Richland Sanitary Sewer System Evaluation (SSES) Phase 1
CM Archer is working with the City of Richland to perform a phased Sanitary Sewer System Evaluation (SSES). The initial phase will involve the inspection and inventory of the existing wastewater collection system. The inspection and inventory activities shall start at the Richland WWTF headworks and extend south to the existing peak flow lagoon. All manholes in this area of the collection system will undergo comprehensive inspections to assess the condition of each structure and verify materials of construction. Available mapping of the collection system shall also be verified and updated as necessary, to reflect geometry of the system observed in the field. From the inspections of the manholes and verification of the system layout, an updated map shall be compiled and submitted to the city for review. Finally, a GPS survey of the influent lines to the existing peak flow lagoon shall be performed to ascertain the feasibility of its utilization for storm water equalization storage.
The second phase shall involve the flow metering of the sanitary sewer collection system through the use of ultrasonic area-velocity flow meters installed in manholes at multiple locations throughout the Phase 1 area. The placement of the flow meters shall provide specific information regarding the total volume I&I received at the WWTF and the nature of the excess flows observed in the system. Secondly, the flow metering shall provide specific data regarding those areas of the collection system that are most strongly influenced by I&I. The third phase shall involve the reduction of all data collected in the field. The flow metering data shall be analyzed and areas of high I&I influence shall be identified. The conditions of existing manholes in the system shall be reviewed and proposals for improvements and repairs shall be provided to the City. The feasibility of using the existing wastewater lagoons (Richland WWTF Outfall No. 3) for storm water equalization storage shall be reviewed. Recommendations for improvements may be provided, along with the proposed scope, schedule and fees associated with the complete evaluation to the City in an Engineering Report.