external services-road & drainage

7/30/2019 External Services-Road & Drainage

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E2-E3/Civil Rev date: 01-04-11

BSNL India For Internal Circulation Only Page: 1

E2-E3: CIVIL

CHAPTER-4

EXTERNAL SERVICES ROAD

&

DRAINAGE


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External Services Road & Drainage

SSaannii ttaarryy IInnssttaa ll llaatt iioonnss Basic Philosophy

It is a non pressure system, in a building is a non pressuresystem. This means that hydraulic pressure does not exist in the

systems against water supply which is a pressure system. In case

of water supply there is always full bore flow where it is

essential that sanitary pipe should not have flow more than 1/4 to

3/4 of its bore capacity if noise in the system and excessive air

pressure fluctuation are to be avoided. The flow in the vertical

stack finally becomes horizontal at bottom The self cleansing

velocity concept therefore becomes important should serve the

primary purpose of convenience and comfort to provide a

system of conduits which are designed to be self cleansing while

conveying soil, waste water to the sewer without risk of nuisance

and Hazard to health. To carry waste and soil water without any

leakages Water tight & air tight easy access for cleaning most of

the horizontal branches will not have a continues flow but only a

surge flow which is sufficient for cleaning However a cleansing

velocity of 1 Mt/sec is recommended

Design

All fittings are not in constant use therefore if the system isdesigned assuming all fixtures being used continuously it would

be uneconomical, would also make velocity of flow less making

it less than self cleansing velocity leading to deposition of solids

The probabilities of simultaneous discharge are:

0 in 10 probability 1.000






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For office buildings, size could be decided on following

considerations

Layout should be as simple as possible Make sure that WCs discharge directly in to the stack without

unnecessary bends

Pipes should be approachable Pipes when not embedded should run clear on t he wall Holes made in the wall for laying of pipes should be closed to

stop entry of mosquitoes

Any unused drain pipe should be demolished to keep it free fromrodents

Gradient and pipe sizes

The self cleansing velocity of 0.75 m/sec should be aimed Sometimes people tend to increase the Dai. of pipe where

gradient is not available.

Wherever not possible a flatter gradient can be used but min.velocity should not be less than 0.61 m/sec

wherever unavoidable velocity should not be greater than 2.4m/sec- If so use Cast-iron pipes

The approximate gradients which give this velocit y when flowinghalf full are as follows

DIA mm GRADIENT DISCHARGE

m3/min.

100 1 IN 57 0.18

150 1 IN100 0.42

200 1 IN 145 0.73

230 1 IN 175 0.93

250 1 IN 195 1.1

300 1 IN 250 1.7

DIA. GRADIENT DISCHARGE

100 1 IN 5.6 0.59

150 1 IN 9.7 1.32

200 1 IN 14 2.40

230 1 IN 17 2.98

250 1 IN 19 3.60

300 1 IN 24.5 5.30


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Fixture Unit Value

Flow in the stack depends upon simultaneous probable use ofappliances. All appliances do not have similar discharge rate andcharacteristic Hence one way to approach the problem would be

to assign some weight age to each appliances-

Loading Unit

Layout of Sewer System:

Flowing layout for sewer system may be followed:-

Separate System Combined System Partially Separate System

sl.no Type of fixtures load factors

1 kitchen sink(with drain board) 3

2 Kitchen sink, 2

3 Wash basin 1

4 shower 2

5 urinal,wall lip 4

6 urinal stall 4

7 water closet,tank operated 4

8 water closet,valve operated 8

* A shower head above bath tub does not increase the f ixture value

** Wash basin with 32mm and 40 mm trap hav e tha same load v alue

FIXTURE UNITS FOR DIFFERENT SANITARY APPLIANCES

SI.NO FIXTURE TRAP SIZE FIXTURE UNIT VALUE1 30 MM OR SMALLER 1

2 40 MM 2

3 50 MM 3

4 65MM 4

5 75MM 5

6 100MM 6

FIXTURE UNITS VALUE FOR FIXTURES BASED ON FIXTURE DRAIN OR TRAP SI


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Comparison of Separate & Combined System

Separate Combined

1. Quantity to be treated isless

2. More suitable for areahaving more intensity of

rainfall

3. It sewage pumping isrequired more suitable

4. Cheaper; storm water inopen drains

5. Less degree of sanitation.Storm water directly

disposed

6. Difficult to use in narrowstreets

7. If less intensity through-outyear Not suitable

Treatment cost is high

More suitable for areas havingless rainfall

Cost of pumping is high because

load increases

Overall construction cost is more

than separate.

