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MECHANICAL & ELECTRICAL WORKS
MEASUREMENT (SBEQ3213)
Week 7 : Underground Drainage
Sr. Dr. Sarajul Fikri Mohamed
Faculty of Built Environment
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MEASUREMENT FOR PLUMBING WORKS
Divided into 4 section:
1. Cold water installation
2. Sanitary fittings
3. Soil, waste and vent pipe
4.Underground drainage
PLUMBING WORKS
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UNDERGROUND DRAINAGE
STAGES OF PLUMBING SYSTEM IN BUILDING
SOIL, WASTE & VENT PIPE
WASTE DISPOSAL SYSTEM
SANITARY FITTINGS
COLD WATER SERVICES
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Drainage in building can be divided into two main types:
1. STORMWATER DRAINAGE
For surface water i.e rainwater. Normally it is included
under ExternalWorks. Sometimes called surface water
drainage.
2. FOUL/SOIL DRAINAGE
For wastewater from soil and waste pipe.
TYPES OF DRAINAGE
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Separate system Combined system
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1. Trench excavation
SECTION V DRAINAGE
Generally
V.1 Information
1. Work beyond the boundary of the site shall be so described and
any restriction regarding access, etc. shall be stated.
2. The nature of the ground in which the excavations are to be
made shall be given in accordance with clause D.1.
ITEMS TO BE MEASURED
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Drains
V.2 Excavation
1. Excavating pipe trenches shall be given in METRES stating the
starting level, the depth-range in increments of 2.00 m and the
average depth within the depth-range to the nearest 0.25 m.
2. Excavating curved trenches shall be so described irrespective of
radius.
3. Earthwork support, treating bottoms, filling in compaction and
disposal of surplus soil shallbe given in the description.
ITEMS TO BE MEASURED
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Drains
V.2 Excavation (continued)
4. Trenches next to roadway, next to existing building or in unstable
ground shall each be so described.
5. Trenches in rock as defined in clause D.12.2 shall be described.
Alternatively rock may be given in METRES as EXTRA OVER the
trench in which they occur.
6. Breaking up concrete, reinforced concrete, brickwork,
tarmacadam and the like shall each be given separately in METRES
as EXTRA OVER the trench in which it occurs stating the pipe
diameter as clause V.2.3.
ITEMS TO BE MEASURED
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V.3 Disposal of water
Disposal of water shall be given in accordance with
clause D.15 16.
ITEMS TO BE MEASURED
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METHOD OF CALCULATIONMH1 MH2
G.L = 10.00
I.L = 9.45
G.L = 10.00
I.L = 7.55
Adjustment to invert level for pipe support, sand blinding and thickness of pipe:
1 Thickness of pipe 19mm
2 Concrete support 100mm
3 Blinding 25mm
TOTAL 144mm
MH1 MH2
IL 9.45
0.144 (less)
9.31 meter
IL 7.55
0.144 (less)
7.41 meter
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METHOD OF CALCULATION
Note: Excavation has to be divided into two section:
i) Not exceeding 2.00m
ii) Exceeding 2.00 but not exceeding 4.00m
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METHOD OF CALCULATIONTHEREFORE, THE AVERAGE DEPTH FOR (I) SECTION
THEREFORE, THE LENGTH OF EXCAVATION FOR (I) SECTION I.E XM:
Note: The length of (x+y) can be measured directly from drawing.
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EXAMPLE : Trench excavation
Excavate trench for pipe not exceeding 200 mm nominal size starting
from ground level not exceeding 2.00 m deep average 1.50 m deep
including support, grading bottom, filling in, compaction and disposal of
surplus soil as directed.
x Stage (i) n.e 2.00 m deep
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METHOD OF CALCULATION
Once the length of x is known, the length for y can be establish bysubtracting the value of x from the length of (x+y).
AVERAGE DEPTH FOR SECTION (II):
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EXAMPLE : Trench excavation
Excavate trench for pipe not exceeding 200 mm nominal size starting
from ground level exceeding 2.00 m but not exceeding 4.00 m deep
average 2.25 m deep as before described.
