The sewer collection system in the City of Manhattan Beach consists of 92 miles of City and County pipelines. The City’s portion of the collection system is comprised of approximately 86 miles of sewer pipeline ranging in size from 6 to 21 inches in diameter, with most lines being 8 inches in diameter and six pump stations. Pipeline materials are predominantly vitrified clay pipe (VCP) with the exception of some ceramic-lined concrete pipe in the older part of the system located in the Sand Section (beach area) of the City.
In 2010, the City completed the previous Sewer Master Plan, and in 2022 the City completed a Sewer System Management Plan Update. A comprehensive CCTV investigation of the City’s sewer system is ongoing. CCTV inspection reports will be used extensively in rating the sewer system defects and the development of the final rehabilitation priority list. The City will implement improvements identified as a high priority in the updated Sewer Master Plan and will continue to provide ongoing maintenance services, including cleaning and inspection.
Notably, since the completion of the City’s previous Wastewater Master plan in 2010, the City has undergone substantial redevelopment of residential properties, which in turn has increased the volume of flow directed to the sewer system. An evaluation of the capacity of the sewer network and identification of which pipes should be upsized is needed to ensure that the network operates as intended to prevent sanitary sewer overflows.
The Sewer Master Plan (SMP) will include proposed improvements designed to correct pipe deficiencies, such as capacity issues, cracks and root intrusion. The resulting improvements are grouped as ‘projects’ to make sure proposed repairs are grouped in an efficient manner. The identified improvement projects are prioritized based on factors including benefit/cost analysis. Projects that would correct large scale deficiencies are prioritized over projects that would correct minor defects. In addition to pipes not being large enough to carry design flows, a component’s physical condition is considered when determining the adequacy of existing infrastructure. A pipe may be large enough to carry the flow, but if it is compromised (root intrusion or cracking or misaligned pipes due to settlement are the most common deficiencies), then the pipe will likely not be able to carry the flow and is also labeled as deficient.
The Master Plan Report will summarize pertinent findings, including System Capacity and the Sewer Conveyance System Replacement/Rehabilitation Priority Program to be approved by City Council.
