Water Quality Best Management Practices O&M
Regular operations and maintenance are critical for sustained performance of water quality BMPs over their service life. Neglect or inadequate operation and maintenance activity will lead to reduced BMP lifespan, performance, benefits, and potential failure to achieve water quality objectives. Conversely, proper planning and execution of operations and maintenance from upstream pretreatment devices through all other BMP components can significantly improve the lifespan of BMPs and thereby improve the project benefits at the project and watershed scales.
Water quality BMP operation and maintenance includes major elements such as:
Passive/flow-through BMP captures debris, trash, and other coarse particles as water flows through the system. Examples of passive/flow-through BMPs include catch basin inlet screens, trash nets, hydrodynamic separators, and sedimentation basins. Captured trash, debris, and coarse particles should be regularly removed from the passive/flow-through BMP to prevent system clogging. These BMPs should conform with the requirements of the LA River Trash TMDLs for full-capture systems to be installed in all catch basins with drainage to the LA River.
Regional-scale infiltration BMPs often include mechanical systems such as diversion pumps to divert water into the BMP. Such mechanical systems require regular preventative maintenance and testing to ensure proper function.
Green Infrastructure/Vegetated BMPs
Water quality BMPs such as bioretention basins, bioswales, and constructed wetlands rely on established vegetation to capture and remove pollutants from the influent. Green infrastructure/vegetated BMP requires regular maintenance activities such as plant maintenance, irrigation, and removal of trash, sediments, and debris.
Additional Flood Risk Reduction O&M Guidelines
Water quality BMPs in the LA River watershed are primarily a combination of resources, planning, and collaboration amongst LA County Public Works, LACFCD, USACE, and various cities within the watershed. These BMPs should conform with the requirements of the LA River Trash TMDLs for full-capture systems to be installed in all catch basins with drainage to the LA River. Water quality BMP operation and maintenance responsibility is often coordinated amongst agencies through Memorandums of Understanding (MOU) or Memorandums of Agreement (MOA), which are negotiated amongst agencies based on asset ownership, staff availability, resource allocation, and other logistics that are agreed upon amongst different agencies. In addition, any established MOU/MOA is subject to change upon agreement of responsible parties.
At times, public agencies will partner with private organizations or non-profit organizations to collaborate on the operations and maintenance of a water quality project. For example, a private company may agree to pay for a green street project, with the understanding that a public agency will maintain the project after construction. This type of public-private partnership can relieve public agencies of upfront capital costs and also allow them to better focus resources on long-term performance of projects.