1. DESIGN OF EARTHEN AND
CONCRETE GRAVITY DAM AT
DALHORE, RAWALPINDI
By
Sarmad Shakeel (2010-NUST-SCEE-BE-CE-166) (Group Leader)
Rana Muhammad Saad Khan (2010-NUST-SCEE-BE-CE-149)
Zeeshan Ul Hassan (2010-NUST-SCEE-BE-CE-214)
Muhammad Mohsin (2010-NUST-SCEE-BE-CE-111)
Asad Ali (2010-NUST-SCEE-BE-CE-28)
Project Advisor: Dr. S. Muhammad Jamil
NUST Institute of Civil Engineering (NICE)
School of Civil and Environmental Engineering (SCEE)
National University of Science and Technology (NUST), Sector H-12,
Islamabad
2014

2. 1
This is to certify that thesis entitled
DESIGN OF EARTHEN AND CONCRETE GRAVITY DAM AT
DALHORE, RAWALPINDI
Submitted by
Sarmad Shakeel (2010-NUST-SCEE-BE-CE-166) (Group Leader)
Rana Muhammad Saad Khan (2010-NUST-SCEE-BE-CE-149)
Zeeshan Ul Hassan (2010-NUST-SCEE-BE-CE-214)
Muhammad Mohsin (2010-NUST-SCEE-BE-CE-111)
Asad Ali (2010-NUST-SCEE-BE-CE-28)
Has been excepted towards fulfilment of the requirement for
Bachelors in Civil Engineering
____________________________
Dr. S. Muhammad Jamil
Dean SCEE
National University of Sciences and Technology (NUST)
School of Civil & Environmental Engineering (SCEE), NUST
H-12 Islamabad
Tel: +92-51-90854004
Email: dean@scee.nust.edu.pk

3. 2
Acknowledgements
All praise to ALLAH the Almighty on whom we depend ultimately upon for
sustenance and guidance.
We would like to express our special thanks of gratitude and deep appreciation to
our teachers especially Dr. S. Muhammad Jamil (Dean SCEE) for giving us
opportunity to carry out this Project under his supervision and guiding us to finish
this Project, Dr. Kamran Akhtar (HOD Geotechnical Engineering Department) for
his constant support and guidance, Col. Nasrul Haq (HOD Survey Department) for
providing us with detail topographic maps of area, Mr. Ahsan Mehboob (Lectures
IGIS) for providing us with his valuable guidance in GIS related part of project.

4. 3
Synopsis
Pakistan has been blessed with a rich water resource which has driven mainly through
agriculture, economic development of the country. Increase in population and industrialization has
led serious water management crisis due to which per capita water availability is decreasing and
agriculture and power sector are losing their strength. So there is now a growing need to manage
this precious resource to ensure water for all on sustainable basis.
Dams help in resolving of water management issues by storing water. A dam is a barrier
that impounds water. Pakistan topography has built in dams. Potohar region has great potential of
small dams. Besides providing water for irrigation, these dams have many secondary benefits.
They will help recharge the groundwater, control soil erosion, offer water for domestic and
municipal purposes, help to develop fishing and also provide recreational activities.
In order to enhance economic situation, agriculture, tourism, a dam has been proposed on
tributary of river Soan at Dalhore, Rawalpindi. Proposed site of dam is located in vicinity of Nilore,
Islamabad. Main sources of data were Pakistan Meteorological dept., NUST-IGIS and Survey of
Pakistan. Both earthen and concrete gravity dams were designed in order to get glimpse of cost,
sustainability and suitability to site associated with each type.
At least, this project will help us to apply our knowledge in field along with the use of
different tools and software’s, in fact this project will be the revision of whole civil engineering.

5. 1
[Date]
Contents
INTRODUCTION.................................................2
1.1 WHAT IS DAM ...............................................3
1.2 TYPES OF DAMS...........................................3
1.2.1 BY STRUCTURE ............................................3
1.2.2 BY SIZE ........................................................6
1.3 IMPORTANCE OF DAMS IN PAKISTAN ...6
1.4 BENEFITS OF DAMS.....................................7
1.5 GENERAL CAUSES OF FAILURE...............7
HYDROLOGY AND GEOLOGY ........................8
2.1 LOCATION.....................................................9
2.2 CLIMATE .....................................................10
2.3 METEOROLOGICAL DATA ......................11
2.4 FOUNDATION CONDITIONS ....................12
2.4.1 STRATIGRAPHY..........................................12
2.4.2 STRUCTURAL GEOLOGY............................13
2.4.3 JOINTS AND FRACTURES............................13
2.5 SEISMICITY OF AREA...............................13
2.6 CATCHMENT AREA...................................13
2.7 HEIGHT OF DAM ........................................15
2.8 RESERVOIR AREA .....................................15
2.9 CATCHMENT YIELD..................................16
2.10 PEAK FLOODS...........................................16
2.11 DESIGN OF SPILLWAY............................17
INITIAL DESIGN INVESTIGATION...............18
3.1 SITE MATERIAL .........................................19
3.2 SITE SURVEY ..............................................19
3.3 LABORATORY INVESTIGATION.............20
3.3.1 SOIL CLASSIFICATION ...............................20
3.3.2 PERMEABILITY ..........................................21
3.3.3 STRENGTH PARAMETERS ..........................21
3.3.4 SPECIFIC GRAVITY ....................................21
3.3.5 STANDARD PROCTOR TEST .......................21
3.3.6 MOISTURE CONTENT BY OVEN METHOD ..21
3.4 STORAGE CAPACITY................................22
3.5 VOLUME OF EARTH WORK ....................22
3.6 STORAGE RATIO .......................................23
EARTHEN DAM ................................................24
4.1 EARTH DAM................................................25
4.2 HOMOGENOUS DAM.................................26
4.2.1 DIMENSIONS OF HOMOGENOUS DAM .......26
4.2.2 SLOPE PROTECTION ..................................27
4.3 ZONED DAM................................................28
4.3.1 CORE ..........................................................28
4.3.2 FILTERS......................................................29
4.3.3 SHELL MATERIAL......................................31
4.3.4 FOUNDATION DESIGN ................................31
4.3.5 STEADY STATE SEEPAGE ANALYSIS..........33
GRAVITY DAM.................................................38
5.1 GENERAL ....................................................39
5.2 TERMINOLOGY .........................................39
5.4 DAM CROSS SECTION ..............................40
5.4.1 TOP WIDTH/CREST WIDTH.......................40
5.4.2 BASE...........................................................40
5.4.3 UPSTREAM DIAGONAL BASE......................40
5.4.4 HEIGHT OF SUPERIMPOSED COLUMN........40
5.4.5 UPSTREAM HEAL HEIGHT.........................40
5.4.6 FREEBOARD ...............................................40
5.5 DESIGN OF CONCRETE GRAVITY DAM41
5.5.1 COMPUTATION OF FORCES........................42
5.5.2 ANALYSIS FOR FACTOR OF SAFETY ..........47
5.5.3 COMPRESSION AND CRUSHING .................47
5.6 CONTRACTION JOINTS............................49
5.7 FLUSHING PIPES........................................51
CONSTRUCTION SPECIFICATION OF
EARTHEN DAM ................................................52
6.1 SITE PREPARATION..................................53
6.1.1 CONTROL AND DIVERSION OF WATER: .....53
6.1.2 EARTH FOUNDATION..................................53
6.2 FOUNDATION PREPARATION..........53
6.2.1 CLEARING AND GRUBBING .................53
6.2.2 STRIPPING ..................................................53

6. 2
6.3 EXCAVATIONS WORKS ............................54
6.3.1 CORE CUT OFF TRENCH .............................54
6.3.2 CONCRETE CUT OF WALL ..........................54
6.4 UTILIZATION OF EXCAVATED
MATERIAL ........................................................54
6.5 EMBANKMENT:..........................................54
6.5.1 SITE REQUIREMENT ...................................54
6.5.2 FOUNDATION PREPARATION OF
EMBANKMENT.....................................................55
6.5.3 PLACEMENT ...............................................56
6.5.4 MOISTURE CONTROL.................................56
6.5.5 COMPACTION.............................................56
6.5.6 FINISHING EMBANKMENT..........................58
6.6 TEST ON EMBANKING MATERIAL ........58
6.7 RIPRAP .........................................................58
6.8 FILTER .........................................................59
6.9 PROPOSED CONSTRUCTION
INSPECTION ACTIVITIES ..............................60
6.9.1 FREQUENCY OF SITE INVESTIGATION .......60
6.9.2 QUALITY ASSURANCE TESTING PROGRAM60
6.9.3 SAMPLING AND TESTING OF SITE MATERIAL
.............................................................................60
6.9.4 FILTER SAMPLING .....................................61
6.9.5 FIELD COMPACTION TESTS........................61
6.10 CONSTRUCTION EQUIPMENT ..............62
6.10 COMMON REFERENCE STANDARDS...63
CONSTRUCTION SPECIFICATION OF
GRAVITY DAM .................................................64
7.1 FOUNDATION PREPARATION.................65
7.2 LIFT THICKNESS........................................65
7.3 CONSTRUCTION JOINTS..........................65
7.4 CURING ........................................................65
7.5 INSTRUMENTATION IN CONCRETE
GRAVITY DAMS ...............................................66
7.5.1 MEASUREMENT OF UPLIFT PRESSURE......66
7.5.2 MEASUREMENT OF SEEPAGE ....................66
7.5.3 MEASUREMENT OF TEMPERATURE DURING
CONSTRUCTION ..................................................66
7.5.4 MEASUREMENT OF TEMPERATURE OF THE
DAM INTERIOR....................................................66
7.5.5 MEASUREMENT OF TEMPERATURE OF
RESERVOIR WATER AND AIR.............................66
7.6 MIX PROPORTION.....................................67
COST ESTIMATION.........................................68
8.1 EARTHEN DAM ..........................................69
8.1.1 QUANTITY OF MATERIALS ........................69
8.1.2 COST OF EXCAVATION ..............................70
8.1.3 COST OF HAULING.....................................70
8.1.4 COST OF EXCAVATION ..............................71
8.1.5 COST OF CLEARING AND GRUBBING.........71
8.1.6 TOTAL COST ..............................................72
8.2 CONCRETE GRAVITY DAM.....................72
8.2.1 COST OF CONCRETE ..................................72
8.2.2 COST OF SAND AND AGGREGATE..............73
8.2.3 TOTAL COST ..............................................73
ENVIRONMENTAL ASSASMENT REPORT .74
9.1 SCOPE OF STUDY ......................................75
9.2 ENVIRONMENTAL AND SOCIAL IMPACT
.............................................................................76
9.2.1 LAND ACQUISITION AND RESETTLEMENT76
9.2.2 ENVIRONMENTAL IMPACTS.......................76
9.3 WATERSHED CONSERVATION...............76
9.4 RESERVOIR AND DAM .............................76
9.5 DAM CONSTRUCTION ..............................77
9.5.1 DOWNSTREAM IMPACTS............................77
9.6 GENERAL CONCLUSIONS........................77
CONCLUSIONS.................................................78
10.1 CONCLUSIONS .........................................79
10.2 EARTH DAM..............................................79
10.3 CONCRETE GRAVITY DAM...................79
10.4 COST ESTIMATES....................................79

