How do I seal crevices in dry stack wall to prevent gophers from pushing dirt out onto patio?

I've recently had a retainer wall built in the landscape using the dry-stack method (see photos). Unfortunately, there has already been two occasions within past month of gopher activity behind the wall which has caused the soil to spill out onto the patio. I would like to seal the crevices between the stones with concrete to keep the gophers from pushing the soil outward. I'm not sure if portland cement or posthole concrete would be preferable. Although there isn't a french drain behind the wall, I don't think that drainage will be a problem as there should be plenty of smaller weep cracks for water to drain.

Hi Grant;  Welcome to Permies!

Well those are some large piles of dirt those gophers dug out. Very nice looking wall though.

Were you planning on just plugging the spots where they made it leak?  Or the whole wall ?
Have you considered trying to eliminate said "bad" gophers?  

If it were me, I would clean out the leaking spots of dirt.  Locate suitable small rocks to jam deep into the hole. Seal those in completely with a quickcrete, then place more smaller rock in front,with no concrete. To maintain the dry stack look.

As to which quickcrete is better to use . I would guess either would do well.

Thanks Thomas!  I'm not able to jam any stones any deeper into wall. I suppose I should have back filled behind the wall with gravel, but too late now!  I was surprised how little room between the crevices where the dirt had spilled out onto patio!  The cement patching will have to be visible.  So you think the Quickrete portland cement Type I/II in photo will work OK?

Grant Winslow wrote:Thanks Thomas!  I'm not able to jam any stones any deeper into wall. I suppose I should have back filled behind the wall with gravel, but too late now!  I was surprised how little room between the crevices where the dirt had spilled out onto patio!  The cement patching will have to be visible.  So you think the Quickrete portland cement Type I/II in photo will work OK?

That will work perfectly.

Trace, if I use the Quickrete I/II portland cement then would I need to add sand to the mixture?  I would be using it as a "grout" to fill in the crevices and not as a binding agent to secure the stones.  But with a normal grout, if the joints are >1/4", then it's recommended to use a sanded grout!  Would that apply in my situation?

Grant Winslow wrote:Trace, if I use the Quickrete I/II portland cement then would I need to add sand to the mixture?  I would be using it as a "grout" to fill in the crevices and not as a binding agent to secure the stones.  But with a normal grout, if the joints are >1/4", then it's recommended to use a sanded grout!  Would that apply in my situation?

Quickrete already has sand/gravel in it, so I wouldn't add anything.  It will do both things mentioned.  It will secure the stones and fill the crevices.

It might be a semantic difference, but instead of patching, have you thought about thinking of it as plugging?

They make bags very similar to cake-decorating bags that let you inject the concrete. With a long enough plastic or metal tube, you might be able to get the concrete far enough back behind the face to maintain your dry-stack look entirely.

Just an idea.

D

Daniel,

I ended up filling in most of the joints using a gray Type S mortar and applied with grout bag & skinny trowel.  Water should be able to seep through small crevices that weren't mortared.  Even with mortared joints, thankfully it still retains a "dry stack wall" appearance!

Looks great! A mortar bag is what I was referring to. For whatever reason, the word didn’t come to mind

D