There’s something about water-reuse projects that give me a treated-wastewater-slurping grin when I tour them, and it was no different last week when I elatedly toured the City of Austin’s on-site, building-scale wastewater reuse demonstration project during its ribbon cutting.
The 2011 to 2015 drought gave Austin quite the scare as the Highland Lakes disturbingly dropped to levels not seen since the drought of the 1960s. In fact, this more recent drought replaced the drought of the 1960s as Central Texas’ new drought of record. In response, the city council created a task force led by Austin Water and councilmember-appointed stakeholders to develop a 100-year water plan that considers climate change with the goal of maximizing local resources to avoid importing water. Some of those local resources include rainwater, condensate water from air conditioning, and, yes, the water that swirls down our drains.
Part of responding to climate change and increasing Austin’s water-supply resiliency is the City of Austin itself leading by example and showing the community how it can be done. And swooping in to save the day is OSCAR and CLARA!
OSCAR is a backronym that refers to the On-Site Collection and Reuse system and consists of two 20,000-gallon tanks buried in the courtyard of Austin’s new Permitting and Development Center. The tanks collect and store rainwater and air-conditioning condensate from the building. This water is then primarily used to irrigate on-site landscaping, although some of the water may be used as make-up water for CLARA.
CLARA is the Closed-Loop Advanced Reclaimed Assembly where wastewater from the building (toilets, urinals, and sinks) is treated and then pumped back into the building for toilet and urinal flushing. Also located in the courtyard and beautifully bracketed by landscaping, CLARA consists of two modules each about the size of a shipping container. The treatment all occurs in the northern container and includes pre- and post-anoxic tanks, a hydroponic reactor, advanced membrane technology, and UV to zap the wriggling uglies. What looks like a tiny green roof on the container is actually the hydroponic system using plants to reduce nitrogen in the water. The southern container holds plumbing and system controls. In all, the system can handle 5,000 gallons of blackwater a day. Because the same water can loop numerous times through CLARA (flush, treat, repeat), Austin refers to it as a closed-loop system.
OSCAR and CLARA, working hand-in-hand, are expected to reduce potable water use in the building up to 75 percent. They show Austinites and the development community how the city can reduce its water footprint to increase water-supply resiliency in a changing climate and, through energy savings by using rainwater and condensate that doesn’t need much treatment, reduce carbon emissions.
There’s still work to be done to make projects like CLARA easier to implement at the building scale, but having CLARA operational (the first such project in Texas, reportedly only the third in the US) allows people to see how it’s done. CLARA would be challenging to permit under current state guidelines, but the Texas Water Conservation Association is working with the Texas Commission on Environmental Quality to address these challenges. Cost is another challenge. The city reports that CLARA cost $1.7 million including $145,000 for dual-distribution plumbing and that OSCAR cost $625,000. Since CLARA and OSCAR are still babies, operating costs are still being assessed. However, as we learn more about these systems and more of them are installed, costs are sure to go down. As a warming climate decreases the reliability of our source waters, the more efficient use of water through approaches like CLARA and OSCAR become more important.
OSCAR and CLARA are open to the public and available to visit at the Permitting and Development Center at 6310 Wilhemina Delco Drive. The city has interpretative signs, and you can get a peek at CLARA from the sides and even from the top via a catwalk to see the hydroponic system. If you are there during business hours, you can even make a (ahem…) contribution to the blackwater reuse system, just like I did!