7. 1

8. 2
CHAPTER 01
INTRODUCTION

9. 3
1.1 What is a Dam?
A dam is a barrier that impounds water or underground streams.1
A barrier constructed across a waterway to control the flow or raise the level of water.2
1.2 Types of Dams
There are variety of dams, a man has been using since the history. However, we can
categorize them to understand it more conveniently. Following are the different categories:
 By structure
 By size
 By materials
 By use
1.2.1 By Structure
Based on structure and material used, dams are classified
as
1. Arch Dams: Arch dams and Buttress Dams can be
built using a smaller amount of concrete than that
required for a Gravity Dam and, as a result, are
cheaper to build. This is possible because Arch and
Buttress Dams are designed to transfer some of the
loads (forces) on them to the foundation on which
they are built i.e. the strength of the foundation is
used to help resist the loads which could not be resisted simply by the weight of the
dam wall alone. In all cases the impermeable membrane of concrete dams is the
whole dam wall.
2. Gravity Dams: Gravity dams rely on the weight of the material of which they are
built to resist the forces (gravity, water pressure, and earthquake) to which they are
subjected.
1
http://www.wikipedia.org/
2
http://www.thefreedictionary.com/Dam/
Figure 1 concrete arch dam

10. 4
3. Arch-Gravity Dams: A gravity dam can be
combined with an arch dam into an arch-gravity
dam for areas with massive amounts of water flow
but less material available for a purely gravity dam.
4. Barrages: A barrage dam is a special kind of dam
which consists of a line of large gates that can be
opened or closed to control the amount of water
passing the dam. The gates are set between flanking
piers which are responsible for supporting the water
load, and are often used to control and stabilize water
flow for irrigation systems.
5. Embankment Dams: Earth embankments have been used since the earliest times
to impound and divert water. They are simple compacted structures that rely on
their mass to resist sliding and overturning and are the most common type of dam
found worldwide. Modern haulage methods and developments in soil mechanics
since the end of the nineteenth century have greatly increased the safety and life of
these structures.
The main advantages involved in the construction of small earth dams are:
 Local natural materials are used.
 Design procedures are straightforward.
 Comparatively small plant and equipment are required.
 Foundation requirements are less stringent than for other types of dam.
The broad base of an earth dam spreads the load on the foundation. Earth fill dams
resist settlement and movement better than more rigid structures and can be more
suitable for areas where earth movements are common. However, disadvantages
also exist and these are:
 An earth embankment is easily damaged or destroyed by water flowing on, over
or against it. Thus, a spillway and adequate upstream protection are essential
for any earth dam.
 Designing and constructing adequate spillways is usually the most technically
difficult part of any dam building work. Any site with a poor quality spillway
should not be used.
 If not adequately compacted during construction, the dam will offer weak
structural integrity, offering possible pathways for preferential seepage.
 Earth dams require continual maintenance to prevent erosion, tree growth,
subsidence, animal and insect damage and seepage.
Figure 2 concrete Gravity dam

11. 5
 The earliest embankments were constructed on the principle of a solid wall of
earth, whether impervious or not, across a stream or river. When built properly,
such homogeneous embankments can still be cheap and reliable. They are,
however, generally inferior to the modern method of zoned construction in
which an embankment is built in three sections:
1. upstream and relatively impermeable section;
2. central core or hearting of highly impermeable material (which, with any
below ground cutoff, will effectively seal the dam against seepage)
3. Downstream section of poorer, coarser material that allows freer drainage
of the structure and which, by its weight, anchors the complete embankment
to its foundation and prevents slip and other movement.
Types of embankment dams
a. Rock fill Dams: The rock fill dams have a relatively narrow, impermeable
earth or clay core inside the dam but most of the dam is constructed of
permeable rock fill which, by itself, would be incapable of retaining water.
The impermeable membrane in these dams is the clay core.
b. Concrete-face rock fill dams: A
concrete-face rock-fill dam (CFRD) is
a rock-fill dam with concrete slabs on
its upstream face. This design offers
the concrete slab as an impervious
wall to prevent leakage and also a
structure without concern for uplift
pressure. In addition, the CFRD design
is flexible for topography, faster to
construct and less costly than earth-fill
dams.
c. Earth fill Dams: Earth-fill dams, also
called earthen dams, rolled-earth
dams or simply earth dams, are
constructed as a simple embankment of
well compacted earth.
A homogeneous rolled-earth dam is
entirely constructed of one type of
material but may contain a drain layer to collect seep water.
Figure 3 concrete face rock fill dam
Figure 4 Earth fill Dams

12. 6
d. Asphalt-Concrete core: A type of embankment dam which is built
with asphalt concrete core. The majority of such dams are built with rock
and/or gravel as the main fill material.
1.2.2 By Size
International standards (including International Commission on Large Dams, ICOLD)
define large dams as higher than 15 meters and major dams as over 150 meters in
height. The Report of the World Commission on Dams also includes in the large category, dams,
such as barrages, which are between 5 and 15 meters high with a reservoir capacity of more than
3 million cubic meters.
1.3 Importance of dams in Pakistan
Pakistan has been ranked as water scare country according to UN where per capita water
available is less than 1000m3
/capita/year. Pakistan has signed UN millennium development goals
to provide safe and clean drinking water to its citizens. So it is intense need to build small dams
which will not only fulfill its domestic and industrial water requirements but also play an important
role in development of our economy
Water availability in Pakistan by FAO (Food and agricultural organization UN Pakistan)
Area of the Country 208 79610000ha
Cultivated area 2008 21200000ha
As% of total area of country 2008 27%
Arable land 2008 20347000ha
Area under permanent crops 2008 853000ha
Population
Total population 2008 176952000inhabitants
Of which rural 2008 64%
Population density 2008 222inhabitants/km2

13. 7
Water required in future (FAO)
Year Water required
(MAF)
Water available
Surface + Ground
(MAF)
Shortage
(MAF)3
2000 149 109 40
2013 215 107 108
2025 277 126 151
These statistics are the clear indication of importance of dams in Pakistan.
1.4 Benefits of Dams
 It provides water for domestic, agricultural and industrial purposes.
 Provides employment for local people.
 It controls and reduce sedimentation.
 It provides fishing opportunities to local people.
 It increases vegetation cover
 Control and reduce floods
 Brings out social uplift in area
1.5 General Causes of Failure
The most common causes of dams being breached appeared to be
 Internal erosion or subsurface erosion of fine grained material
 Overtopping
 Sliding or slope failure
 Earthquake
 Rapid Drawdown
 Substandard construction material/techniques
 Geologic instability in area
3
MAF, million acre foot

14. 8
CHAPTER 02
HYDROLOGY AND GEOLOGY

15. 9
2.1 Location
The area lies in Soan River catchment basin in Potwar Plateau. Proposed Dam site is
located on North-East side of Islamabad, in vicinity of Nilore at an elevation of 692m from Mean
Sea Level. Site can easily accessed by Lethrar road, which in end also joins Islamabad highway.
During preliminary site visit, three different dam sites were surveyed and most economical section
was chosen. Coordinates of dam site are:
Longitude=33’ 40” 32.90999
Latitude= 73’ 23”21.395
Yellow pin on map show Dam site location.
N
Figure 2- 1: Location of Dalhore with respect to Islamabad

16. 10
Figure 2- 2: Location of Dam near Dalhore Village
2.2 Climate
The climate of Islamabad has a typical version of humid subtropical climate, with five
seasons: Winter (Nov−Feb), spring (March−April), summer (May−June), Rainy Monsoon
(July−August) and autumn (September−October). The hottest month is June, where average highs
routinely exceed 38 °C (100.4 °F). The wettest month is July, with heavy rainfall and evening
thunderstorms with the possibility of cloudburst. The coolest month is January, with temperatures
variable by location. In Islamabad, temperatures vary from cold to mild, routinely dropping below
zero.
Figure 2- 3: Site View of Dalhore Dam

17. 11
2.3 Meteorological Data
Detail meteorological data of past 10 years was analyzed in order to get glimpse of rainfall,
temperature, wind speed and humidity trends of area. Following tables show monthly rainfall,
mean temperature and wind speed variations of area.
Total Monthly Rainfall(mm) Data of Rawalpindi
Year/Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2003 39.3 176.4 82.8 20.7 22.8 100.0 312.2 267.4 258.1 2.9 17.3 45.0
2004 91.2 37.0 0.1 92.3 12.0 124.3 161.9 343.1 30.5 80.8 19.8 35.6
2005 39.3 191.8 79.4 16.4 30.5 14.0 193.0 214.1 58.6 54.3 6.3 0.0
2006 63.2 25.6 45.5 20.3 62.9 91.2 550.9 327.2 13.9 55.9 14.2 134.1
2007 0.5 93.6 143.2 19.6 79.6 99.6 262.4 486.3 200.1 0.0 10.0 0.1
2008 110.1 41.8 19.1 92.9 10.1 225.2 432.5 221.0 65.8 24.0 18.0 71.5
2009 61.9 49.2 58.6 116.2 35.6 12.5 88.5 202.4 45.0 0.1 16.0 0.0
2010 18.0 80.0 115.5 49.7 22.6 37.6 322.3 245.5 104.5 22.0 0.1 22.0
2011 9.0 109.6 68.2 71.4 17.0 145.0 299.0 193.0 130.0 34.6 9.2 0.0
2012 44.6 48.4 21.2 26.8 16.2 9.0 74.9 247.9 162.0 6.0 1.2 77.4
Mean Annual Rainfall 912.5 mm/year
Mean Minimum Temperature(°C) Data of Rawalpindi
Year/Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2003 2.7 6.3 10.1 16.8 20.3 23.8 23.5 23.6 21.8 13.4 7.3 4.8
2004 4.7 6.2 11.9 17.3 19.4 22.7 23.4 21.6 20.8 12.6 6.8 4.1
2005 2.0 5.0 9.8 13.2 17.4 23.1 22.5 23.1 22.4 14.8 7.0 1.1
2006 3.8 9.7 11.4 15.3 23.0 23.0 24.0 23.3 20.5 15.9 9.4 4.1
2007 1.0 6.6 9.0 15.9 19.8 23.0 21.5 21.8 19.5 12.6 8.2 5.1
2008 3.0 4.9 11.5 15.8 20.7 22.2 22.8 23.0 19.7 15.4 8.1 5.5
2009 3.9 6.4 9.9 14.2 18.7 21.6 24.7 28.3 21.1 14.0 7.5 3.8
2010 3.4 7.9 14.3 17.8 22.0 23.6 24.5 27.2 22.3 17.5 9.9 3.1
2011 2.8 6.8 11.9 15.5 23.0 25.8 24.4 24.3 22.7 16.1 11.2 0.5
2012 2.0 4.5 9.8 16.1 19.6 22.3 26.2 24.0 21.3 15.3 8.4 5.1

18. 12
Mean Wind Speed(km/h) Data of Rawalpindi
Year/Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2003 2.4 4.0 4.7 4.7 5.3 5.4 3.9 3.7 2.5 1.8 1.5 1.3
2004 2.3 3.3 4.1 3.5 4.4 4.5 3.4 3.6 3.9 2.6 2.9 2.1
2005 2.3 3.7 3.0 4.0 4.7 4.8 3.7 2.9 2.1 2.4 3.0 2.1
2006 2.7 3.5 4.3 4.7 4.8 4.5 4.5 3.8 3.4 3.1 2.7 2.8
2007 3.3 3.8 4.5 4.4 6.1 5.1 3.9 3.4 3.3 2.9 1.9 2.8
2008 3.3 4.2 3.7 12.0 4.7 5.5 4.5 4.4 7.2 3.3 2.4 2.5
2009 2.9 4.6 0.4 4.7 4.7 4.6 4.8 4.5 3.8 3.2 2.4 1.7
2010 3.1 3.8 3.9 4.8 9.1 4.3 3.8 2.7 2.1 1.3 2.6 1.9
2011 1.7 2.1 2.4 2.4 2.6 4.2 2.3 2.7 1.2 1.7 1.0 1.2
2012 1.3 2.1 2.3 2.3 2.8 2.5 2.8 2.7 1.8 1.1 1.7 1.7
2.4 Foundation Conditions
Due to lack of information about foundation conditions of dam site, subsurface geologic
conditions were assumed as that of nearby Simly dam. At the depth of 22m there is impervious
rock foundation. The dam site is underlain by sediments of chinji group of formation of Siwalk
(Middle Miocene) age. The rock of these formations consists of alternate beds of sandstone,
siltstone and clay stone. These formations usually tend to be leaky. The permeability of this
pervious foundation is order of 10−5
m/sec. Bearing capacity at depth of 1 m can be taken dubbed
as 12000psf.
2.4.1 Stratigraphy
The dam site is underlain by sediments of Chinji group of formation of Siwalik (Middle
Miocene) age, The rocks of this formation consists of alternating beds of sandstone, siltstone and
clay stone. The layers of resistant sandstone form sharp ridges and are separated by depression
formed due to erosion of soft rocks which also include friable sandstone.
Figure 2- 4: Panoramic View of Dam site

