GL-29 Construction Operation FGL
GL-29 Construction Operation FGL
GL-29 Construction Operation FGL
List of Guidelines
Part III: Feasibility Study and Detail Design Guidelines for SSID
GL 11: Free River Side Intake Study and Design Guideline for SSID
GL 13: Irrigation Pump Facilities Study and Design Guideline for SSID
GL 15: Surface Irrigation System Planning & Design Guideline for SSID
GL 17: Sprinkler Irrigation System Study and Design Guideline for SSID
GL 18: Drip Irrigation System Study and Design Guideline for SSID
GL 19: Spate Irrigation System Study and Design Guideline for SSID
GL 25: Environmental & Social Impact Assessment (ESIA) Guideline for SSID
Part IV: Contract Administration & Construction Management Guidelines for SSID
TABLE OF CONTENTS
ACRONYMS................................................................................................................................V
1. INTRODUCTION.................................................................................................................1
1.1 SCOPE OF THE GUIDELINE.......................................................................................1
1.2 SETTING OF THE GUIDELINE....................................................................................1
2. WORKS CONTRACT MANAGEMENT...........................................................................2
2.1 ADVANCE PAYMENT REQUEST AND COLLECTION................................................2
2.2 CONSTRUCTION SITE HANDOVER...........................................................................2
2.3 PROJECT LAUNCHING AND JOB ORDER.................................................................3
2.4 MOBILIZATION............................................................................................................ 3
2.5 PROJECT FOLLOW-UP AND SUPERVISION.............................................................4
2.6 PERFORMANCE & CONSTRUCTION MATERIALS UTILIZATION ANALYSIS...........5
2.7 INTERIM PAYMENT REQUEST AND FOLLOW UP....................................................5
2.8 VARIATION WORKS....................................................................................................6
2.9 TIME EXTENSION....................................................................................................... 7
2.10 REPORT PREPARATION............................................................................................7
2.11 PROJECT PROVISIONAL HANDOVER.......................................................................7
2.12 REQUEST AND COLLECTION OF THE FIRST RETENTION MONEY.......................8
2.13 DEMOBILIZATION OF THE CONTRACTOR...............................................................8
2.14 PROJECT FINAL HANDOVER.....................................................................................8
2.15 REQUEST AND COLLECTION OF THE FINAL RETENTION MONEY........................9
2.16 REQUEST AND COLLECTION OF FINAL PAYMENT.................................................9
2.17 CONTRACT CLOSEOUT.............................................................................................9
3. CONSTRUCTION PLANNING AND SCHEDULING...................................................11
3.1 CONSTRUCTION PLANNING....................................................................................11
3.2 CONSTRUCTION SCHEDULING...............................................................................11
4. CONSTRUCTOR PERSONNEL AND THEIR RESPONSIBILITIES.........................14
5. ACTIVITIES IN CONSTRUCTION OF SMALL SCALE PROJECTS.......................16
5.1 SIT CLEARING........................................................................................................... 16
5.2 EXCAVATION............................................................................................................. 16
5.3 HARDCORE...............................................................................................................16
5.4 MASONRY STRUCTURE...........................................................................................17
5.5 CONCRETE STRUCTURE.........................................................................................17
5.6 PLASTERING.............................................................................................................17
5.7 POINTING..................................................................................................................17
5.8 BACKFILL AND COMPACTION.................................................................................17
5.9 STONE RIPRAP......................................................................................................... 17
LIST OF TABLES
LIST OF FIGURES
Figure 3-1: Typical Time Planning/Scheduling Process............................................................12
Figure 5-1: Trench for pipe laying.............................................................................................16
Figure 5-2: Stone Masonry........................................................................................................17
Figure 5-3: Hallow Concrete Block Masonry.............................................................................17
Figure 5-4: Pipe Lying..............................................................................................................18
Figure 5-5: Sheet piles..............................................................................................................20
Figure 5-6: Cofferdam made of soil and stone..........................................................................20
Figure 6-1: Wrong Storage of Cement......................................................................................22
Figure 6-2: Correct Storage of Cement.....................................................................................22
Figure 6-3: Main Canal Lined by Geo-membrane.....................................................................28
Figure 6-4: Night Storage Reservoir Lined by Geo-membrane.................................................28
Figure 6-5: Vibrating wire piezometers......................................................................................29
Figure 6-6: Inclinometer system................................................................................................29
Figure 11-1: Flowchart-showing Preparation Activities Implementation Procedure...................43
Figure 11-2: Flow Chart: Excavation Works..............................................................................45
Figure 11-3: Flow Chart: Fill and Compaction Works................................................................48
Figure 11-4: Flow Chart: Masonry Works..................................................................................51
Figure 11-5: Flow Chart-Concrete Works..................................................................................55
Figure 11-6: Flow Chart-Gabion Works.....................................................................................61
Figure 11-7: Flow Chart-Pipe Works.........................................................................................64
Figure 11-8: Flowchart-Procedure for Electro-Mechanical Equipments Supply, Installation,
Testing, and Commissioning Works..........................................................................................68
Figure 11-9: Flowchart-Procedure for Hydro-Mechanical Equipments Supply, Installation,
Testing and Commissioning......................................................................................................70
ACRONYMS
1. INTRODUCTION
This comprehensive technical guideline is developed for improving the knowledge and capacity
of the sector to scale up the effectiveness and efficiency of small scale irrigation implementation
so as to accelerate irrigation development of the country at large.
It also aims to support the existence of an effective project management system at the
operational level on the site in order to accomplish the job as per the contract.
Construction operation guideline for small scale irrigation development addressed the issues in
detail chapter by chapter. There are twelve chapters having the following its own contents: -
Chapter one presents introduction of the guideline and deals with the scope and setting out of
the guideline. Chapter two deals with works contract management focusing on the day to day
and periodical contract administration task within the members of construction crew.
Chapter three discusses construction planning and scheduling. Chapter four deal with
construction personnel and their responsibilities. Chapter five describes activities in
construction of small scale projects. Chapter six discusses type and use of construction
materials associating with technical specification that forms the contract. Chapter seven deals
with construction equipments, plants and instruments required in the course of small scale
irrigation implementation.
Chapter eight discusses construction methodology for small scale irrigation project. Chapter
nine deal with construction control underlining quality, time and cost that are the three areas of
equal importance in a construction project to be controlled progressively. Chapter ten deal with
construction safety issues by describing steps to be followed at site level to ensure safety at
construction site and very important safety issues and measures.
Chapter eleven presents construction procedure for preparatory works, excavation and fill
works of earthworks, masonry works, concrete works, pipe installation and testing works, pump
installation and testing works, and gate fixing works using work flowchart. Finally, construction
management software’s that are currently applied by the engineers assigned in construction
industry are discussed on chapter twelve.
Works contract is a legally binding agreement entered into between the employer and the
contractor for the execution of the works desired by the employer. Here, it is an expression of
the willingness of the employer to pay the contractor and of the contractor to do the work as per
the agreement.
Irrigation projects are capital projects that need to follow general contract management
procedures during their implementation. In order to accomplish the job as per the contract,
the contractor needs an effective project management system at the organizational level as
well as at the operational level on the site.
Both parties must now make arrangements to fulfill their obligations and protect their interests
under the contract. Some of the respective obligations and interests of client and contractor are
as tabulated here under.
CLIENT CONTRACTOR
Obligation Interests
Efficient project and contract management Realize the profit from the contract
Ensure contactor’s access to the site be able to work as planned
Secure adequate cash flow and payment Be paid on time
procedures Be informed of decisions and
Promptly communicate decisions and conditions pertaining to the
information pertaining to the contract contract
Interests Obligation
Fulfillment of project objectives Efficient construction and contract
management
Be informed on progress and actions taken Adhering to specifications
by the contractor Effective planning and site
Good quality of the Works management
Delivery on time Promptly act on decisions and
Delivery at contract price other information received
Provide adequate warning on
technical and other problems
pertaining to the contract
The day to day and periodical contract administration tasks within the members of construction
crew is described and discussed in sequential order as follows.
After signing a new contract agreement, the contractor can request the advance payment as
specified in the contract attaching disbursement schedule which shows for what purpose the
advance payment will be used and advance guarantee bond. The contractor should follow that
the advance payment approved by the client/consult to be sent to the client for further approval
and also that the responsible experts approve the payment and transfer to their finance to be
effected. Finally, the contractor delegate should collect the approved advance payment.
The contractor should arrange the way site hand over will be conducted in the presence of the
client’s, supervisor’s, contractor’s, and beneficiaries representatives to locate the exact position
of the works and the format prepared for this purpose should be signed by the three parties
(Appendix Part IV/GL 29/I-1 SSI Project Site Handover to Commence Construction Format).
The contractor shall set out the works in relation to original points, lines and levels of reference
specified in the contract or notified by the engineer during the site hand over and approved by
Engineer.
The contractor should arrange a meeting for the concerned bodies and present the overall
content of the agreement signed. The contractor should give job order to the respective
construction crew along with agreement documents and working drawings. The job order letter
and agreement document should also be copied for other supporting teams and Archive. The
code/job order number given indicates the project type, project office/zone and number of
agreement in a particular year.
2.4 MOBILIZATION
The contractor should mobilize to the site within the period specified in SCC forming the
contract. The project contractor must utilize the mobilization period to finalize arrangements,
which could not be completed before signing of the contract or are still outstanding. The
following checklist provides an overview of the mobilization task to be carried out contractor.
Variation works should be clearly identified and clear contractual procedures should be set prior
to execution of any variation work. (Both item or quantity variation). Contractual claims should
be raised for every unforeseen problems like design changes, price escalations, time extension,
weather and force majeure conditions and site related problems.
Contractor delegated supervise should also play an important role in settling any contractual
disputes and disagreements between the contractor and the resident engineer during
supervision. The activities (check lists) which should be performed during supervision are:
Whether or not construction is on progress as per the contract agreement (i.e. cost
wise, time wise and quality wise)
Identifying variation works and informing the project office the contractual procedures
or the way these works will be requested and approved on payment.
Identifying the difference between report and payment and assessing the causes of
this difference by observing the executed works. The difference is may be because of:
Works executed but not approved since it was executed without permission
of the resident engineer.
Reporting error (Report uncertainty).
Works executed but payment not requested (Expected payment).
Incomplete works.
Settling any contractual disputes and disagreements between the project office and
the resident engineer
Identifying the problems and reasons for construction delays and suggest possible
solutions.
Assessing the utilization of construction materials:
Materials supplied purchased,
Received at projects,
Issued from store,
Utilized for construction, and
Materials on site or at stock/stock balance.
Finally, the detail report, problems observed and suggestions given shall be reported
for the concerned bodies for their immediate action.
All the necessary data like the materials supplied to project, cash transferred from offices which
are used as inputs for analysis to be made both at office and at project site during supervision
should be regularly collected and various analyses should be made based on this data by
supervise.
Store keeper should give the report of each construction material, equipment and
other inputs supplied for all the projects and feedback of the materials received at
projects. This data will be used for analysis of materials supplied, revived at project,
issues from store and utilized for construction.
ii. Weekly, monthly, quarterly and annual plan & report of project
Revised project(s) annual and monthly construction plan or schedule to follow their
performances.
