Gap in galvanized iron pipe - creating a path for ants?

[conradical]

I noticed a pile of dirt/gravel on a ledge in my basement, and I've vacuumed it up a couple times, but it continues to return, and it seems more common to return in the summer. I'm located in Minnesota so I'm guessing whatever critter is causing that dirt pile is only active in the summer. I had a pest control guy take a look at it because I thought it was frass (bug poop). He said it may be carpenter ants, but he didn't have much to say beyond that. After taking another close look at it, I don't think it's frass. Directly above the dirt pile is a pipe that goes out to my garage, and the pipe supplies gas to the gas heater hanging in the garage. I noticed that there's a pretty good gap between the inner pipe and the outer pipe, and I'm wondering if maybe ants are carrying the dirt through that gap and dropping it on the ledge in my basement? Does that make sense? If so, what could I use to seal the gap to keep the ants out of my basement. See attached picture. Thanks for the help!

 

[Twowaxhack]

Silicone caulk the gap

 

[pasadena_commut]

I'm wondering if maybe ants are carrying the dirt through that gap and dropping it on the ledge in my basement? Does that make sense?

Not really. Ants only carry dirt a few inches from the colony opening then drop it. Maybe if the outer pipe only goes up a short ways then terminates right at the surface of dirt next to an ant colony. That just doesn't sound very likely.

What is the route of that outer pipe? (The inner one does not matter, the dirt path is "inside the outer", not "outside the inner".)

Could the material be rust, or flaked off galvanization coating? If there was some movement due to thermal expansion or vibration the inner pipe might be grinding this stuff off the inside of the outer pipe, and then eventually it just falls out the bottom. Less likely, but maybe possible, is a pressure difference between the ends of the outer pipe, which would in effect suction dirt from the inside to the outside.

My house has a strange problem where dirt is getting behind a low ornamental brick facade which is below some clapboard. The dirt gets in there because there is a small gap, and the gardeners blow dirt all over the place, first up onto the ledge from the ground, then into the crack from the ledge. My temporary fix is a long piece of painter's tape to seal the crack.

 

[MicEd69]

the dirt path is "inside the outer", not "outside the inner"

Isn't that describing the same annular space?????

 

[Geofd]

Caulking would work or even that great stuff/foam spray at home depot

 

[pasadena_commut]

Isn't that describing the same annular space?????

I was trying to say that essentially the dirt was being transmitted inside the outer pipe. That would happen whether or not the inner pipe was present. Assuming this is just a case of dirt being transported, and not a case of one pipe rubbing on the other.