  This Letter considers the design for computing facilities that are
complementary to the leadership class High Performance Computing (HPC)
facilities. This design envisions a future where funding agencies are
allocating greater resources for leadership class facilities and these
facilities will provide a significant part of the total compute cycles for HEP
Experiments. While a leadership class facility (LCF) may provide cycles and
advanced architectures, the facility does not necessarily provide all of the
services needed to help HEP users make the best use of the HPC facility, as
well as the services needed to provide computing for workflows that are not a
good fit for the HPC facilities. This Letter outlines some of the necessary
components of a facility designed to provide those services and capabilities.