The detail physical report of projects should be collected by supervise for comparison
between payment and report for executed activities monthly.
iii. Analysis
Based on the above data, the following analyses should be made periodically and the result
should be reported each time to the concerned bodies.
a. Construction materials analysis by comparing materials supplied, received at projects,
issued from store, the stock balance and those utilized for construction. This analysis is
made both at head office and also at projects during supervision by physically observing
the executed works, materials on site and those at store.
b. The detail physical report of projects should be compared with payment requested and
physically executed activities and the reasons for the gap observed should be identified
during supervision.
c. Monthly analysis of the difference between payment and report shall be presented so
that special attention will be given. interim
Monthly payments of projects shall be submitted by site construction crew to head office on the
specified day of the month.
vii. Contract Engineer should follow that the payment approved by the consult is sent to the
client for further approval and also that the responsible experts approve the payment
and transfer to their finance to be effected.
viii. Contract Engineer should give feedback copy of the approved payment certificate to
construction team, so that project offices shall use it as feedback for the next interim
payment.
ix. Contract Engineer should give the necessary documents of the approved to Financer for
their collection.
x. Contract Engineer should regularly check that payments due to price adjustment are
regularly requested and should also follow the approval for those materials, labor or
other inputs listed in the special condition of the contract.
Construction team should follow that any variation (item or quantity variation) should be ordered
by the resident engineer in written form prior to execution. Execution of variation works prior to
written order and approval of supervisor delays the payment and also makes the client not to
adjust its budget beforehand.
Site construction crew should analyze the variation works, fix the unit rate for new activities and
sent to the client/supervisor for approval. The contractor should follow that the variation
approved by supervisor is sent to the client for further approval according to the GCC
“Engineer’s Decisions” Clause forming the contract document. After the variation is approved
by the client, the contractor should act accordingly.
Project A is an irrigation dam construction project. The works include: (i) foundation excavation;
(ii) construction of dam; and (iii) construction of 5 km irrigation canal. The Particular Conditions
of contract restricts the Engineer’s authority to issue variation order of more than ETB
250,000.00.
While reviewing the design of the dam, the Engineer noticed errors and reviewed the design
accordingly. According to the review, the volume of works has been increased by ETB 0.5
million. The Engineer has issued a variation order to the Contractor in line with the revised
design.
If you are assigned as the Contractor’s Project Manager on site and noted that the VO has not
been copied to the Employer. What would you do upon receipt of such instruction?
Response
Extraction of existing matters with respect to GCC
1. There is a variation work due to increase of volume of works as the result of dam design
error rectification that amount ETB 500,000.
2. There is restriction by the client for the engineer in accordance to GCC “Engineer’s
Decisions” Clause that is stated in the particular conditions of contract that restricts the
Engineer’s authority to issue variation order of more than ETB 250,000.00.
3. There is variation order by the engineer to the contractor in accordance to GCC
“Instructions” Clause but not copied to the employer.
4. The Engineer didn’t obtain approval from the employer before ordering the contractor
the variation work according to the restriction laid up on hem according to the particular
conditions of contract. S/he failed to notify the variation occurred, due to the dam design
error rectification, for approval.
Having this understanding the contractor has to communicate with the engineer to get approval
from the employer or directly communicate the employer for its consent prior to commencing
the variation work ordered.
The contractor organizes and examines time extension data approved by the resident engineer.
The data which should be collected and approved are types of activities delayed, justifiable
reasons approved by third party, number of delayed days for each activity, and total number of
delayed days. Finally the contractor should check the time extension and send it to the
client/supervisor for approval. After the time extension is approved by the client, the contractor
should act accordingly.
Weekly report: The contractor should perform preparation of the overall weekly report and
submit to the concerned bodies, Preparation of weekly payment attendance,
and updating payment follow up once in a week.
Monthly report: The contractor should prepare the overall monthly report and submit to the
concerned bodies.
Annual report: The contractor should prepare the overall annual report and submit to the
concerned bodies.
Having completed all essential tasks the contractor will request the client/supervisor to
undertake the inspection for substantial completion. Substantial Completion means that the
Client can make use of the works in accordance with the objectives and that there are no
significant defects or essential parts of the works missing. During this inspection all defects
and outstanding works are noted and time limits given for the contractor to correct or carry
them out.
Contractor should submit the following to the supervisor to notify the substantial completion of
the project activities and initiating provisional handover.
The completion report approved by the supervisor engineer shows that construction is
completed as per the agreement,
As built drawings prepared by construction engineer and approved by the supervisor
engineer, and
Operation & maintenance manual prepared by construction engineer and approved by
the supervisor engineer.
Then the contractor requests the client/supervisor by letter to conduct provisional hand over.
Provisional project handover shall be conducted in the presence of the three parties signing on
the format/certificate prepared for this purpose (Appendix Part IV/GL 29/I-2 Constructed Project
Handover Format).
When the Substantial Completion Certificate has been issued, the contractor can apply for the
release of the first retention money, which is meant to cover the Client’s costs for
completion of outstanding works or rectification of works not done according to specifications.
The Retention Money is specified in the Contract Data as a percentage to be deducted from
the value of the works approved for payment and as a maximum of total money that can be
retained. It is usually 5% in small scale irrigation infrastructures construction which is deducted
from each interim payment certificate.
Up on issuance of Substantial Completion Certificate the first 50% of retained payment (2.5%
of the total contract amount) is request by the contractor and effect by the client accordingly.
An orderly scaling down of activities and demobilization from site, require good planning
and supervision by the site staff, as there are many diverse activities, usually spread over the
whole project location, to be undertaken. The demobilization tasks come in addition to the
finishing activities of the works and include:
Giving notice to labourers as the labour force is scaled down for termination of the
temporary employment in accordance with labour regulations;
Settling accounts for suppliers and utility services;
Taking down temporary works used in the construction activities and for the camp and
site facilities;
Re-instating areas used as close as possible to their original condition;
Collection and stocktaking of tools and equipment;
Maintenance, repair and removal of construction equipment from site;
Planning and preparations, including training, for operation and maintenance during
the Defect Liability Period.
Project final handover shall be effect during the period specified on the provisional handover
format of the project at the end of the defect liability period (usually 365 colander days). The
contractor should check the site during defect liability period and correct the defected works if
any. At a time the site is ready for final handover the contractor request the supervisor/client to
undertake the final inspection.
During the final inspection, representatives from the Client and other stakeholders should be
present for the formal handing over of the works and signing on the format/certificate prepared
for this purpose (Appendix Part IV/GL 29/I-2 Constructed Project Handover Format). Provided
that all outstanding works and correction of defects as noted on the Substantial Completion
Certificate have been carried out to the satisfaction of the Supervisor Engineer and the project
has been well completed, the Client/Supervisor will issue the signed and stamped Final
Completion Certificate to this effect.
Up on issuance of the Final Completion Certificate, the contractor requests the final retention
money and the client release the remaining portion of the Retention Money usually 50%
retained payment (2.5% of the total contract amount).
After receiving the Final Taking-Over Certificate for the Works, the Contractor shall submit to
the Engineer a Statement at completion with supporting documents.
After receiving the Performance Certificate, the Contractor shall submit, to the Engineer a draft
final statement with supporting documents showing in detail in a form approved by the
Engineer:
a) the value of all work done in accordance with the Contract, and
b) any further sums which the Contractor considers to be due to s/him under the Contract
or otherwise.
Documents required for final payment to be obtained (refer to contract) may include the
following, but are not limited to:
i. As-built drawings (CAD Format) and specifications on the specified days before final
inspection. The as-built drawings are the original contract drawings adjusted to reflect all
the changes that occurred,
ii. Maintenance/Operations Manuals – specified days after approval of submittal,
iii. Spare Parts List – specified days after approval of submittal, and
iv. Construction completion report
Finally the contractor should collect the Final Payment Certificate which shall state:
a. the amount which is finally due, and
b. after giving credit to the Employer for all amounts previously paid by the Employer and
for all sums to which the Employer is entitled, the balance (if any) due from the
employer to the Contractor or from the Contractor to the Employer, as the case may be.
The contractor shall coordinate and plan for closeout submittals (if any) and closeout
conference with contracting officer and customer. Assessment of the project team’s
performance is crucial in this stage for avoiding mistakes in the future. Actual activity costs and
durations should be recorded and compared with that was planned. This updated costs and
durations will serve as the basis for the estimating and scheduling of future projects. Some of
contract closeout best practices for the considered concerns are tabulated hereunder as an
example.
Construction planning & scheduling is an application of common sense and a logical analysis of
construction activities using a thorough knowledge of construction methods, materials &
practices.
Construction planning process is simply an application of the thoughts and process that must
be entered into before detail scheduling is done. It requires the following to be considered.
Planning serves as a foundation for several related functions, such as cost estimating,
scheduling, project control, quality control, safety management, and others. It also answers the
questions
What is going to be done?
How?
Where?
By whom? and
When (in general terms, the project’s start and end)?
The efficient and effective implementation of construction projects requires good management
of relationships for and among resources, activities and stakeholders as applied to the context
where such projects are implemented. Materials, Money, Manpower and Machineries (the 4
M's) are usual resources recognized in most situations.
Construction planning should consider the following but not limited to:
items that require purchase orders to be placed long in advance,
mobilization of labour may need conferences and discussion with the direct & indirect
beneficiaries,
access to construction site are requirements prior to mobilizing equipments and
other construction utilities,
if there are tasks in the project that are dependent upon the completion of other
activities due consideration has to be made,
if special environmental controls are required, it has to be sorted out,
the time allotted to complete the project should be adequate for the location and the
seasons. Otherwise increment in construction unit size or premium time will be a
necessary
Scheduling is the determination of the timing and sequence of operations in the project and
their assembly to give the overall completion time. Scheduling focuses on one part of the
planning effort. It deals with when on a detailed level.
Contractors need project scheduling to (1) calculate the project completion date, (2) calculate
the start or end of a specific activity, (3) coordinate among trades and subcontractors, and
expose and adjust conflicts, (4) predict and calculate the cash flow, (5) improve work efficiency,
(6) serve as an effective project control tool, (7) evaluate the effect of changes, and (8) prove
delay claims.
Scheduling requires determination of the work activities, activities’ durations, and logical
relationships; drawing of the logic network; and performing of the total time required
calculations.
The Critical Path Method (CPM) is a schedule network analysis technique currently used with
the following advantages: -
Time Scheduling
Crash the Schedule
e) Time required for proper execution of various activities without compromising quality
and safety.
In its characteristics, SSIPs are infrastructure project by type of work, special short-term
projects having less than one year completion time, relatively small value projects, and normal
pace projects.
During construction planning and scheduling use formats listed under Appendix Part IV/GL3/B
Planning and Scheduling Format.
Man power is the most influential element in construction industry. Construction team for a
project can comprise a compliment of professional technical and administrative staff. In
general, the following skilled/professionals, semi-skilled and unskilled man power as technical
staffs together with other administrative staffs as per the demand have a paramount importance
for construction of small scale irrigation projects at site level.
The followings are major activities that should be well articulated and presented in the technical
specification, drawings and bill of quantity of a given project. The existence and scope of the
activities may vary project to project based on the site condition that determines the type of
structure even.
The work shall consist of clearing, grubbing, removing, and disposing of all vegetation and
debris within the limits of project and such other areas as may be indicated on the plans or
required by the work.
5.2 EXCAVATION
This work shall consist of excavation, disposal, shaping, or compaction of all material
encountered within the limits of the work. Broadly, excavation can be categorized as trench
excavation, foundation excavation, and mass excavation. Excavation is required found
structure foundation, canal, and ditches; to obtain material for small earth dams; to form the
embankments of irrigation canals; to produce a level road formation platform in virgin terrain.
5.3 HARDCORE
It is stone place over soil to form foundation of the main structure. It is usually 20cm to 25cm
thick.
In most cases small scale irrigation infrastructures could be built out of stone masonry. It is
relatively cheap and is easy to work with as compared to other construction materials. Shaped
stone masonry is the commonly used stone masonry. The stones are shaped to a rectangular
prisms is easier to produce a wall with proper bonding and uniform surface.
Besides, hallow concrete block (HCB) masonry made from sand-cement can be used in
irrigation construction for building of pump and generator houses.
