East Orange County Water District provides sewer service to an area of 10,000 acres and 18,000 customers. The gravity sewer system consists of 171 miles of pipe, ranging in size from 4-inches to 27-inches.
The scope of work included the development of a calibrated hydraulic model, development of system evaluation criteria, determination of future development areas and loads, hydraulic capacity analysis, condition assessment of pipes and 500 manholes, and a risk analysis to prioritize gravity pipes and develop recommendations for future inspection, rehabilitation, and/or replacement work.
The gravity sewer risk analysis was conducted utilizing Innovyze’s InfoMaster program (InfoAsset Planner), an ArcGIS based asset integrity management and capital planning software package. AKM compiled 7 years of historical CCTV data and used it along with the hydraulic model results to develop a likelihood of failure (LoF) for each pipe. The proximity to waterways and maximum rate of flow were utilized to develop the consequence of failure (CoF) for each pipe. The LoF and CoF were then used to assign each pipe a risk category/priority and a decision tree was created to also assign each pipe with an associated action item for future inspection and/or maintenance.
It is estimated that there are about 500 parcels in the EOCWD service area that currently have septic systems in place. In the future, EOCWD may have to provide sewer service to these parcels. AKM completed a Septic to Sewer Connection Study. The study identified the location of septic systems in the service area and then planned out how sewer service could be provided to these properties in the future. This may involve the construction of gravity sewers, grinder pumps at individual properties discharging to common force mains, lift stations, and force mains. It also may require easements to be obtained and/or other properties to be purchased. Cost estimates were developed for proposed sewer facilities as well as for the conversion of septic systems and connection to EOCWD’s sewer system.