19. 13
2.4.2 Structural Geology
These rocks have been folded into sharp anticlines and synclines trending northeast to
southwest.
2.4.3 Joints and Fractures
The stratification joints are well marked and cause open fractures in and near weaker
formations such as friable, siltstone and clay stone. These joints are however inconspicuous in the
main body of sandstone. The cross joints have been widened by weathering and solution near the
surface. At the dam site most of the joints and fractures are closely spaced, opened, partly coated
with calcite and occasionally silken sided.
Most of the clay stones show sign of shearing and the parting are generally coated with
chlorite. This shearing appears to be very irregular in strike and dip. The sandstone/clay stone,
contact is sheared and at places up to 2 ft. clay stone at the contact is crushed.
2.5 Seismicity of Area
Dam site lies in zone 2b with 𝑎 𝑚𝑎𝑥 ranging from 0.16g to 0.24g. Therefore 𝑎 𝑚𝑎𝑥 taken
is 0.2g. Vertical acceleration values is usually taken as 2/3 of 𝑘ℎaccording to Newmark. But it is
usually safe to use 𝑘ℎ values as 50 % of the PHA proposed by Hynes-Griffin. (see ref. xvi)
Horizontal earth quake acceleration = 0.1g
Vertical earthquake acceleration=0.0667g
2.6 Catchment Area
Catchment Area is an extent or an area of land where surface water from rain and melting
snow or ice converges to a single point at a lower elevation, usually the exit of the basin, where
the waters join another water body, such as a river, lake, reservoir, estuary, wetland, sea, or ocean.

20. 14
Detail Catchment area calculations were carried out using Arc GIS. Digital elevation model
(DEM) of whole Rawalpindi division was searched for drainage points. Catchment area is
approximately 95 Square Km. Following GIS map shows DEM of Rawalpindi along with
catchment area marked as blue.
Figure 2- 5: Watershed Area of Dam site

21. 15
2.7 Height of Dam
Height of dam is taken as 26m. It was decided using detailed contour map of region taking
care of different nearby structures. Tributary runs in 30m deep valley. FSL was decided to be 716m
from Mean Sea Level.
2.8 Reservoir Area
Detail topographic map of 1 m contour interval was made using DEM of catchment area.
After selecting the height of dam (716m from MSL), 716m contour was traced on topographic
map. Following parameters were deducted from topographic map
Reservoir area 0.235sq.km
Fetch 1.58km
Parameter of reservoir 3912.74m
Figure 2- 6: Fetch Length of Dalhore Dam

22. 16
2.9 Catchment Yield
The catchment yield, ‘Y’, is based on the expected annual runoff from a catchment and is
an important factor in assessing the feasibility of a dam.
Yield = C A P
Where,
A =Area of Catchment= 95 km2
P =Precipitation = 912.5 mm/year
C =Runoff Coefficient= 0.2
Runoff Coefficients
Type of Catchment C Value
Rocky & Impermeable 0.8-1.0
Slightly permeable bare 0.6-0.8
Cultivated, Vegetated 0.4-0.6
Cultivated absorbent soil 0.3-0.4
Sandy Soil 0.2-0.3
Heavy Forest 0.1-0.2
Which gives; Runoff = 0.549 m3/sec
2.10 Peak floods
When detail hydrologic information is missing, rational Method can be used to calculate
Probable Maximum Flood. According to FAO, the peak flood is the probable maximum flood
(PMF) to be expected from a catchment following a rainfall of estimated intensity and duration for
a selected return period taking into account the hydrological characteristics of the catchment.
Method describe by FAO in manual of small dams include time of concentration Tc, storm depth
ratio R and various others variables. In absence of such data, a very approximate peak flood
estimate can be made by taking the highest daily rainfall figure for the catchment and assuming
that all dams in the same catchment are 100 percent full, the ground is saturated and that 100
percent runoff will occur.
According to MET department, highest daily rainfall of area is around 100mm.
Catchment area= 95 sq. km
PMF or 𝑄 𝑝 = 95*1000*100/ (24*3600) = 109.95 m3/sec over 24 hour period.

23. 17
2.11 Design of Spillway
According to FAO, spillway width can be calculated as
Qp = 2.25 b D1.5
Where
b= width = 17.27m
D= freeboard = 2m
R

24. 18
CHAPTER 03
INITIAL DESIGN INVESTIGATION

25. 19
3.1 Site Material
Laboratory investigation of soil samples collected from site showed that material available
at site was predominantly sand. 4 samples were taken 1 from left abutment facing downstream, 1
from stream bed and 2 from right abutment facing downstream. After soil classification, soil on
left abutment and channel bed was classified as Silty Sand and Poorly Graded Sand from right
abutment.
3.2 Site Survey
Site survey was performed in order to stream cross section and channel profile.
Figure 3 - 1: Valley Section (upper diagram) and channel profile (Lower diagram) of Dalhore Dam

26. 20
3.3 Laboratory Investigation
Detail soil investigation was carried out on sample collected from river bed. Following tests
were performed and their results are shown.
• Gradation tests (LL, PI , sieve analysis)
• Direct Shear Test
• Standard Proctor Test
• In situ density
• Moisture content (oven dry method)
• Specific Gravity
• Hydrometer analysis
3.3.1 Soil Classification
Gradation Curve onsite soil sample
Soil was classified using USCS classification system
Based on gradation curve and Atterberg limits following results were obtained
LL 20%, PL 13%, PI 0%
Passing no.200 23%
Passing no.4 98%
0
10
20
30
40
50
60
70
80
90
100
0.0010.010.1110
GRADATION CURVE

27. 21
10
60
D
D
Cu 
 1060
2
30
DD
D
Cc


D60=0.21mm, D10=0.03mm, D30=0.092mm
Cu=7, Cc=1.343
Results: Silty Sand
3.3.2 Permeability
Hazen (1930) proposed an empirical relationship for hydraulic conductivity in the
form;
𝑘 = 𝑐(𝐷10)2
C=1, 𝐷10=0.03mm
k=9 × 10−4
cm/sec =9 × 10−6
m/sec
3.3.3 Strength Parameters
Direct shear test was performed. Following results were obtained
c =30KN/m2, ϕ = 25.14
3.3.4 Specific Gravity
𝐺𝑠 = 2.684211
3.3.5 Standard Proctor Test
Optimum Moisture Content (OMC) = 12%
Maximum Dry Density (MDD) = 2.143 gm/𝑐𝑚3
.
Bulk density of soil=1.84(gm/𝑐𝑚3
.)
Unit weight=18.05KN//𝑚3
3.3.6 Moisture Content by oven method
Moisture content= 14.22%

28. 22
3.4 Storage capacity
According to FAO, at this stage, this is
worked out as follows:
Q=.22 x K x L x T x H
L= Length of dam
T= throw of dam or Fetch (F)
H=height of water
K=0.5-1.6 (shape of Valley
K 1
L 122.29 m
T 1580 m
H 24 m
Q 1020192.096 m3
1.020192096 MCM (Million Cubic Meters) can be
stored.
3.5 Volume of Earth Work
According to FAO, volume of earthwork can be estimated as follows:
V = 0.216 HL (2C+HS)
Where:
V is the volume of earthworks in m3.
H is the crest height (FSL+ freeboard) of the dam in m.
L is the length of the dam, at crest height H, in m (including spillway).
C is the crest width in m.
S is the combined slope value.
Parameter Value Units
H 26 m
L 122.29 m
C 18 m
S 5.5
Volume of earth work came out to be 122933.7346 /𝑚3

29. 23
3.6 Storage Ratio
Ratio of the amount of water retained to the amount of soil used to retain it
Storage ratio = volume of water/ volume of earthwork = 1020192.096/122933.7346 = 8.29
Site can be rated as excellent on the basis of following information
Storage Ratio Site Rating
<2 Poor
2-4 Moderate
4.1-6 High
>6 Excellent

30. 24
CHAPTER 04
EARTHEN DAM

31. 25
4.1 Earth Dam
The most economical and suitable option would be use locally available material. Laboratory
investigation of samples taken from site shows that material was Silty sand. Homogeneous dam
was designed using that material.
Basic Terminology
Abutment: The part of valley side against which the dam is constructed.
Base Width: The width of the dam measured along the dam/foundation interface.
Crest Width: Top width of dam section.
Core: A zone of low permeability in an embankment dam.
Shell: A pervious zone (less pervious than filter) placed on both upstream and downstream
of dam to provide stability to the dam.
Cut off Wall: A wall of impervious material built into the foundation to reduce seepage
under the dam.
Drainage layer: A layer of pervious material placed directly over the foundation material
or downstream slope to facilitate seepage drainage of the embankment.
Drawdown: The resultant lowering of water surface level due to release of water from the
reservoir.
Freeboard: The vertical distance from the water surface to the crest of the dam.
Riprap: A layer of large course material placed in random fashion on the upstream as
protection against wave and ice action.
Spillway: A structure over or through which flood flows as discharged.
Figure 4 - 1: Different Components of Earthen dam

32. 26
4.2 Homogenous Dam
4.2.1 Dimensions of Homogenous Dam
Height of Dam
Height of dam is taken as 26m. Description about value of height has already been
explained earlier.
Freeboard
Freeboard is vertical distance between reservoir water level and crest without
camber. It serves to protect dam from overtopping. Minimum freeboard was calculated
using formula given in manual of design of small dams by FAO.
Fetch = 1.58km = 1580m
Freeboard=0.55m
According USBR, min. free board should not be less than 0.91m for 1.58km fetch.
Freeboard was taken to be 1.5m. By taking into account settlement after construction
camber of o.5m was provided at center.
Valley bed level = 692m (MSL)
Height of reservoir = 716(MSL) 24m
Total height of dam = 716 + 1.5 + 0.5 = 718(MSL) 26m (85.3 feet)
Crest width
The dam crest must resist all mechanical affects and effect of climate. Width of
crest is related mainly to it purpose, to serve the traffic as road or any other mean. Crest
width was calculated using formula given in manual of design of small dams by FAO.
Cw=11.4 m
Crest width of 18m is provided.
Curvature of Dam
According to number of experts, it has been evident that curvature in dam axis has
favorable effect in dam stress distribution on downstream side, favorable conditions at
abutments and many more. Therefore curvature of 1500m radii is provided with center of
circle at downstream side of dam.

