- SCOPE OF SERVICES
The selected topographical contractor shall be required to carry out topographical survey of all pipelines and other works described herein and in Annex IIA to the following specification, and will involve topographic surveying and leveling (longitudinal, cross sections, site survey at bridges, stream and other crossings and layout plan) along the pipe traces and selected other locations and preparation of drawings on electronic files and hard copies.
1.1
G
ENERAL

The topographical survey shall be carried out using Total Station technology and profiles with Dumpy / Engineering Level.

The contractor shall establish Temporary Bench Marks (TBM) from established Bench
Marks (Government or otherwise) in all significant locations such as intakes, reservoir locations or any other important locations and selected places in pipelines. The locations for
TBM for pipelines shall be agreed with UNOPS in such a manner that no two TBM are more than 2km apart, measured along pipe routes or roads.

All TBMs shall be established with concrete poles, securely held in ground to be used during construction, and numbered in sequence. The contractor shall produce a drawing showing designated number of TBMs, its co-ordination and elevation.
1.2
P
IPELINE
P
ROFILES

A closed traverse survey showing and identifying all important features such as bridges, culverts, underground electric lines, electric posts, telephone posts, existing utilities, manholes and any other shall be carried out and shown on drawings for each of the pipeline route. The existing utilities (if any) such as telecommunication manholes shall be clearly identified in the drawings with an appropriate abbreviation for utility agency.

When pipelines traverse along roads, full road width shall be shown on the drawings clearly demarcating paved edge (if any) and all utilities described above. The stretches of roads belonging to different authorities shall also be indicated with chainages.

For surveying pipelines and production of drawings, the contractor shall use the same node numbers that UNOPS incorporates in the map in Annex IV or to be provided during surveys.
The survey shall always commence from lower node to a higher node.

The levels shall be taken at least every 20m intervals for longitudinal section and shall include the junctions of by-roads and points of change of gradients such as soffit and invert levels of culverts, soffit and invert levels of bridges and water levels of relevant rivers and streams.

The level lines shall always be closed with a fly-back.

The levels shall be determined with reference to bench marks established by the accepted country surveys (National Grid).

Cross sections along the pipeline routes up to 10m on either side of the centerline of the road shall be taken at special locations where culverts, bridges, water courses, etc. are

encountered. For pipelines traversing along roads, levels shall be taken at the edge road to facilitate pipe laying on shoulder. The contractor shall at all times verify the side of the road for proposed pipeline or follow instructions from UNOPS prior to commencement of surveys for each route.

All important features along the pipeline route shall be identified and plotted while performing the survey work with particular emphasis on the following items.
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–
–
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Existing utilities, manholes (shall be marked with utility), culvert and bridge details
(width, length, invert level, type, size of opening, depth between road surface and top of structure, etc.)
Important buildings (schools, mosques, government buildings, etc.)
Rivers and streams
Details regarding existing water supply pipe lines or other (diameter of pipe, type, side of the road along which it is laid, etc.)
Details relating to other underground service installations (sewers, electrical cables, telephone cables, storm water drains, etc.)
Location of electricity and telephone poles.
Details of any property which is likely to be damaged or affected by pipe laying.

The starting point and end points of all pipelines shall be carefully selected so as not to miss any pipe stretches in the middle. (e.g. when pipelines originate from intake to treatment plant, the start and end of the pipeline shall be taken as the boundary of intake and treatment plant)

All existing pipeline ground levels shall be plotted against longitudinal distance (measured along pipe route) versus elevation to a scale shown in 4.6 using AutoCAD or similar engineering drafting software.
1.3
C
ROSS
-S
ECTION
S
URVEY

Cross sections shall be taken at every 100m intervals along the transmission pipeline routes up to 10m on either side of the centerline of the road, or up to the road boundary where it extends beyond 10m from the road centerline. Additional cross sections shall be taken at special locations where culverts, bridges, water courses, etc. are encountered. The levels shall be taken at the centre of road, edges of surfaced area, shoulder edges, boundary fences, etc. as required.
1.4
S
URVEY OF
E
XISTING
B
RIDGES

The bridges encountered along the pipe route shall be surveyed separately in detail. A
“bridge” for this purpose is defined as a structure over a water course with and opening of more than 4m or as indicated by UNOPS.

The length of the bridge, deck width, type of the bridge and other relevant details shall be provided.

