This paper presents a risk analysis model merging Analytic Hierarchy Process (AHP) and Monte Carlo simulation (MCS) that enables risk prioritization, providing a contingent cost analysis. The model has six steps: risk factors definition; risk frequency prioritization using the AHP; probability estimation for risk effects; probability distribution for other variabilities; correlation analysis between cost and time; and MCS for cost estimation. The proposed model was applied to 12 industrial wastewater projects. Data were gathered from interviews and documents. The results show three major contributions: a decision tool to identify, analyze and assess the risks, experts’ engagement (knowledge and perception), and visual output for risk analysis.