City seeks to join South Bay reuse system

The City of Sunnyvale in California voted on 6 March 2012 to explore connecting its recycled water system to the South Bay Water Recycling (SBWR) system operated by the City of San Jose in partnership with the Santa Clara Valley Water District (SCVWD).

SCVWD and SBWR are currently constructing a US$ 60 million Advanced Water Treatment Facility based on microfiltration, reverse osmosis and ultraviolet disinfection. The plant with a capacity of up to 10 MGD (37,850 m³/d) will serve San José, Santa Clara and Milpitas.

Sunnyvale council officers reported to the council that the city’s current system, based on effluent from Sunnyvale Water Pollution Control Plant, provides an average of about 800,000 GPD (3,000 m³/d) of recycled water. This is used for irrigation purposes in the north third of the city, almost entirely between May and October.

However, the salt concentration in the recycled water is high, ranging from 800 to 850 ppm. While this is acceptable for most irrigation, it is problematic for salt-intolerant plant species and undesirable for most industrial uses without additional treatment.

The officers gave the city the alternatives of upgrading its own system or joining the SBWR. An SBWR intertie, plus a connection to Cal Water in the south, would allow Sunnyvale to add customers, both irrigation and industrial, and grow its system and revenue base of recycled water.

The intertie would also allow more time to address upgrading the city’s own recycling system.

Some of the recycled water could be used for Apple’s new campus at Cupertino.