Volume-II of IV - GAIL

MECON LIMITED
REGD. OFF : RANCHI (BIHAR)
PROCESS & PIPING
DESIGN SECTION
NEW DELHI
\\Akjha\work contrac\standard TS for Pipe Line WC (Vol-II) MASTER FOLDER\04A major water crossing\Major Water Crossing -Final 04.doc
STANDARD SPECIFICATION
TITLE MAJOR WATER CROSSINGS SPECIFICATION NO. PAGE 12 OF 14
7.2 Bank Protection
MEC/S/05/62/04 REVISION 0
7.2.1 Trenches in banks of major water crossings shall be backfilled with soil
approved by COMPANY. The fill at the banks shall be tamped firmly and
reinforced with sacked earth, rip-rap, or by other means as directed by
COMPANY to the satisfaction of authorities having jurisdiction thereof. In areas
where the backfilled soil is expected to be of loose type which is prone to flow,
the trench shall be backfilled with boulder/ crushed rock of minimum 75mm
thickness. The boulder/ crushed rock shall be derived from solid, stable, nonsoluble
and approved quality store approved by COMPANY and pipe shall be
provided with adequate padding of soil of a quality approved by COMPANY.
Wherever necessary the boulder/ crushed rock shall be held to the bed by use
of 6.1 wire nets of minimum dia. of 3.2mm, made from steel having tensile
strength of 400 N/mm 2 and with a minimum elongation at failure of 12%. The
minimum zinc coating of 275 gm -2 shall be applied on single/ double twisted
wire. After the trench has been backfilled and during the clean up works, the
water crossing shall be cleaned across the whole width of ROW. The existing
bed profile shall be maintained after restorations.
7.2.2 Unless stipulated otherwise by the authorities or by COMPANY, CONTRACTOR
shall protect the banks of the major water crossings by using gravel and
boulders filled embankment mattresses of galvanized iron wire (of specification
as in 7.2.1 above) to be laid over the backfilled, compacted and graded banks.
In case slope of the banks is 1:1 or more, bank protection shall be carried out
using gabions. Bank protection works shall be carried out by CONTRACTOR in
accordance with the drawings included in the CONTRACT. All materials required
for such works shall be supplied by CONTRACTOR and all works carried out in
accordance with specifications, approved drawings, instructions of COMPANY
and to the complete satisfaction of authorities having jurisdiction at no extra cost
to COMPANY.
The length of the above protection shall be equal to the actual bank excavation
edge including damage and further extending 10 m on either sides, The width of
the restoration on the slope shall be determined by the levels :
• 2m above Highest Water Level, (recordable) or upto the top of bank ,
whichever is higher.
• 5m below Low Water Level (recordable) or upto pipe trench level in the
bed.
7.2.3 Before final hydrostatic testing, CONTRACTOR shall `prove' the diameter of the
pipeline by passing a gauging (caliper) pig through the pipeline. The gauging
pig shall have a diameter equal to 95% of the internal diameter of the
pipe.