High degree of sanitation is

achieved

Suitable for narrow streets.

More suitable.

Merits and demerits of partially separate system

Merits:

1. Economical with reference to a combined system. More efficientwith reference to a separate system.

2. House plumping is reduced (bath & Kitchen sullage taken fromsame pipe).

3. No flushing required.Demerits:

1. Possibility of overflow.2. In dry weather. Self-cleaning velocity may not be obtained.

Some Important Points

Two type of pipes are available Sand cast iron pipes -conforming to 1759-available in

1.8 m length-

spun cast iron pipes conforming to 3989-available in1.74 m length

There is a tendency on the part of contractor to use Rain watergrade pipes

There is a tendency to use more of yarn and less of lead


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Sanitary fittings are classified as First, Commercial& off grade,A the standard companies mark commercial fittings boldly. The

commercial quality wall have defects which are not visible but

the later performance is poor. off grade fittings should be

avoided at all costs

Check list

Pipes-check for size and strength of materials Valves- check for conformity to specification for fitting pressure Check jointing Check that all installations are approachable for maintenance Check standard weights, Dimensions Check clamps check Quality of lead Water tanks, size, fittings, whether mosquito proof-whether lid

fixes properly

General lines and levels of installationsSome Common Usual Defects

In laying Less slope No provision for clean out Incorrect &improper jointing Pipes not periodically cleaned pipes & joints not tested incorrect supervision

In designing flat slope results Numerous pipe joints result Network clash with each other No provision for clean out

Important Pipes less than 75 mm should not be used as waste pipes For self cleansing velocity use:

use slope not less than 1 in 48 for 100 mm pipe 1 in 36 for 75 mm pipe

General Guidelines for execution o f works.

1. Plinth level is to be decided with reference to compound drainage

scheme. Compound drainage should be finalized prior to giving the

layout of the building.


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2. Casting of RCC slab should be depressed to the following extent,

W.C 600mm, Bath 300mm, Kitchen 300mm, Balcony 150mm.

As soon as the structural / Architectural drawings for the slab and

beams are received, the problem of taking out soil and waste pipes

should be studied thoroughly. Due to carelessness on this account, theentire purpose of giving above depressions may be defeated.

3. Before starting the work of flooring, Floor level plan should be

finalized showing the final levels of rooms, bathroom, Kitchen,

balcony and W.C. etc.

4. Bathroom flooring should have a drop of 20mm from the outer face

of the shutter with further slope of 1 in 72 towards trap.

5. W.C. flooring should have a cut of 25mm. From the outer face of

the shutter with further slop of 1 in 60 towards trap.

6. Kitchen and balcony should have a fillet of 20mm with a further

slope of 1 in 100.

7. Separate plans for Bathroom, W.C. Toilet and Kitchen details

should be drawn from the utility point of view. All the traps with

levels should be marked in the plan. Layout of G.I pipes (inlet and

outlet) is also to be shown along with layout of trap and soil / waste

pipes in different colors. Numbers of urinals / wash basins are not to

be provided blindly as shown in the Architectural drawings. In case 3

urinals /2 wash basins have been shown but the space available can

accommodate only 2 urinals / 1 wash basin, it will be advisable to go

for 2 urinals / 1 wash basin ins tead of making it congested.

8. Drops for rain water pipes, soil pipes, waste pipes, vent pipes, GI

Inlet and outlet pipes should be drawn on plan and elevation in

different colors immediately on award of work.

9. The niche of 35cm. X 55cm. With a dividing self, should beprovided to serve as storing space for soap & surf etc. at the proper

location after making proper study of bathroom plan.

10. Instead of Glass shelf a Niche of size 150 x 110 mm equal to the

width of wash basin should be provided in the brick wall above the

wash Basin with a slope of 1 in 20.

