United Nations Plaza Fountain Project

Water Storage and Distribution Project

The UN Plaza sump (foundation drainage) water pump is located along Market Street between 7th and 8th Streets in San Francisco’s Civic Center area. The sump pumps water from the underground foundation infrastructure that is part of the plaza construction to the Sewer system. This project is going to restart previous sump water reuse operations to provide non-potable water to a truck fill station (for street cleaning and irrigation needs) and to serve as make-up water in the UN Plaza Fountain. Municipal street sweeping operations in the Civic Center and Tenderloin neighborhoods require multiple truck fills each day. Therefore, providing non-potable water from the sump (in lieu of potable water from fire hydrants) would offset large amounts of potable water use. Similarly, there are large irrigation demands in the Civic Center district which could be met using this non-potable water supply. Finally, the non-potable water could also be used as make-up water for the UN Plaza fountain.

Currently the foundation drainage around the United Nations Plaza Fountain is collected in a sump in the fountain pump and electrical vault below grade adjacent to the fountain and is discharged to the combined sewer system.  Multiple step media filtration (ultra-filtration), coupled with disinfection will be constructed to treat the water.  The treated water will be used for street and sidewalk cleaning in the downtown area as well as makeup water for the UN Plaza Fountain.  The existing sump will be thoroughly cleaned and lined to minimize contaminants from the sump itself.  The foundation drainage will be pumped from the sump through an Iron and Manganese removal filter and then through an Ultrafiltration 10-20 micron filter. The Iron and Manganese removal filter will bring the total iron and manganese concentrations to below the regulation levels, and the Ultrafiltration will bring the particle size down to the levels needed by San Francisco Public Works street sweeping vehicles.  After filtration, a chemical metering pump will inject chlorine into the filtered water to provide the required chlorine residual per Article 12C, Section 853 of the San Francisco Health Code for foundation drainage.  Continuous chlorine and turbidity monitors will be installed downstream of the storage tank to ensure compliance with the regulations.  

The Treated water will be stored in a 15,000 gallon tank that will be created by partitioning the existing UN Plaza Fountain reservoir.  Some of the treated water will be used to backwash the treatment filters as well.

The existing outlet valve along Market Street will be refurbished and/or replaced as required.  An additional outlet valve along with required piping will be constructed at McAllister Street.