PACKAGE : I Bid Document VOLUME : II - Public Health Engineering

Erection/laying/hoisting, fitting and fixing of D.I. Pipes specials and valves of
various sizes including embedding in R.C.C. floor or wall of over head reservoirs or
at ground level where ever necessary, excavation of pipe line trenches, providing
necessary supports and staging including supply of all jointing materials required
for flange or joints.
All R.C.C. works shall be finished perfectly smooth and no plastering shall be
allowed except in the inside surface of walls and floors which shall be finished with
a coat of epoxy paint & cement punning with water proof compound over 20mm
thick cement plaster in cement mortar (1:3).
All exposed faces of the concrete and plaster over masonry shall be
given two coats of waterproofing cement paint of approved shade.
All exposed iron works outside the reservoir shall be painted with two
coats of approved synthetic enamel paint. All exposed iron works
inside the reservoir shall be essentially stainless steel of suitable
grade.
All masonry works shall be plastered with 12mm thick cement plaster
in 1:6 cement mortar.
25.5 Design criteria & specification.
Capacity: Capacity of the tank shall be the volume of water it can restore between
the designed full supply level and lowest supply level (that is, the level of the lip of
the outlet pipe). Due allowance shall be made for plastering the tank from inside if
any when calculating the capacity of tank.
Height of staging: Height of staging is the difference between the lowest supply
level of tank and the average ground level at the tank site.
Water depth: Water depth in tank shall be difference of level between lowest
supply level and full supply level of the tank.
Free board: Free board shall be minimum 500mm.
Dead storage: Minimum dead storage of 80mm shall be assured for that bottom
reservoir.
Design: Before taking up the design, the designer should first decide the most
suitable type of staging of tanks and correct estimation of loads including statistical
equilibrium of structure particularly in regard to overturning of overhanging
members shall be made. The design should be based on the worst possible
combination of loads, moments and shears arising from vertical loads and
horizontal loads acting in any direction when the tank is full as well as empty.
DTS : Detailed Tender Specification. Page 283