The CDC has issued a Resuming Business Toolkit to assist businesses with re-opening: Resuming-Business-Toolkit
There is a lot of other helpful information for businesses here: https://www.cdc.gov/coronavirus/2019-ncov/community/office-buildings.html
General guidance for Oregon employers can be found here: OR General Guidance
Finally, the US Chamber of Commerce has published guidance on keeping employees calm during the Pandemic: https://www.uschamber.com/co/run/human-resources/keeping-employees-calm-during-coronavirus-pandemic
