	60	Shelby	54
Blackford	60	Greene	54	Martin	48	Spencer	36
Boone	54	Hamilton	54	Miami	60	Starke	60
Brown	48	Hancock	54	Monroe	48	Steuben	60
Carroll	60	Harrison	36	Montgomery	60	Sullivan	54
Cass	60	Hendricks	54	Morgan	48	Switzerland	42
Clark	36	Henry	54	Newton	60	Tippecanoe	60
Clay	54	Howard	60	Noble	60	Tipton	60
Clinton	54	Huntington	60	Ohio	42	Union	48
Crawford	36	Jackson	48	Orange	42	Vanderburgh	36
Daviess	48	Jasper	60	Owen	54	Vermillion	60
Dearborn	48	Jay	60	Parke	60	Vigo	60
Decatur	48	Jefferson	42	Perry	36	Wabash	60
Dekalb	60	Jennings	48	Pike	42	Warren	60
Delaware	60	Johnson	54	Porter	60	Warrick	36
Dubois	42	Knox	48	Posey	42	Washington	36
Elkhart	60	Kosciusko	60	Pulaski	60	Wayne	54
Fayette	54	LaGrange	60	Putnam	54	Wells	60
Floyd	36	Lake	60	Randolph	54	White	60
Fountain	60	LaPorte	60	Ripley	48	Whitley	60

(e) In addition to the liquid holding capacity of a dosing tank stated in section 62(f) of this rule the following shall apply:

(1) If the effluent force main drains to the soil absorption system, or if it does not drain between doses, the dose volume shall be the DDF.
(2) If the effluent force main drains back to the dosing tank, the dose volume shall be the DDF plus the volume contained in the effluent force main.

(f) The distal end of the effluent force main in the distribution box must be fitted with an elbow turned down or a sanitary tee, or else the distribution box must be baffled.

(g) The minimum inside diameter of the effluent force main shall be one (1) inch. The maximum inside diameter of the effluent force main shall be four (4) inches.

(h) Tables IX and X, as follows, shall be used in determining friction losses in the effluent force mains and manifold when plastic pipe is used:

Table IX – Friction Losses in Plastic Pipe (per 100 feet of pipe)
Pipe Diameter, Flow (gpm), Velocity (v)², and Friction Loss Head (H_f)¹
Flow (gpm)	1"		1 1/4"		1 1/2"		2"		2 1/2"		3"		4"
Q	v	H_f	v	H_f	v	H_f	v	H_f	v	H_f	v	H_f	v	H_f
1	0.37	0.11
2	0.74	0.38	0.43	0.10
3	1.11	0.78	0.64	0.21	0.47	0.10
4	1.49	1.31	0.86	0.35	0.63	0.16
5	1.86	1.92	1.07	0.52	0.79	0.24
6	2.23	2.70	1.29	0.71	0.95	0.33	0.57	0.10
8	2.97	4.59	1.72	1.19	1.26	0.56	0.77	0.17
10	3.71	6.90	2.15	1.78	1.58	0.83	0.96	0.25	0.67	0.11
15	5.57	14.7	3.22	3.76	2.37	1.74	1.43	0.52	1.01	0.22
20	7.43	25.2	4.29	6.42	3.16	2.96	1.91	.87	1.34	0.37	0.87	0.13
25	9.28	38.6	5.37	9.74	3.94	4.46	2.39	1.29	1.68	0.54	1.09	0.19
30			6.44	13.6	4.73	6.27	2.87	1.81	2.01	0.76	1.30	0.26
35			7.51	18.2	5.52	8.40	3.35	2.42	2.35	1.01	1.52	0.35	0.88	0.10
40			8.59	23.6	6.30	10.7	3.83	3.12	2.68	1.28	1.74	0.44	1.01	0.12
45					7.09	13.5	4.30	3.85	3.02	1.54	1.95	0.55	1.13	0.15
50					7.88	16.5	4.78	4.68	3.35	1.93	2.17	0.67	1.26	0.18
60					9.47	23.6	5.74	6.62	4.02	2.72	2.60	0.94	1.51	0.25
70							6.70	8.86	4.69	3.67	3.04	1.25	1.76	0.33
80							7.65	11.5	5.36	4.69	3.47	1.59	2.02	0.42
90							8.60	14.3	6.03	5.83	3.91	1.99	2.27	0.52
100									6.70	7.13	4.34	2.42	2.52	0.63
125									8.38	10.9	5.43	3.72	3.15	0.96
150											6.51	5.16	3.78	1.34
175											7.60	6.90	4.41	1.79
200											8.68	8.93	5.04	2.27
225													5.67	2.84
250													6.30	3.37
275													6.93	4.13
300													7.56	4.87
325													8.19	5.70
¹ This figure is based on flows for PVC Schedule 40 pipe (flow coefficient: C-150). Other values for friction loss may be used if documentation from the pipe manufacturer is provided with the plan submittal. Calculations using the Hazen-Williams equation may be used if provided with the plan submittal.
² Flow velocity must be at least 2 fps; flow velocities above 5 fps should be avoided.

Table X - Plastic Pipe Fittings: Friction Loss - Equivalent Length of Straight Pipe (ft.)*
Fitting:	1"	1 1/4"	1 1/2"	2"	2 1/2"	3"	4"
90° elbow, standard sharp, inside radius	5.3	6.7	7.5	8.6	9.3	11.1	13.1
90° elbow, long sweep radius	2.5	3.8	4.0	5.7	6.9	7.9	12.0
45° elbow, standard	1.4	1.8	2.1	2.6	3.1	4.0	5.1
Tee Flow (run flow)	1.7	2.3	2.7	4.3	5.1	6.2	8.3
Tee Flow (branch flow)	6.0	7.0	8.0	12.0	15.0	16.0	22.0
Gate Valve	0.6	0.8	1.0	1.5	1.6	2.0	3.0
Male/Female adapter	2.0	2.8	3.5	4.5	5.5	6.5	9.0
*Assigned values. Other values for friction loss may be used if documentation from the pipe manufacturer is provided with the plan submittal.

(Indiana Department of Health; 410 IAC 6-8.3-76; filed Oct 19, 2012, 2:06 p.m.: 20121114-IR-410120156FRA; filed Apr 9, 2014, 9:51 a.m.: 20140507-IR-410130350FRA; readopted filed Sep 26, 2018, 2:48 p.m.: 20181024-IR-410180328RFA; readopted filed Nov 14, 2024, 1:24 p.m.: 20241211-IR-410230798RFA)