Managing Water Resources With Graywater and Stormwater

Increasing attention is being paid to graywater and stormwater as solutions for both water replenishment in the drought-starved western United States and reduction of water pollution in the Midwest and eastern states.

Three white papers or research reports have been released in February 2016 on the need for water replenish­ment and reuse. The National Academies of Science, Engineering, and Medicine published a study that analyzed the risks, costs, and benefits of various beneficial uses of stormwater and graywater and the approaches needed for its safe use.

Noting that stormwater and graywater can serve a range of nonpotable uses, including irrigation, toilet flushing, washing, and cooling, all likely requiring treatment, “many questions remain that have limited the broader application of graywater and stormwater capture and use,” the report says. The study analyzes the quantity and suitability of stormwater capture and graywater reuse in the US, as well as its treatment, storage, risks, costs, benefits, and implementation. The report is available at http://bit.ly/1Sy0TMP.

The University of Arizona also announced in February the availability of a research report demonstrating that by 2050, climate change will increase the groundwater deficit for economically important aquifers in the western US. In the West, 40% of the water comes directly from groundwater, says Thomas Meixner, a University of Arizona professor and the lead author of the report, in the announcement.

The climate models developed in the research predict that, in general, wet regions will become wetter and dry regions will become drier, in particular the Southwest. “Our study reveals that the western US needs to redouble efforts to manage water resources to maximize benefits to individuals and society,” says Meixner.  “We can’t be wasting water.”

The team’s research article, “Implications of projected climate change for groundwater recharge in the western United States,” is online here. It is scheduled for publication in the March 2016 issue of the Journal of Hydrology.

ROI Is Important
The Water Reuse Foundation released a white paper that studied the drivers, successes, challenges, and opportunities for onsite industrial water reuse. It concluded that increases in wastewater disposal and energy costs—as well as water scarcity—drive many industries to implement water reuse in their facilities.

When a project was able to demonstrate a two- to three-year return on investment (ROI), projects were implemented, the white paper concludes. The major difficulty in reaching this ROI appeared to be undervaluation of source water supplies and treatment of residual disposal issues.

The easiest and most readily used applications of recycled water appeared to be for irrigation, process-related cleaning and rinsing, and makeup water for cooling towers. Wastewater could be cleaned with such simple technologies as membrane treatment and ultraviolet purification along with addition of chlorine, the white paper says. Drivers, Successes, Challenges, and Opportunities for Onsite Industrial Water Reuse: A Path Forward for Collaboration and Growth, is available on the Water Reuse Foundation website.

Finally, a mention of EPA’s 2012 Guidelines for Water Reuse must be included here. It contains many profiles of institutions and companies that recycle or reuse wastewater for a wide variety of applications. In particular see Appendix D, US Case Studies. It can be found here.

The guidelines discuss planning and management considerations, types of applications, state regulatory programs for water reuse, regional variations, treatment technologies, funding systems, public outreach, participation, consultation, and finally, global experiences in water reuse.

Recycled Water Competes With Rain
The Village Creek Water Reclamation Facility, owned by the Fort Worth Water Department in Texas, treats 166 million gallons of domestic wastewater each day. During the drought, it sent 2.5–3%, following treatment, through the regional reclaimed water pipeline, to a series of customers as recycled water, according to Steve Nutter, the environmental program manager at the reclamation facility.

But demand slowed once it started raining, says Nutter. Just 2% was sent through the pipeline—about 60 million gallons—in July 2015. Nobody was irrigating, he says.

Customers include the city of Fort Worth, the cities of Arlington and Euless, and the Dallas Fort Worth International Airport. Nutter says the city has a goal of increasing water reuse by 10% each year by adding more customers and increasing customer capacity.

“This is the future—a drier environment,” predicts Nutter. Texas has just come out of a deep four-year drought and the reservoirs are full, but he doesn’t expect the rain to come regularly.

Nutter says the wastewater must be treated to remove fecal, chemical, and biological matter to meet Texas’s Type “A” water quality standards. It is monitored once a week at Village Creek and at the distribution system level where it is collected and sent to a third-party laboratory for testing. The wastewater is regulated by the Texas Commission of Environmental Quality.

At Village Creek, the wastewater is sent through bar screens to remove large debris and on to primary clarification where it is aerated with microorganisms, which eat the nutrients. The water then overflows to secondary clarification where microorganisms are removed, says Nutter. The water
is then sent to filtration in a sand bed. Chlorine is added at that time.

The majority of wastewater is discharged into the Trinity River and is dechlorinated before discharge.

DFW Airport Diversifies Resources
The Dallas Fort Worth International Airport entered into an agreement with the Fort Worth Water Department in 2009 to buy recycled water. Construction on a distribution system and pumping station at the airport was completed in 2012. Initially the recycled water was used for irrigation. Distribution to the heating and cooling system was added in 2014 for cooling tower make-up water.

About one-third of the recycled water purchased goes to the cooling tower, says Rusty Hodapp, DFW’s vice president for energy, transportation, and asset management. The remainder is used to irrigate the landscaping in the entryway, grass, and trees on some of the 175 acres of airport property.

