This report sets out the findings of an investigation that was undertaken into the feasibility of implementing the detention basin scheme that forms part of the Gundaroo Floodplain Risk Management Plan (denoted herein as “the FRMS Detention Basin Scheme"). This report also provides details in the form of a concept design of a refined version of the FRMS Detention Basin Scheme which was found to provide improved flood mitigation benefits to the affected community (denoted herein as “the Refined Detention Basin Scheme”).