Re-Planning the Plan – A New Master Planning Approach for Capital Savings

This manuscript will summarize the approach utilized by Citizens Energy Group in updating its 12-year old sanitary sewer master plan. The master plan update identified reduced capital savings of $548 million from the previous master plan developed in 2004 (Citizens, 2015). The plan update included:Developing focused level of service goals for wet-weather performance, capacity for expansion, and self-cleansing velocities;Reconciling previous growth assumptions to current population projections;Leveraging synergy with Citizens’ other wastewater capital investments at the two treatment plants, the combined sewer system, and the sewer rehabilitation program;Prioritizing projects based on customer service requests and simulated capacity deficiencies;Use of a dynamic model to evaluate the systemwide impact of alternatives; andReconciling cost estimates to recent bid tabs for sewer construction and rehabilitation.Prior to Citizens’ acquisition of the wastewater assets, a master plan for the sanitary interceptor system was developed in 2004 with conservative assumptions for growth and interceptor capacity (Indianapolis, 2004). As projects from the master plan were carried forward for facility planning and design it was often found that projects were conservatively sized.In 2014, Citizens initiated an update to the sanitary sewer master plan. The early execution of 2004 master planning projects identified the need to “re-plan the plan” by not only re-evaluating interceptor alternatives but re-thinking the level of service goals for the sanitary interceptor system, reconciling growth projections, and evaluating the three elements of the collection system as a whole, since the sanitary system, combined system, and treatment plants have effects on each other’s capacity. The updated master plan alternatives evaluated the impacts of conveying additional peak flow to plants versus storage or inflow and infiltration (I/I) reduction, which led to the development of a recommended configuration that would not only improve conveyance capacity in the interceptors, but also reduce peak wet-weather flow to the treatment plants.The prioritization identified three tiers of projects, with the first in the 0-5 year planning window, the second for 5-10 years, and the third for beyond 10 years. The three tiers give Citizens flexibility in executing the master plan. Capital cost estimates were reconciled with recent bid tabs, and sewer rehabilitation unit costs were utilized to develop cost estimates for I/I reduction.