Emergency planning makes business sense on multiple levels. Having a plan and process in place to guide the company and your employees through emergency situations will help to ensure effective response. It may be too that local first responders require cooperative planning especially if the facility handles notable quantities of hazardous materials.
Now the OSHA Emergency Action Plan provides a reasonable template and foundation for site emergency plans. See: https://www.osha.gov/SLTC/etools/evacuation/eap.html. While OSHA requirements center on protecting employees, it naturally follows that an effective site emergency plan can also be effective in protecting the public and property. When there is an effective plan in place, and one that is implemented when necessary, then it follows that response will be organized, effective and orderly. But that depends upon effective training, drills and continuous improvement of the process.