Dear Sir,
As per the Civil Drawing “Waterway Headrace Pipe Cross section” and ““Waterway
Penstock Pipe Cross section”, drawing number: LJKHP-WW-C07-26, Note 4, the outer pipe
surface shall be filled by gravel with full of compaction. So as per the Engineering and
Research Center Bureau of Reclamation, MODULUS OF SOIL REACTION (E'),
VALUES FOR BURIED FLEXIBLE PIPE, we selected the soil modulus value of 2000 lb/in2
for coarse grain soil with little or no files for moderate compaction of 80-95% having 40-70%
relative density.
Also, As per ASCE-79: Steel penstock, the suggested compaction is 85% with layerwise
compaction for the steel pipe.