Mississippi Administrative Code › Title 15 - Mississippi Department of Health › Part 18 - Division of On-site Wastewater › Subpart 77 - On-site Wastewater Regulations › Chapter 5 - INDIVIDUAL ONSITE WASTEWATER DISPOSAL DESIGN STANDARD › Subchapter 5 - AGGREGATE REPLACEMENT › Rule 15-18-77-5.5.19 - Sizing of the Chamber System

Current through June 25, 2024
1. Chamber systems
					 installed in a trench configuration shall be sized in accordance with Table
					 VIII.
2. Chamber systems installed
					 in a bed configuration shall have the same number of chamber sections as
					 indicated for a trench system. The length and width of the bed to be
					 constructed will depend on the number of chamber sections to be installed as
					 indicated by Table VIII. Any side-by-side placement of chambers shall
					 constitute a bed.
a. Absorption beds and
					 trenches should be located a minimum of 10 feet from any trees.
b. The bottom of the bed should have a
					 relatively level grade; the grade within the bed shall not exceed the grade
					 allowed for trench installations.
c. The chambers shall be placed side by side
					 in a bed with separation between each chamber row per individual manufacturer's
					 requirements.
d. Care should be
					 taken to prevent heavy machinery from damaging the bed during backfilling.
e. The effluent must be equally
					 distributed to the bed by means of a distribution box or with a pipe manifold.
SETBACK REQUIREMENTS FROM SENSITIVE WATER
Minimum Distance from the Water Edge
Soil Textural Class
Slope of Less Than 8 Percent
Slope of More Than 8 Percent
Gravel
NOT APPLICABLE
Coarse
Sand
50 feet
50 feet
Medium
Sand
50 feet
50 feet
Fine
Sand
50 feet
50 feet
Loamy Sand
50 feet
50 feet
Sandy Loam
50 feet
50 feet
Light
Loam
50 feet
50 feet
Heavy
Loam
50 feet
50 feet
Silt Loam
50 feet
50 feet
Sandy Clay Loam
50 feet
50 feet
Light
Clay Loam
50 feet
50 feet
Heavy
Clay Loam
50 feet
50 feet
Light
Silty Clay
								  Loam
50 feet
50 feet
Heavy
Silty Clay
								  Loam
50 feet
50 feet
Sandy Clay
50 feet
50 feet
Silty Clay
50 feet
50 feet
Clay
50 feet
50 feet
The effluent disposal setback is based on the soil
						texture of the horizon in which the absorption trench or bed is to be placed.
						These setbacks are to be used on all individual on-site wastewater disposal
						systems except
spray irrigation disposal and overland discharge
.
SIZING - AGGREGATE REPLACEMENT (Large Diameter
						Pipe)
Results of the Soil and Site Evaluation
Soil Textural Class
Ribbon Lengths (Inches)
EPA Manual
Application Rate
GPD/ Ft 
								  2
Absorption Area Per Bedroom**
Additional Absorption Area Over 2 Persons Per
								  Bedroom**
Ft 
								  2
*Lf
Ft 
								  2
*Lf
6
8
10
6
8
10
6
8
10
6
8
10
Gravel
-
-
NOT SUITABLE
Coarse
Sand
-
1.2
164
164
108
55
55
36
82
82
54
27
27
18
Medium
Sand
-
1.2
164
164
108
55
55
36
82
82
54
27
27
18
Fine
Sand
-
0.8
247
247
165
82
82
55
124
124
82
41
41
27
Loamy Sand
-
0.8
247
247
165
82
82
55
124
124
82
41
41
27
Sandy Loam
<.5
0.6
325
325
217
108
108
72
163
163
108
54
54
36
Light
Loam
<.5
0.6
325
325
217
108
108
72
163
163
108
54
54
36
Heavy
Loam
.5 - 1
0.45
437
437
290
146
146
97
218
218
145
73
73
48
Silt Loam
<1
0.45
437
437
290
146
146
97
218
218
145
73
73
48
Sandy Clay Loam
1 - 2
0.45
437
437
290
146
146
97
218
218
145
73
73
48
Light
Clay Loam
1 - 1.5
0.30
650
650
433
217
217
144
325
325
217
108
108
72
Heavy
Clay Loam
1.5 - 2.0
0.20
975
975
650
325
325
217
488
488
325
163
163
108
Light
Silty Clay
								  Loam
1 - 1.5
0.30
650
650
433
217
217
144
325
325
217
108
108
72
Heavy
Silty Clay
								  Loam
1.5 - 2.0
0.20
975
975
650
325
325
217
488
488
325
163
163
108
Sandy Clay
>2.0
-
NOT SUITABLE
Silty Clay
>2.0
-
NOT SUITABLE
Clay
>2.0
-
NOT SUITABLE
Minimum and maximum trench widths are 24 and 36 inches,
						respectively.
