Central Coast Blue is a regional recycled water project that will develop a sustainable water supply and protect the Santa Maria Groundwater Basin (SMGB).
Recent drought impacts have highlighted the need for a sustainable, drought-proof source of supply to ensure that reliable water supplies will be available for future extended droughts. Currently, water from the Pismo Beach Wastewater Treatment Plant (WWTP) and the South San Luis Obispo County Sanitation District (SSLOCSD) WWTP is being treated and discharged to the ocean. Central Coast Blue will provide an opportunity to capture this lost water and use it to recharge the SMGB to create a drought proof, sustainable water supply for the community.
Central Coast Blue protects our shared groundwater, while providing a sustainable local water supply to support our thriving communities and diverse economy.
Central Coast Blue is based on the idea that all water is connected, and all water has value – from our reservoirs and streams to our groundwater basins and imported supplies. By working together to manage our water holistically, we can achieve multiple benefits and enhance the sustainability of our Central Coast communities.
Central Coast Blue is the right investment for the future, carrying on our water legacy and stewardship for a resilient water foundation.
HOW DOES IT WORK?
Central Coast Blue will include construction of a new Advanced Water Purification Facility (AWPF) to treat wastewater from the Pismo Beach and SSLOCSD WWTPs. AWPF treatment technologies include Microfiltration/Ultrafiltration, Reverse Osmosis, and Ultraviolet disinfection with Advanced Oxidation. These process upgrades are referred to as Advanced Treatment and they are in use throughout the United States and the rest of the world.
In addition to the AWPF, Central Coast Blue will also include construction of injection wells to recharge the groundwater basin with purified water and a piping network to carry the purified water from the AWPF to the injection wells.
ADVANCED TREATMENT PROCESS
The AWPF will include the following advanced treatment technologies: Microfiltration/Ultrafiltration, Reverse Osmosis, and Ultraviolet Disinfection with Advanced Oxidation. These processes are described below.
Microfiltration/Ultrafiltration is exactly what it sounds like. Water is filtered through a physical membrane barrier with very small pores. These pores come in a range of sizes ranging from 0.2 micrometers to 0.005 μm. For comparison, 0.2 μm is 1/300th the diameter of a human hair. MF/UF removes very small particles and prepares the water for the next step, reverse osmosis.
Reverse Osmosis (RO)
Reverse osmosis removes dissolved solids from the water. It also uses a physical membrane barrier with pore sizes that range from 0.001 μm to 0.0001 μm depending on the membranes used. For comparison, the width of a strand of spider web silk is 3-8 μm. Unlike Microfiltration/Ultrafiltration, reverse osmosis produces a clean water stream and a waste stream of salty water, or brine. This means that not all the water is recovered from this process as purified water. A percentage of the water becomes brine (about 10-20%), which contains a higher concentration of the dissolved particles that were in the flow. This brine will ultimately be discharged to the ocean through the existing ocean outfall that currently receives all the flow from the Pismo Beach WWTP. While the brine stream is more concentrated than typical drinking water it is still much less salty than ocean water or brine from ocean desalination facilities. After the dissolved solids have been removed, the water that passed through the RO membranes is of very high quality and is suitable for the Advanced Oxidation treatment process.
Ultraviolet Disinfection with Advanced Oxidation (UV/AOP)
The last treatment step in this advanced treatment train is UV/AOP. Advanced oxidation uses ultraviolet light and oxidation chemicals, to initiate a series of chemical reactions to break down compounds in the water that cannot be broken down by biological treatment or removed using the membranes.
Advanced treatment results in purified water ready for injection into the groundwater aquifer. The months the water spends in the aquifer before being pumped back out is known as the environmental buffer, after which the water can be re-pumped to the surface and used as drinking water.
PRELIMINARY ENGINEERING & PILOTING
CONSTRUCTION & STARTUP
Resilient water foundation achieved!
Central Coast Blue was initiated as a result of the City of Pismo Beach’s Recycled Water Facilities Planning Study in 2015. The effort became a regional project in 2016 through collaboration with the SSLOCSD and its member agencies, the Oceano Community Services District and the Cities of Arroyo Grande and Grover Beach. Since then, the project has been a joint effort driven by a collective goal to mange our water holistically by investing in a resilient water supply.