Removing Food Sources
First, consider their food source. Obviously, bird feeders attract urban wildlife. Although chipmunks are omnivores, their preferred diet is seeds. Therefore if you want to control your chippies, then stop feeding the birdies. However if bird feeders are not around, consider tree fruit. Acorn nuts and even those winged maple seeds give them plenty of good eating. Make an attempt to remove these seeds as they fall. Leaf blowers make easy work out of this. Blow them into piles, and bag them up. Keep in mind that these rodents store this type of food. It makes perfect sense to take away their food reserves. Make them eat frogs and earthworms instead. Perhaps they will end up moving elsewhere.
Second, look at your yard. Figure out where they are nesting. Most of the time they burrow under tree roots. One example is underneath surface roots of mature trees. They can even find old roots from previously removed trees. Alternatively, they burrow right down into the shrubbery around the house. There is not too much you can do about all of this. One thing you can try is filling their burrows in. After trapping, pack concrete into the burrow. Just remember that there is an emergency exit hole to fill too. Another option is ground screening. Stainless steel 1/4″ hardware fabric can be laid down, and then back filled. Similarly, Xcluder makes Geo blankets for professional use.
When they get too close to the house, people take to chipmunk control. Chipmunks commonly take advantage of brick stoops, landscape rock, and patio steps. Certain homes have additions built on. Many of these have inaccessible crawlspaces underneath. This is a rodent safe haven. In this instance, you may find them burrowing underneath the foundation. Otherwise they jet into gaps underneath the siding. Not good either way.
How To Get Rid Of Chipmunks Underneath a Porch
In order to get rid of chipmunks nesting under porches, you have to trap them. The best method is to seal potential entry points, while leaving the main entry open. After that is done, set traps directly over the entry point. That way you get whatever is in there, out. You can be sure that everything is out after 7 days of not catching anything. Remove the traps, and seal the remaining entry point.