Waste not, want not: putting wastewater to work
In the 1980s, drought-stricken Californians watched as their water supplies literally vanished in front of them, leading officials to look in ernest at alternatives for replenishing the state’s aquifers. The search led them to wastewater reclamation – planned use of purified effluent to replace treated water – which became a primary method of preserving the precious water supply.
Although wastewater reuse is distasteful to some, it remains a commonly-used and effective means of increasing local water supplies. In some areas, reclaimed wastewater (ReW) may be the only water source.
Reuse has been practiced in various forms since the days of the first settlers, particularly in the West. Planned reuse began in the mid-1960s when Colorado Springs, Colo., started irrigating municipal golf courses and other public areas with ReW.
During the ’70s, ReW projects grew in response to federal laws restricting effluent discharge into local streams. Usage increased as wastewater technologies improved, and, by the end of the ’80s, reuse was widely accepted in supplementing local water supplies.
The California droughts spotlighted the role that ReW plays in water management strategies, and increased usage during this time – with no negative health effects – provided proof of safety and effective replacement of potable water for nonpotable uses. Today, every major water-short city in Southern California has ordinances requiring dual distribution ReW systems.
In addition to California, where officials foresee the use of one million acre-feet of ReW by the year 2000, Florida has long-term plans to replace up to 40 percent of its potable water with ReW. In Altamonte Springs, Fla., for example, a dual distribution and storage system has been built to meet ReW demands.
In 1992 the U.S. Environmental Protection Agency published Guidelines for Water Reuse, a set of recommended practices (there are no federal regulations) on safe use of reclaimed wastewater. The guidelines provide information to municipalities interested in implementing wastewater reuse projects and describe treatment levels and application methods to ensure successful ReW projects.
The guidelines cover six major categories of ReW use:
* urban reuse and irrigation; * industrial reuse; * agricultural reuse; * environmental and recreational application; * groundwater recharge; and * augmentation of potable water supply.
Communities ranging in size from a few thousand citizens to major metropolitan areas have successfully implemented ReW projects in these categories.
The minimum standard for most ReW projects is secondary treatment, although tertiary filtration is recommended. Physical or chemical processes such as carbon filtration eliminate metals and organic compounds, and advanced treatment processes such as reverse osmosis or membrane filtration are necessary when water is used for potable purposes.
No health threats have resulted from use of disinfected, highly-oxidized ReW. (ReW with less than 2.2 total coliform and no detectable viruses is considered safe for unrestricted human contact.)
In water-short areas, the possibility of not only replenishing but expanding water supply is a major selling point of ReW projects. In Tempe, Ariz., for example, ReW was used to increase the total water supply by about 25 percent. Farmers in Monterey County, Calif., were able to expand operations despite cutbacks in potable water, and Los Angeles is depending on ReW to meet a substantial portion of a projected 715-mgd shortfall in water supply over the next several decades.
Growing With Rew
The value of ReW’s nutrients has led many communities to start agricultural reuse programs, which account for 50 percent of ReW use nationwide. These projects provide disposal sites for municipal wastewater plants and guarantee high-quality water for farmers.
In 1979, Orlando, Fla., faced a crisis when the city was ordered to stop discharging effluent into local surface waters by 1988. After extensive study, the city teamed up with Orange County and approached local orange growers about using ReW to irrigate orange groves.
The result of the partnership was the Water Conserv II project which provides ReW to local orange growers for irrigation and freeze protection. The growers are using two-thirds of the ReW, and the remainder is in rapid infiltration basins (RIBs) to recharge Florida’s aquifer.
“Orange County and Orlando have found a highly-satisfactory place to landspread reclaimed water, and they are doing it in a very cost-effective method,” says University of Florida County Extension Agent John Jackson. “By using private land to spread the reclaimed water [the city and county] weren’t forced to buy a large amount of acreage.”
Today, 27 growers use 25 mgd of ReW on 10,000 acres of orange groves, with plans to double the flow rate. Growers sign 20-year contracts to receive specific amounts of free ReW that is piped directly to the edge of their property.
A complex 31-mile pipeline system takes ReW from two water reclamation facilities to distribution points. ReW is then pumped to growers’ properties, where it is used to irrigate and prevent freeze.
Sprinklers next to each tree are activated in freeze conditions and spray the tree’s trunk and supporting limbs with water to prevent freezing. While the system does not provide complete freeze protection (fruit cannot be protected, for example) the base of the tree and main limbs can be saved.
Growers who benefit from the system also play an important role in its maintenance. “We helped from the conception of the system, the writing of the contracts and development,” says Lester Austin, owner of Austin Groves, Winter Park, Fla. “[The project is] excellent, and we have been very pleased with it.”
Water Conserv II received the 1994 David W. York Reuse Award from the Florida Water Environment Association. Expansion of the project is underway, increasing the number of participating growers to 65.
Playing With Rew
In addition to health concerns that are likely to be voiced in any community considering widespread use of ReW, one of the greatest planning hurdles is identifying an outlet for the effluent.
Ideally, as in Florida, there should be a year-round demand for the ReW. And in California, officials are finding innovative ways to ensure that demand.
