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| CONSTRUCTION OF PITS |
Construction notes
The distance between the diagonally opposite corners in the figure below should be 143 cms, with an errormargin of not more than 1-2cms.
Excavation
Mark a circle in the ground using 2 sticks and a string. For a family latrine, the circle should be 1.5 meters (5 feet) across, so the string should be 75 cms long between the two sticks. For a school or community latrine, the diameter should be 1.8 meters across, so the string should mark a radius of 90-cm (3 feet)
Layout- 3:4:5 method
Put Peg A, Tie a string to it. Put another peg B 2 meter away from this peg. Put the third
peg C about 30 cms
from the peg B towards A. Take the string from Peg B to the outside of Peg C and
mark the point where the string crosses the AB line, keeping the string
straight. Mark another point 30 cms from this mark. Measure 40 cms from the
first mark along the CD line and mark a third point. The distance between the
second and the third marks should be 50 cms exactly. Place a Peg D about 1,5
meters from Peg C. Take the string from around the outside of the peg. Put Peg E
about 30 cms from Peg D. Take the string around the outside of Peg E. The string
must cross the line from C to D at 75 cms mark. Measure 75 cms again from Peg a
and put Peg F on line with Peg A. Put in Peg G and Peg H making sure that both
the long sides are 1.2 meters from the CD line. Measure the diagonals. They
should both be 143 cms with a leeway of 1-2 cms
LINING-Areas with unstable ground
Lining is a must in such areas to avoid the pit from collapsing. In areas where the ground is very stable only ring beams are required.
For Hard Ground
1. Dig to full depth, mark out 20 cms all around
2. Dig soil out 5cms deep all around
3. Put concrete on ledge&impact itwell until it is levelwith ground
4. Leave it overnight to set well.
For Soft Ground
1. Mark out an extra of 30 cms all around the pit
2. Dig the soil out until the ground is firm
3. Remove lose soil and level the ground
Lining
1. Mix 1 part cement, 3 parts sand and 6 parts aggregate
2. Pour this concrete on the ledge to form a foundation 5 cms thick
3. Put two 8mm steel bars as reinforcement in weak places
4. Leave overnight to set.
How to build Lining
The distance between the diagonally opposite corners in the figure below should be 143 cms, with an errormargin of not more than 1-2cms.
Excavation
Mark a circle in the ground using 2 sticks and a string. For a family latrine, the circle should be 1.5 meters (5 feet) across, so the string should be 75 cms long between the two sticks. For a school or community latrine, the diameter should be 1.8 meters across, so the string should mark a radius of 90-cm (3 feet)
Layout- 3:4:5 method
Put Peg A, Tie a string to it. Put another peg B 2 meter away from this peg. Put the third
peg C about 30 cms
from the peg B towards A. Take the string from Peg B to the outside of Peg C and
mark the point where the string crosses the AB line, keeping the string
straight. Mark another point 30 cms from this mark. Measure 40 cms from the
first mark along the CD line and mark a third point. The distance between the
second and the third marks should be 50 cms exactly. Place a Peg D about 1,5
meters from Peg C. Take the string from around the outside of the peg. Put Peg E
about 30 cms from Peg D. Take the string around the outside of Peg E. The string
must cross the line from C to D at 75 cms mark. Measure 75 cms again from Peg a
and put Peg F on line with Peg A. Put in Peg G and Peg H making sure that both
the long sides are 1.2 meters from the CD line. Measure the diagonals. They
should both be 143 cms with a leeway of 1-2 cms
LINING-Areas with unstable ground
Lining is a must in such areas to avoid the pit from collapsing. In areas where the ground is very stable only ring beams are required.
For Hard Ground
1. Dig to full depth, mark out 20 cms all around
2. Dig soil out 5cms deep all around
3. Put concrete on ledge&impact itwell until it is levelwith ground
4. Leave it overnight to set well.
For Soft Ground
1. Mark out an extra of 30 cms all around the pit
2. Dig the soil out until the ground is firm
3. Remove lose soil and level the ground
Lining
1. Mix 1 part cement, 3 parts sand and 6 parts aggregate
2. Pour this concrete on the ledge to form a foundation 5 cms thick
3. Put two 8mm steel bars as reinforcement in weak places
4. Leave overnight to set.
How to build Lining
- Pour water over concrete
- Place a layer of mortar [ 6 parts sand , 1 part cement ] at the corners and lay the corner bricks 5 cms from the edge
- After placing the first line of bricks measure the diagonals. They should be 155 cms each.
- Continue building until the lining is 10 cms above the ground level.
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