11. Only one tap should be provided in the wash basin where water

supply is being fed from one source. No tap in wash basin should be

provided where proper water suppl y system does not exist.

12. Dado of at least 15cm. Should be done along with the flooring ofW.C., bath and kitchen and is to be rounded at the junction.


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13. Black chips should not be added in Terrazzo flooring of W.C. bath

and kitchen.

14. Height (finished) of wash basin, cooking platform and urinalsshould be 800, 775 and 630 mm. r espectively.

15. The plastering and white washing work in W.C. and bathroom is

generally observed to be poor in finishing. White washing should not

be allowed till the plastering has been done properly.

16. The width of door in W.C. and Bathroom should not exceed 700

mm and 750 mm respectively.

17. Terrace drainage plan should be prepared showing slope and

levels in advance before actual execution of Ter racing.

18. Terracing should be allowed to start only after the work of khurra

and rain water pipes have been completed.

19. Khurra of size 600 x 600 instead of 450 x 450 should be

provided.

20. RCC tanks should be provided instead of M.S. / Sintex tanks

specially where there is no provision of vertical extension. The clear

space available between bottom of the tank and Terracing ( finished )

should not be less than 600 mm.

21. Schedule of doors, windows, ventilators ( fixed & open able )

with drawing drawn to scale showing sizes with reference to grill

details should be finalized immediately on award of work.

22. While fixing steel windows, sagging of lintels / chajjas andthickness of the plaster below lintel and on jams is not considered

with the result , opening of windows becomes difficult. The thickness

of the plastering on lintel and jams should be kept in mind while

leaving opening in brick work for windows or while preparing the

schedule of door and windows.

23. Geometry of jams of the door and windows and also that of niches

and chajjas / fins should be in true plan.


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24. Windows provided in the stair case partly above and partly below

the landing are not desirable.

25. All the windows must be operated by J.E / A.E. to confirm that

the windows are opening and closing smoothly and properly.

26. Finished thickness of RCC shelves should not exceed 40 mm.

Finished thickness of RCC railing should not exceed 65 mm. The

corner of plaster on brick work, RCC should be rounded.

27. Details of cupboard and wardrobe should be drawn from utility

point of view. Hanger height in wardrobe should not be less than

1000mm and depth not less than 520 mm. Inside surface should be

neatly finished.

28. Stair case details with reference to Tread, Riser, angle iron nosing,

Railing with hand rail should be studied properly before asking the

contractor to start the work blindly. Inverted and projected Angle Iron

nosing should be provided on the steps of stair case and open

platform. Treads should have dead level.

29. Parapet should have a slope of 1 in 3, 40 mm. CC 1:3:6 coping

should be provided at the top of parapet with projection of 2 0mm on

the inner face.

30. Drip moulding is to be p rovided in chajjas & balconies etc.

31. Junction of outer wall and chajjas should be rounded with

sufficient slope towards spouts to check dampness.

32. Water supply including water connection, sewerage scheme

including sewer connection / septic tank and internal roads along with

compound wall should be complete along with building from the users

point of view. Effort for solving the difficulty such as U.G. tank,Pump house, O.H. tank, pumps, water / sewer connection should be

taken much in advance, right from framing of Preliminar y Estimate to

the award of work, if the provision did not exist in the sanctioned

Preliminary estimate.

33. Data required by the EE (E) for installing the pumps should be

supplied as early as possible to minimize the chance of getting

unnecessary blame for the delay of installation of pumps.


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34. Copy of specifications, D.S.R., P.E, D.E (Schedule of Quantities )

and plinth area rates should be available at the site at least for the

major work.

35. Registers such as cement and steel register, Drawing (Structuraland Architectural) register, Hindrance Register, site order book,

Technical register in proper Performa should be available at site.

Road Work

Review of Geometric Design Standards for Rural Roads in

Plains S.