At the Snow Valley ski resort near Running Springs, Calif., the Running, Springs Water District is working to put ReW on ice. The project proposes that ReW be used for irrigation of grass ski slopes in the summer and snow-making in the winter.
After extensive studies on the effect of runoff and snow melt from the ski resort into Deep Creek, the receiving water body, the irrigation phase was approved by the Lahontan Water District which controls the creek’s water quality. On the other hand, the snow-making phase, which will involve a greater amount of runoff has been stalled temporarily.
“Eventually they are hoping to have Lahontan approve the use of the reclaimed water for snow-making,” says Steve Weiner, environmental project manager for URS Consultants, San Bernandino, Calif., the consultants on the project.
Several alternatives, including building additional reservoirs and a drainage system to catch snow-melt or further upgrading the treatment facility to meet higher water-quality standards are being considered to get approval for snow-making.
Construction of the pipeline system and treatment facility upgrades is scheduled to begin in Spring 1995 with plans for the irrigation system to go on-line the following summer.
“This is the first time that anything like this has been proposed in the country, and they are a little hesitant to approve it,” says Weiner.
Recharging With Rew
In addition to agricultural and recreational applications, ReW has proven to be a valuable resource for recharging underground aquifers. For example, in Hayes, Kan., where groundwater depletion and aquifer contamination threatened the local water supply, reclaimed water was a cost-effective answer to the city’s problems.
“Every potential water source within 90 miles was investigated, and the best solution was to use reclaimed water to supplement the local aquifer,” says Jeffery Henson, an engineer with Black & Veatch, Kansas City, Mo., who designed Hayes’ system. “Without the use of reclaimed water we would have been forced to develop very expensive alternate supplies.”
With approval from the State Water Board, the city established an ReW water bank that allows additional water from the aquifer – equal to the volume deposited through ReW surface recharge – to be recovered.
The city legally increased its claim on available water, and, through ongoing aquifer recharge, the water supply increased.
Recharge also accomplishes other goals. In Orange County, Calif., for example, ReW is injected into aquifers to impede salt water intrusion, and in Texas, ReW prevents surface subsidence. The Metropolitan Water District of Southern California projects that by the year 2000 its largest use for ReW will be groundwater recharge.
The Central Basin Aquifer in Los Angeles has been injected with ReW for more than 30 years. Studies conducted by the Los Angeles Sanitation District concluded that the area’s water quality had not been compromised, there was a decrease in total solids, trace organics were below detection levels and no heavy metals except iron and manganese were found. Tests on citizens in the east Los Angeles area showed no short-term health effects, increased infant mortality rates or increased cancer risks.
Although drought is the cause of many water shortages, up to 50 percent of a community’s total water demand may be used for summer irrigation needs. In Denver, water usage jumped four-fold in a recent summer.
Past projects indicate that using ReW for urban irrigation can reduce a community’s water demand by about 20 percent. Often, even as consumption increases, the need for high-grade water does not.
Many states – including California, Arizona and Florida – require ReW usage on public green areas. Golf courses, in particular, are widely-accepted sites for ReW use.
“Recreational turf-golf courses, parklands and athletic fields provide a very important public service to the community as a disposal/treatment site for effluent,” says Joe Much of the National Golf Federation. “In using reclaimed wastewater, golf courses can help conserve water and indirectly replenish aquifers as the water filters down through the soil. At the same time, the golf course or recreational area is saving money in water and fertilizer costs.”
Carbondale, Ill., supplies the entire effluent flow from its northwest wastewater plant to the Carbondale Park District’s Hickory Ridge Golf Course. The project began when the district requested a steady supply of low-cost water to maintain the course.
ReW is pumped from the plant and discharged into a man-made lake from which it is then pumped to the golf course. The system, which was implemented in Spring 1992 and paid for by the park district, recovered all of its capital costs in just the first year of its operation.
“While the city itself did not need a reuse program, it was glad to help the park district, as that benefits all the citizens,” says Ed Reeder, city engineer.
“Without the usage of the 40 million gallons of ReW in just the first year, the park district would not have been able to develop or operate the course,” says Park District Director George Whitehead. No special precautions besides additional signs have been necessary at the course, and the project has been so successful that a private golf course in the area is studying the possibility of securing the remainder of the effluent stream.
Experience indicates that once ReW systems are in place, a significant demand for the ReW exists. A study in Florida showed that households would use up to 400 gallons per person, per day for lawn irrigation when given free ReW. A high demand exists even when ReW is priced up to about 85 percent of the potable water price.
Thus, many communities are expanding ReW systems to incorporate residential irrigation. For example, Castle Rock, Colo., installed a dual distribution system to each new residence starting in the mid-’80s. St. Petersburg, Fla., installed ReW lines to almost 8,000 new residential dwellings, and Altamonte Springs, not only requires all new residential and commercial structures to be connected to the ReW system, but also requires all older structures to be retrofitted.
To protect public health, special valves, different size connections and warning signs are used to prevent cross-connection. “The notion that water should be discarded after one use is not acceptable as the cost of recovering the wastewater is too great,” says Donald Newman, Altamonte Springs public works director.
James Chansler, director of utilities for Boca Raton, Fla., agrees. “The era of using water once and throwing it away is ending,” he says.