Note on Design.

1. 1. Considerationof existingWaterPipe Line:
Clause No.13 of Schedule B (Page no. 277) states that there is “A major transmission water
pipeline runs parallel to the project road within ROW from Km Km. 5+150 to 9+150 (RHS).
Development of road has been conceptualized without disturbing the stability / relocating
the pipelines.Special safetymeasuresasrequired to ensurecontinuous water supply may be
taken during the construction stage.Provision of future maintenance of pipeline is also to be
kept into consideration. Minor shifting of project road centreline, if indispensable may be
made. “
However, todeal withthe existingpipeline,whichisinsome place goes underground and in
some places, it is exposed over ground need a detailed attention in terms of design and
protection requirement criteria. First, due to the presence of the water pipe line (which is
alsocomingin RE wall approachsection), the alignment needs to shift towards left. In such
placesthe alignmentmaygobeyondROW limit at the left side of the road section. Second,
to take care the stabilityof the pipeline acasingstructure intermsof covered box structure,
whichitself isgoing to affect hugely in Quantity. Third, in terms of future maintenance the
casingof the pipe line while going underground need to be so spacious that one can easily
access the pipe line forminorormajormaintenance work.The size of the covered structure
will affect in service road FRL. Which will increase due to the underground cased box
structure, affecting also in quantity.
2. Raising of Profile at Pond Location:
In fewcaseswhere there isapresence of pondlocations,the FRLof designed alignment has
beenraisedto cater the HFL criteria for the safety of the pavement subgrade. A total of 2.5
m has been raised from the existing road level. By raising the profile at those selective
locations andmaintainingthe minimumvertical slopecriteriafor drainage, profile has been
modified. But due to the raising the earthwork quantity has been increased along with
Retaining wall and Toe wall to restrict the slope of the earthwork within the ROW limit.
Those raisingcan alsobe optimize by assessing actual HFL at the particular location and the
raising the profile accordingly.
3. Providing Sand filling in Marshy area:
Locations along the project corridor where water logged area has been observed, a sand
layerof 500 mm hasbeen placed as a layer to densify the area. As those areas are prone to
settlement, laying of sand layer has been indicated. However, the total length of such
sections has been considered as 4.5 Km. in BOQ, which also includes areas near pond
location.Butthat can be optimizedbyeliminatingthe pondlocations and only retaining the
waterlogged areas along the project stretch.