33. 27
Slopes
According to FAO manual on small Dams, the side slopes must not be steeper than
1:2 on the upstream and 1:1.75 on the downstream sides. Upstream slopes of 3H: 1V and
downstream slope of 2.5H: 1V is provided.
4.2.2 Slope Protection
Upstream slope
Upstream slope must be protected mainly from wave action and erosion. Dumped
rock riprap will be used for this purpose. Dumped rock riprap consists of stones or rock
fragments dumped in place on the upstream slope of an embankment to protect it from
wave action. According to USBR for 3:1 slopes, a thickness of 30 inches should be used
with following properties. These boulders can be excavated from site.
Nominal
Thickness(m)
Weight of rock (kg) at various percentages
0.762m(30in) Maximum
size
40 to 50% 50 to 60% 0 to 10%
1134kg
(2500lbs)
>567kg(1250lbs) 34-567kg(75 to 1250
lbs)
<34kg (75lbs)
Downstream slope
Downstream slope must be mainly protected from damage and erosion from
rainfall. Damage can also be caused by digging animals and winds. Vegetation cover would
be enough for erosion caused by rainfall. As an alternative to this rock layer having rocks
of 25cm edge length with thickness of 0.5m can also be used.
Filters under rip-rap
There are two requirements for these filters:
1. That they are coarse enough not to wash out of the rip rap;
2. They are fine enough to prevent erosion of the soil beneath the filter.
Design of these filter is not as critical as that of filter in which flow is perpendicular
to them. In these filters flow is parallel. Therefore if damage does occur, it can usually be
repaired, and so a relaxation of the strict no erosion rules may be appropriate. According
to Robin Fell in “Geotechnical Engineering of Embankment dams”, well-graded sandy
gravel/ gravelly sand from 0.075 mm to 50 mm or 75 mm available either naturally or with
a minimum of processing, this should be satisfactory in most cases. Outer Filter material
called as poorly graded sand meet this criterion.

34. 28
4.3 Zoned Dam
4.3.1 Core
Soil samples taken from dam site show that material available is Silty Sand. It is not
suitable for use as core material. Due to large permeability, it results in considerable seepage losses
through embankment. In case of homogeneous Dam (made entirely of Silty Sand), 7.1987 ×
10−5
𝑚3
/𝑠𝑒𝑐/m of seepage was observed during analysis in Phase 2.7. Therefore for core material
should be excavated from borrow areas and quarries. Clayey Silt is available in Tamair valley
located on west at distance of 3km of Dam Site which can serve as a core. Central core was
designed with outer slopes 0.8H: 1V.
Properties of Clayey Silt used in analysis
Permeability =5× 10−8
𝑚/𝑠𝑒𝑐
Φ = 31
C=67KN/𝑚2
Unit weight=15.6 KN//𝑚3
Figure 4 - 2: Proposed Homogeneous dam cross-section

35. 29
4.3.2 Filters
Filters in embankment dams and their foundations are required to perform two basic
functions:
(a)Prevent erosion of soil particles from the soil they are protecting;
(b) Allow drainage of seepage water.
To achieve these functions the ideal filter or filter zone will (ICOLD 1994):
 Not segregate during processing, handling, placing, spreading or compaction;
 Not change in gradation (by degradation or break down) during processing, handling,
placing and/or compaction, or degrade with time e.g. by freeze-thaw or wetting and
drying by seepage flow;
 Not have any apparent or real cohesion, or ability to cement as a result of chemical,
physical or biological action, so the filter will not allow a crack in the soil it is protecting
to persist through the filter;
 Be internally stable, that is the fines particles in the filter should not erode from the
filter under seepage flows;
 Have sufficient permeability (and, if a drain, thickness) to discharge the seepage flows
without excessive build-up of head;
 Have the ability to control and seal the erosion which may have initiated by a
concentrated leak, backward erosion, or suffusion (internal instability) in the base soil.
Inner Filter Material
Silty Sand with less than 5% is used as inner filter material. It meets Sherard’s,
conventional and USBR (1973) filter criterion. Silty Sand is readily available at site and
can be excavated from river bed.
According to USBR (1973), the filter must not contain more than 5% fines. Inner
Filter contain approximately 5% fines which satisfy this criterion. In order to minimize
segregation and bridging of large particles during filter placement, the maximum grain size
should not exceed 75mm. Inner filter meets this criterion too. Gradation curve of report is
attached at the end of report.(See Annex B)
Outer Filter Material
Poorly graded Sand is used as inner filter material. It meets Sherard’s, conventional
and USBR (1973) filter criterion. Poorly graded Sand can be excavated from right bank of
stream facing downstream side.
According to USBR (1973), the filter must not contain more than 5% fines. Inner
Filter contain approximately 5% fines which satisfy this criterion. In order to minimize
segregation and bridging of large particles during filter placement, the maximum grain size

36. 30
should not exceed 75mm. Outer filter meets this criterion too. Gradation curve of report is
attached at the end of report. (See Annex B)
Internal Stability or Suffusion of filters
Numerous criteria exist for the assessment of suffusion. These criteria are based on
the analysis of the grain size distribution of the soil. For gap-graded soils, use the method
of splitting the grain size distribution (According to John Lowe) at the point of inflection
in the gap, the soil is considered to be self-filtering if:
𝐷15 𝑐𝑜𝑎𝑟𝑠𝑒
𝐷85 𝑓𝑖𝑛𝑒
< 5
For inner filter
𝐷15 𝑐𝑜𝑎𝑟𝑠𝑒
𝐷85 𝑓𝑖𝑛𝑒
= 3.5
For outer filter
𝐷15 𝑐𝑜𝑎𝑟𝑠𝑒
𝐷85 𝑓𝑖𝑛𝑒
= 2.318
Therefore both filters were found safe against suffusion. Grain size distribution of
above results is shown at the end of report. (See Annex B).
Thickness of filters
The theoretical minimum width or thickness for filters designed according to no-
erosion criteria, is very small, and does not control the dimensions of filters. Witt (1986,
1993) carried out some calculations and experiments which demonstrated that the depth of
penetration of the base soil into the filter is small, even if the filter is somewhat coarser
than required by the design criteria Given that the width needed to achieve a proper filter
against the protected soil is small, the width of filter zones is often determined by
construction requirements.
In typical filter and drain construction, the filter and drain materials are delivered
to the dam in dump trucks and moved into the final location by loaders, dozers, or graders,
after which they are compacted.
Thickness of both Filters is taken as 2.5m.
Horizontal Drains
Cedergren (1972) gives a design method for estimating the discharge capacity of a
horizontal drain without pressurization based on:

37. 31
Where
k1 permeability of the drain material – m/sec
h vertical thickness of the drain – m
L1 length of the drain – m as shown
q Discharge capacity per meter width of drain (width measured across river) –
m3/m/sec.
2.5 m thick drain is provided of the same material as that of outer filter (poorly graded
sand). Using above formula its capacity comes out to be 10.93 m3/day. Steady state seepage shows
that without any foundation seepage measure, 5.05m3/day of discharge has to pass through drain
which is safe.
4.3.3 Shell Material
The purpose of shell is provide structural stability to dam therefore it must enough shear
strength against sliding forces.
Downstream Shell
Downstream Shell material should not be made saturated in any case. Silty sand is
used for this purpose. This material is readily available at site.
Upstream Shell
Poorly graded gravel is used upstream shell material. Gradation curve of material
is shown at end of report.
4.3.4 Foundation Design
Although the foundation is not actually designed, certain provisions for treatment are made in
designs to ensure that the essential requirements are met. As impervious strata is at depth of 22m
so some measures must be taken for reduction of seepage in pervious foundation, and selection of
types and locations of devices for the interception of under seepage must be made. Different
alternatives were considered and designed to check their efficiency. Following methods were taken
under consideration.
 Cutoff trenches.
 Upstream Impervious Blanket
 Concrete cutoff wall.

38. 32
Cutoff trench
Experiments by Turnbull and by Creager on homogeneous isotropic pervious
foundations have demonstrated that a cutoff extending 50 percent of the distance to the
impervious stratum will reduce the seepage by only 25 percent; an 80-percent cutoff
penetration is required to reduce the seepage 50 percent. Excavation greater than 6m (25%
of 22m impervious strata depth) depth would be highly uneconomical. Therefore partial
cutoff trench was designed of 6 m depth. Minimum bottom width of 20ft (6m) must be
provided so that excavating and compacting equipment can operate efficiently in trenches.
Bottom width was calculated formula given by USBR.
w=h-d
Where;
w = bottom width of cutoff trench,
h = reservoir head above ground surface, and
d = depth of cutoff trench excavation below ground surface.
Therefore;
w=24-6
w=18m
Side slopes were provided 0.5H: 1V with factor of safety of 2.0 and slope stability
analysis was performed using in situ strength properties of foundation material (Silty sand)
in rder to make it safe against faliure.
Figure 4 - 3: Cross-section of cutoff trench under Zoned Dam

39. 33
Upstream Impervious blanket
In order to reduce seepage upstream impervious blanket was designed using
Bennet’s method. Following dimensions are selected and used in analysis.
Kf Permeability of Foundation 0.00001 m/sec
Kb Permeability of Blanket 0.00000005 m/sec
Zb Thickness of Blanket 1.5 m
Zf Thickness of permeable foundation 22 m
X Length of blanket 150 m
A transition material should also be provided between blanket and foundation
material in order to prevent erosion of blanket material into foundation. Silty Sand of 2.5m
thickness same as used as inner filter will serve the purpose.
Positive Cutoff Wall
Positive Concrete cutoff wall constructed using Tremie concrete placement method
was designed. Two locations were brought under consideration either to construct it
upstream side or at center of dam. Steady state seepage analysis was performed on both
locations concluded that best suited site would be at center of dam at bottom core of trench.
Permeability of wall used in analysis was 1 × 10−10
m/ sec according to USACE
EM_1110-2-1901.
4.3.5 Steady State Seepage analysis
Steady state seepage analysis was performed in Rocsience Phase 2.70. Pervious foundation
of 22m depth was assumed.
Following results were obtained. Large amount of seepage was observed. Following
alternatives were analyzed to reduced amount of seepage through embankment.
Earthquake loading data
Horizontal earth quake acceleration = 0.1g
Vertical earthquake acceleration=0.0667g

40. 34
Parameters used in analysis are shown as follows:
Dam Dimensions
Parameter Value
Upstream Slope 3H:1V
Downstream Slope 2.5H:1V
Height of Dam 26m
Height of Water 24m
Depth of foundation 22m
Height of Core 25m
Top Width of Core 10m
Bottom Width of Core 50m
Thickness of filters (inner and outer both) 2.5m
Material Properties
Component Parameter Values
Core 𝑐 (Cohesion KN/m2) 67
∅ (phi) 31
𝛾(unit Weight KN/m3) 15.6
K (Permeability m/sec) 5× 10−8
Inner Filter 𝑐 (Cohesion KN/m2) 0
∅ (phi) 25.14
𝛾(unit Weight KN/m3) 18.05
K (Permeability m/sec) 9× 10−6
Outer Filter 𝑐 (Cohesion KN/m2) 0
∅ (phi) 35
𝛾(unit Weight KN/m3) 20
K (Permeability m/sec) 1.6 × 10−3
Downstream Shell 𝑐 (Cohesion KN/m2) 30
∅ (phi) 25.5
𝛾(unit Weight KN/m3) 18.05
K (Permeability m/sec) 9 × 10−6
Upstream Shell 𝑐 (Cohesion KN/m2) 0
∅ (phi) 40
𝛾(unit Weight KN/m3) 22
K (Permeability m/sec) 1.6 × 10−3
Foundation K (Permeability m/sec) 1 × 10−5

41. 35
Methods of Analysis
Both Limit equilibrium and finite element methods were used to compute the
following:
 Factor of safety against slope failure on both upstream and downstream sides.
 Amount of seepage in foundation and embankment.
PHASE 2.70 and Slide 6.0 was utilized for above mentioned purposes.
Slope Stability analysis
Following three conditions were taken into consideration while computing factor of safety.
 Steady State Seepage
 Rapid Drawdown
 Transient
In Transient analysis following Conditions were assumed
Stage Name Time (Days) Head (m)
Stage 1 10 24
Stage 2 5 12
Stage 3 0 0

