This invention is directed to systems including one or more trenches or wells that include one or more perforated pipes through which a gas, such as air, can be injected into the vadose zone of ground located beyond a methaneogenic source to create a positive-pressure gas curtain and/or aerobic conditions in the vadose zone that inhibits migration of and/or facilitate the remediation of mobile volatile organic compounds that are capable of contaminating groundwater surrounding the methaneogenic source.