Abstract: The paper focuses on secondary bio streams not captured efficiently in the value supply chain. Specifically, roadside grass clippings were chosen based on logistical optimization potential, direct feasibility, locality, biomass potential, and economic valorization value. The main objective is determining how this secondary flow can be brought to the "gate of a factory" – road transport and inland shipping – and at what cost per unit. To this end, various scenarios were developed for a case study in East-Flanders, considering multiple combinations of first collection points, secondary collection points, and processing points. The result is a generically applicable Excel-based tool that combines these variations with a decision considering both inland waterways and road transport. The East-Flanders scenarios become valuable in applying the tool and optimizing this value chain located in East Flanders. With this, reducing the number of collection points is favorable for the utilization of inland waterways as it reduces costs related to transshipment. Nevertheless, unimodal road transport is still the most cost-effective in transporting this secondary material stream from the collection point to the processing point. Consequently, a lower weight and a higher density will lead to lower costs that bottom out due to regulations and conditions to be met.