Which of the following is an example of a landfill maintenance project?

The option that signifies a landfill maintenance project is cleaning out sedimentation from retention ponds. This task is part of the ongoing upkeep necessary to ensure that the landfill operates correctly and complies with environmental regulations. Retention ponds play a crucial role in managing stormwater runoff and preventing sediment and pollutants from entering surrounding areas. Regular maintenance of these ponds helps maintain their functionality, ensures that they effectively manage water flow, and minimizes environmental impacts, thus falling under the category of maintenance projects.

The other options represent different types of activities related to landfills but do not focus on maintenance. Expanding landfill boundaries involves physical alterations to the landfill footprint, which is a developmental activity rather than maintenance. Conducting community outreach programs relates to public relations and community engagement efforts, rather than the physical maintenance of the landfill. Developing new waste processing technologies pertains to innovation and improvements in waste management, rather than maintaining existing landfill operations.