The list of services the Contractor shall be required to provide include, but are not limited to, a dedicated on-site building engineer, routine custodial service, day porter service, non-routine custodial service, grounds keeping, snow removal, extermination services, preventative maintenance on various mechanical, plumbing, and electrical systems and oncall repairs or other needed work related to the management and maintenance of the building and surrounding property. The on-call service will be an element of the resulting contract on a time and materials basis. The Contractor and approved Sub-Contractor(s) providing services on this contract shall be licensed with Department of Professional and Occupational Regulation (DPOR) in the Commonwealth of Virginia with the proper endorsement(s) for specialty trades.