Scientific modeling and simulation software is ubiquitous at Sandia National Laboratories and is integral to providing empirical justification to critical mission decisions. Models are increasingly being expressed as workflows to simplify the many steps needed in scientific analyses but keeping these models and workflows alive for the decades-long timescales needed by Sandia remains a struggle. Additionally, the manual use and (lack of) maintenance of these models creates significant risks for duplicated work and model capability loss over time from changing personnel and computing environments. To address these issues, we are building the Engineering Common Modeling Framework (ECMF), a platform for scientific model sustainment at Sandia. ECMF enables the automatic evaluation of models over time and will ensure that models created at Sandia are discoverable and ready to be revisited, extended, and reused. In this paper, we report our current and planned capabilities as well as lessons learned from our framework development process.