A detailed survey at the site, including spot levels on the embankment and bed of the watercourse shall be included.


Detailed drawing of bridge surveys covering at least 20m either side from the centerline of the road shall be prepared to an appropriate scale incorporating the spot levels and contours.
1.5
S
URVEY OF
N
EW AND
E
XISTING
S
TRUCTURE AND
S
ITES
(I
NTAKE
, R
ESERVOIR
S
ITES
, P
UMP
H
OUSE ETC
.)

When a pipeline originates from a Premise such as Intake, Pump House, Reservoir or any other, a full site contour survey showing all structures, important features, manholes, valve chambers, flow meter chambers, underground utilities etc shall be carried out and shown on respective drawings for the site with contours at 1m intervals.

There are six (6) new lands and 6-7 existing lands for which site surveys are required. The extent of land for each plot is 100mx75m for all new locations and 50mX50m for existing locations or as required by UNOPS. All new locations are determined during the course of surveys by UNOPS Engineer.

The contractor shall also be required to show the location of all existing boreholes and record the ground elevations at these places. Further, site survey for existing reservoir locations shall show, in addition to contour map of respective land, the ground level of the tank, level of tank bottom, level of tank top, level of inlet, outlet, overflow and washout etc. In the event tank is in different elevations, above data should be recorded for each component of the tank.
1.6
O
THER
R
EQUIREMENTS
The contractor shall abide by following instructions/ guidelines during the course of survey.

Contractor shall promptly notify UNOPS of any ongoing or proposed development activities such as new underground telephone service, electricity service, property development etc.

Establish local names of the roads correctly including all byroads and indicate in the drawings.

Identify any stretch of pipe route requiring specials attention (e.g. marshy lands, rock out crops, etc.) and include on the drawings.

Identify any record any land (other than road reserves) involved along the surveyed pipeline routes.

Key plan shall be prepared to a scale of 1:10,000

Longitudinal sections shall be drawn to the scales of 1:1000 (horizontal) and 1:100 (vertical).
L.S and traverse survey shall be drawn on the same sheet.

Cross sections shall be drawn to a scale of 1:100 (horizontal) and 1:20 (vertical) on separate sheets.

Locations and levels of Bench Marks shall be indicated on the traverse. A separate Table shall be provided indicating all TBMs along the route and their respective locations.

PBM and TBM used on the survey work shall be marked with an appropriate paint and photographs submitted for the bench marks both in soft and hard copy.
Refer to Annex IIA for detailed site information, and Annex IV for the Zalingei Project Area
Map.


The existing distribution pipeline network –
This comprises existing water pipeline network of the town comprising materials such as HDPE,
A/C, uPVC and any other and the attached map shows the approximate Road map of Zalingei town, where pipelines are laid. It is estimated that the total lengths of these proposed pipelines are in the range of 30-45 km.

The transmission system
The transmission system comprises following pipelines.
Proposed transmission pipelines –
There are three borehole locations from which water is extracted for Zalinge water supply scheme. Each proposed transmission system comprises pipe lines from the borehole to the booster pump house within the borehole compound and to convey water to remote reservoir locations. See attached map in annex IV
Existing transmission pipelines –
The contractor is also required to survey all existing pipelines originating from boreholes to existing reservoirs / network. The routes of these lines are well known and will be shown to the contractor by UNOPS Engineer.
It is estimated that total length of transmission pipelines is in the range of 12-20 km.

Proposed & Existing reservoir and booster pump station
There are three proposed site for booster stations in the three borehole fields and three sites for new reservoirs. There are 6 to 7 existing water tank reservoir locations on the Zalinge water supply system. s for which site surveys are required. All new locations are determined during the course of surveys by UNOPS Engineer.
Please refer to attached proposed tentative schematic diagram of Zalingei and existing road network map, where pipeline are laid. The exact roads of pipelines will be shown to the contractor by UNOPS Engineer at the commencement of surveys.
Bidders are strongly advised to visit the site, obtain local information and get acclimatized to the project area prior to submission of their bids.

Bidders are advised that UNOPS, during the course of surveys, may add or delete any pipeline (s) shown on the map or reservoir location if such changes are deemed necessary without incurring any liability for such changes. Since the work is paid for by measure and pay basis, in the event of such changes, UNOPS does not entertain any claim of what so ever nature arising as a result of work quantity being modified due to UNOPS requirements.