With wastewater being reused for irrigation during the hot summer months, the Dublin San Ramon Services District Board of Directors revised its recycled water policy to address supply limits at its July 7 meeting.
General Manager Dan McIntyre told the Weekly, "We've reached the limit of how much wastewater coming into the plant is being 100% recycled on our peak days, so we're really not in a position right now to produce anymore (recycled water). It's not really a concern, but there's really no opportunity for new customers right now."
The revised policy's "key elements" include providing no more new recycled water connections until new wastewater supplies are identified, helping existing customers find ways to more efficiently use recycled water, and implementing the mandatory conservation of recycled water during the next drought when conservation of potable water will also be required. According to DSRSD, 23% of their total water demand supply comes from recycled water.
According to McIntyre, it's possible the agency has "reached our limit, but as the Tri-Valley further develops, there may be additional wastewater flow that comes to our plant."
One possible new source of wastewater could come from more people eventually moving into the region.
"Basically there would be new customers flushing, and if that's the case, there's a new supply in the future that can be recycled," McIntyre said. "For example, ten million gallons come in a day but we know in the future that number will grow to something over 12 million gallons, so when that materializes, there will be more wastewater we can recycle."
A second possibility is fringe groundwater basins on the periphery of the Tri-Valley which have lower quality groundwater that can't be used as a drinking water supply but could otherwise be extracted.
"But we don't know yet the technical feasibility of that--how much of the fringe groundwater basin is available, how easy it is to extract," McIntyre added. "That's not clearly understood so that's something we're exploring, but until we can identify the feasibility of that, we can't hook up additional customers."
Potential interagency partnerships are also being explored like a planned pilot project that will divert water from the Central Contra Costa Sanitary District (CCCSD) into DSRSD's sewer water. When construction is finished, DSRSD will bring in one million gallons of water a day from CCCSD, though McIntyre stressed that "it's just a pilot project, it's not a permanent commitment or source."
Overall, the agency's recycled water program "is really successful, so on summer days we're recycling 100% of wastewater that comes in the plant," McIntyre said. About 40% of DSRSD's wastewater is recycled and the agency is looking at other opportunities for recycling the wastewater like potable reuse.
"There may be opportunities for wintertime wastewater to be used for those potable reuse and advanced purification," McIntyre said. "That's something we're studying over the next few years."