42. 36
Methods GLE/Morgenstern-
Price
Janbu
Simplified
Ordinary
Fellenius
Spencer
Steady State Seepage
Upstream 2.505 2.504 2.506 2.504
Downstream 1.755 1.753 1.753 1.755
Steady State Seepage With Seismic Loading
Upstream 1.593 1.593 1.48 1.593
Downstream 1.368 1.367 1.367 1.368
Rapid Draw Down
Upstream 2.011 2.009 2.043 2.009
Downstream 1.755 1.753 1.753 1.755
Rapid Draw Down With Seismic Loading
Upstream 1.455 1.457 1.493 1.455
Downstream 1.368 1.367 1.367 1.368
Transient Stage 1
Upstream 2.506 2.505 2.507 1.594
Downstream 1.755 1.753 1.753 1.755
Transient With Seismic loading Stage 1
Upstream 1.594 1.594 1.481 1.963
Downstream 1.368 1.367 1.367 1.368
Transient Stage 2
Upstream 2.292 2.096 2.171 2.096
Downstream 1.755 1.753 1.753 1.755
Transient With Seismic loading Stage 2
Upstream 1.577 1.565 1.578 1.581
Downstream 1.368 1.367 1.367 1.368
Transient Stage 3
Upstream 2.011 2.009 2.043 2.009
Downstream 1.755 1.753 1.753 1.755
Transient With Seismic loading Stage 3
Upstream 1.455 1.457 1.493 1.455
Downstream 1.368 1.367 1.367 1.368

43. 37
Steady State Seepage Analysis
Place of measurement Amount of Seepage m3/day
Homogeneous
Embankment 2.076
Foundation 3.1959
Zoned Without foundation Seepage Control measures
Embankment 0.15
Foundation 3.1959
Zoned With central positive cutoff up to 22m depth
Embankment 0.011
Foundation 0.2002
Zoned With upstream impervious blanket
Embankment 0.072
Foundation 2.62
Zoned With upstream positive cutoff up to 22m depth
Embankment 0.072
Foundation 2.03
Figure 4 - 4: Proposed cross-section of Zoned Dam

44. 38
CHAPTER 05
GRAVITY DAM

45. 39
5.1 General
A gravity dam is a structure so proportioned that its own weight resists the forces exerted
upon it. This type of dam is the most permanent one, requires little maintenance and is most
commonly used. The ancient gravity dam on record was built in Egypt more than 400 years B.C.
of cemented masonry.
A gravity dam may be constructed either of masonry or of concrete. However, now-a-days
with improved methods of construction, quality control and curing, concrete is most commonly
used for the construction of gravity dams. A gravity dam is mostly straight in plan and is known
as “Straight gravity dam”. However, it may also be slightly curved in plan.
Gravity dams are particularly suited across gorges with very steep side slopes. Where good
foundations are available, gravity dams can be built up to any height.
5.2 Terminology
Crest: The elevation of the uppermost surface of a dam excluding any parapet wall,
railings, etc.
Heel: The heel of the dam is the upstream edge of the base
Toe: The toe of the dam is the downstream edge of the base
Spillway: A structure used to provide the controlled release of flows from a dam
Freeboard: The Difference in elevation between the crest of the damand the normal
reservoir water level
5.3 Basic Structure Layout
The basic shape of a concrete gravity dam triangular in section, with the top crest often
widened to provide a roadway.
Figure 5 - 1: Components of Gravity Dam

46. 40
5.4 Dam Cross section
5.4.1 Top Width/Crest Width
Typically top of the gravity dam is widened because of stability or to provide a road for
the traffic. Top width of dam is calculated using following formula:
a= 1.65(H+1.5) ^1/3 or √𝐻
Where; H= height of water
The formula gives; Top width = 4.85m but actual value ranges from 6m to 10m. Hence,
we’ll take the value as 9m.
5.4.2 Base
Base of dam is calculated using following formula:
B =
𝐻
√𝑆 𝑠−𝐶
Where;
𝑆𝑠 = 𝑢𝑛𝑖𝑡 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑐𝑜𝑛𝑐𝑟𝑒𝑡𝑒 𝑖𝑛 𝑡/𝑚3
C = uplift pressure coefficient ranging from 0.95 to 1 (taken as C=1)
This formula gives the base as 24m.
5.4.3 Upstream diagonal Base
Upstream diagonal base is usually taken as 1/16 of base. There for the upstream diagonal
base in this case is taken as 1.5m.
5.4.4 Height of superimposed column
Water above the upstream diagonal is known as height of superimposed column which, in
fact, increase the stability of dam and can be calculated as:
H1= 2a√(𝑆𝑠 − 𝐶)
H1=21.3m
5.4.5 Upstream Heal Height
H2=H-H1
H2=2.7m
5.4.6 Freeboard
Freeboard of gravity dam is usually taken as 5% of height of water which is 1.2m. Here
freeboard is taken as 2m same as of earth dam

47. 41
Summary of Dam layout:
Dimensions Units
top width 9 M
bottom width 25.5 M
Height 26 M
upstream diagonal base 1.5 M
downstream diagonal base 15 M
height of downstream diagonal 15 M
height of upstream diagonal 2.7 M
5.5 Design of Concrete Gravity Dam
Dams should be design in such a way that it can:
a) Contain the water and resist leakage
b) Maintain shape
c) Resist downstream movement.
The design shall satisfy the following requirements of stability:
a) The dam shall be safe against sliding on any plane or combination of planes
within the dam, at the foundation or within the foundation;
b) The dam shall be safe against overturning at any plane within the dam, at the
base, or at any plane below the base;
c) The safe unit stresses in the concrete or masonry of the dam or in the foundation
material shall not be exceeded.
Forces that must be considered whiling designing the concrete dam are as followed:
i. Water Pressure
ii. Weight of Dam
iii. Uplift pressure
iv. Pressure due to earthquake
v. Ice pressure
vi. Wave pressure
vii. Silt pressure

48. 42
viii. Forces from gates or other appurtenant structures
These forces fall into two categories as:
a) Forces, such as weight of the dam and water pressure, which are directly calculable from
the unit weights of the materials and properties of fluid pressures; and
b) Forces, such as uplift, earthquake loads, silt pressure and ice pressure, which can only
be assumed on the basis of assumption of varying degree of reliability.
It is in the estimating of the second category of the forces that special care has to be taken
and reliance placed on available data, experience, and judgment.
5.5.1 Computation of forces
Water Pressure
This is the major external force acting on dam. When upstream face of the dam is
vertical, the water pressure acts horizontally. The intensity of pressure varies triangularly,
with zero intensity at the water surface, to a value “w x h” at any depth “h” below water
surface.
This force can be calculated as:
P=H2
/2*1000
Which provides the value of P= 288000kg.
Weight of Dam
The weight of dam is major resisting force because gravity dams resist the
horizontal thrust of the water entirely by their own weight. For analysis purposes,
generally, unit length of the dam is considered. The cross-section of the dam may be
divided into several triangles and rectangles, and the weights W1, W2, W3, etc. of each
these may be computed conveniently, along with determination of their lines of action. The
total weight “W” of the dam acts at the center of gravity of its section.

49. 43
Uplift Pressure
To reduce uplift pressures full concrete cutoff is provided on upstream side of dam.
Uplift pressure diagram is shown.
Uplift Force= 212.57kg
Earthquake
The earthquake sets up primary, secondary, Raleigh and Love waves in the earth’s
crust. The waves impart accelerations to the foundations under the dam and cause its
movement. In order to avoid rupture, the dam must also move along with it.
𝑐 𝑚 = 𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑣𝑎𝑙𝑢𝑒 𝑜𝑓 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑓𝑜𝑟 𝑎 𝑔𝑖𝑣𝑒𝑛 𝑐𝑖𝑛𝑠𝑡𝑎𝑛𝑡 𝑠𝑙𝑜𝑝𝑒
𝜃 = 𝑎𝑛𝑔𝑙𝑒 𝑜𝑓 𝑢𝑝𝑠𝑡𝑟𝑒𝑎𝑚 𝑓𝑎𝑐𝑒 𝑖𝑛 𝑑𝑒𝑔𝑟𝑒𝑒𝑠
w= unit weight of water
h= depth of water in reservoir
y= vertical distance from reservoir surface to required elevation
𝑐 𝑚=0.237
𝑐 𝑠=0.237
Figure 5 - 2: Forces exerted by the water on Gravity dam

50. 44
𝛼ℎ = earthquake coefficient= 0.1
𝑝 𝑒𝑦=568.8
𝑃𝑒𝑦=0.726𝑝 𝑒𝑦∗ℎ
𝑃𝑒𝑦=9911𝑘𝑔
Moment of Earth quake force
The moment of earthquake forces can be found using following formula:
Which gives the value of 98288 kg-m.
Ice Pressure
The ice pressure is more important for dams constructed in cold countries, or at
higher elevation. The ice formed on the water surface of the reservoir is subjected to
expansion and contraction due temperature variations.
Area of Dhilore Dam doesn’t fall into the snow region. Therefore, we can exclude
the effect of ice pressure as there will be no ice on the dam.
Wave Pressure
Waves are generated on the reservoir surface because of the wind blowing over it.
The upper portions of dams are subject to the impact of waves. Wave pressure against
massive dams of appreciable height is usually of little consequence. Wave height can be
calculated from the following formula given by D.A. Molitor;
With; Fetch length = F= 1.58km
And; Wind velocity = Vw= 3.372km/hr. gives the wave height as hw = 0.533m
The wave pressure can be calculated as;
Pw = 2000hw
2
= 568.2 kg
And this act at a distance of 3/8hw above the reservoir surface.

51. 45
Silt Pressure
Water has a tendency to seep through the pores and fissures of the material in the
body of the dam and foundation material, and through the joints between the body of the
dam and its foundation at the base. The seeping water exerts pressure. The uplift pressure
is defined as the upward pressure of water as it flows or seeps through the body of dam or
its foundation.
Due to lack of availability of sedimentation data, silting capacity of reservoir of
Dasu dam was taken. Catchment characteristics were same as that our catchment. Life of
dam was taken as 30years.
Table: Suspended Sediment Yields at Selected Stream Gauging Stationson the Indus River
Stream Gauging
Station
Drainage Area Period of
Record
Suspended Sediment
Yield
Km2
Short tons/km2/yr
Kachura 112,700 940
Partab Bridge 142,700 1963 – 95 1,290
Barsin 157,500 1974 – 79 1,430
Besham Qila 162,400 1969 – 2000 1,600
Average Suspended sediment yield short tons/km2/year =1315i
=1174.1t/km2/year
Density of silt = 1.925 t/m3
∅ = 25.14
Height of silt= 0.2461m/year
𝑆𝑖𝑙𝑡 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒𝑃𝑠 = 0.5 ∗ 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑠𝑖𝑙𝑡 ∗ ℎ^2
1 − 𝑠𝑖𝑛∅
1 + 𝑠𝑖𝑛∅
Silt pressure= 14962.6kg (for 30 years)

