Answer Happy

Design a septic system with gravity flow subsurface soil
adsorption for a three-bedroom house with two baths and a basement
that is currently occupied by a family of four.
The building site is depicted in topographic map A and in the
cross sectional transects A3-C3, A2-C2, A1-C1. Based on an initial
site investigation, soil percolation tests were conducted in areas
C1 and A3 to assess their suitability as locations for the
absorption bed. The pertinent data from these tests is given
below.
Area C1
Water Level Drop in Inches per 30 Minute Interval
Percolation Rate (min/in)
Hole
1
2
3
4
5
6
7
8
1
3.56
.57
.36
1.24
.22
1.22
1.21
1.2
2
2.2
1.78
1.1
.78
.64
.63
.65
.65
3
2.44
1.46
1.02
.76
.8
.92
.75
.71
4
1.76
.78
1.6
1.44
1.36
.28
1.26
1.26
5
1.85
1.5
.92
.87
.8
.78
.78
.78
Average:
Area A3
Water Level Drop in Inches per 30 Minute Interval
Percolation Rate (min/in)
Hole
1
2
3
4
5
6
7
8
1
1.34
0.94
0.90
0.88
0.84
0.78
0.76
0.75
2
1.45
1.18
0.98
0.92
0.9
0.88
0.88
0.86
3
0.98
0.88
0.84
0.81
0.82
0.80
0.79
0.77
4
1.14
0.96
0.9
0.87
0.85
0.84
0.82
0.83
5
1.21
1.02
0.92
0.88
0.85
0.83
0.82
0.81
Average:
Your solution to this exercise should include the following and
should be in accord with the State of Virginia “Sewage Handling and
Disposal Regulations” (A summary of the appropriate regulations is
available within the course notes):
a) The design and sizing of a septic tank. This design should
include a fully labeled sketch that notes all appurtenances.
b) The design for a complete gravity, subsurface trench
drainfield system. Depict your system on the layout sketch for the
site and note all setback distances. Discuss the reasons behind
your choice of a location for the drainfield.
c) If you were to utilize a bed-based design, how would the
surficial area of your drainfield change? (Answer
qualitatively)
3 A3- 2 A2 A1 1 964' A3 964' A2 964' A1 6' 10' 9' 200 ft House A Well 8' 12' 11' 962 B Groundwater Flow Direction V 10' 9' 946 942 950 954' 958' C3 C2 C1 C3 958' 11' C2 958' 10' C1 Property Boundary