Hennepin County

Welcome, Guest!
Log in | Employee Login | License
 

Messages

Project Question: Does the 4? Perf TP Pipe Drain need fine filter aggregate around pipe?

Question:
Does the 4-inch Perf TP Pipe Drain need fine filter aggregate around pipe?

Response:
There are two conditions in which the bid item 4-inch PERF TP PIPE DRAIN is used: within the road subcut and behind retaining walls.
Within the road subcut, the TP pipe drain shall be wrapped with geotextile and surrounded by fine filter aggregate per Standard Plan 5-297.430 on page 45 of the plan set. Construction and payment of the TP pipe drain shall follow Standard Specification 2502.
Behind retaining walls, the TP pipe drain shall be wrapped with geotextile and surrounded by course filter aggregate per detail on page 148. (Fine filter aggregate is NOT required for subsurface drains behind retaining walls.) All other construction and payment requirements of Standard Specification 2502 shall apply.