Filter Collapse Due to Improper Wash Water Distribution [with Discussion]

ters through a 30-in. horizontally operating gate valve and pipe. Both the sand and gravel media arrangement would be considered fairly standard. The gravel size and layer depths are as follows: a 3-in. layer of 1-1^-in., a 3-in. layer of ^-1 in., a 3-in. layer of %-% in., a 2^-in. layer of -J-J in., and a 2^-in. layer of r^-i~mma~ terial. The gravel was topped by a 4-in. layer of torpedo sand with an effective size of 0.80 to 1.20 mm and