This suggests that relatively coarse turbidity particles in water urns may entrap bacterial cells as they settle under gravity to below invert level
. In the pretest of the water urn, acceptable water quality was reached after a settling time of about two and a half hours, when all the coarse particles had sunk past the outlet.
Employing a company to do a camera survey of the property's drainage layout and recording the invert levels
would be a useful exercise at preliminary design stage.
WAPDA said that KBD could not, in any way, block drainage or cause water logging or salinity as invert levels
of main drains of Mardan SCARP are higher than the reservoir elevation of 915 feet and the back water level in Kabul River and Kala Pani Khwar.
Engineers gathered information on the Long Beach pipeline system - including pipe size, slope, material, invert levels
, and any other information needed to operate the engineering models - and entered it into the database.