No.Item As per IRC:SP:20 (Rural Roads Manual)

1. Classification (a) Other District Roads (b) Village Roads

2. Carriageway width 3.75m but can be reduced to 3.00m where trafficless than 100 motorised vehicle per day.

3. Roadway width minimum ODR and VR : 7.5 m for traffic more than100 motorised vehicles per day

: 6.0 m for t raffic less than 100

motorised vehicles per day

4. Widening at Curves Widening of Pavement and Roadway Upto 20m radius 0.9 m

21 60m radius 0.6 m More than 60 m radius Nil

5. Width of Bridges 5.5 m

4.25 m where traffic less than 100 motorised

vehicles per day

6. Roadway width of culverts andcauseways

7.5 m


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7. Minimum radius of horizontalcurves

As per IRCSP:20

Plain

TerrainRolling

Terrain

(i) ODR

Ruling 90 m 60 m

Absolute

Minimum 60 m 45 m

( i i) VR

Ruling 90 m 60 m

Absolute

Minimum 60 m 45 m

8. Longitudinal gradients

Plain

TerrainRolling

TerrainRuling Gradient 3.3 % 3.3 % Limiting

Gradient 5 % 5 %

Exceptional

Gradient 6 % 6 %

Compaction Requirement for Embankment & Sub-Grade

As PER IS: 2720 (PART 8)

Sr.No.

Type ofWork/Material

Relative Compaction as percentage of Max.Laboratory Dry Density

1. Sub-Grade &Earthen

Shoulders

Not More than 97

2. Embankment Not More than 953. Expansive

Clays:

(i) Sub-Grade &

500 mm Portion

below Sub-Grade(ii) Remaining

Portion of

Embankment

Not allowed

Not more than 90

General Guide to the Selection Of Compaction Plant for Different Types of

Soil

Type of compaction

plant

Suitability of compaction plant for

different type of soil

Remarks

Cohesive

soil

Well-graded

granular and dry

Cohesive Soils

Uniformly-

graded

materials1 2 3 4 5


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1 Smooth-wheeled

roller

Suitable Suitable Suitable only

if the roller

is towed by

tractors and

the load per

cm width of

the roller is

less than 55

kg

2 Pneumatic-tyred

roller

Suitable Suitable when

load on each

wheel is more

than 2 tonnes

(tons)

Suitable only

if the roller

is towed by

tractors and

the load on

each wheel is

less than11/2 tonnes

(tons)

3 Vibratory roller Suitable

only

when the

static

load per

cm width

of the

vibratory

roller ismore

than 7 kg

Suitable Suitable; but

when the

static load

per cm width

of the

vibratory

roller is

more than 12

kg, the rollershould be

towed by

tractors.

4 Sheeps foot roller Suitable Unsuitable Unsuitable

5 Power rammer* Suitable Suitable Unsuitable

Note:- For the purpose of this table, soils are grouped as follows:-

1. Cohesive soil includes clays with upto 20 per cent of gravel andhaving a moisture content not less than the value of the plastic limit

minus 4;

2. Well-graded granular and dry cohesive soils include clays containingmore than 20 per cent of gravel and/or having a moisture content lessthan the value of the plastic limit minus 4; well graded sands and

gravels with a uniformity coefficient exceeding 10 and all shales and

clinker-ash.

3. Uniformly-graded material includes sands and gravels with auniformity coefficient of 10 or less and all sits and pulversied fuel

ashes. Any soil containing 80 per cent or more of material in the

particle size range 0.06-0.002 mm will be regarded as sit for this

purpose.

Density Requirements of Embankment & Sub-Grade Material When TestedAS PER IS : 2720 (PART 8)


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S.

No.

Type of Work Maximum Laboratory Dry

Unit Weight

1. Embankments up to 3 metres height, notsubjected to extensive flooding

Not less than 15.2

KN/Cum.

2. Embankment exceeding 3 metres heightor embankments of any height subject to

long period of inundation

Not less than 16.0

KN/Cum.

3. Sub-grade & earthenshoulders/verges/backfill

Not less than 17.5

KN/Cum.