*Linear footages assume 24 inch trench width.
** Bedroom is equivalent to 130 gallons per day.
SIZING - AGGREGATE REPLACEMENT (Multi-Pipe
						System)
Results of the Soil and Site Evaluation
Soil Textural Class
Ribbon Lengths (Inches)
EPA Manual
Application Rate
GPD/ Ft 
								  2
Absorption Area Per Bedroom**
Additional Absorption Over 2 Person Per
								  Bedroom**
MPS -14 &
36XX 
								  ***
MPS-13
MPS-11
MPS-9
MPS-14 &
36XX 
								  ***
MPS-13
MPS-11
MPS-9
Ft 
								  2
Lf
Lf
Lf
Lf
Ft 
								  2
Lf
Lf
Lf
Lf
Gravel
-
-
NOT SUITABLE
Coarse
Sand
-
1.2
108
36
28
32
38
54
18
14
16
19
Medium
Sand
-
1.2
108
36
28
32
38
54
18
14
16
19
Fine
Sand
-
0.8
163
54
42
49
58
81
27
21
24
29
Loamy Sand
-
0.8
163
54
42
49
58
81
27
21
24
29
Sandy Loam
<.5
0.6
217
72
55
64
76
108
36
28
32
38
Light
Loam
<.5
0.6
217
72
55
64
76
108
36
28
32
38
Heavy
Loam
.5 - 1
0.45
289
96
74
86
102
144
48
37
43
51
Silt Loam
<1
0.45
289
96
74
86
102
144
48
37
43
51
Sandy Clay Loam
1 - 2
0.45
289
96
74
86
102
144
48
37
43
51
Light
Clay Loam
1 - 1.5
0.30
433
144
110
128
171
217
72
55
64
77
Heavy
Clay Loam
1.5 - 2.0
0.20
650
217
165
193
230
325
108
82
97
115
Light
Silty Clay
								  Loam
1 - 1.5
0.30
433
144
110
128
171
217
72
55
64
77
Heavy
Silty Clay
								  Loam
1.5 - 2.0
0.20
650
217
165
193
230
325
108
82
97
115
Sandy Clay
>2.0
-
NOT SUITABLE
Silty Clay
>2.0
-
NOT SUITABLE
Clay
>2.0
-
NOT SUITABLE
Minimum and maximum trench widths are 24 and 36 inches,
						respectively.
** Bedroom is equivalent to 130 gallons per day.
***XX represents either 9, 11, or 14 pipes.
SIZING - AGGREGATE REPLACEMENT (Expanded
						Polystyrene System) "Horizontal" Configuration
Results of the Soil and Site Evaluation
Soil Textural Class
Ribbon Lengths (Inches)
EPA Manual Application Rate GPD/
Ft 
								  2
Absorption Area Per Bedroom**
Additional Absorption Over 2 Person Per
								  Bedroom**
3-10H
1-12
2-12
3-12
1-14
3-10H
1-12
2-12
3-12
1-14
Ft 
								  2
Lf
Lf
Lf
Lf
Lf
Ft 
								  2
Lf
Lf
Lf
Lf
Lf
Gravel
-
-
NOT SUITABLE
Coarse
Sand
-
1.2
108
30
75
37
25
36
54
15
38
19
13
18
Medium
Sand
-
1.2
108
30
75
37
25
36
54
15
38
19
13
18
Fine
Sand
-
0.8
163
46
114
57
38
55
81
23
57
29
19
28
Loamy Sand
-
0.8
163
46
114
57
38
55
81
23
57
29
19
28
Sandy Loam
<.5
0.6
217
60
151
75
50
72
108
30
76
38
25
36
Light
Loam
<.5
0.6
217
60
151
75
50
72
108
30
76
38
25
36
Heavy
Loam
.5 - 1
0.45
289
81
201
101
67
97
144
40
101
52
33
49
Silt Loam
<1
0.45
289
81
201
101
67
97
144
40
101
52
33
49
Sandy Clay Loam
1 - 2
0.45
289
81
201
101
67
97
144
40
101
52
33
49
Light
Clay Loam
1 - 1.5
0.30
433
120
299
153
100
144
217
60
100
77
50
72
Heavy
Clay Loam
1.5 - 2.0
0.20
650
178
449
225
150
217
325
89
225
113
75
109
Light
Silty Clay
								  Loam
1 - 1.5
0.30
433
120
299
153
100
144
217
60
100
77
50
72
Heavy
Silty Clay
								  Loam
1.5 - 2.0
0.20
650
178
449
225
150
217
325
89
225
113
75
109
Sandy Clay
>2.0
-
NOT SUITABLE
Silty Clay
>2.0
-
NOT SUITABLE
Clay
>2.0
-
NOT SUITABLE
Minimum and maximum trench widths are 24 and 36 inches,
						respectively.
