Leachfield next to Gravity Wall

[JSJzoom]

Hi All-

We have about a 6 foot high gravity wall holding back soil and we will be putting in a wastewater leachfield next to it. The county requires 10 foot seback from retaining walls, but we don't have 10 feet so we are looking to put the leachfield in about 5 feet away from the base of the wall, parallel to it. Is this a problem structurally for the wall, maybe for the leachfield? Any suggestions on where I can find more info on this?

Thanks!

 

[jdmm]

From the perspective of the wall it is not a problem to provide adequate drainage but the question remains about the rate of drainage from the leachfield. I once did a wall for a cemetary. Leachate from the dead bodies was not nice and they wanted to plant people within 10 feet of the wall. As a wall designer this was not a problem but the leachate was (it backed on to residential property)

 

[dgillette]

Is the leachfield at the base of the wall, or at the top of the wall? Sounded like you were talking about it being at the base of the wall (right?), where it could raise the water table. This might affect sliding stability (which is easy enough to design around with a small shear key), and perhaps global stability. I don't think either is likely to be an actual problem, but to prove that, you do need to crank through some analysis assuming a pretty high water table (at or near the ground surface) on the low side of the wall. It would be much worse to have the leach field on the high side of the wall, since that could force you to build some new drains on the back of the existing wall, in addition to requiring you to analyze for larger active pressures for sliding and overturning, and do the global stability analysis with high water table on BOTH sides.

In contrast, sounded like jdmm's cemetary was on the high side and the residence was on the low side, and leachate flows down hill. That would argue in favor of cremation, provided one's religion permits it.