I've seen the condition you've noted regarding air lock on the collection lines. One way to make sure that it is air locked is by examining the flow. If the flow surges, it is vapor locked.) If the pipes between the landfill and the collection manhole are completely enclosed (common) it may...
We have used ECB's and TRM's extensively. Briefly, (1) you need to identify the shear force which will be exerted by the water; (2) examine the options available for erosion protection (vegetation - ECB - TRM - Armour such as rip-rap, gabion, concrete, ect) and choose your protection based on...