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Possible Defects and Causes in Hot Laid Flexible PavementsDefect in

Pavement

Possible cause of defect

Insu-

ffici-

en tBitu-

me n

Mi x

ture

to oco a

rs e

Ex c

es s

finesin

mi x

Ex c

es s

Bitume n

Ex c

es s

Mo isture

inmi x

Mi x

to o

Ho tor

Bu rne d

Mi x

to o

cold

Poor

Spre

ederOp e

ra tio n

In a

de q

uateroll

in g

Over

Roll

in g

Ro l

ling

whenmi x

to oho t

Roll

in g

whenmi x

to ocold

Ro l

lers

standing

onho t

pave

ment

Ro l

lers

to ohe a

vy

Pa v

e

ropera t

in gto o

fast

Tra

ffic

al lowed

be for e

cool

Mi x

laid

into o

thicka

co u

rs e

Bleeding XBrown

Dead

Appreance

X X X

Rich Fa t

SpotsX

Poor

Surface

Texture

X X X X X X X X X

Rough

Uneven

Surface

X X X X X X X X X

Honeycomb

or rave l ingX X X X X X

Uneven

Joint sX X X X X X

Rol le r

MarksX X X X X X X X

Pushing orWaves

X X X X X X X X

Cracking

(Fine

Cracks)

X X X X X

Cracking

(Large

Crack)

X X X

Aggrega te

Broken byX X X X X X


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Rol le r

Tearing of

Surface on

Laying

X X X X X X

Surface

Sl ipping on

Base

X X X X X X X

Note: Some of these can be corrected on si te, others at mixing plant . If there is any doubt the load, samples should be takenand sent to laboratory of test ing.


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Clause 17.12.4.1

ANNEXURE 17.23

THICKNESS OF SLAB FOR CEMENT CONCRETE PAVEMENTS RECOMMENDED BY

IRC

Average Daily Number Commercial Vehicles (Wi th laden weight over 8 tonnes)

both directions anticipated to develop the nest 20 years

Thickness

of slabNot Exceeding 200 Nos .. Exceeding 200 Nos. b ut up t o 350 Nos Exceeding 350 Nos.

150 mm

175 mm

200 mm

Description of sub-

grade

Thickness of

base (mm)

Thickness of slab based on Traffic Intensity (mm)

Very

Heavy

Heavy Medium

Heavy

Medium

Light

Light Very

Light

Very stable Normal

Unstable

Reinforcements

None 80

Upto 150

Kg/sqm.

230

250

280

7.5

200

230

250

5.4

180

200

230

5.4

150

180

200

3.8

130

150

180

3.8

100

130

150

2.7

Recommended Spacing of Expansion and Contraction Joints(Clause 5.3.1.2)

Sl.

No.

Type of Slab Thickness

of Slab

Mass of

Reinforcement

Spacing of

Expansion

Joints*

Spacing of

Contraction

Joint

(1) (2) (3) (4) (5) (6)

m kg/m2

m m

(i) Reinforced concrete

slabs with expansion

joints only

0.25

0.20

0.150.10

7.6

5.5

3.82.7

45

36

2512.5

-

-

--

(ii) Reinforced concrete

slabs with expansion

and dummy

contraction joints

0.25

0.20

0.15

0.10

5.5

3.8

2.7

2.2

51

45

36

30

17

14

13

7.5

(iii) Unreinforced

concrete slabs

0.210 and

above

0.15

0.10

-

-

-

36

27

27

4.5

4.5

4.5

Note : In case of thicker airfield pavements, somewhat higher expansion joint spacing

may be permitted particularly when construction is mainly carried out during summer

months. Construction joint spacing could be increased to some extent in case a smooth

under-layer of sand and polyethylene sheeting, etc., is provided below the pavement.

Type of cement and its early strength development characteristics also have a bearing on

contraction joint spacing. Whereas limited experience with higher spacing indicates the

possibility of increasing the contraction joint spacing to 6-7.5 m and expansion joint

spacing to abou 60 m, each case may need individual consideration in view of variety of

factors involved.


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Questions:-

1. Describe the layout of sewerage systems.2. List the common defects in sanitary installations.3. What is the self cleansing velocity for SW Sewers?4. What is the maximum velocity for SW Sewers?5. What is minimum gradient for 100 mm dia sewer?6. What is maximum gradient for 150 mm sewer/7. Compare the combined and separate sewer s ystems.8. List the common defects of sewer in design.9. What is partially separate system of sewer10.List the advantage and disadvantage of partially separate system

of sewer

external services-road & drainage

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