Figure 5-3: Stone Masonry Figure 5-4: Hallow Concrete Block Masonry
It is an activity of casting a structure with the specified cement, sand and gravel mix. It may be
lean, mass or reinforced cement concrete depending on the quality of works as specified in the
technical specification, drawings, and bill of quantity forming contract. In some description
concrete works includes supply, cutting, placing and fixing in a position of reinforcement bar.
But, mostly supply, cutting, placing and fixing in a position of reinforcement bar work treated
separately.
5.6 PLASTERING
It is application of cement mortal to the internal and external walls of structures as specified in
technical specification and drawing.
5.7 POINTING
It is an activity of application of cement mortal between building stones or the bricks leaving the
latter undressed.
It is an activity of refill a trench or other excavation around a structure with the specified back fill
material and compact the fill to the recommended degree of compaction to make it firm. The fill
material may be surplus native excavated or selected material from borrow area.
Pipe lying is an activity commonly used for construction of canal system and pressurized
irrigation system.
Gabion structures are wire mesh boxes filled with stones and tied together to form
basic structures. They are used principally for retaining walls, drifts and erosion protection. The
standard size of gabion boxes is: 2m length, 1m width and 1m height.
Gabion boxes may be made from purpose made gabion cages, welded steel mesh sheets
or galvanized chain link fencing.
Cages have to be woven together using 3mm galvanised binding wire, securing all edges
every 0.15m with a double loop. Tighten the binding wire with a pair of heavy-duty pliers and
secure with multiple twists.
Stretch and stake the connected baskets with wires and pegs to achieve the required shape
(all sides rectangular).
Fill baskets by hand using hard durable stones not larger than 250 mm and not smaller than
the size of the mesh. The best size range is 125 - 200 mm. Place the stones as if for dry
stone masonry.
Fill the boxes to 1/3 of the height. Fit horizontal bracing wires and tension with a
windlass to keep the vertical faces even and free of bulges. Further bracings should be fixed
after filling to 1/3 of the height.
Lids are closed and stretched tightly over the stones, (carefully) using crowbars if
necessary. The lid is securely woven to the tops of the walls using galvanized wire.
5.12 DEWATERING
It is an activity to removing water from working area. The water may be from surface flood, sub
surface or ground sources. It is mainly happen during diversion weir construction and spring
eye capping.
5.13 COFFERDAM
Cofferdam is a temporary dam or barrier used to divert a stream or to enclose an area during
construction of headwork structures such as Earth Dam and Diversion Weir.
Cofferdams may be constructed of soil, sandbags or sheet piles depending to the
complexity of the work. Generally, cofferdams are constructed of materials available
at the site.
Different construction materials are used for irrigation construction. Some of them and the
respective unit of measurement are as tabulated under.
No. Construction Materials Unit of Measurement Remarks
1 Sand m3
2 Gravel m3
3 Stone m3
4 Selected Material m3
5 Timber m2
6 Cement qt
7 RCC Bar kg
8 Eucalyptus poles pcs
9 CIS 32 Gauge pcs
10 HCB pcs
11 Plywood pcs
12 Chip wood pcs
13 Morale pcs
14 Nail kg
15 Roof Nail kg
16 Soft Wire kg
17 Gabion kg
18 RCC Pipe, of different ø pcs
19 PVC pipes of different ø pcs
20 Geo-membrane m2
21 Red Ash m3
All materials to be used in the work shall be in conformity with the requirement laid down in the
technical specification forming the contract. If any special material not covered in the technical
specification is required to be used, it shall conform to the relevant Ethiopian Standard, or
specified by the Engineer.
Selected Material are used for embankment fill from the borrow area recommended by the
geologist and adapted by design engineer during design phase and specified in the technical
specification forming the contract. Generally, borrow material shall be pit-run, granular, well
graded material free from rocks larger than 100 mm in maximum dimensions and free from
large roots, stumps, or other debris.
Soil materials used for back filling of structures may be native material excavated from
foundation or trench and borrow materials as discussed above (Section 5.1). Back fill materials
shall be as specified in the technical specification or recommended by the supervisor engineer.
6.3 STONE
The stone used for hard coring and masonry works is to be hard basaltic granite, gneiss or
other hard, dense stones in larger piece, free of cracks or veins of soft matter. The unit weight
of basaltic stone is 2700kg/m3. It should be as specified in the technical specification that is
used for structural analyses during design phase.
6.4 CEMENT
Ordinary Portland Cement (OPC) produced from limestone and clay is the commonly cement
type used in Ethiopia for mortar and concrete mixes. It is normally sold in paper bags containing
50 kg each. 50 kg of cement equals 36 liters cement
Hardened lumps found when opening the bag should be removed by sieving the cement.
Figure 6-8: Wrong Storage of Cement Figure 6-9: Correct Storage of Cement
6.5 SAND
Sand is referred to as fine aggregates and is used to designate aggregates in which the
nominal maximum size as specified in the technical specification forming the contract. The sand
particles should be smooth, rounded and hard.
Sand is used as ingredient for mortal and concrete mixes. It is very important to use only
clean sand as impurities, like organic material and clay, can cause considerable loss of
strength in the finished concrete. If the aggregates need to be washed, attention must be given
in order not to wash off the fine particles.
To assess the cleanliness of aggregates a simple bottle test can be carried out. Fill a clear
bottle half with aggregates, add water to the top and shake well and then allow the aggregates
to settle. After about 30 minutes, if the aggregate is clean, there should be no or very little (less
than 5%) dirt or silt deposited on top of the aggregates and the water above should also be
clear.
On site sand should be deposited on a clean ground (no dirt and no topsoil) on clearly
separate heaps to avoid uncontrolled mixing. During the rains it is also advisable to cover sand
with a polyethylene sheet or taurpeline in order to avoid the fine particles being washed off.
6.6 GRAVEL
Gravel is referred to as coarse aggregates and has diameters ranging from 2 mm to 50 mm.
The stone diameter selected for the preparation of concrete depends on the structure under
construction. For example, for 5-cm thick concrete-lined canals the ideal stone size is 19 mm
(¾ inch). The gravel should be round or chunky, hard and strong. Poorly-shaped stones, such
as those that are flaky and long, should be avoided as this would mean that more of the other
materials are needed. The stones should be about the same size. It is used as ingredient in the
concrete mixes of different class as specified in the technical specification forming the contract.
On site gravel should be deposited on a clean ground (no dirt and no topsoil) on clearly
separate heaps to avoid uncontrolled mixing.
Reinforcement steel bar is a load bearing construction material used for construction of
reinforced concrete of different grades as specified in the technical specification forming the
contract.
Table 6-1: Useful Constants of Steel
Parameters Value Unit
Modulus of elasticity 2x105 N/mm2
Poisson's Ratio 0.25 to 0.30
Modulus of Rigidity 7x104 to 8x104 N/mm2
Coefficient of thermal expansion 12x10-6 persC
Specific weight 7.85x104 N/m3
6.8 WATER
Water is used for mixing of mortal and concrete as well as curing of masonry and concrete
structures. It is an important ingredient as it actively participates in the chemical reaction with
cement. It does have two functions in concrete mix namely chemical reaction with cement, and
lubricates all other materials & makes the concrete workable.
Water used in concrete and mortal shall be reasonably clean and free from objectionable
quantities of silt, organic matter, alkalis, salts, oils, acid, sugar and other impurities. It can be
taken form rivers, lakes (For example Lake Tana and Lake Ziway), wells and from taps. Salt
water (sea or lake), surface run-off water and water with other chemical or organic impurities
must not be used. Generally, drinking water is suitable for making good concrete and mortal
mixes. As guidance, value of different prosperities of drinking water according to Ethiopian
Guidelines Specification for Drinking Water Quality March 2002 is as tabulated under.
6.9 FORMWORK
Strong and rigidly braced formworks made of either timber or metal as specified in the technical
specification are used for casting of concrete in situ.
Currently unplasticized polyvinyl chloride (uPVC) is commonly used for construction of canal
system. Steel pipes and fittings are used for pressurized irrigation system. The type, diameter
and nominal pressure of the pipe should be as specified in the technical specification and
drawings forming the contract for each specific project.
Cement mortar made of cement and sand as specified proportion on the technical specification
forming the contract is used for wet masonry, plastering and pointing works. For example, to
produce 1 m3 cement mortal of a 1:2 mixture requires 13 bags of cement and 0.88 m3 of sand.
Table 6-3: Quantity of cement and sand to produce 1m3mortar for different mixes
Cement Sand
Mixture
Calculated Recommended Number of
(Cement : Sand) Kg m 3
Kg m3
number of bag* number of bag* Box**
1:2 612.5 0.438 12.3 13 1610 0.88 24
1:3 459.4 0.328 9.2 10 1811 0.98 27
1:4 367.5 0.263 7.4 8 1932 1.05 29
*One Bag of cement weighs 50kg.
** Box made of Timber having 0.4m*0.30m*0.30m standard dimension and capacity of 0.036m3.
Inside measurements:
W
• length = 40 cm
• width = 30 cm
• height = 30 cm
H
• volume = 0.036 m3 = 36 litres
L
In irrigation construction C-7, C-10, C-15, C-20, C-25, C-30, and C-35 grades of concrete
commonly used. A set of mix for concrete should be well defined either in terms of the
proportion of cement, sand and gravel or in terms of the 28days compressive strength
requirements. The commonly used concrete mix in terms of proportions of the components are
the following but not limited to:
1:4:8 used for lean concrete,
1:3:6 used for mass concreting and the rear sides of dams,
1:2:4 and 1:2:3 used for general reinforced concrete works,
1:1.5:3 used for front faces of dam, water tanks columns, etc.
The following are some of grade of concrete based on 28 days cube strength used in irrigation
construction.
Note that the actual value of mix proportion for each grade of concrete for the specific project
should be determined by mix design in the laboratory. The material from the query site and type
of cement used matters the value.
Cement, sand and gravel quantity to produce 1m3 of concrete mix for different grade of
concrete:-
6.13 GABION
Construction materials for gabion walls and mattresses used in aprons for retaining walls, lining
of channels, revetments, and other anti-erosion structures in accordance with the Drawings or
as ordered by the Engineer are as discussed here under but not limited to:
Rock: stones or rock for filling gabions shall be clean, hard, sound, durable and un-weathered
boulders or rock fragments. It can be obtained from sources located by the Contractor and
approved by the Engineer.
No rock particles shall exceed the maximum size given in table below and at least 85% of the
rocks shall have a size equal to or above minimum size given in the table.
Wire: All wire used in the fabrication of the gabions and in the wire operations during
construction shall be to ASTM A 910, Grade # 1010 or 1015, having a tensile strength of not
less than 350 MPa. Cold drawn steel wire fabric shall meet the requirements of AASHTO M-55.
Galvanizing: All wire used in the fabrication of gabions shall be galvanized in accordance with
the provisions of ASTM A 641 with Class 3 coating or aluminized with a coating weight as per
ASTM A 809 for Class A heavy galvanized mild steel wire. The minimum mass of the zinc-
coating shall be according to the figures shown in Table below.
Source: ERA Standard Technical Specifications and Method of Measurement for Roadwork, 2013
The adhesion of the zinc coating to the wire shall be such that when the wire is wrapped six
turns round a mandrel of four times the diameter of the wire, it shall not flake or crack to such
an extent that any zinc can be removed by rubbing with bare fingers.
Wire Mesh and Clip Fasteners: Wire mesh shall be hexagonal-woven mesh wherein the joints
are formed by twisting each pair of wires through three half turns. The tightness of the twisted
joints shall be such that a force of not less than 1.7 kN is required when pulling on one wire in
order to separate it from the other wire provided each wire is prevented from turning; and the
applied forces and the wire are all kept in the same plane. The diameter of the wire and the size
of mesh used shall be as shown in Table below.
The shorter dimensions of the mesh shall be taken from centre to centre of the twisted joints,
and the larger dimensions shall be between the inside ends of twisted joints.