A Hyatt Hotel was just constructed on the property. Hodapp says the idea of nonpotable water use at the hotel was discussed during the design phase, but the developer decided the overall project budget was constrained, making it unfeasible.

Hodapp says the basis for the project is to diversify water resources. Population growth in the region is impacting the airport, so a “prudent measure on our part is to have long-term resource management, such as conservation and supply diversification,” he says.

Two municipal agencies supply potable water to the airport and the costs for it differ. Dallas city water is cheaper than Fort Worth water. The reclaimed water coming from Fort Worth is priced at the same rate as potable water to recoup the cost of building the municipal nonpotable system. As the system is expanded, the cost will drop below potable water costs, says Hodapp.

The major lesson learned is that recycled water management is much different than using potable water, says Hodapp. The water quality going into the cooling tower is different. The recycled water has much higher rates of phosphates and alkalinity, so “we’re having to run the tower at a much higher rate, and we use more chemistry to keep corrosion under control,” says Hodapp. “But we have no regrets,” he adds.

LADWP Expands Recycling System
Playa Vista is a very large housing and light commercial property development in the heart of the west Los Angeles urban area, probably the last one of its kind that will be built in the city. It has faced long-term city council and environmental scrutiny.

One of the conditions the city required in its approval process in 2000 was to build a water recycling system to serve homeowner associations, office buildings, street medians, parks, and the Playa Vista Elementary school, says Bill VanWagoner, manager of the planning section for the Los Angeles Department of Water and Power (LADWP) Water Department. The complex receives approximately 250 acre feet per year of recycled water.

The water department built a purple pipe distribution system to bring tertiary water from the Edward C. Little Water Reclamation Facility in nearby El Segundo. A state regulatory requirement (Title 22) requires that the nonpotable purple pipe system be constructed independently of the potable water system.

LADWP’s nonpotable ductile iron distribution system, approximately 50,000 linear feet, also pipes recycled water to Los Angeles International Airport (LAX), Loyola Marymount University, and parks on the west side of the city in addition to Playa Vista.

LAX receives about 1,000 acre feet per year for irrigation purposes. VanWagoner says the department has an agreement to expand the system to 1,500 acre feet per year, but it has been difficult to implement because the airport is active around the clock. He expects the project will happen within the next five years.

A 7,000-linear-foot addition is being built to add two high schools to the distribution system, and polyvinyl chloride pipes are being installed this time, says VanWagoner. Installation will be complete this summer.

Mario Acevedo, manager of the water recycling group in LADWP’s planning section, says Loyola Marymount, next door to Playa Vista, may expand its system as well. The department is also exploring the potential of expanding the water recycling system with the West Basin Municipal Water District to nearby Culver City, albeit in a cost-effective manner.

VanWagoner says the department is charging Playa Vista customers for recycled water at the rate it charges for potable water. LADWP had loaned the developer money to build the purple pipe infrastructure as part of the 2000 agreement and the loan is being paid back through the potable water rates. The developer paid for the infrastructure on the customer side of the meter. The other projects will have different payment schemes and will depend on how much water they use, he says.

LADWP’s costs include installing and maintaining the infrastructure. The cost to the customer includes separating the two water distribution systems in their facility. If the recycled water is to be used for irrigation, the cost would include replacing the current irrigation system. Industrial customers would need to make changes in the piping system to separately route recycled water to the cooling tower for make-up water.

VanWagoner says there are challenges with water quality at Playa Vista since it is located at the end of the pipeline from the Edward C. Little Reclamation Facility and it takes time for the water to get there. The Hyperion Water Treatment Plant is also looking to upgrade its treatment of the water being sent to the Edward C. Little plant. Currently, the water is not being denitrified. If it is, the water quality will be improved, he says.

Inspections by the Los Angeles County Department of Health are required to guarantee there are no cross-connections between the potable and nonpotable systems. VanWagoner explains this requires a lot of coordination between LADWP, the county health department, developers, and contractors. “We have to have a lot of eyes on the connections,” he says.

The testing requirements to meet the state’s Title 22 standard is the responsibility of West Basin Municipal Water District, says VanWagoner.

LADWP has other water recycling projects. The Donald C. Tillman Reclamation Plant on the northern edge of Los Angeles sends its recycled water to the department’s power plants for cooling tower make-up water. It is also delivered to parks and golf courses for irrigation.

LADWP’s Terminal Island Water Reclamation Plant in the Los Angeles Harbor area is working with oil refineries to potentially send reverse osmosis-treated water to them to replace potable water currently being used for boiler feed water and cooling tower make-up water. VanWagoner says it takes one gallon of water to produce one gallon of gasoline, making this potential project an extremely lucrative one for meeting the department’s goal to eventually avoid importing Colorado River water. The project could take two to five years to construct, depending on the necessary customer retrofits, he says.

SFPUC Builds Hedge Against Drought
The San Francisco Public Utilities Commission (SFPUC) chose an unusual name for its in-house water reuse system—Living Machine. At the heart of it, the name reflects how the building’s wastewater is treated in a constructed wetland onsite and distributed within the building for toilet flushing.