52. 46
Summary of Forces

53. 47
5.5.2 Analysis for Factor of Safety
Factor of safety against sliding
Many of the loads on the dam are horizontal or have horizontal components which
are resisted by frictional or shearing forces along horizontal planes in the body of the dam,
on the foundation or in the foundation. A dam will fail in sliding at its base, or at any other
level, if the horizontal forces causing sliding are more than the resistance available to it at
that level. It should be greater than 1
FOS=
𝜇 ∑ 𝑉
∑ 𝑉𝐻
Where 𝜇 ranges from 0.75 to 0.65
0,75∗657865
397087
=1.24>1
Factor of safety against shear friction
It should be greater than 5
FOS=
𝜇 ∑ 𝑉+𝑏𝑞
∑ 𝑉𝐻
Where;
B=base of dam=25.5m
q= unit shear of concrete=14*104
kg/m2
0,75∗657865+25.5∗14∗104
397087
=10.23>5
Factor of safety against Overturning
The overturning of the dam section takes place when the resultant force at any
section cuts the base of the dam downstream of the toe. For stability requirement, the dam
must be safe against overturning. It should be greater than 2
FOS=
∑ 𝑀 𝑅
∑ 𝑀 𝑂
=
14198625
6932053.9
= 2.048 > 2
5.5.3 Compression and Crushing
In order to calculate the normal stress distribution at base let ∑ 𝐹 𝑣 is total vertical force and
∑ 𝐹 𝐻 is total horizontal force, R is the resultant force cutting the base at and eccentricity e from
the center of the base of width b, which is equal to 𝑋̅ is the distance of resultant force R from the
toe given by
𝑋̅ =
14198625 − 6932053.836
657865
= 11.04

54. 48
Whereas eccentricity of dam is calculated using following formula;
e=
25.5
2
– 11.04=1.71m
e <
𝑏
6
= 1.71<
25.5
6
1.71 < 4.74 OK
Compression load
Compression load exerted by the gravity dam on the foundation can be found
using following formula;
657865
25.5
(1 ±
6∗1.71
25.5
)
𝑝 𝑛,ℎ𝑒𝑒𝑙=15454.9 kg/ 𝑚2
𝑝 𝑛,𝑡𝑜𝑒=36142.3 kg/ 𝑚2
Figure 5 - 3: Compression force exerted by Gravity dam
at toe and heel

55. 49
Compression Load in Empty Dam:
In case of e <
𝑏
6
compression forces at heel and toe are
𝑝 𝑛,𝑡𝑜𝑒=
2∗657865
25.5
=51597.25 kg/ 𝑚2
𝑝 𝑛,𝑡𝑜𝑒 = 10568𝑝𝑠𝑓
𝑝 𝑛,ℎ𝑒𝑒𝑙 = 0
Compression strength of material is 12000psf which is greater than require stress capacity
so Dam is safe in case of compression
5.6 Contraction joints
If a concrete gravity dam is appreciably more than 20 m in length measured along the top
of the dam from one bank of the river valley to the other, then it is necessary to divide the structure
into blocks by providing transverse contraction joints. These joints are in vertical planes that are
at the right angle to the dam axis and separated about 18-20 m. The spacing of the joints is
determined by the capacity of the concreting facilities to be used and considerations of volumetric
changes and attendant cracking caused by shrinkage and temperature variations. The possibilities
of detrimental cracking can be greatly reduced by the selection of the proper type of the cement
and by careful control of mixing and placing procedures. The contraction joints allow relieving of
the thermal stresses.

56. 50
The construction joints in a concrete gravity dams provide passage through the dam which
unless sealed, would permit the leakage of water from the reservoir to the downstream face of the
dam. To check this leakage, water stops are installed in the joints adjacent to the upstream face
PVC pipes can be used for this purpose. The recommended cross section of a PVC water stop is shown in
Figure
Figure 5 - 4: Construction joint
Figure 5 - 5: Cross-section of PVC water stop (all dimensions in mm)

57. 51
5.7 Flushing pipes
Flushing pipes are provided at the bottom gravity dam in order to remove sediment and
water in emergency. Drawdown period od 10days was assumed. Scourinf or flushing velocity is
usaually taken as 1 fps for design puposes. Keeping in view 10 pipesof 0.7m dia are propesed to
be used at bottom of main structure with slope of 0.04H:1V.
Figure 5 - 6: Proposed cross-section of Gravity Dam

58. 52
CONSTRUCTION SPECIFICATION OF
EARTHEN DAM
CHAPTER 06

59. 53
6.1 Site preparation
6.1.1 Control and diversion of water:
Surface runoff should be minimized in order to reduce the damage to completed work, thus
facilitating future operations. The contractor should work according to the proposed plan for
diversion and care of stream during construction and removal of water from the foundation and
other parts of the work. The contractor should furnish and procure all material and labor for
construction and maintaining coffer dam, channel, flumes, drains for diversion and protective
work. Detail regarding location of site offices, coffer dams and diversion channels is given in site
plan.
Site requirement
Coffer dam should be constructed to minimize surface runoff. Diversion channel need to
be constructed to prevent saturation of the foundation and prevent excessive erosion.
6.1.2 Earth foundation
Site requirement:
The proposed site is 320 m in length comprising 150m length and dam 150m upstream blanket for
the proposed dam site.
6.2Foundation preparation
6.2.1 Clearing and grubbing
 Areas to be cleared and grubbed consist of reservoir area, site of dam embankment, 50-
foot strip adjoining the downstream toe of embankment, borrow and stockpile area.
 It also consist of removal and disposal of all tress, brush and rubbish, stumps and large
roots in approximately the top 3 ft. below the natural ground surface level.
6.2.2 Stripping
 The entire foundation area and a minimum of 5 feet beyond the footprint of dam and outlet
works should be stripped to a minimum of depth of 12 inches.
 Stripping to remove sod, topsoil, boulders, organic materials, rubbish fills, and other
undesirable materials. It is not generally necessary to remove organic-stained soils. Highly
compressible soils occurring in a thin surface layer or in isolated pockets should be
removed .After stripping, the foundation surface will be in a loose condition and should be
compacted. Where possible without disturbing the foundation soils, traffic over the
foundation surface by the heaviest rollers or other construction equipment available is
desirable to reveal compressible material that may have been overlooked in the stripping,
such as pockets of soft material buried beneath a shallow cover. Stump holes should be
filled and compacted by power-driven hand tampers.

60. 54
1. Overburden and weathered rocks should be removed from entire foundation of the
impervious core.
2. Sharp knobs and rock bluffs should be removed
3. Small opening and cavities should be Tremie grouted and covered with dental
treatment.
6.3 Excavations works
All the construction work shall be conducted to avoid stream sedimentation in the dam. All
excavation work should be done keeping in view of the lines and grades as specified in drawings.
6.3.1 Core cut off trench
Site requirement
Core trench comprises of 24 m length at base of dam and 18m at 6m depth with sides slopes
0.5H: 1V as shown on the drawing
.
The entire area to be occupied by the foundation of dam should be stripped to the material
to the desired strength parameters .open cracks or joints shall be filled with backfill
concrete or grout after removing top soil then the core excavation should be done up to the
specified dimensions. Field testing should be carried out to reach the desired compaction
and strength parameters. ASTM D 1556 and ASTM D 1557 test should be carried out.
6.3.2 Concrete cut of wall
Site requirement
Cut of wall of 16m should be excavated from the base of core trench base by trimmie
method of construction.
6.4 Utilization of excavated material
It is the intent of these specification that all the excavated suitable for embankment shall
be utilized in permanent construction site material i.e. silty clay shall be segregated by loads
during excavation operation and shall be placed lose to the site. This is to be used as the filter
material.
6.5 Embankment:
6.5.1 Site requirement
Shell dimensions:
Designed upstream embankment is 26m high with side slopes 3H: 1V .and
downstream embankment with slopes of 2.5H:1v. Length of the embankment is 150m.

61. 55
Core dimensions
Core crest of embankment has dimension of 10 m from top and 50m at bottom and
has height of 25 m with side slopes of 1H: 0.8V.
It should be constructed to the lines and grades and cross section indicated on the drawing,
or as directed by the engineer. The contractor is responsible for protection and maintaining
the embankment in satisfactory conditions till its final conditions
Material:
Shell material requirement:
Designed upstream embankment consist of shell of poorly graded sand (SP) with
permeability of 1.6x10^-3 and designed downstream shell comprises of site soil material
with permeability of 9x10-6.
Downstream shell material is site material and can be utilized effectively;
Core material
Designed core material is clayey silt (MC) with the proposed permeability of 5x10^-8 m/s.
the material is excavated from Tamair valley at haul distance of 3km from site.
Material containing brush, root, sod or other perishable material will not be considered
suitable. Contractor is requires to select suitable borrow area for the specified material
closer to the side as possible. Blending may be required depending on the type of borrow
material.
6.5.2 Foundation preparation of embankment
 After clearing and stripping has been completed as specified, earth foundation shall be
prepared as follow.
 The sides of stump holes, test pits and other similar cavities or depression shall be broken
down, so as to flatten out the slopes. and the side of the cut or hole shall be scarified to
provide bond between foundation material and the fill where required
 If required each depression shall be filled with proper moisture-conditioned impervious
material. the fill material as per requirement should be placed in layers and compacted if
proper clearing is not feasible and compaction cannot be done with roller equipment
material should be spread in 4 in thick layer and each layer shall be compacted with power
tampers to the required density of the contiguous material.
 After filling of the depressions and prior to the placement of compacted fill in the
embankment, excluding the cut off trench foundation, shall be scarified to a depth of 3
inches.
 After scarification and removal of the roots the entire surface of the embankment
foundation material shall be moisture conditioned and compacted.

62. 56
6.5.3 Placement
 Thickness of layer before compaction shall not be more than 8 inches.
 Compaction of each layer shall be conducted in systematic and continuous manner so to
ensure specified coverage.
 Rolling should be done parallel to the axis of the dam for greater efficiency.
 Embankment shall be brought up in layer such that the surface is essentially level at all
times, except for a slight slope for drainage.in general, the more fine impervious material
shall be placed toward the center of the embankment ,and the coarser material toward the
outer portion of the embankment.
 Material placed in cut off trench and in the central portion of the dam shall have at least 15
percent of the material; by weight passing no 200 sieve .material larger than 6 inch shall
not be used in 8 inch thick layer and larger piece should be surrounded by fine material.
Embankment construction should not be done if temperature drops below 32 degree F.
6.5.4 Moisture control
 The fill material shall have a moisture content throughout each layer at the time of
compaction of from “optimum minus one percent ”to “optimum plus two percent” as
determined by ASTM D -1557-78.
 In general, placement water contents should fall within the range of 2 percent dry to 3
percent wet of optimum water content as determined by the standard compaction test (EM
1110-2-1906). Contractor will be required to add water and manipulate the fill material by
harrowing or by any other method to keep uniform distribution of moisture in the material
within the specified limits .the application of water to the fill material shall be done at site
of excavation or at the stockpile area .and if necessary, by sprinkling on the embankment.
6.5.5 Compaction
Compaction requirement
The density, permeability, compressibility, and strength of impervious and semi-
impervious fill materials are dependent upon water content at the time of compaction.
Consequently, the design of an embankment is strongly influenced by the natural water
content of borrow materials and by drying or wetting that may be practicable either before
or after delivery to the fill. While natural water contents can be decreased to some extent,
some borrow soils are so wet they cannot be used in an embankment unless slopes are
flattened. However, water contents cannot be so high that hauling and compaction
equipment cannot operate satisfactorily. The design and analysis of an embankment section
require that shear strength and other engineering properties of fill material be determined
at the densities and water contents that will be obtained during construction.