Alternatively; wire used in the body of the mesh shall not be thinner than 11-gauge for
galvanized baskets and 12-gauge for PVC coated baskets. Selvage wire shall not be less than
10 gauge, and lacing and tie wire shall not be thinner than 13-gauge. Clip fasteners shall be
galvanized and/or PVC coated as required and may be of any type that provides positive lock
when installed. They shall be stronger than the mesh to which they are attached.
Galvanizing on the steel clips shall be in accordance with ASTM A 641 with a Class 3 coating,
and aluminizing shall be in accordance with ASTM A 809.
Gabions using PVC Coated Wire: When gabions using PVC coated wire is specified, the wire
used for the gabion mesh, and for wiring the gabions during construction shall be galvanized
wire as specified in Clause 9102(b) onto which is extruded a polyvinylchloride (PVC) coating.
The average thickness of the PVC coating shall be as specified, either 0.30 mm for use in
mildly corrosive conditions or 0.55 mm for use in marine and other severely corrosive or
abrasive conditions. The minimum thickness of the coatings shall be 0.25 mm and 0.4 mm
respectively, and the coatings shall be capable of resisting the deleterious effects of natural
weather and salt-water exposure. The PVC coated gabions shall be of a proven brand and the
brand shall be subject to the Engineer's approval.
Geotextile Filter Fabric: Where indicated on the Drawings or ordered by the Engineer, one
layer of approved geotextile material shall be placed on the prepared surface prior to the
placing of gabions. The material shall be placed as directed in vertical strips with a minimum
overlap of 300 mm, and shall be properly fastened to prevent any movement or slipping during
the placing of gabions.
For detailed information refer GL 24: Technical Specifications Preparations Guideline for SSID.
6.14 RIPRAP
Stone for riprap shall be hard field or quarry stone not susceptible to disintegration or excessive
Weathering on exposure to the atmosphere or water.It shall be free from soft material such as
sand, clay, shale or organic material and shall not contain an excessive amount of elongated or
flakey stone.
The required size of stone shall be determined by the "critical mass" specified. At least 50% by
mass of the material comprising the riprap shall consist of stones having a mass heavier than
the critical mass and not more than 10% by mass of the material shall consist of stone having a
mass of less than 10% of the critical mass or more than 5 times the critical mass.
The grading requirements for riprap are shown in Table below.
6.15 GEO-MEMBRANE
Geotechnical instrumentation may be designed and constructed in conjunction with mall earth
dam to measure performance of structure during construction and long-term monitoring of
structure behavior and health so as to save lives, save money and/or reduce risk of failure of
the dam.
Generally, the reasons to install dam instrumentation are: -
Indicate impending failures,
Provide a warning,
Reveal unknowns,
Evaluate critical design assumptions,
Assess contractor's means and methods,
6.16.1 Piezometers
Piezometer is instrument used for measuring pressure head. Periodic piezometer observations
furnish data on pore water pressures within the embankment, foundation, and abutments,
which indicate the characteristics of seepage conditions, effectiveness of seepage cutoff, and
the performance of the drainage system. Generally, piezometers installed at different location of
a give earth fill dam used to control placement of fill, monitor pore water pressures to find shear
strength and measure uplift pressure, and monitor seepage.
6.16.2 Inclinometers
Inclinometer is instrument used to monitor the lateral displacement of earth fill dam. Generally,
inclinometers installed in the dam body at different location to monitor lateral earth movements
in embankment e.g. detect movement of D/S of earth fill dam, particularly during impounding;
determine type of shear and zone in foundation; monitor stability of U/S slope during and after
impounding; and determine depth, direction, magnitude and rate of movement.
6.16.3 Accelerometer
Accelerometer helps to indicate the response of the dam body vibration due to the influence of
external loads i.e. seismic. Hence, for important structures in areas of seismic activity, it is
desirable to install strong motion, self-triggering recording accelerometers/acelerographs to
record the response of the dam to the earthquake motion.
The efficient and effective implementation of construction projects requires good management
of relationships for and among resources, activities and stakeholders as applied to the context
where such projects are implemented. Materials, Money, Manpower and Machineries (the 4
M's) are usual resources recognized in most situations. Equipment types used in a construction
project is largely dependent on their
Direct input to unit prices or not,
Type of work or job,
Scope of work,
Mobility,
System of control, and
Availability.
Small scale irrigation project uses the following construction equipments, though; it is labor
intensive construction works or services that largely focusing on tool utilizations. For norm and
efficiency of machineries the reader can use the recent research out put in the subject matter.
Norm and efficiency of machineries used in Ethiopia can be referred from the unit rate analysis
presented under GL 20: Quantity Surveying Guideline for SSID prepared as part of the main
this guideline.
Earth work is a process of moving soil or rock from one location to the other and processing it,
so that it meets construction requirements of location, elevation, density, moisture content, etc.
Earth work equipments are broadly classified into earth moving and compaction equipments.
Some of earth work equipments used in small scale irrigation construction is as tabulated
under.
Name of Earth
No. Purposes
Work Equipments
A dozer is used to moves earth by lowering the blade and cutting until a full
1 Dozer blade load of materials is obtained as well as to pushes the material across
the ground surface to the required location.
2 Excavator It is used to move large quantities of earth or soil or for lifting.
It is used primarily to load excavated materials to a hauling unit, excavate
3 Loader soft to medium materials, loading hoppers, stockpiling materials, backfilling
ditches, and moving concrete and other construction materials.
A handheld power tool, usually powered by compressed air and used for
4 Jackhammer
splitting or drilling rock, or for breaking up paved areas.
Grader is a machine with a wide blade that levels the ground, used in earth
5 Grader
dam road construction.
A heavy cylinder, which is moved mechanically or by hand. It is used for
6 Compactor compacting soil. A compactor is also used for compacting the soil, using a
vibrating plate.
Hauling or the transportation of excavation is a major earthmoving activity. There are many
different types of hauling equipment available to the contractor.
Name of Hauling
No. Purposes
Equipments
1 Low/High bed A truck having a rounded part that projects from its main body and used
to transport chain wheel dozer to the project site from somewhere else.
A heavy truck with an open bed that can be tilted up and back to unload
cargo such as gravel, sand, selected materials, cart away materials from
construction sites. It is also used to transport cement from the factory to
2 Dump Truck the project site.
A large vehicle, the front section of a truck used to haul heavy loads, with
a driving cab, engine, and coupling for trailers. It is sometimes used for
3 Tractor inter site transportation of construction material.
4 Vehicle It is vehicle used on land for carrying people or goods.
It is a small cart used to transport construction materials, usually in the
form of an open container with a single wheel at the front and two
5 Wheel barrow handles at the back.
Name of
No. Purposes
Construction Plants
A machine or device used for mixing concrete. Mixer having the capacity of
1 Mixer
1.5 m3 up to 1.8m3 is commonly used in SSIP.
An electric device used to vibrates concrete during placing so as to
2 Vibrator
strengthening the concrete by reducing water from the mix.
3 Crusher A plant used to produce crushed gravel from massive stone.
1. Size of the job: -Larger volumes of excavation will require larger excavators, or smaller
excavators in greater number.
2. Activity time constraints: -Shortage of time for excavation may force contractors to
increase the size or numbers of equipment for activities related to excavation.
3. Availability of equipment: -Productivity of excavation activities will diminish if the
equipment used to perform them is available but not the most adequate.
4. Cost of transportation of equipment: -This cost depends on the size of the job, the
distance of transportation, and the means of transportation.
5. Type of excavation: -Principal types of excavation in building projects are cut and/or
fill, excavation massive, and excavation for the elements of foundation. The most
adequate equipment to perform one of these activities is not the most adequate to
perform the others.
6. Soil characteristics: -The type and condition of the soil is important when choosing the
most adequate equipment since each piece of equipment has different outputs for
different soils. Moreover, one excavation pit could have different soils at different
stratums.
7. Geometric characteristics of elements to be excavated: -Functional characteristics
of different types of equipment make such considerations necessary.
8. Space constraints: -The performance of equipment is influenced by the spatial
limitations for the movement of excavators.
9. Characteristics of haul units: -The size of an excavator will depend on the haul units if
there is a constraint on the size and/or number of these units.
10. Location of dumping areas: -The distance between the construction site and dumping
areas determine selection of the type and number of haulers.
11. Weather and temperature: -Rain and severe temperature conditions affect the job‐site
productivity of labor and equipment.
Name of Electro-
No. Mechanical Purposes
Equipments
Pumps are used extensively on construction projects for such
operations as: -
1. Removing water from pits, tunnels, and other excavations
Pump (Surface pump,
1 2. Dewatering cofferdams
Submersible pump)
3. Furnishing water for jetting and sluicing
4. Furnishing water for many types of utility services
5. Lowering the water table for excavations
It is a machine or device that is used to convert mechanical energy
mainly provided by the combustion of fuel into electricity. It is used
as: -
Main source of power for lifting or pressurized irrigation
2 Generator
system where there is no national hydropower grid line,
Stand by source of power for lifting or pressurized irrigation
system even where there is national hydropower grid line,
Source of electric light for the camp compound.
A device that transfers electrical energy from one alternating circuit
to another with a change in voltage, current, phase, or impedance. It
3 Transformer is used as a source of power for lifting or pressurized irrigation
system. It is supplied, installed, and repaired by Ethiopian Electric
Power Corporation.
The complete system that drive energy obtained from radiation
4 Solar System
emitted by the Sun.
It is the collection of lights, digital displays, and switches used to
5 Control Panel
monitor and control the operation of machine.
A long cylindrical tube that water from deep production wells passes
6 Riser Pipe
through
7 Check valve A valve designed to allow water to flow in one direction only.
It is used to allow air to escape the discharge piping when
8 Air release valve pumping begins, and to prevent vacuum damage to the
discharge piping when pumping stops.
A device that records the amount of water that passes through
9 Water meter
a pipe.
10 Elbow It is a bend in pipe to change the alignment to the standard degree.
Dejino
The following are some of common surveying instruments used during construction of irrigation
projects.
Name of Surveying
No. Instruments, Tools and Purposes
Equipments
1 Total Station It is used to set out location of structures on the ground.
An optical instrument consisting of a rotating telescopic sight,
2 Theodolite
used by a surveyor to measure horizontal and vertical angles.
An instrument used to measure elevation differences using
3 Automatic Level
vernier readings.
An instrument used to determine positions (3D), time and
4 Hand GPS velocity of an object using three segments: space, operational
control and user equipment segments.
Woky toky/ Radio
5 Meter Tape A graduated tool used to measure distance.
6 Compass An Instrument used to show directions.
A staff with a standard measurement or scale of measurement
7 Staff Gauge
used to measure ground elevation using Automatic Level.
It is an electronic device that accepts, processes, stores, and
outputs data at high speeds according to programmed
instructions. It mainly used for:
8 Computer Computer aid design,
Drawing preparation and production, and
Topographic survey map preparation and production.
It is a device used to compute arithmetic operations, especially
9 Calculator a small hand-held electronic device. It is mainly used during
ground elevation surveying using Automatic Level.
It is a pole, usually held vertically and used to mark a specific
10 Range Pole
position when surveying a plot of land.
Hammer is a hand tool consisting of a shaft with a metal head
11 Hammer at right angles to it, used mainly for driving in nails and beating
metal.
It is a small piece of wood used to mark the position of the
12 Peg
woks. It is mainly used during set out of the works.
In this guideline, construction methodology deals with the techniques used to build small scale
irrigation infrastructures of different forms. The construction of every activity shall be executed
according to sequence of work specified in the specification forming the contract, the
construction crew and necessary equipment for each activity shall be arranged based on the
given work schedule, and quality of workmanship and consistency with the specification for
each activity shall be to the satisfaction of the engineer,
Construction of irrigation infrastructure may be done in day work, task work and piecework
bases as far as task assignment modality for a given work force is concerned.
