QUESTION (100) 1-A sewer is to be laid at a uniform gradient between two points X and Y, 200m apart. It is supposed that invert level (lowest level) will be on the manhole X. Bench mark BM 0.00m which is near to the manhole X. In order to fix sight rails at X and Y, readings are taken with a level in the following order; Readings BS 2.50m IS 2.0m IS 'a'm FS 1.5m staff station BM (near X), RL0.00 Top of sight rail at X Peg at X CP between X and Y BS 3.0m CP between X and Y IS 2.0m FS 'b'm Top of sight rail at Y Peg at Y i-(30)Draw up a level book and find the reduced levels (excavation levels) of the manholes, if a boning rod of length 3m is to be used. ii-, (35) If depth of excavations of manhole X and manhole Y 2.0m and 1.5m, then find the level readings a and b iii-(35)Find the gradient between X and Y points.