Planning for Potable Reuse in Silicon Valley

Silicon Valley may be known for its innovative start-ups and multi-billion-dollar companies, but the region has been on the cutting edge of water resources management long before its tech fame. When Santa Clara Valley Water District (SCVWD) was established 1929 the region was grappling with groundwater shortages and has been working hard to drought-proof its water supply ever since. Woodard & Curran has been supporting the SCVWD in its regional potable reuse initiative since 2012.

Strategic planning conducted by Woodard & Curran on behalf of the SCVWD in partnership with the City of San Jose identified up to 45,000 acre-feet per year (AFY) of potable reuse potential and concluded that beyond a baseline amount of non-potable reuse, potable reuse would best achieve the region’s long term recycled water goals. Based on the South Bay Water Recycling (SBWR) Strategic and Master Planning (Master Plan) completed by Woodard & Curran in December 2014, SCVWD decided to expedite implementation of the Purified Water Program and is now targeting construction of advanced treatment, conveyance and groundwater replenishment facilities to support potable reuse by 2024 rather than the 2035 target date in the Master Plan.

Woodard & Curran conducted preliminary engineering on an array of advanced treatment, purified water conveyance, and receiving facilities. Based on this preliminary engineering, alternative potable reuse projects were identified and evaluated primarily on cost and operational factors. In addition to conventional potable reuse projects that augment a regional water supply via a domestic supply groundwater basin, preliminary engineering was conducted on two new types of potable reuse projects, one sourcing a drinking water supply reservoir, and the other directly sourcing a conventional water treatment plant, eliminating the typically required “environmental buffer”.  Woodard & Curran developed a regulatory strategy that relied on innovative monitoring and response techniques to support the facilities planning for this “first-of-its-kind” direct potable reuse project alternative.

Technical assessments and facilities planning was conducted on over $800 million of infrastructure, including:
  • Three Advanced Water Purification Facilities (membrane filtration, reverse osmosis (RO), and UV advanced oxidation) ranging from 4 mgd to 24 mgd, each treating potentially different source water (secondary, Title 22 Tertiary, membrane bioreactor). Technical assessments were also conducted on alternative advanced treatment technologies including ozone and biologically active filtration (BAF).
  • Two purified water pump stations (1,800 HP and 400 HP)
  • 26 miles of 48-inch and 8 miles of 27-inch purified water pipelines to potable water receiving facilities
  • 24 injection wells 
  • Groundwater recharge basin (4 mgd)
  • Two 3-million gallon purified water storage tanks 
Woodard & Curran services included preparing a regulatory strategy and providing support as the SCVWD engaged both of California’s applicable regulatory agencies; Division of Drinking Water (public health) and Regional Water Quality Control Board (environmental compliance) permitting. A key component of this permitting support was an NPDES analysis and Chronic Toxicity Testing to support use of San Jose/Santa Clara’s Regional Wastewater Facility outfall for RO concentrate disposal.

The outcome of this project will be a Program Plan, which will support programmatic elements of implementation such as final design (or design/build), environmental documentation, financial planning, and public outreach.

Details

Santa Clara Valley Water District
San Jose, CA

Team

Practice Leader
Water Recycling
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