IS "WASTE" WATER RECLAMATION AND REUSE IN YOUR FUTURE?
by David Venhuizen, P.E.
Despite a 1985 report by an engineering consultant which indicated that a system of decentralized, small-scale facilities would be the most cost efficient, environmentally benign, and socially responsible way to manage wastewater in the fast-developing Hill Country watersheds, the City of Austin has continued to extend conventional, centralized sewer service to that area. The institution of a project to study decentralized management methods, ordered by the Austin City Council in 1993, appears to have done nothing to slow this trend. Potentially leaky sewer lines and problematic lift stations continue to proliferate in the Lake Austin watershed and in the Edwards Aquifer Recharge Zone and tributary areas, all the while piping water away to be dumped in the river rather than beneficially reusing it.
In the meantime, where on-site wastewater systems-known popularly as "septic" systems-continue to be used, these are treated largely as plumbing projects, focusing on the cheapest way to pipe wastewater underground so it won't come back to the surface on that lot. In short, the emphasis has been on making it "go away" with very little concern for what happens when the water-and the pollutants it contains-gets to wherever "away" is. This despite the environmental sensitivity of these areas, especially the recharge zone and nearby contributing area. These "plumbing" systems also waste precious water resources which could be used to irrigate landscaping on these lots. Methods which are more environmentally sound and more socially responsible are readily available, but regulatory agencies are concerned about their operations and maintenance liabilities.
A solution to this concern is to integrate these "better" on-site systems into a decentralized management system which also addresses the needs of higher density development throughout the area. This "alternative" wastewater management system may be more cost efficient, it would definitely be more environmentally benign, and it would drastically reduce overall water demand. The importance of the latter in this region is highlighted by the current dry spell.
This begs the question - Can such an "alternative" decentralized wastewater management system actually be practical and workable? Imagine this scenario. The year is 2020 ...
Jim wheels his electric car into the Uplands Commercial Center. I've got to get to the photovoltaic plant today for a new battery pack, he thinks as he drives over to the center's management office. Jim's official title is Southwest Quadrant Water Reclamation Plant Engineer. Far less officially, he is known by another title.
"Hey, if it isn't the turd patrol!" cries Ken, operations manager for the commercial center, as Jim is ushered into his office. Jim and Ken exchange insults and other pleasantries, then head out toward the back of the complex.
"The water reclamation plant is doing great," Ken reports. "We scraped the slow sand filter last week after a 4 month run, as usual. And we pulled pump number 3 for it's annual maintenance checkout. That's all we've had to do since your last inspection."
Jim thinks as they walk along about that term, "water reclamation plant". They used to be called "wastewater treatment plants" he recalls. Jim wonders why anyone would have ever thought of this resource as "waste" water. In his job as the "turd patrol", he provides quarterly inspection services for industries and commercial management companies that operate and maintain their own reclamation plants, and he is the chief inspector for all the city-owned reclamation plants that serve residential and neighborhood commercial areas.
As he and Ken approach the plant, Jim can't help but notice the expanse of metal roof gleaming in the sunlight. He knows that the commercial center's large rooftop is a major rainwater harvesting facility in this section of town, providing all the water for the center-easy to do since all its "waste" water is reused-and part of the residential water demand in nearby areas. Overall, rainwater harvesting supplies about a third of the annual water use in the southwest quadrant. Jim also smiles at the thought that this rainfall also used be considered a problem, to be piped away as "efficiently" as possible.
The water reclamation plant isn't much to look at as Jim walks up to it. Just concrete boxes and tanks with domes covering them. The first box is a septic tank. Water coming out of it is sprayed onto intermittent sand filter beds in the larger tanks. Water coming out of that filter flows into a holding tank, to be routed through a slow sand filter in the last box, then finally through an ultra-violet light disinfection unit. That light and pumps to move water through the system are the only mechanical parts. The plant is so simple and unobtrusive, Jim thinks, that it's no wonder Ken never has complaints about system operation.
Water coming out of this plant is practically up to drinking water standards. But with all the non-potable water demands-toilet flushing, landscape irrigation and cooling tower supply-sitting right there to use the reclaimed water, Jim knows there is no point in further treatment. He wonders why, back in the 1990's, it was thought of as intelligent to use drinking quality water for these purposes at the same time all that "waste" water was piped away and-well-wasted, at considerable cost.
Jim marvels that before the "Water Revolution" was started by the City of Austin in the early years of this century, bringing these simple technologies into broadscale municipal use for decentralized wastewater management, all of them had languished, hardly ever used by cities, even though they had been in existence for over 100 years at that point, and were known to be well-proven, reliable methods. Times sure have changed, Jim thinks, since people actually thought this "waste" water should all be treated at one large, complex, electricity-hungry plant and then dumped in the river.
The Uplands Commercial Center was the first major project to be installed using this small-scale treatment and reuse concept. Since then, all development in the southwest quadrant had employed these methods, and even formerly sewered areas had "unhooked" and converted to reuse systems. Jim recalls the stir that was created, because of concern about aerosols from cooling towers, when Westlake Village became the first development to change over. But reuse had been proven to be safe by that time, and people soon came to accept it as readily as they had previously accepted the liabilities of lift stations used in the old centralized management concept. Jim still shudders to think about the time one simple mishap polluted an aquifer and led to a rash of illnesses. Kinda hard, he thinks, to get too excited about a vanishingly small risk from aerosols in light of the liabilities that the new decentralized system avoids.
It doesn't take Jim very long to give the plant a good "once-over" and take a couple water quality samples. He trades one last good-natured insult with Ken, then drives to the first of the four quarterly inspections of city water reclamation plants he has scheduled for this day.
As he drives along Bee Cave Road, Jim exchanges a wave with George, a field operator for the Cooperative Council. Jim recalls how very small-scale reclamation systems-once called on-site wastewater systems-were also integrated into the overall area-wide management system in the first decade of this century. Introduced into this area by a local engineer way back in 1987, sand filter treatment and subsurface drip irrigation reuse became the standard small-scale reclamation system for the same reason the Uplands uses these technologies-they are extremely simple and stable. All the local jurisdictions banded together, forming the Cooperative Council to coordinate management of these systems. George was no doubt on his way to do semi-annual inspections of small-scale reclamation systems.
On down the road, Jim passes the Lake Point subdivision, one of the last urban fringe developments to use a "waste" water system which mimicked the old centralized strategy-conventional sewers, a package plant, and a land-dumping disposal system. Jim thinks with a wry smile, they thought they were just waiting for a trunk sewer to be built to that area so they could waste their water more "efficiently". He remembers what a hassle it was dealing with that package plant. Since it had been replaced with a sand filter plant and a reclaimed water distribution system was installed in 2010, the system had been far easier to manage, not to mention less wasteful.
Jim thinks as he drives along that it's hard to believe people once had a problem with neighborhood treatment and with reusing reclaimed water for irrigation and toilet flushing, or that industries and commercial developments weren't expected as a matter of course to recycle or reuse their "waste" water. Nowadays, he reflects, they enthusiastically embrace these concepts because of the water savings they afford. The droughts of the late 1990's and of 2009-2013 had a lot to do with that, of course. By going to extensive reuse, the Austin area had managed to avoid the "water wars" which plagued other area cities until they got smart and did the same thing. Now, Jim knows, about half of all water demand in the metropolitan area is supplied by direct reclamation and reuse.
But no time for idle thoughts today, Jim realizes. He still has to inspect the city reclamation plants and get his water samples to the lab, then get the reports of the day's inspections prepared. The job is never over till the damn paperwork is done, Jim sighs. And, oh yes, he still has to get to the photovoltaic plant for that battery pack...