Drilling into mortar

[jfdub]

Can I drill into this part of my plaster/mortar?

 

[ajw22]

I guess so, but why? What are you trying to do?

 

[jfdub]

Good question! Pool builder lost the conduit they placed to run irrigation to a landscaping area near my pool so I'm trying to hide as best as possible the irrigation line to the area. Right now I'm drilling into the mortar for the flagstone but it'd be better hidden if I can drill into the part in the first Pic.