Day work means simply that a worker is paid a fixed rate for being present on a site for a full
working day, which is usually eight hours of work. The amount of work produced depends
entirely on the supervisor’s ability to encourage the worker, and the worker’s own motivation
and sense of responsibility. In many circumstances this can lead to very low productivity,
especially with permanent staff who have no particular incentive to work hard.
Piecework is a method of setting work, usually preferred by the private sector. The worker is
allocated an amount of work for an agreed rate of pay. The work they do is measured and the
more they do the more they are paid. This approach can give very high productivities, but it can
also result in exploitation, especially when the rate for the work is too low. Casual workers are
seldom in a good position to negotiate favorable rates. The most dangerous situation is when
workers have to put in very long hours to achieve even a subsistence rate of pay.
Task work evolved on projects where the workers were subject to government regulations,
which meant they could not be paid more than the prevailing government wage for a day’s
work. Some other incentive had to be provided. Setting a realistic task, or amount of work to be
completed for the day, meant that workers could work as hard as they wanted and then go
home to do other things.
The past experience revealed that, piece work is preferably used for efficient utilization of
workforces when there is effective quality control system in place.
Clearing work shall be carried using earth moving machines or man power as required.
All earth work, stripping top soil, excavation for foundation of major structure and others
excavation shall be carried out using earth moving machines or man power as required.
For example headwork foundation excavation mostly by earth moving machines like
Dozer or Excavator, whereas, canal and small canal structures foundation excavation
mostly by Person Power.
All excavation works shall be carried out to lines and grades shown in the drawings with
care to avoid over excavation under the structure.
Steel panel or timber materials would be used for the form work as specified in the
technical specification forming the contract.
Standard type and size of formwork shall be supplied, fixe and dismantle by the skilled
carpenter in accordance to the technical specification forming the contract and
satisfaction of the engineer.
Cement will be supplied in bags and will be stored as per the specification and the
supply schedule is stick to the concrete work schedule.
Crushed aggregates can be produced by crushing plant to be installed at selected
quarry site by the project Engineer near by the project.
Sand shall be supplied from the approved quarry site by the project Engineer.
Prior to any concrete work, grade of concrete shall be determined by mix design and
then get approval by the Engineer.
Mixing of concrete shall be done by the appropriate mixers.
Placing of concrete would be done manually with buckets of concrete as well as with
concrete pumps as required.
Compaction of the concrete shall be done by vibrators immediately after placing.
Curing of casted concrete shall be done by wetting as well as by shading the surface
area of the structures.
To keep the quality of concrete such as batching, mixing, handling, transporting,
compacting and curing shall be perform as per the specification and to satisfaction of
the engineer.
The stone for masonry work shall be selected from the nearby quarry
site on the approval of the engineer.
The stone masonry work shall be done according to the specification & also to the
satisfaction of the project Engineer by qualified masons.
Cement Mortar usually mixed by hand commonly used for construction of wetted
stone masonry.
All carpentry works shall be done by Carpenter as per the given drawing and the
specification.
All the steel works shall be done by qualified Bar-Bender according to the
specification & also to the satisfaction of the Engineer.
Referring design drawings, the contractor prepare Shop Drawings for reinforcement
bars and submitted to the engineer for approval including the bar schedule.
Reinforcing steel, before being placed, shall be thoroughly cleaned of coatings that
will destroy or reduce bond.
Place reinforcement to maintain minimum coverage as indicated for concrete
protection. Arrange, space, and securely tie bars and bar supports to hold
reinforcement in position during concrete placement operations. Set wire ties so
ends are directed into concrete, not toward exposed concrete surfaces.
All finishing works shall be done as per the specification by semi-skilled manpower
such as Plasterer, Electricians, Plumber, Welder, etcfor the satisfaction of the
Engineer.
Quality, time and cost are the three areas of equal importance in a construction project to be
controlled progressively. Control of quality, time and cost depend on effective allocation of
responsibilities among participants and their performance of their respective duties. So, the
contractor is expected to withdraw his/her responsibility laid down in the contract and play
his/her role for successful completion practicing construction control monitoring system.
It is a function of monitoring the quality of construction materials and workmanship referring the
technical specifications forming the contract.
The contractor should strictly perform construction after get approval for the followings from the
supervisor engineer: -
Manufactures certificate for those material purchased and supplied from the factories,
Laboratory test result for those naturally available construction materials of specified
quarry site,
Mortal mix design for the supplied type of cement and already approved sand from
specified quarry site,
Concrete mix for the supplied cement, sand, and gravel,
Water from approved source.
The contractor should perform tests when the query and type of construction materials get
difference from the approved one.
The contractor should control workmanship by continuous monitoring of the following but not
limited to: -
Before reinforcement is placed, the reinforcement shall be cleaned of heavy flaky rust, loose
mill scale, dirt, grease, or other foreign substances. Reinforcement shall be accurately placed
and secured in position so that it will not be displaced during placement of concrete.
Forms shall be used to shape the concrete to the required lines. Exposed unformed surfaces
shall be brought to uniform surfaces and given a, reasonably smooth, wood-float or steel-trowel
finish as directed. The temperature of the concrete when it is being placed shall be not more
than 320C and not less than 100C. Otherwise it will dry up or frozen before attaining its full
strength respectively under these conditions.
The concrete should be cured with dirt-free water, curing compound, or polyethylene sheets. If
water cured, the concrete shall be kept continuously moist by sprinkling or spraying for at least
14 days after being placed. Similarly, concrete cured by covering with polyethylene sheeting
shall be kept continuously moist for at least 14 days after placement. The implementer shall
protect all concrete against injury until final acceptance by the client.
Premeditated nominal maximum size of aggregate and mix proportions should also be
maintained as per the design so as to obtain the required quality of concrete works.
Masonry Work
This is also one of the activities required for structural works which need to be kept as per the
design especially its mortar ingredients, quality of dressed stone, and placement (keeping
centroid of the material vertical). It should be placed on uniformly distributed mass or lean
concrete mattress where the soil is of bad in nature.
Some construction joints should be provided to protect the constructed structure from cracking
depending on basement conditions.
Earth works
Earth works need to be done by maintaining the required dimensions of excavation and or
clearing. Otherwise it incurs additional cost so as to backfill unnecessarily widened section. The
excavated material should also be carted away at a distance so that it will not slide back to the
working area. Appropriate implements shall also be used so as to be efficient and prevent being
fatigued. Use Appendix Part IV/GL 29/H Laboratory Test Format.
Time and the work contract are inseparable. Construction time control mainly associated
with control of construction schedule. The contractor should play its role in respect to the
agreed time frame in the contract. To control the time of construction the contractor should
perform the following but not limited to: -
The contractor should collect payments equal to the value he adds to the project during a given
period. The contractor should control the cost of construction to finalize the project as per
agreed time frame and quality with maximum expected profit. In construction cost control the
contractor should take care for the following but not limited to: -
Assign the optimum number of skilled and/or unskilled laborers to accomplish the
considered works in a certain predetermined time span,
Strictly follow up the attendance of the assigned skilled and/or unskilled laborers,
Record daily output of each staff on daily base, evaluate, and take measures when
there is intolerable under performance,
Improve performance of the construction by increasing productivity of the manpower
and machinery input,
Proceed execution of works after getting work instruction from supervisor engineer,
Construction safety should be properly implemented consistently throughout the life of project
implementation to maintain conducive working environment.
It is the responsibility of the contractor to prepare and implement safety plan as specified in the
technical specification forming the contract. The supervisor should ensure the implementation
of the agreed safety plan and even the required safety measures as per site condition and
current situation by the contractor.
The following are steps to be followed at site level to ensure safety at construction site: -
i. The contractor should prepare and submit safety plan to the supervisor for approval,
ii. The supervisor should review the contractor safety plan for its conformation with the
specification and its implementation on the ground,
iii. All unsafe or unhealthy conditions observed should be reported to the contractor so that
immediate corrective actions or measures can be practiced in place,
iv. Construction equipments and hand implements/tools should be inspected regularly and
should be properly maintained,
With so many risks on the job, it is no surprise that construction workers are more prone to
serious injuries and in some cases, fatalities, than other industries. As a result, employers must
continually strive for workplace safety compliance and most importantly, their employees’ health
and vitality.
Some of very important safety issues and measures are as discussed here under but not
limited to: -
a. Workers assigned to scaffolding jobs should be properly trained and continually aware
of their environment as falling debris, electrocution from power lines, and falls related to
unstable platforms can result in serious injuries. Supported and suspended scaffolds
should be properly outfitted with guardrails to prevent workers from falling from an open
side, and workers should be secured in appropriate fall protection.
b. All employees whose work conditions include the danger of falling should undergo fall
protection training regularly. Company training courses should identify specific hazards
and familiarize employees with all fall protection equipment used in the workplace.
c. The misuse of portable ladders can lead to injuries such as sprains and broken bones,
but in extreme cases also head and neck trauma or even death. Ladders should be
secured and safely positioned at appropriate angles and prior to use be visually
inspected for damaged components including hinges, rungs/steps, side rails and feet.
d. At site level workers should use personal protective equipment (PPE). Hard hats, eye,
ear and hand protection, earplugs and other protective equipment provide protection
from falling objects, head injuries, sparks, dust/fragments and burns.
e. It is common sense that first aid and fire safety are key programs on any given job site.
f. Maintaining up-to-date records of equipment inspections and injury logs is the best way
to protect employers from legal ramifications in the event of injury and death.
g. The key to preventing many workplace accidents and injuries is frequent and effective
employee training programs.
h. Fence has to be provided around dams, night storage reservoirs, canals, pump stations
and any other hazardous areas to protect animals and human from hazards and
unnecessary interfere during project/scheme operations. But, where water sources and
canals are fenced, drinking access areas should be provided. Similarly, to permit
1. Construction Plan
3. Construction Survey
6. Camp Construction
7. Temporary Work
End
1. Construction Plan
Before any construction works is being started, shop drawing as per the design, method
statement which can indicate how the construction work shall be preceded including list of
required resources and schedule shall be prepared for each component of the project and
submitted to projects supervisors for approval.
The details of the work and the area affected during the construction period shall be clearly
described. Meeting with beneficiary and local authorities shall be held to explain the work and
get consent.
3. Construction Survey
Setting out shall be prepared for each component of projects and precise data shall be
recorded in order to place framework of structures on proposed ground/site one after another.
The contractor should determine with the project supervisor the proposed borrow site (for fill
material, masonry stone query site, crushed aggregate query site, natural sand query site) and
disposal area during study and design phase. He has to discuss with both local authorities and
with land owner and/or tenant farmer about the condition of land after construction (such as
elevation, landform, and area) until they reached on consensus on the usage of the considered
land. Finally, he has to measure the volume of soil material from borrow-pits and disposal area.
A sample from the major activities on the earth, concrete and masonry works have to be taken
jointly in the presence of contractor and supervisor/client representatives and tested for its
compliance with the specification before the realization of the whole works commencement.
Test result should be issued and recorded by both parties.
6. Camp Construction
Immediately after required construction materials are secured, camp construction should be
executed maintaining the following steps: -
Clearing and grabbing the camp site,
Setting out surveying works,
Foundation excavation,
Substructure construction,
Superstructure construction,
Finishing works, and
Furnishing the required camp facilities and offices as per agreement.
7. Temporary Work
Temporary works need to be executed as preparatory works of small scale irrigation project
implementation are the following but not limited to:
Access
Water source for construction work
Dewatering work
Cofferdam
Safety facilities
Power supply
Concrete plant
Earth works can be broadly divided in to two namely excavation, and fill and compaction works.
It is discussed in this section separately hereunder.
Excavation works can be also divided in to foundation excavation (for structures like headwork,
canal structures), mass excavation (for micro earth dam and night storage reservoir), and
trench excavation (for earthen canal system). Furthermore, excavation can be further grouped
as normal soil excavation, soft rock excavation, and hard rock excavation.
