7 Underground Drainage Measurement

7/23/2019 7 Underground Drainage Measurement

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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.



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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.



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V.3 Disposal of water

Disposal of water shall be given in accordance with

clause D.15 16.



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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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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.



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CAST IRON PIPE,300MM DIAMETER


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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.



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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



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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.



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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.



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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.



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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


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


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


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


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


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


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

7 Underground Drainage Measurement

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