** Bedroom is equivalent to 130 gallons per day.
SIZING - AGGREGATE REPLACEMENT (Expanded
						Polystyrene System) "Triangular" Configuration
Results of the Soil and Site Evaluation
Soil Textural Class
Ribbon Lengths (Inches)
EPA Manual
Application Rate
GPD/ Ft 
								  2
Absorption Area Per Bedroom**
Additional Absorption Over 2 Person Per
								  Bedroom**
3-10 Inch
3-10 Inch
Ft 
								  2
Lf
Ft 
								  2
Lf
Gravel
-
-
NOT SUITABLE
Coarse
Sand
-
1.2
54
27
26
13
Medium
Sand
-
1.2
54
27
26
13
Fine
Sand
-
0.8
83
42
42
21
Loamy Sand
-
0.8
83
42
42
21
Sandy Loam
<.5
0.6
109
55
55
28
Light
Loam
<.5
0.6
109
55
55
28
Heavy
Loam
.5 - 1
0.45
146
73
73
36
Silt Loam
<1
0.45
146
73
73
36
Sandy Clay Loam
1 - 2
0.45
146
73
73
36
Light
Clay Loam
1 - 1.5
0.30
217
108
109
55
Heavy
Clay Loam
1.5 - 2.0
0.20
326
163
163
81
Light
Silty Clay
								  Loam
1 - 1.5
0.30
217
108
109
55
Heavy
Silty Clay
								  Loam
1.5 - 2.0
0.20
326
163
163
81
Sandy Clay
>2.0
-
NOT SUITABLE
Silty Clay
>2.0
-
NOT SUITABLE
Clay
>2.0
-
NOT SUITABLE
Minimum and maximum trench widths are 24 and 36 inches,
						respectively. The
Triangular Configuration
can only be installed
						in a trench.
** Bedroom is equivalent to 150 gallons per day.
CHAMBER SYSTEM
Classification
CLASS
SQUARE FEET/CHAMBER SECTION
7.51 - 9.50
II
9.51 - 11.50
III
11.51 - 13.50
IV
13.51 - 15.50
V
15.51 - 17.50
VI
17.51 - 19.50
VII
19.51 - 21.50
VIII
21.51 - 23.50
SIZING - AGGREGATE REPLACEMENT (Chamber
						System)
Results of the Soil and Site Evaluation
Soil Textural Class
Ribbon
Lengths
(Inches)
EPA Manual Application Rate GPD/ Ft 
								  2
Absorption Area in Ft 
								  2 Per
								  Bedroom**
Number of Pieces Per Bedroom based on Chamber
								  Class**
Additional Pieces Over 2 Persons Per Bedroom
								  Based on Chamber Class**
I
II
III
IV
I
II
III
IV
Gravel
-
-
NOT SUITABLE
Coarse
Sand
-
1.2
76
9
7
6
5
5
4
3
3
Medium
Sand
-
1.2
76
9
7
6
5
5
4
3
3
Fine
Sand
-
0.8
115
13
11
10
8
7
6
5
4
Loamy Sand
-
0.8
115
13
11
10
8
7
6
5
4
Sandy Loam
<.5
0.6
152
17
15
12
10
9
8
6
5
Light
Loam
<.5
0.6
152
17
15
12
10
9
8
6
5
Heavy
Loam
.5 - 1
0.45
204
23
19
16
14
9
8
6
5
Silt Loam
<1
0.45
204
23
19
16
14
12
10
8
7
Sandy Clay Loam
1 - 2
0.45
204
23
19
16
14
12
10
8
7
Light
Clay Loam
1 - 1.5
0.30
303
33
28
24
21
17
14
12
11
Heavy
Clay Loam
1.5 - 2.0
0.20
455
50
43
34
30
25
22
17
15
Light
Silty Clay
								  Loam
1 - 1.5
0.30
303
33
28
24
21
17
14
12
11
Heavy
Silty Clay
								  Loam
1.5 - 2.0
0.20
455
50
43
34
30
25
22
17
15
Sandy Clay
>2.0
-
NOT SUITABLE
Silty Clay
>2.0
-
NOT SUITABLE
Clay
>2.0
-
NOT SUITABLE
Minimum and maximum trench widths are 18 and 36 inches,
						respectively.
** Bedroom is equivalent to 150 gallons per day.
Figure I - Top View of Connecting Laterals for
						Large Diameter Pipes
Click Here To View
						Image
Figure II - Connection Laterals of Multi-pipe
						System, Expanded Polystyrene System, and Chamber System
Click Here To View
						Image