Yes
6. Measurement of cleared area
No 9. Is excavation completed?
Yes
The project contractor should submit work requesting letter mentioning his readiness to perform
the task.
Step-3: Delineate the area to be clear, and grub& removal of surface soil
The contractor together with supervisor/client should delineate the area to be clear, and grub &
removal of surface soil as specified.
Step-7: Set out the exact area of structure and fix design dimensions of excavation
The contractor surveyor should perform set out of the exact area of structure and fix design
dimensions of excavation. The final set out should be confirmed by supervisor/client.For
headwork and canal structures foundation excavation working space should be considered in
addition to the exact design dimensions of structures, whereas, for earthen canal and small
canal structures suited on shallow cut depth the exact design dimensions may be dimensions
excavation dimensions.
Design dimensions to be considered for structures foundation excavation are width, length and
depth; whereas, design dimensions to be considered for canal excavation are width, length,
depth and longitudinal.
The contractor together with supervisor engineer checking the compliance of excavation works
with the specification. If it is compliant go to Step-10. If not, continue excavation operation until
it becomes compliant to specification (Step-8).
Excavation for canals drains and open cuts will be measured at the volume in place of
excavation actually carried out within the lines of the typical cross-section and below the ground
surface before construction starts, but after clearing and grubbing, if any. Structural excavation
will be measured as the volume in place actually excavated below the ground level within the
vertical plains coincident with the outer sides of the culverts, floors or structure and above the
elevation of the foundation as indicated in the drawing or as directed, i.e. the volume will be
calculated as a products of the exact length and width of the lowest strip of the foundation
according to the drawings and the depth measured vertically; where ground is not level,
average depth shall be taken. Measurement should be done jointly with the supervisor
engineer.
The entire excavated canal sections and structures foundation area shall be left in neat and
presentable conditions.
No
No
The project contractor should submit fill and compaction works requesting letter mentioning his
readiness to perform the task.
Step-3: Delineate the area to be clear, and grub& removal of surface soil
The contractor together with supervisor/client should delineate the area to be clear, and grub &
removal of surface soil as specified.
Step-7: Set out the exact area and fix design dimension of fill and compaction
The contractor surveyor should perform set out of fill and compaction area and fix its design
dimensions. The final set out should be confirmed by supervisor engineer.
Spread soil by layer keeping the recommended layer thickness in the specification. Usually the
layer thickness ranges 20cm to 30cm. Compact spread soil layer by layer at decided the
number of Compaction. Compaction speed shall be optimum (less than walking speed of
person). For high grade compaction do the following control.
Check the number of compaction and compaction speed
Measure the density of soil by field density test on each layer at the interval on the
construction plan and the criteria of construction
If the test result is out of the criteria, examine the followings check the water content of
soil and,
a. If water content is over allowable range, remove the soil and bank with
allowable soil again and adjust water at stock yard for the next work place
b. If water content is lower than allowable range, spread water and compact at
the place again and adjust water at stock yard for the next work place.
c. If water content is in allowable range, cut the top soil (thin thickness) and
compact again and change the thickness of soil spreading to thin from next
place.
The contractor together with supervisor engineer checking the compliance of fill and
compaction works with the specification. If it is compliant go to Step-10. If not continue fill and
compaction operation until it becomes compliant to specification (Step-8).
Fill for embankment construction will be measured as volume of embankment within the lines of
the typical cross-section or as directed by the Engineer, in its final compacted position after
finishing and trimming, and above the ground-surface before embankment construction starts
but after clearing and grubbing, if any.
Compacted backfill measurement will be made of the actual number of cubic meter of material
placed in the earth fill and approved by the Engineer. Calculation of volume will be made after
compaction operation have been completed and within dimensions and elevations shown on
the drawing or modified by the resident Engineer so that they represent the existing field
condition accepted by the Engineer.
The entire fill and compaction shall be left in neat and presentable conditions.
6. Masonry work
8. Back filling
9. Measurement
The project contractor should submit work requesting letter mentioning his readiness to perform
the task.
The supervisor engineer should give job order to the contractor within the specified period
checking the fulfillment of logistics to start the task from the contractor side.
Step-3: Cleaning, grubbing and removing of surface soil
The contractor together with supervisor engineer should delineate the area to be clear, and
grub & removal of surface soil as specified if any. Clearing, grubbing and removing of surface
soil works should be performed by the contractor either by machine or man power as specified
based on scope of the works. Measure the surface area where cleaning, grubbing & removal of
surface soil performed prior to excavation.
The Contractor shall set out the working corners and alignment using the data shown on the
Drawings or as instructed by the Engineer. The Engineer shall certify his acceptance of the
setting out of corners and alignment to the Contractor in writing before commencing masonry
works foundation excavation.
Excavation for stone and/or gravel lining shall be accurately trimmed to the specified
dimensions. Where over excavation occurs it shall be back filled with gravel as specified below,
or such other fill material as the Engineer may order, entirely at the Contractor's expense.
Excavation for structures shall be done according to the drawing and specification. Elevation
shall be checked using Leveling by contractor and supervisor jointly for its conformity with the
drawing and specification. Measurement should be done jointly with the supervisor engineer.
Stone for hard coring shall be obtained from an approved source. It shall be clean, hard,
durable, sound and free from impurities or decomposed rock. Stones shall be set in position
with their natural beds as near as possible to the horizontal. The commonly depth of hard
coring is 20cm. Measurement of hard core is in m2.
Bottom concrete work (if any) can be executed mix proportion for plain concrete of material as
recommended and stated in the specification. The commonly depth of bottom concrete work is
10cm. Measurement of bottom concrete work is in m3.
Stone for masonry shall be obtained from an approved source. It shall be clean, hard, durable,
sound and free from impurities or decomposed rock.
Because the masonry walls of headwork retaining walls and canal are required to be as water
proof as possible against the hydrostatic pressure of the water inside, particular attention must
be paid to the workmanship of the masons. The stones should be lightly taped down into the
mortar, and then securely fixed using mortar. Do not leave air voids between stones.
Stone for various masonry works shall be selected and shaped as follows: -
Stone for facing work shall generally be selected for consistency in grain, colour, and
texture throughout the work.
Stone for below grade work concealed from view shall be chiseled natural stone
average size 450mm.
Stone for rough dressed exposed faces shall be fair chiseled and in average 450mm
and individual not less than 380mm length.
Stone to receive other finish shall be chiseled natural stone in average 450mm and
individual not less than 380mm.
Cement mortar is used for stone masonry considering 1:4 Cement to Sand mix ratio. The
mortal that results of mixing sand cement and water fill the spaces between the stones and
coats them thickly to keep them apart.
Provide cement, aggregate, labour, equipment and tools for plaster and pointing as required for
the satisfactory installation of the works. Aggregate for plaster and pointing shall be naturally
occurring sand or crushed aggregate. The aggregate shall be hard, clean, and free from
adhered coatings with no clay content. Or the clay and fine silt content of aggregate shall not
exceed 5% by weight. Aggregate shall be free of harmful organic and inorganic material that
may affect the setting, strength, durability and appearance of render or undercoat and material
in contract with it.
In instances where hand mixing is unavoidable, the cement content shall be increased by 10%.
The dry and wet mixes shall be turned over sufficient number of times to produce the respective
consistencies as required by batch mixers. Cement mortar shall be used within half hour of
adding cement to the mix.
Plaster shall be applied in two coats with the following mix proportion for mortar. The aggregate
for mortar to be used shall comply with table 1 of BS (British standard) 1199.
First coat: 1 Part cement to 2.5 parts aggregate (fine) by volume.
Second coat: 1 Part of cement to 4 parts of aggregate (fine) by volume.
The first coat shall be wetted and the plumb line for the second coat established after 24 hours.
The second coat of plaster shall be applied within 4 hours of the establishment of plumb line on
the surfaces.
The second coat shall be applied by trowel to a maximum thickness of 12mm. This coat shall
be allowed to cure for days before further finish is applied as per specification.
Measurement will be made for the plain area m 2 of plastering or pointing work acceptable to the
level and quality of finishing shown on the drawing or to the satisfaction of the Engineer.
Payment shall be made for the number of m2 of measured area as provided above at the
contract unit price for each plastering and pointing works that shall constitute full compensation
of material transportation and mixing mortar together with its cost of application to the required
work quality of finishing.
Cement mortar is used for plastering and pointing considering 1:2 Cement to Sand mix ratio.
Back filling around structures shall be executed spreading and compacting the recommended
fill material layer by layer as per the specifications.
Measurement will be made for the number of m3 of masonry work acceptable placed to the line,
Level, grades and cross-section shown on the drawing or established by the engineer.
Payment shall be made for the number of m3 measured as provided above at the contract unit
price for the masonry work shall constitute full compensation for quarrying transporting material
to the site ,mixing mortar and all other work related to item.
Masonry works shall be well finished and left in neat and presentable conditions for the
satisfaction of the Engineer.
2. Work
GL 29: Construction Operation order byfor
Guideline theSSID
supervisor engineer
6. Reinforcement work
7. Frame work
8. Concrete work
11. Measurement
The project contractor should submit work requesting letter mentioning his readiness to perform
the task.
The supervisor engineer should give job order to the contractor within the specified period
checking the fulfillment of logistics to start the task from the contractor side.
The contractor together with supervisor engineer should delineate the area to be clear, and
grub & removal of surface soil as specified if any. Clearing, grubbing and removing of surface
soil works should be performed by the contractor either by machine or man power as specified
based on scope of the works. Measure the surface area where cleaning, grubbing & removal of
surface soil performed prior to excavation.
The Contractor shall set out the working corners and alignment using the data shown on the
Drawings or as instructed by the Engineer. The Engineer shall certify his acceptance of the
setting out of corners and alignment to the Contractor in writing before commencing concrete
works foundation excavation.
Excavation for stone and/or gravel lining shall be accurately trimmed to the specified
dimensions. Where over excavation occurs it shall be back filled with gravel as specified below,
or such other fill material as the Engineer may order, entirely at the Contractor's expense.
Excavation for structures shall be done according to the drawing and specification. Elevation
shall be checked using Leveling by contractor and supervisor jointly for its conformity with the
drawing and specification. Measurement should be done jointly with the supervisor engineer.
Mass/plain concrete can be casted to make the weight of structure spread evenly to the ground,
and to make reinforcing bars assembled so that reinforcing bars can be placed properly (level
or vertically, etc. as indicated in drawings. The commonly depth of level concrete work is 10cm.
Measurement of level concrete work is in m3.
Steel reinforcement for concrete shall consist of steel bars or welded deformed steel wire fabric
except where otherwise shown. Steel bars shall consist of deformed and plain billet-steel bars
as specified in ASTM A.615. Steel wire fabric for concrete reinforcement shall be in accordance
with the requirements of ASTM A.497.
All deformed and plain steel bars to be used as reinforcement in concrete constructions shall be
of Grade 60 and Grade 40 respectively in accordance with the requirements as described in
ASTM A.615.
Test specimens shall be taken in the presence of the Engineer and shall be of a size sufficient
to carry out the tests as described below.
They shall be tested in a nominated laboratory and the certified copies of the results of the tests
shall be submitted to the Engineer.
The specimens shall be tested on bending and tensile properties and the steel wire fabric also
on weld shear strength. The methods and requirements for testing shall be carried out in
accordance with the applicable specifications of A.S.T.M. A.497 and ASTM A.615.
No steel reinforcement shall be used in the Works until the testing results have been approved
by the Engineer. If ordered by the Engineer, test procedures shall be repeated at the
Contractor's expense for any new supply of reinforcement during the course of the Works.
Storage of reinforcement shall be on racks or supports clear of the ground. Different types and
dimensions of the reinforcement shall be kept separate.