Y Section (ii) exc. 2.00 n.e 4.00 m deep
Using the same principles, calculation can be made from manhole to
manhole until it reaches the soil treatment system.
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2. Pipe/drain
Types of pipe/drain commonly used for underground drainage:
a. VITRIFIED CLAY PIPE (VCP) Nominal size : 100 mm 900 mm diameter.
b. CONCRETE PIPE
Nominal size : 150 mm 1800 mm diameter.
c. CAST IRON PIPE
Nominal size: 75 mm 900 mm diameter.
UNDERGROUND DRAINAGE
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UNDERGROUND DRAINAGE
CAST IRON PIPE,300MM DIAMETER
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UNDERGROUND DRAINAGE
INSPECTION
CHAMBER
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V.5 Pipework and surface water channels
1. Pipes (measured over all pipe fittings) shall each be given in
METRESstating the kind and quality of pipe, the nominal
size and the method of jointing. Any pipe not laid in bottomof the trench shall be given separately and the depth stated in
accordance with the depth-range stages in clause V.2.1.
UNDERGROUND DRAINAGE
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METHOD OF CALCULATION
P = Length of pipe in trench
D1 & D2 and (x+y) are known and using the
Pythagoras theorem:
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EXAMPLE : Pipe/ drain
Vitrified clay pipe and fitting with roll-in rubber ring joint to B.S 65 and
B.S 2494 as described:
100 mm diameter drain pipe, laid on concrete support (m/s) in trench
(m/s).
P (MH1
MH2)
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3. Pipe support
Types of pipe support:
a. Bedb. Haunching
c. Surround
d. Class A
e. Class B
f. Class D
UNDERGROUND DRAINAGE
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V. 4 Beds, benchings and coverings
1. Beds, benchings and coverings shall each be given separately
in METRESstating:
a. Nominal size of the pipe to be laid
b. Widths and thickness of the beds, benchings, haunching,
surround and the like.
c. Materialsfrom which the beds, benchings, haunching,
surrounds and the like are to be constructed. Anyformwork required shall be deemed to be included.
UNDERGROUND DRAINAGE
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EXAMPLE : Pipe support
100 mm thick mass concrete Grade 15 as described bed 457 mm wide
under 150 mm diameter pipe (m/s) including haunching on both sides to
center line of pipe including all necessary formwork
12.55 (MH1 MH2)
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TYPICAL HAUNCHING
150 mm thick x 450 mm wide mass concrete Grade 15 as described bed
under 150 mm diameter pipe (m/s) including surround with similar
concrete 150 mm thick including all necessary formwork.
M (measured in metre)
EXAMPLE : Haunching
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EXAMPLE : Haunching
100 mm thick crusher run bed, 457 mm wide under 100 mm diameter
pipe (m/s) including filling crusher run to center line of pipe and backfill
with 300 mm thick (minimum) selected sand compacted to Architects
approval.
M(measured in metre)
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4. Manhole
Sumps, manholes, soakways, cesspits, septic tanks, imhoff tank and
the like.
V.6 Generally
1. Sumps, manholes, soakways and the like shall each be groupedtogether and GIVEN IN DETAIL under an appropriate heading
stating the number.
2. Cesspits, septic tanks, imhoff tanks, oxidation ponds and the like
for the treatment and disposal of sewage shall each be groupedtogether and GIVEN IN DETAIL under an appropriate heading
stating the number.
UNDERGROUND DRAINAGE
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4. Manhole (continued)
V.6 Generally
3. Excavation, concrete works, brickwork and other works shall be
given IN ACCORDANCE WITH THE APPROPRIATE SECTIONS.
4. Building in ends of pipes shall be ENUMERATED stating the
nominal size of the pipe.
5. Channels, concrete benchings, step irons, covers and intercepting
traps shall each be ENUMERATED SEPARATELY stating the type,the quality, the size and the method of bedding or fixing.
