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GATE 2021 AR – Question 18

Infrastructure, Services and Utilities · Sewerage layout and network design · 1 mark · Multiple choice

A wastewater pipe falls at 1:200 between two inspection chambers 40 m apart. The first invert level is−450 mm. Find the second invert level.

  1. −650 mm
  2. −200 mm
  3. −250 mm
  4. −550 mm

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Correct answer: (A) −650 mm

Explanation

The fall is 40000/200=200 mm. Moving downstream lowers the invert, so the second level is−450−200=−650 mm, A. Adding the fall to a negative level would reverse the direction of drainage.