Reinforcement processing consisting clean reinforcing bar, cut reinforcing bar by the total
length of each bar, and bend reinforcing bar by following processing plan. Please note that
reinforcing bar shall be bent without heating.
Assembling of the reinforcing bar consisting placing spacer blocks on the leveling concrete to
secure the designated clearance between the structure bottom and reinforcement bars, placing
the reinforcing bar on the position of structure, binding the reinforcing bars each other by
binding wire tightly not to move them by concrete placing, and putting the spacer for keeping
space between the reinforcing bars and forms assembly at right position. Payment for
reinforcing steel will be made at the price tendered per kilogram or tone for “reinforcing in
place".
Example-1
What is the unit weight of 10mm diameter bar?
Given
Diameter, d = 10mm
Required
Unit Weight = Weight per unit length of 10mm diameter bar, kg/m
Solution
Unit Weight = Specific Weight of bar * Cross sectional Area of bar
Where,
Specific Weight of bar = 7.85x104 N/m3
Cross sectional Area of bar = πd2/4
D = bar diameter = 10mm
π = 3.14
g = specific gravity = 10m/s2
Unit Weight = 7.85x104 N/m3 * 3.14 * (0.01m) 2/4 = 6.165 N/m = 6.165kg.m/s2/m/10m/s2 =
0.617kg/m. Therefore, Unit Weight of 10mm diameter bar = 0.617kg/m.
Example-2
The length of steel, with a diameter of 8mm, required for X irrigation scheme is 4,000 meters.
How manytons of steel should be ordered for the project?
Given
Diameter, d = 8mm
Length, l = 4000m
Required
Weight of 8mm diameter bar, tons
Solution
Weight of 8mm diameter bar = Unit Weight * length = 0.395kg/m * 4000m = 1580kg = 1.58tons
Therefore, the quantity of 8mm diameter bar to be ordered for project X is 1.58tons.
Example-3
What is the payment if the 1510m of 12mm diameter bars supplied, cut, bent, and fixed in place
as per technical specification and for the satisfaction of supervisor engineer? Consider the
tendered price for bar is 45 birr per kilogram.
Given
Diameter, d = 12mm
Executed quantity of bar = 1510m
Tendered price = 45 birr/kg
Required
Payment, birr
Solution
Amount executed, Birr = Executed quantity, kg * tendered price, birr
Executed quantity of bar in terms of bill tendered = 1510m * 0.888kg/m = 1340.88kg
Amount executed = 1340.88kg * 45 birr/kg = 60,339.60 birr
Therefore, payment request for the executed 1510m of 12mm diameter bars tendered price for
bar is 45 birr per kilogram worth 60,339.60 birr only excluding VAT.
Forms for exposed surfaces shall be coated with approved non-straining from oil, which shall
be applied shortly before the concrete is placed. All forms shall be so constructed that they can
be removed without damaging the concrete.
Form shall be sufficient and properly braced. The maximum tolerance is 1cm in width and
elevation, and 5cm in length.
Mix Proportion
The proportion of concrete ingredients given in the "Standard mixes for ordinary Structural
Concrete" of this Specification shown below or proportions obtained by tests shall be used for
concrete mixing.
The proportion of ingredients shall be such as to produce a mixture, which will work readily into
the corners and angles of the forms and around reinforcement without segregation of the
material components. Where the proportion of ingredients given in the Concrete Class Section
of the Specification is not applicable, trial batches shall be made and the mix from which the
desired strength is established by testing shall be used for the works.
General Formula used to determine the required material in concrete mix design is:
Concrete Mix ratio = 1:2:4
Note: Hand mix shall only be allowed for class II concrete, and shall not be allowed for
concrete of class C-20 and above.
Back filling around structures shall be executed spreading and compacting the recommended
fill material layer by layer as per the specifications.
Step-11: Measurement
Measurement will be made of the number of cubic meters of concrete acceptably placed as
directed by the engineer.
Payment will be made of the number of cubic meters measured by provided above at the
contract unit price per cubic meters.
Immediately after removal of forms, all unsightly or lips shall be removed and undesirable local
building on the surface to be permanently exposed shall be remedied. All finishing shall be
performed immediately after the forms are removed. Care shall be taken to see that all free
water which has accumulated at the surface, is removed before making any finish.
3. Site preparation
9. Measurement
10. Finishing
excavate any loose and soft or unsuitable material and back fill with sound material. Besides,
any uneven surfaces, ruts and holes should be filled by the contractor. A granular fill of about
200mm with material such as sand or gravel graded and compacted to the correct line and level
as specified is recommended.
Where geotextile fabric is used as lining under the gabion structure, care should be taken so
that any sharp material fill does not puncture and damage the fabric. Care should also be taken
before gabion boxes are laid, that they do not have sharp loose wire ends that may damage the
fabric. All loose ends are to be tucked inside the gabion boxes.
Finally elevation shall be checked using Leveling by contractor and supervisor jointly for its
conformity with the drawing and specification. Measurement should be done jointly with the
supervisor engineer.
The unit of measurement shall be the cubic meter of each class of excavation and for backfilling
made in accordance with the authorized dimensions. The tendered rate shall include
excavating in each class of material; over break; trimming trenches, compacting and
consolidating backfill; and disposal of surplus material.
Individual boxes are to be tensioned by using steel or wooden stakes to avoid bulging or
sagging before filling with stone. The stakes can be easily removed after stone filling, or left in
place where recommended. Proper formwork for tensioning the gabion boxes is used as an
economy measure for large repetitive jobs.
Each partition is made to stand vertically on its base; the height is adjusted to the required
level. The sides of the boxes are then unfolded and also made to stand vertically, taking
measurement of the height. All corners of gabion boxes should match exactly as designed. The
sides and partitions are then fully laced as per “lacing procedure” provided by the manufacturer
or the recommendation given by supervisor engineer.
Note that when gabions are one third full, the first pair of bracings shall be made tie using lacing
wire in single or double strands to avoid bulging and deformation of basic shape gabion
structure.
The tendered rate shall include procurement of materials; tying and connecting wires; loading,
transporting and off-loading; and assembling and filling of the cages.
Pipe works may happen in irrigation infrastructure for conveying irrigation water as main canal,
secondary canal, and tertiary canal; pressure line in irrigation pump system; and irrigation or
drainage culverts.
The common nominal pressure (PN) pipe used for irrigation is 4bar, 6bar, 10bar. The outer
diameter of uPVC Pipe currently used are 600mm, 500mm, 450mm, 400mm, 350mm, 300mm,
250mm, 200mm, 150mm, 100mm, 75mm.
Construction of underground pipelines involves the initial setting out of the trench, the actual
trenching, preparation of the trench bottom, bedding, pipe laying, pipe jointing, back-filling,
placing thrust blocks and pressure testing.
6. Trench excavation
8. Bedding
9. Pipe lying
11. Back-filling
14. Measurement
15. Finishing
Certificate of pipe that compliant to the technical specification and works methodology should
be submitted and approved by supervisor engineer.
Step-3: Delineate the area to be clear, and grub& removal of surface soil
The contractor together with supervisor/client should delineate the area to be clear, and grub &
removal of surface soil as specified.
To avoid the anticipated load damaging the pipe, it should be covered as specified in the
technical specification made for the same. For example, ASAE EP340.2 standards recommend
a minimum cover of 75 cm and a maximum of 120 cm when traffic will be passing above the
uPVC pipes, whereas, at least 45 cm cover for 63 mm uPVC pipes, and at least 60 cm for
larger uPVC pipes.
Measure the excavated volume based on cross-sections and formation levels taken at intervals
of specified length and located at the specified Chainage points on the trench centre line.
Measurement should be done jointly with the supervisor engineer.
Step-8: Bedding
Where an uneven trench bottom is encountered, especially in rocky or hard ground, a 10 cm (or
at least one third of nominal diameter) fine back-fill or bedding should be provided for during
setting out. This layer has to be back-filled, using suitable bedding material such as free-
draining coarse sand, gravel, loam or a soil of friable nature, and be leveled.
Pipe type,
Nominal diameter of the supplied with respect to the designed pipe diameter,
Nominal pressure of the supplied with respect to the designed pipe diameter,
Physical condition of the supplied pipe,
Rubber seal compatibility, etc
Pipes can be cut if shorter pipes are needed, but, if jointing is not done immediately, the pipes
have to be temporarily closed in order to avoid the entrance of animals or dirt. It also, is
important to ensure that the temporary closures are opened on re-commencement of pipe
laying works. Valves and outlets should be closed every day.
Step-11: Back-filling
After checking that the levels of all joints are correctly set out, side filling can then be done in
layers that are 75 mm thick, using fine material for the fill. The layers have to be tamped by
hand, ensuring that the joints are left exposed. Tamping should be done simultaneously on both
sides of the pipe, in order to avoid misalignment. This should continue up to a height of two
thirds of the pipe diameter, or up to 10 cm above the crown when the material is spread over
the whole length of the pipeline except the joints. Beyond that, the rest of the back-filling can be
done in layers of 15-30 cm. The trenches should be over-filled to allow for settlement.
Note that the space between the joints is backfilled after the pipeline has been pressurized and
the joints inspected to ensure that there are no leaks. It is necessary to ensure that all pipes are
back-filled once they are installed, in order to prevent them from floating due to rainwater or
groundwater.
Normally, at least 7 days should be allowed after constructing the last thrust block before the
system is tested. By this time, the last thrust block should be able to withstand the load.
When pressure testing, the pressure should not exceed one and half times the maximum
working pressure. It is also important that the valves and all other outlets be opened and closed
slowly.
The flushing is intended to remove all the dirt that inevitably gets into the system during pipe
laying and it should be done for a couple of hours with the flush valves at the end of the lateral
lines open (in the case of pressurized irrigation system). The flushing process should be
stopped once clean water starts coming out of the valves.
Step-14: Measurement
Measurements of pipe works will be taken jointly in the presence of contractor and supervisor
engineers as in the drawing and itemized in the billed quantity.
2. Bidding
3. Bid Offer
No
4. Approval of the Bid Offer
Yes
5. Supply to the site
6. Installation
7. Testing
8. Commissioning
Up on submission of the contractor for approval, the supervisor engineer should evaluate the
technical bid offer with respect to specification, design drawing, and bill of quantity forming the
contract. Then, he/she has to give written confirmation whether it is conformance or no-
conformance.
Step-5: Supply to the site
Once the contractor gate approval from the supervisor, he/she has to give award for the
selected bidder and supply the equipments at site level.
Step-6: Installation
Installation of electro-mechanical equipments shall begin after fulfillments of the following but
not limited to: -
Arrival of the whole electro-mechanical equipments and their accessories. For example,
o Pumps and accessories
Surface pump
Submersible pump
Riser Pipe
o Head work fittings
Check valve
Air release valve
Water meter
Elbow
o Equipments for Power sources
Generator
Transformer
o Solar System
o Control Panel
Pre requisite activities completed and get consent by the supervisor,
Capability of Contractor’s and consultant manpower available at site, and
Fulfillment of installation equipments and tools arrived at site.
as per the specified methods and duration set in the specification forming the contract.
Step-8: Commissioning
Commissioning should be done after fulfillment of conditions specified in the contract
document.
11.8 HYDRO-MECHANICAL EQUIPMENTS SUPPLY, INSTALLATION, TESTING, AND
COMMISSIONING PROCEDURE
1. Design Drawing
2. Shop Drawing
No
3. Check the S. Drawing
Yes
4. Manufacturing
gate
No
5. Check the M. Gate
Yes
7. Installation
8. Testing
9. Commissioning
The construction engineer should review the design drawing with respect to the design
calculation and specification made for the same and update it if required.
Construction engineer should prepared shop drawing (working drawing) based on the
specification and design drawing forming the bid and submit to supervisor engineer for
approval.