63. 57
Field densities
Densities obtained from field compaction using conventional tamping or pneumatic
rollers and the standard number of passes of lift thickness are about equal to or slightly less
than maximum densities for the standard compaction test. This has established the practice
of using a range of densities for performance of laboratory tests for design. Selection of
design densities, while a matter of judgment, should be based on the results of test fills or
past experience with similar soils and field compaction equipment. The usual assumption
is that field densities will not exceed the maximum densities obtained from the standard
compaction test nor be less than 95 percent of the maximum densities derived from the test.
Field compaction Requirement
While it is generally impracticable to consider possible differences between field
and laboratory compaction when selecting design water contents and densities, such
differences do exist and result in a different behavior from that predicted using procedures
discussed in preceding paragraphs. Despite these limitations, the procedures described
generally result in satisfactory embankments, but the designer must verify that this is true
as early as possible during embankment construction. This can often be done by
incorporating a test section within the embankment. When field test section investigations
are performed, field compaction curves should be developed for the equipment used.)
Proper compaction at the contact between the embankment and the abutments is important.
Sloping the fill surface up on a 10 percent grade toward a steep abutment facilitates
compaction where heavy equipment is to be used. Where compaction equipment cannot be
used against an abutment, thin lifts tamped with hand-operated powered tampers should be
used, but tamping of soil under overhangs in lieu of removal or backfilling with concrete
should not be permitted. Specific guidance on acceptable characteristics and operating
procedures of tamping rollers, rubber-tired rollers, and vibratory rollers is given in guide
specification UFGS-02330A, including dimensions, weights, and speed of rolling; also see
EM 1110-2-1911.
Proposed Site compaction
When the embankment material achieved the specified moisture content and
conditions compaction process follows..
 Fill material of the embankment placed can be compacted by a minimum of eight
passes by vibratory roller or approved equivalent.
 Roller drum should not be less than 60 inches in diameter and not less than 60 inches
in length. The weight of the roller should not be less than 4,000 pound per linear foot
of drum length.

64. 58
 If necessary with the required water content it is found to roll 8 inches layer more than
8 times number of passes can be changed accordingly. However, the fill of the
embankment shall be compacted to the average density of 97 percent, with no field test
less than 95 percent, according to ASTM D 1557-78.
6.5.6 Finishing embankment
After completion of the embankment, the slopes of the embankment shall be dressed so as
to provide a uniform surface and slope. The crest shall be dressed and sloped according to the
drainage as shown in the drawings
6.6 Test on Embanking Material
Whilst embanking is in progress periodic site tests will be made by the Engineer in the
borrow
Pit and on the material, to ascertain the grading, moisture content, index properties,
compaction characteristics and other such properties of the embanking material.
 Unless otherwise approved by the Engineer field control tests of the fill materials will be
made for every layer, or approximately every 400 m³ of material placed to ascertain the
density and moisture content of the fill, to ensure adequate compaction.
 Tests will be made by the Engineer’s Representative on the filter, drainage and bedding
material for approximately every 200 m³ placed on the embankment.
 All tests will be made in accordance with the various parts of BS 1377: 1990 where
applicable or In accordance with other recognized standards, as specified.
 In all cases the tests will be performed at the laboratory provided in accordance with under
the Supervision of the Engineer but the Contractor shall deliver samples to the laboratory
as required by the Engineer.
.
6.7 Riprap
The contractor is requires to furnish all the material and labor for proper placing riprap and
bedding to the lines and dimensions shown on the drawing.
Site Requirement
The proposed material for embankment is…..
Quality
Rocks fragments used in riprap shall be dense, sound, and resistant to abrasion and shall
be free from cracks, seams, and other defects that increase the risk to be effected by water
and frost action. Angular shaped rocks are preferred for used as riprap material

65. 59
Installing Riprap
Compaction of the riprap material is not required, but riprap material shall be uniformly
distributed to ensure proper distribution of larger fragments. Smaller size rocks particles
tend to fit into the gaps between the larger particles to form densely packed, uniform layers
of riprap of specified material.
6.8 Filter
Site specification.
The proposed design specifies two filter material layers. They are laid in parallel layer
along the core material with thickness of each layer 2.5m.proposed height of the filter layer
is 25m with side slopes same as that of core i.e. 1H:0.8V
 Inner filter material categorized as silty sand (SM) according to USCS
classification. Designed permeability of inner filter material is 9x10^-6. Site
material can be used effectively for inner filter material. Wider particle size
gradation is used to make it more compatible with the available material and to
make it more cost effective. Proposed range of particles is between 0.002mm to
4.5mm.
 Outer filter material is classified as poorly graded sand (SP) according to UNCS
method of classification of soil. Designed permeability is proposed to be 1x10^-
6m/s. the material can be hauled from kottli Sattian area. Proposed range of
particles for outer filter material is between 0.2mm to 80mm.
Filters placement requirement:
In placement of the filter following considerations should be taken in account.
 Breakdown of particles (particularly coarser particles) occurs during placement and
compaction so the material should be carefully placed.
 Specifications should apply to the filter after placement in the dam. This means that
the contractor may have to manufacture the filters coarser than the specifications.
 It is more effective that concrete aggregates and filters are produced in the same
crushing and screening plant, so sieve sizes on which specifications are based
should be the same as specified.
Method of placement of filters
 The average in-place relative density of zones containing filter should be at least
85 percent, and no portion of the fill should have a relative density less than 80
percent. Field density test should be carried out as specified .
 Filter drain material should be compacted in layers not exceeding eight inches by
at least three passes of heavy duty ,vibrating baseplate compactor weighing no less

66. 60
than 200 pounds, and having a vibration frequency of no less than 1,600 cycles per
minute.
 The filter material should be clean and compacted in as nearly a saturated condition
as possible. Otherwise compaction at bulking water contents might result in
settlement upon saturation
 Filter material should be prevented from clogging to prevent hindrance to the flow
of water.
6.9 Proposed construction inspection activities
6.9.1 Frequency of site investigation
1. Continuous inspection of site is required throughout the construction process
2. Site inspector should supervise the construction process especially during construction of
critical elements.
6.9.2 Quality assurance testing program
 Maintain On-Site Complete Set of Daily Inspection Memoranda and All Test Results
 Maintain Periodic Compaction Control record
 Gradations of Representative Samples of Embankment Materials
 Concrete Cylinders for all Structural Concrete and air entrainment testing
 Complete Photo Record Construction Chronology
6.9.3 Sampling and testing of site material
The Contractor shall provide all pertinent data for the laboratory tests of the construction works
which will at all times be done under the supervision of the Engineer. Test specimens shall be
collected, prepared and tested in accordance with internationally recognized standards by the
Contractor under the supervision of the Engineer.
The Contractor shall take samples as directed by the Engineer to enable the following tests to
be carried out:
 Field bulk density and moisture content
 Laboratory compaction
 Particle size distribution
 Plastic and liquid limits

67. 61
Minimum rate of sampling and testing
Location of
material
Quality of fill placed per sample(m3)
Embankment
fill
Field density
and moisture
content tests
Laboratory
compaction
tests
Particle size
distribution
test
permeability Shear
strength
400 600 1200 2000 3-4
6.9.4 Filter Sampling
The gradation of each filter layer shall meet the requirements with respect to the material to
be protected and also with respect to the adjacent filter layers. The Contractor shall take samples
as directed by the Engineer to enable the following tests to be carried out:
 In site compaction
 Particle size distribution
The minimum rate of sampling and testing shall be 100m3 the filter.
 The actual frequency of sampling may be greater than this and shall be determined from
the results of previous tests, the quality of the material revealed during such tests and the
uniformity of such quality.
 The frequency may be amended as required by the Engineer.
6.9.5 Field compaction tests
Site requirement:
Field test should be carried for every 1000 to 3,000 yd^3 of the soil used for compaction
or whenever site engineer proposes test due to significant change in soil.
Method of sampling:
Excavate a hole in the compacted fill at the desired sample point take at about
20m.determine the weight of the excavated material.
• Determine the water content.
• Measure the volume of the excavated material. Sand cone or Balloon method, in Sand cone
method (AASHTO T 191 :ASTM D 1556 ), dry sand of known dry density is allowed to
flow through the cone –shaped pouring device into the hole .the volume is then calculated
by weight of the sand and the dry density. Balloon method (AASHTO T 205: ASTM D
2167).the volume of the excavated material is determined directly by expansion of balloon
in the hole.
• Compute the total density .the total weight of the material excavated from the hole and the
volume of the hole are known to compute wet density. Dry density can be determined as
water content is known.

68. 62
• Compute the field dry density and the proctor density for the soil and calculate relative or
percent compaction.
Determination of field moisture content:
• Pan drying method can be used for determination of field moisture content of the sample.
• Frying the sample over the flame can also be used for quick field estimation of water
content of the sample.
• Calcium carbide pressure meter (AASHTO T 217) can be used. The water in the soil reacts
with carbide to produce acetylene gas; its pressure is proportional to the water content of
the sample.
• If electricity is available in the field, a microwave oven can be used rapidly to determine
the water content of the sample.
• Density and water content by nuclear method. It is categorized as nondestructive field test
to determine water content using radioactive isotopes.it is quick method for determination
of field moisture content
6.10 Construction Equipment
Vibratory Rollers
 Vibratory rollers shall have a total static weight of not less than 13-15 ton with at least 90
percent of the weight transmitted to the ground through a single smooth drum for granular
material and pad foot (7” high) roller, when the roller is standing in a level position.
 The diameter of the drum shall be larger than 1.5 m. The frequency of vibration during
operations shall not be greater than 25 Hertz, and at these frequencies, the dynamic force
shall be not less than 18,000 kg.
 The roller shall be operated at speeds not to exceed 3km per hour.
Power Tampers
Compaction of material, in areas where it is impracticable to use a heavy roller or tractor, shall be
performed by the use of approved power tampers or vibratory rollers of smaller size, which will
give the Target Density at the correct moisture.

69. 63
6.10 Common reference standards
Common reference standards included in specification package and geotechnical
investigation for embankment dam design and construction.
• ASTM D 421: Practice for Dry Preparation of Soil Samples for Particle Size Analysis
• ASTM D 422: Method for Particle-Size Analysis of Soils
• ASTM D 698: Test Methods for Moisture-Density Relations of Soils and Soil Aggregate
(Standard Proctor)
• ASTM D 854: Test Method for Specific Gravity of Soils
• ASTM D 1140: Test Method for Amount of Material in Soils Finer than the No. 200 Sieve
• ASTM D 1556: Test Method for Density of Soil In-Place by the Sand-Cone Method
• ASTM D 1557: Test Methods for Moisture-Density Relations of Soils and Soil Aggregate
(Modified Proctor
• ASTM D 1586: Penetration Test Method and Split-Barrel Sampling of Soils.
• ASTM D 2216: Method for Laboratory Determination of Moisture Content of Soil, Rock,
and Soil-Aggregate Mixtures
• ASTM D 2434: Test Method for Permeability of Granular Soils (Constant Head)
• ASTM D 2487: Test Method for Description and Identification of Soils
• ASTM D 2922: Test Method for Density of Soil and Soil-Aggregate In-Place by Nuclear
Methods
• ASTM D 3017: Test Method for Moisture Content of Soil and Soil-Aggregate In-Place by
Nuclear Methods
• ASTM D 4220: Practices for Preserving and Transporting Soil Samples
• ASTM D 4221: Test Method for Dispersive Characteristics of Clay Soil by Double
Hydrometer
• ASTM D 4318: Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
• ASTM D 4253: Test Method for Maximum Index Density of Soils Using a Vibratory Table
• ASTM D 4254: Test Method for Minimum Index Density of Soils and Calculation of
Relative Density
• ASTM D 4546: Test Method for One-Dimensional Swell or Settlement Potential of
Cohesive Soils
• ASTM D 4644: Slake Durability of Shales and Similar Weak Rocks
• ASTM D 4647: Test Method for Identification and Classification of Dispersive Clay Soils
by the Pinhole Test
• ASTM D 4718: Practice for Correction of Unit Weight and Water Content for Soils
Containing Oversize Particles
• ASTM D 4767: Test Method for Consolidated Undrained Triaxial Compression Tests of
Cohesive Soils
• ASTM D 4829: Test Method for Expansion Index of Soils
• ASTM D 5080: Test Method for Rapid Determination of Soil Density (3-Point Compaction
Test)
• ASTM D 5084: Test Method for Permeability of Fine Grained Soils (Falling Head)
• ASTM D 5333: Test Method for the Measurement of Collapse Potential of Soils

