11-2016 Winter Surface Water Pilot Project
Posted on October 26th, 2016
As we've mentioned in our previous columns, Soquel Creek Water District (District) has been working with the City of Santa Cruz Water Department (City) on a 5-year pilot project to purchase a small amount of treated surface water (also referred to as river water), if available in the winter months. This project would introduce a new source of supply into our distribution system which solely has been groundwater since the District was founded in 1961. While the opportunity to pump less groundwater in the winter by purchasing treated surface water from the City may provide a benefit for the District, we are approaching this project carefully and cautiously - and here's why.
Making a Careful Transition
Switching sources or blending sources can be a tricky business that requires a good understanding of the potential issues resulting from changing water. Recent issues with source water changes in Flint, Michigan, and Fresno and Woodland, California, for example, are reasons we are exercising prudence in planning for implementation of this water purchase. The District pipes are not conditioned or accustomed to surface water and as a new source, we want to ensure we understand any potential pitfalls before taking this important step.
Water Quality Is Our Priority
The chemical characteristics of groundwater and surface (streams and rivers) water sources are different. The District consulted with internationally recognized engineering firm Black and Veatch to study and provide recommendations on how to successfully introduce the treated surface water into the District's existing distribution system that is fed by groundwater wells.
Based on the recommendations of Black and Veatch and guidance from the California State Division of Drinking Water (DDW), the District is currently:
- Flushing Pipelines: District crews are flushing pipelines to scour buildup and remove sediment from within the distribution system in the Capitola and Soquel areas that could cause discolored water and release of lead and copper and other metals when surface water is introduced.
- Developing a pipe-loop test: A pipe loop test will examine how different pipe materials in our system may react to surface water and influence water quality changes or pipe corrosion.
- Determining if a corrosion inhibitor is needed: The City currently adds orthophosphate, a corrosion inhibitor to its treated surface water. The District needs to determine if there are adequate amounts of orthophosphate to reach our service area, if additional dosage will be needed, or if intermittent use will be problematic.
- Determining if a Corrosion Control Study and/or changes to the Lead and Copper Rule will be required: Currently, the District is working with DDW to see if additional sampling or a Corrosion Control Study will be required with the new blending of surface water into our system.
- Amending the District's Source Water Permit: With the purchase of treated surface water, the District will no longer be a "groundwater-only" supplier.
- Developing an Operations Plan and Water Quality Monitoring Plan: Staff is working on a plan to sample at the intertie with the City and other locations within the District to monitor aesthetic issues (such as red or discolored water), levels of corrosion byproducts (such as lead and copper), and levels of disinfection byproducts.
Slow & Steady Wins the Race
While there are a few in our community who are urging the District to "hurry up and open the valve," the District does not want to act in haste without doing the recommended preparations and getting the Division of Drinking Water's approval and permit amendment. While we'd like to capture some excess treated surface water this winter, we view this pilot project as an opportunity to further understand the water quality and operational issues for a potential longer-term project. Rather than misstep and be confronted with a water quality challenge that could have been avoided, the District is dutifully devoted to preparing our system prior to introducing the surface water supply.
Diversification Leads to Resiliency: Surface Water plus Purified Water
The District is interested in maximizing surface water transfers as a supplemental water supply source; however, in the "big picture"- surface water is not a guaranteed, reliable source of supply. Limits due to future drought conditions, protection of endangered species, and the City's own water supply needs may impact the availability of this source for the District. To ensure resiliency, the District's Community Water Plan acknowledges the need and value of maintaining a diversified water portfolio and has identified groundwater replenishment using purified water as its preferred option, which could be paired with purchasing surface water, when available.
The District is preparing an environmental impact report (EIR) on its groundwater replenishment using a purified water project. The first step in the EIR process is called scoping, which will define the issues to be evaluated in the EIR and is anticipated to begin in late November. A Release of the Notice of Preparation/ Initial Study (NOP/IS) launches the scoping period and public comments will be welcome on the environmental topics, potential effects, mitigation measures, and range of alternatives to be analyzed in the project EIR. Scoping meetings will be held on December 7 at Twin Lakes Church in Aptos. Our December column will focus on our groundwater replenishment project and our EIR efforts.
As always, if you have any questions about this month's topic or anything else related to Soquel Creek Water District, feel free to email Melanie Schumacher or call 831-475-8501, ext. 153 for more information.