Question: Is there a requirement for DOE sites to purchase biodegradable dishware?
Response: No, but, if your site has a compost pile or service, it could reduce disposal costs by breaking down the dishware into compost. Sending biodegradable dishware to the landfill, though, would neither reduce cost nor biodegrade. Biodegradability has as much to do with the location (landfill or compost pile) as the type of material the product is made of. Biobased products tend to be more biodegradable than petroleum based products. However, if the biobased product goes to the landfill it has very little chance of biodegrading no matter what its percent of biobased material or its biodegradability rating is.
Composting on site can include the traditional grounds and cafeteria debris or it can be a composter specifically designed for cafeterias. Green Mountain Technologies (http://www.compostingtechnology.com/) is one manufacturer of cafeteria composters.
If composting on site is not a possibility, you might consider using/helping establish a regional composting facility.