70. 64
CHAPTER 07
CONSTRUCTION SPECIFICATION OF
GRAVITY DAM

71. 65
7.1 Foundation Preparation
For laying concrete over the rock foundations
 It has to be ensured that the surface is clean and free from mud, dirt, oil, organic deposits,
or other foreign material which may prevent a tight bond between rock and concrete.
 In case of earth or shale foundations all soft or loose mud and surface debris shall have to
be scrapped and removed.
 Then the surface has to be moistened to a depth of about 15 cm to prevent the subgrade
from absorbing water from the fresh concrete.
7.2 Lift thickness
A layer of concrete that is laid is generally kept as 1.5 m, in a view to ease construction
and limit excessive temperature rise. These layers of concreting are called lifts and between two
successive lifts a horizontal joint would invariably arise. The concrete of subsequent lifts has to be
placed after allowing sufficient time for the previously laid concrete to cool and attain its initial
set and become hard. Prior to placement of concrete of the next lift, the surface of the previously
placed concrete has to be thoroughly cleaned by the use of high velocity jet of water and air as
well as by wet-sand blasting. Further immediately before the concrete placing of the next lift
begins, a 12.5 mm thick layer of mortar should be applied to permit proper bond between the
concrete of the lower lift.
7.3 Construction Joints
Since the area of the concrete block near the foundation would be quite large, joints in the
vertical plane, but parallel to the dam axis have to be introduced to ease the concrete placement
and to allow safe dissipation of the heat of hydration of concrete. These joints called the
longitudinal joints are normally spaced at intervals of 15m to 30 m. Thus during construction a
continuous concrete pour is seen to be confined between the transverse joints (defining a block)
and the longitudinal joints.
Once a lift is cast it is thoroughly compacted with needle vibrators. The longitudinal joints
subdivide each block formed by the transverse joints into several smaller sub blocks, but since
each block must be a monolithic, these joints are invariantly provided with horizontal keys (or
undulations)over the entire surface, which helps to make a good bond with the adjacent lift .
7.4 Curing
Curing of concrete is important but a difficult task for the construction engineer. Primarily
it is necessary to maintain satisfactory moisture content in the hardening concrete. This may be
achieved either by the application of water (usually from sprinklers or perforated hoses, or
occasionally by ponding on the top of the lift) or by prevention of loss of water (by application of
some membrane to the surface). A second requirement for good curing is favorable temperature.
This can be achieved by any of the water methods but not by the membrane methods.

72. 66
7.5 Instrumentation in concrete gravity dams
Normally, instruments are installed in a concrete gravity dam to measure the various
parameters that indicate the structural health of the dam and the state of the foundation.
The following measurements are obligatory for all dams:
a) Uplift pressure at the base of the dam at a sufficient number of transverse sections
b) Seepage into the dam and appearing downstream there-from;
c) Temperature of the interior of the dam.
7.5.1 Measurement of Uplift Pressure
It is important to determine the magnitude of any hydraulic pressure at the base of a dam.
The effect of uplift on a dam is to reduce its effective weight on account of resulting buoyancy.
7.5.2 Measurement of Seepage
Seepage is, undoubtedly, the best indicator of the overall performance of a dam because
this reflects the performance of entire dam and not just the condition at discrete instrumented
points. Any sudden change in the quantity of seepage without apparent cause, such as a
corresponding change in the reservoir level or a heavy rainfall, could indicate a seepage problem.
Cutoff wall of 22m depth is provided to intercept seepage.
Measurement of seepage water along with uplift measurement at the plane of contact of
the dam and its foundation will give direct indication of the effectiveness of the cut off wall. The
chemical analysis of the seepage water through the foundation drainage system will help in
assessing whether any foundation material is being washed out.
7.5.3 Measurement of Temperature during Construction
For concrete gravity dams it is very important to know the thermic variations in the dam
during its construction which enables to determine whether the concrete setting process is normal
or otherwise. To achieve this purpose, temperature measuring devices are embedded within the
dam body and also mounted on the surface according to a predetermined plan for useful
observations. Any abnormal setting process indicated by temperature observations may lead to a
change in the concrete lift height, and also changes in the treatment of aggregates before concreting
and of the mass concrete during curing.
7.5.4 Measurement of Temperature of the Dam interior
It is necessary to measure temperature in the body of concrete and masonry dams in order
to ascertain the nature and extent of thermal stresses and the consequent structural behavior of the
dam and also to ascertain when to undertake grouting of contraction joints that may have been
provided for the structure.
7.5.5 Measurement of Temperature of Reservoir Water and Air
Measurement of temperature of reservoir water and air is essential for distinguishing the
effects of ambient and water temperatures on such measurements as deflection, stresses, strains,
joint movements and settlements.

73. 67
7.6 Mix Proportion
Since the basic consideration is to increase the weight of dam, therefore high aggregate ratio
concrete can be used with in central part of dam with mix proportion of 1:6:12 to be used with 2
m outer layer of 1:2:4 concrete.

74. 68
CHAPTER 08
COST ESTIMATION

75. 69
Cost Estimation
Detail cost estimation is performed while keeping in view the cost of different activities
associated with Dam Construction. Rates of different material and activities are extracted from August,
2013 Schedule of Rates of Pakistan Institute of Costs and Contracts.
8.1 Earthen Dam
8.1.1 Quantity of Materials
Quantity
Material
Area
(m2) Length(m)
Volume
(m3)
Unit
Weigh
t
(KN/
m3)
Unit
Weight
(t/m3)
Weight
(Tons)
Clayey Silt (Core and
core trench) 876 122.29 107126 15.6 1.58964
170291.83
82
Clayey silt(Upstream
Blanket) 318 122.29 38888.22 15.6 1.58964
61818.270
04
Silty Sand
(Downstream Shell ,
Blanket Transition
Material and inner
Filters) 1140.02 122.29 139413 18.05 1.839295
256421.71
81
Poorly graded sand
(Outer Filters, filter
of upstream riprap
and Drains) 419.765 122.29 51333.06 20 2.038
104616.78
01
Poorly graded gravel
(Upstream Shell)
547.784
3 122.29 66988.54 22 2.2418
150174.91
36
Concrete Cutoff
Wall 32 122.29 3913.28 23 2.3437
9171.5543
36
Spillway area to be
subtracted 36 17.24 620.64 15.6 1.58964 9681.984

76. 70
8.1.2 Cost of Excavation
8.1.3 Cost of Hauling
Hauling
Material
Weight
(ton) trucks used
distance
to haul
cycle time
of one
truck at
average
speed of
30km/hr.
No
of
hrs.
rate/hr./truc
k Cost
Clayey Silt
to be
excavated
222428
.1
10(18 Ton
Capacity
)working
simultaneously 3km 15min 308 1386.53 4270512.4
Poorly
graded
gravel to
be
excavated
150174
.9 do 8km 35min 14 1386.53 194114.2
Total 4464626.6
Excavation
Material M3
material
rate
Labor
rate
Machinery
rate
overhea
d Profit
Compo
site
rate
Total
cost
Clayey Silt to
be excavated 145393.6 0 1.66 101.59 20.65 123.9
18014269
.52
Silty Sand to
be excavated
from site 139413 0 1.66 101.59 20.65 123.9
17273276
.37
Poorly graded
sand to be
excavated
from site 51333.06 0 1.66 101.59 20.65 123.9
6360166.
363
Poorly graded
gravel to be
bought from
Kotli Sattian 66988.54 598.16 0 0 0 598.16
40069866
.31
total
81717578
.57

77. 71
8.1.4 Cost of Excavation
Compaction of earth work with power roller, including ploughing, moistening and mixing to
optimum moisture content in layers as per drawings and in accordance with the specifications
95% maximum modified dry density
Material M3
material
rate
Labo
r rate
Machiner
y rate
overhea
d Profit
rate
Composit
e rate Cost
Clayey Silt 145393.6 0 3.4 50.12 40.1 93.62 13611750.7
Silty Sand 139413 0 3.4 50.12 40.1 93.62
13051849.3
5
Poorly
graded sand 51333.06 0 3.4 50.12 40.1 93.62 4805801.25
Poorly
graded gravel 66988.54 0 3.4 50.12 40.1 93.62
6271467.30
6
Total
37740868.6
1
8.1.5 Cost of Clearing and Grubbing
Clearing And Grubbing
M2 material Labor Machinery
overhead
Profit Composite Total cost
12800 0 1.33 33.98 7.06 42.37 542336
Striping
12800 0 9.72 305.12 62.97 377.81 4835968

78. 72
8.1.6 Total Cost
Grand Total
Activity Cost Associated with activity
Excavation 81717578.57
Hauling 4464626.6
compaction 37740868.61
Clearing and Grubbing 542336
Striping 4835968
Total Rs 129,301,377.78
Contingency Allowance
Usually it ranges from 3 to 5%
Total Cost of Earthen Dam 135,766,446.669PKR (135.7 million PKR)
8.2 Concrete Gravity Dam
8.2.1 Cost of Concrete
Material
Area
(m2)
Length
(m)
Volume
(m3) Cement rate
Cost of
Cement
1:2:4
concrete 392.4 122.29 47986.596 6855.228 478 3276798.984
1:6:12
Concrete 120.4 122.29 14723.716 774.9324211 478 370417.6973
3647216.681

79. 73
8.2.2 Cost of Sand and Aggregate
Sand rate cost of sand Aggregate rate
cost of
aggregate
13710.456 871.92 11954420.8 27420.91 540 14807292.5
4649.594526 871.92 4054074.459 9299.189 540 5021562.09
16008495.25 19828854.6
Total= 39484566.5
8.2.3 Total Cost
Grand Total
Activity Cost Associated with activity
Materials 39484566.5
Hauling 19742283.25
Total Rs 59,226,849.76
Contingency Allowance
Usually it ranges from 3 to 5%
Total Cost of Concrete Gravity Dams 59,226,849.76PKR (59.226million PKR)
Concrete cutoff wall
Volume Cement
rat
e
Cost of
Cement Sand rate
cost of
sand Aggregate rate
cost of
aggregate
3913.28 559.04
47
8
267221.1
2
1118.
08
871.9
2
974876.313
6 2236.16 540 1207526.4
Total =Rs2449623.834
Cost of Blanket = Rs9399543

80. 74
ENVIRONMENTAL ASSASMENT
REPORT
CHAPTER 09

81. 75
9.1 Scope of study
The proposed dam will contribute to sustained long term environmental, social and economic
development and reduced drought vulnerability in Dalhore Dam region. The scope has following
components:
 Integrated water resource infrastructure development component
 Demand driven irrigated agriculture development and water use component
 Impact on groundwater refilling of aquifers component
 Environmental and ecological migrating birds component
 Recreational and aesthetic applications for the local community component
The spheres of environmental impact of the dam are therefore
Upstream in the watershed
The reservoir itself including related downstream hydrology and command area
Sphere Impact Summary Comment
Watershed Watershed conservation
measures are expected to
result in reduced soil erosion,
better vegetation cover and
less sediment yield to the
reservoir.
These impacts are all
considered as positive
environmental impacts and
require no preventive
measures.
Reservoir/water resource The dam will have a large
impact on hydrology it will
delay and reduce floods allow
controlled release and use.
During EA the impacts on
hydrology is to be carefully
studied.
Infrastructure Workers camp, excavations
and transport for the
construction will adverse
environmental impacts.
Mitigating measures for
construction works should be
included.
Command area Irrigated agriculture
development (IAD) will
intensify the crop rotation and
include more high yielding
and high value crops.
Irrigation without proper
water management and
drainage may potentially lead
to salinization.
IAD promotion will include
the promotion of Integrated
Pest Management and
responsible and safe of agro
chemicals to avoid possible
negative environmental
impact.