Construction engineer should confirm the approval of his shop drawing (working drawing) by
the supervisor engineer prior to manufacturing.
Step-4: Manufacturing
Once the construction engineer get an approval by the supervisor engineer for his shopping
drawing (working drawing), he has to proceed the manufacturing of the gate.
During this period of manufacturing, the supervisor engineer should inspect the workshop to
inspect the process and the final gate manufactured in accordance with the specification, shop
drawing and method statement forming the bid. If it is acceptable he can instruct the
construction engineer to proceed supply at site, if not, give instruction to correct the defect.
Here, the supervisor engineer should check the type of material, design dimensions (height,
width, length, thickness) with respect to specification and drawing forming the bid.
Immediately after the construction engineer get an approval by the supervisor engineer for the
manufactured gate, he has to transport and supply the gate to the site. Supervisor engineer
should check and ensure the proper handling during transportation and supply of full set at site
level without major damage that may require rectification at workshop level.
Step-7: Installation
The supervisor engineer can instruct the construction engineer if and only if the following
activities are per performed but not limited to:
Civil structures are completed or ready to be completed,
Materials required during installation are full filled,
The required Construction staff for installation and related works are ready and well
organized,
Installation plan and method statement are submitted by construction engineer and
approved by supervisor engineer.
Step-8: Testing
After completion of installation operation for the satisfaction of the supervisor engineer, dry and
wet test should be taken jointly in the presences of supervisory and contractor civil and electro-
mechanical engineers.
Step-9: Commissioning
Finally the work should be finished as recommended by the supervisor engineer. The finishing
works may be cleaning, repainting, hammering to rectify minor error, and the like.
AutoCAD, MS-Project, Primavera Project Planner, and ConMIS Software are construction
management software’s that currently applied by the engineers assigned in construction
industry. The reader should refer GL 21: Software Application Guideline for SSID for its
detailed presentation and application guidance.
12.1 AUTOCAD
12.2 MS-PROJECT
Microsoft Project, the project management software program by Microsoft, is a very handy tool
for project managers that help them develop a schedule, assign resources to tasks, track the
progress, manage the budget, and analyze workloads for an ongoing project.
ConMIS Software used for bill of quantity calculation, take-off sheet analysis, payment
certification and report preparation.
REFERENCE MATERIALS
APPENDICES
When done
Mobilisation Action Remark
make a mark (X)
• Bench Marks
Category
Degree Mitigation
No Risk (technical/cost/
(High/Medium /Low) Measures
managerial)
1 Right off way issue
2 Design modification
3 Change in client interest
4 Price escalation
5 Labour availability
6 Limitation in construction material
7
8
9
10
(Use this place to summarize the risk analysis and mitigation measures after discussing with the
responsible persons)
___________________________________________________________________________________
___________________________________________________________________________________
_______________________________________________________________________
Appendix Part IV/GL 29/A-5: Documentation and Record Summary Keeping Format
Final
(Please write a narrative in the following space when a dispute occurs and how it is resolved –
Dispute dispute dates / resolved dates and specific issues are important)
Time
First Extended Completion Time
Contract Completion time ____________ ____________________
Second extended Third extended Completion Actual Completion
Completion time time time _____________
_____________________ ___________________
Warnings letter Ref Conducted meetings with Contractor
Subject &
Letter RF date Subject Venue date minutes
Quality
Use this space if there is quality complain at each interim payment level & where necessary
Result of discussion:
1. _____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
________________________________
2. _____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
________________________________
3. _____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
________________________________
4. _____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
________________________________
Please use this form for Contract monitoring; (items can be increased or decreased based on the specific project. Monitoring indicator also can be
modified)
No Item to be Monitored Compliance to (Yes/No) Remark
Size/Dimension Specification Time Cost Quality Shape Type
1 Head Work
1.1 Weir body
1.2 U/S apron
1.3 D/S apron
1.4 Wing walls
1.5 Gates
2 Conveyance canal
3 Main Canal
4 Secondary Canal
5 Tertiary Canal
6 Other canals
7 Structures
7.1 Drops
7.2 Division boxes
7.3 Turnouts/ Off takes
7.4 Bed bars
7.5 Aqueducts
7.6 Cross drainages
7.7 Culverts
7.8 Level crossing
7.9 Others
General Comment: (use this space for detail comments of the monitoring result)
Consultant:_____________________
_______
Contractor:_____________________________
___
Financial Schedule in ETB for the year _____ EFY
Financi Financial Schedule for the year ______ EFY Monthly Distribution
al Plan July Aug Sep Oct Nov Dec Jan Feb Mar Apr May June
Contr in Birr
A Am Am Am Am Am A A A Am Am Am
Ite act for the
mt, t, t, t, t, t, mt, mt, mt, t, t, t,
m Amou year
Bir Bir Bir Bir Bir Bir Bir Bir Bir Bir Bir Bir
No Descript Un nt, _____
r r r r r r r r r r r r
. ion it Birr EFY % % % % % % % % % % % %
Machinery
Plan for
Machinery Schedule in hours for the year ______ EFY Monthly Distribution
the year
Item Agreed _____
No. Description Unit Machinery EFY July Aug Sep Oct Nov Dec Jan Feb Mar Apr May June
Material
Construction Material Schedule in Quantity for the year ______ EFY Monthly
Plan for
Distribution
the year
Item Agreed _____ Fe
No. Description Unit Material EFY July Aug Sep Oct Nov Dec Jan b Mar Apr May June
With regards,
Person in Charge
Position
C.C
(Insert Client Name)
(Insert the Client Address)
(Insert Nameof different internal stockholders)
(Insert the Contractor Name)
(Insert the Contractor Address)
Dimension
Volume
No Length (m3)/Area
Item No. Description Unit . (m) Width (m) Depth (m) (m2) Remark
Total
1. General Information
1.1 Location: _______________
1.2Altitude: ___________________
1.3 Weather Condition: ______________________
1.4 Working Hours: _____________
4. Problem encountered:
___________________________________________________________________________________
_____________________________________________________.
5. Measures taken:
___________________________________________________________________________________
____________________________________________________________.
9. Others:
___________________________________________________________________________________
______________________________________________________________________________.
Remarks: ________________________________________________________________________________________.
Prepared by Approved by
Project Name:_______________________
Client:__________________________________
Consultant:____________________________
Contractor:________________________________
Remarks: _______________________________________________________________________________________.
Prepared by Approved by
Appendix Part IV/GL 29/D-4 Man Power Mobilized to the Site during the Month
Project Name:_______________________
Client:__________________________________
Consultant:____________________________
Contractor:________________________________
Month, Year
S/No Description Unit Plan Mobilized %
Remarks: ________________________________________________________________________________________.
Prepared by Approved by
Project Name:_______________________
Client:__________________________________
Consultant:____________________________
Contractor:________________________________
Remarks: ________________________________________________________________________________________.
Prepared by Approved by
Appendix Part IV/GL 29/D-6 Construction Materials Used during the Month
Project Name:_______________________
Client:__________________________________
Consultant:____________________________
Contractor:________________________________
Total
Cost Bill Item Number
Item
Description Unit Remark
No.
Total Quantity Cost
Qty.
Birr Cents Birr Cents
Remarks: ________________________________________________________________________________________.
Prepared by Approved by
Project Name:_______________________
Client:__________________________________
Consultant:____________________________
Contractor:________________________________
Machinery/Equipment Allocation
Description of
Unit Quantity Dump Water
works Dozer Excavator Scraper Grader Loader Compactor Transit mixer
truck truck
Remarks: ________________________________________________________________________________________.
Prepared by Approved by
Project Name:_______________________
Client:__________________________________
Consultant:____________________________
Contractor:________________________________
Labour Allocation
Description of
Unit Quantity Daily
works Forman Mason Carpenter Bar bender
Labours
Remarks: ________________________________________________________________________________________.
Prepared by Approved by
Project Name:_______________________
Client:__________________________________
Consultant:____________________________
Contractor:________________________________
Remarks: ________________________________________________________________________________________.
Prepared by Approved by
Name: _____________________________ Name: ____________________________
Signature __________________________ Signature __________________________
Date ______________________________ Date ______________________________
Project Name_________________
Type of work_____________________ Date______________________
Chinage from______________to ________________ Page____________
Location
P B
T Chainage S HI IS FS OGL EL Bed Level Remark
Contractor Consultant
Name_______________ Name________________
Sign_________________ Sign_________________
Date________________ Date_________________
104
GL 29: Construction Operation Guideline for SSID
National Guidelines for Small Scale Irrigation Development MoANR
Project :- Pro.No:-
Client :- Date:-
Location :-
Object :- Clay content and gradation of sand
1. Clay content of sand
Silt content
No Material Type Location %
1 sand
105
GL 29: Construction Operation Guideline for SSID
National Guidelines for Small Scale Irrigation Development MoANR
Appendix Part IV/GL 29/H-2 Laboratory Test Format for Reinforcement Bar
Project :- W.O.No:-
Client :- Date:-
Location :-
106
GL 29: Construction Operation Guideline for SSID
National Guidelines for Small Scale Irrigation Development MoANR
Appendix Part IV/GL 29/H-3 Laboratory Test Format for Compressive Strength
Compressive
Age in Dimension Unit Weight Strength
Marking Date Days (m) Kg/m3 (Mpa)
Poured Tested LXWXH
Checked by ___________
Date- _______________
107
GL 29: Construction Operation Guideline for SSID
National Guidelines for Small Scale Irrigation Development MoANR
108
GL 29: Construction Operation Guideline for SSID
National Guidelines for Small Scale Irrigation Development MoANR
3. Checking and Handing Over of Major Components of the Project at Site Level
Detail of the Structures
Item Description of project
Length Width Depth Elevation Remark
No. major components Shape Type Specification
(m) (m) (m) (masl)
1 Head Work
1.1 Weir body
1.2 U/S apron
1.3 D/S apron
1.4 Wing walls
1.5 Gates
2 Conveyance canal
3 Main Canal
4 Secondary Canal
5 Tertiary Canal
6 Other canals
7 Structures
7.1 Drops
7.2 Division boxes
7.3 Turnouts
7.4 Off takes
7.5 Bed bars
7.6 Aqueducts
7.7 Measuring structures
7.8 Cross drainages
7.9 Culverts
7.10 Bridges
7.11 Level crossing
7.12 Others
Narrative Remarks:
-------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------.
4. Conclusion
-----------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------.
This SSI Project Site Handover to Commence Construction effected on: __________________.
1.
2.
3.
4.
5.
6.
Narrative Remarks:
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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----------------------------------------------------------------------------------------------------------.
5. Conclusion
-----------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------.
Appendix Part IV/GL 29/I-3 Format for Irrigation Project/Scheme Transferring to the Beneficiary
1. General Aspect of the Project
Project Name:
Administrative Location:
o Region:
o Zone:
o District:
o PA:
o Specific Site:
Distance from Towns:
o District Capital (---) = -------km
o Zone Capital () = -----------km
o Country Capital (Addis Ababa) = ------km
Geographic Coordinate of
Headwork Site
o Longitude/East (UTM): --------------------------------
o Latitude/North (UTM): --------------------------------
o Altitude (masl): -----------------------------------------
Command Area
o Longitude/East (UTM): From ----------------- to -------------------------
o Latitude/North (UTM): From ----------------- to -------------------------
o Altitude (masl): From ----------------- to -------------------------
Client: ------------
Contractor: ------------------------
Consultant: ------------------------------------------
Project commencement date: -----------------------
Project completion date: -----------------------
Command Area: ------------------hectare
Total Number of Beneficiaries: ------------------HH
o Male Headed----------
o Female Headed.................
Source of Fund
Total Investment cost: ETB ------------------
Share of Funding Agent: ETB ------------------
Share of Beneficiary: ETB ------------------
Narrative Remarks:
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