UNDERGROUND DRAINAGE
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ITEMS TO BE MEASURED
Before taking off for manholes is carried out, it is good practice to prepare
Scheduleof Manholesreferring to:
a. Size of manhole (internal and external)
b. Depth of manhole (invert and excavated level)
c. Thickness of brickwall
d. Ground level
e. Thickness of base and concrete cover slab
f. Other related information
The SMM requires a heading to be establish stating the number of
manholes to be measured.
MANHOLE
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EXAMPLE : manhole
The following in 6 Nos. manholes:
1. Excavation pit for manhole
Measured in CUBIC METRE(D.12.6) according to
depth classification as in clause D.10.
2. Disposal of excavated materials
Measured in CUBIC METRESwhether disposal on site
(D.18) or off site (D.19).
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EXAMPLE : manhole
The following in 6 Nos. manholes (continued):
3. Blinding
Measured in SQUARE METRESstating the material and
the thickness .
4. Concrete bed for base
Measured in CUBIC METRESstating the thickness
according to classification as clause F.2.1.
5. Brickwall
Measured in SQUARE METRES(measured mean
length x height) stating the thickness, kind and quality of
bricks, type of bond and composition and mix of mortar.
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EXAMPLE : manhole
The following in 6 Nos. manholes (continued):
6. Plastering to internal surface of brickwall
Measured in SQUARE METRESstating the particulars
as in clause S.2.1 and measured the area in contact with
the base as in clause S.2.2.
7. Reinforced concrete suspended cover slab
Measured in CUBIC METRESstating the thickness
according to classification as clause F.2.1.
8. Formwork to soffit of suspended cover slab.
Measured in SQUARE METRES. No deduction shall be made
for voids not exceeding 1.00 m2.
.
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EXAMPLE : manhole
The following in 6 Nos. manholes (continued):
9. Formwork to edges of suspended cover slab
Measured in METRESstating the height of the edge
according to clause F.11.1.
10. Formwork to edges of concrete base slab
Similar to item (9).
11. Reinforcement to suspended cover slab/base slab
If the slab uses fabric reinforcement, it is measured in
SQUARE METRE the area covered. No deduction shall
be made for voids not exceeding 1.00 m2 (F.9.1 3).
.
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EXAMPLE : manhole
The following in 6 Nos. manholes (continued):
12. Concrete benching
Measured in NUMBER stating the quality of concrete, size
method of bedding (V.6.5).
13. Screed to concrete benching
Measured in SQUARE METRE measured the area in contact
with the base (S.2.1 2).
14. Step iron
Measured in NUMBERstating the type, quality, the size or
girth and the method of fixing (V.6.5).
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EXAMPLE : manhole
The following in 6 Nos. manholes (continued):
15. Channel
Measured in NUMBERstating the type, the quality, the size
and method of bedding (V.6.5).
16. Building in ends of pipes/drain to manhole
Measured in NUMBER stating the nominal size of pipe
(V.6.4).
17. Cast iron manhole cover
Measured in NUMBER stating the type, the quality, the
size and method of fixing (V.6.5).
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EXAMPLE : manhole
The following in 6 Nos. manholes (continued):
18. Connection to main sewer
V.7 Generally
1. Connecting ends of drains to main, making good public
highway and other work which may only be carried bya Public Undertaking or Local Authority shall be given
as PROVISIONAL SUM.
2. Connection to existing work shall be ENUMERATED
stating the size of pipe or drain and the structure.
Cutting openings, making good, jointing etc. shall bedeemed to be included with the item.
19. Testing of drains
V.8 Testing the drainage system shall be given as an
ITEM stating the method of testing.
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EXAMPLE : Manhole
The following in 6 Nos. manholes (continued):
NOTE:
Usually, when a taking off is started using a heading, it must beended with a closing remarks.
i.e
(End of 6 NOS. manhole)
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THANK YOUfor your kind attention
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