Trapping is likely the most practical and efficient method for controlling a mole population (or voles, with which they are often confused). More information about moles and options for suppression are available in the linked pages for an Ohio State University publication and a web page by Penn State. (We don't recommend poison bait use, and neither resource places much reliability in the use of castor oil as a repellent.) Despite being an oft-used recommendation among some gardeners and on web forums, dish soap should not be mixed with any pesticide (or repellents, which the EPA regulates like other pesticides) unless explicitly permitted by the product label, since household soaps and detergents risk causing phytotoxicity. (This is plant tissue damage from chemical exposure, and is a risk with many home remedy solutions.)

Fortunately mole populations are almost as quick to disappear as they are to appear, and they are food for a variety of wild animals, so the issue might resolve itself soon.

Miri