When designing a new headquarters in 2009, installing a water reuse system became a primary goal for SFPUC. It sought out ecological sanitation treatment systems, constructed wetlands in particular. Because of its location in a dense urban area—the downtown San Francisco Civic Center—it had to meet the San Francisco Department of Public Heath’s water quality requirements.

The SFPUC selected the Living Machine technology “because of its ability to blend function and aesthetics,” according to an article in theWorld Water: Water Reuse & Desalination Spring 2014 issue, penned by John Scarpulla, a project manager in SFPUC’s water resources group, and Eric Lohan, general manager at Living Machine Systems.

Scarpulla says, in an interview, “We’ve just come off a five-year drought and reclaimed water is a hedge against droughts which will always be there.”

This project, which cost $18.6 million, eventually became a test case for San Francisco’s Non-Potable Program codified in a city ordinance in September 2012. The ordinance created a regulatory framework and streamlined permitting process for installation and operation of nonpotable water systems for commercial, multi-family, and mixed use development in San Francisco. The test case allowed the SFPUC, working with the San Francisco Department of Public Health and the San Francisco Department of Building Inspection, to successfully demonstrate the methods for installing, permitting, and regulating onsite systems.

The ordinance was amended in October 2013 to include district-scale projects for two or more buildings sharing nonpotable water and a $500,000 grant assistance program. In July 2015, the ordinance was again amended to require that all new buildings of 250,000 square feet or more that are to be located within San Francisco must include available alternate water sources for toilet and urinal flushing and irrigation. Detailed information about this ordinance and its requirements can be found at www.sfwater.org/np.

There are now 14 onsite nonpotable water reuse projects in San Francisco. Most recycle rainwater for toilet flushing.

The Living Machine’s constructed wetlands are set in the SFPUC headquarters lobby and the sidewalks surrounding the building. Operating since September 2012, the system is doing really well, says Scarpulla. There are no water-quality issues. The building houses 950 employees and hosts 1,000 visitors a year including students, foreign delegations, engineers, and representatives from public agencies.

Blackwater flushed from the toilets is combined with graywater, which includes water from bathroom sinks and laundry machines, and is directed to

the tank filtration system buried under ground beneath the sidewalk where solids are removed from the wastewater. The constructed wetlands, called tidal-flow or reciprocating wetlands, are 10 feet away above ground next to the sidewalk in front of the building. The wetland cells contain lightweight shale aggregate, microorganisms, and plants. These cells are designed to mimic the natural ebb and flow of coastal wetlands—a natural treatment process.

As the water is cycled through the cells via an automated process, microorganisms are first fed with nutrients in the wastewater when the tank is full, and then aerated by exposure to atmospheric oxygen when the cells are drained. The clean water is then sent to vertical-flow wetland polishing cells to remove the remaining organic matter. Scarpulla says the vertical flow cells look like big planter boxes and sit next to two sides of the building and inside the building lobby.

The water then moves on to the final filtration where it is piped to the disinfection tank under the building. The water passes through screen and cartridge filters followed by ultraviolet disinfection. Chlorine is added to guarantee the water stays clear and then it is stored, ready to be sent to the building’s toilets, says Scarpulla.

The Living Machine System was also profiled in detail in the May 2012 issue of Water Efficiency magazine.

Santa Monica’s SMRRF
The Santa Monica Urban Runoff Recycling Facility (SMRRF) was built and commissioned in 2002 to assist in eliminating the pollution spilling into Santa Monica Bay. It was designed by CH2M Hill and funded at a cost of $12 million by the Cities of Santa Monica and Los Angeles, the State Water Resources Control Board, the Southern California Metropolitan Water District, and county and federal funds.

SMRRF has a capacity to clean approximately 500,000 gallons of runoff per day. However, the actual runoff available to be pumped to SMRRF from the two largest storm drains is currently 100,000–200,000 gallons per day, according to Gil Borboa, the water resource manager for SMRRF. The recycling facility produces about 4% of Santa Monica’s daily water use.

The runoff that flows into Santa Monica Bay, approximately 100 million gallons per day, is far larger than the city is fully capable of treating and distributing. It comes from parts of the City of Los Angeles and the Santa Monica Mountains, as well as from the streets of Santa Monica. Dry weather runoff (excluding stormwater) includes excess irrigation draining into the streets, construction debris, pool draining, car washing, washing down paved areas, and residual wet weather runoff.

Borboa says there are no plans to expand SMRRF, since capacity is far greater than actual production needs, but the department is working on plans to add reverse osmosis technology to the plant to allow it to treat brackish well water. It is now seeking funding, including grants to add the technology in the next two years.

The clean water produced at the recycling center is directed to irrigating the center median of Olympic Boulevard, a major thoroughfare running east-west through the city, the city’s cemetery, and Palisades Park which runs north-south along the bluffs overlooking the ocean.

Recycled water is also pumped to Santa Monica’s Public Safety Building, which houses the Police and Fire Departments and the Rand Corp. Both buildings use it for toilet flushing. It is also pumped to the Water Garden, a large commercial office complex with several water landscaping features including fountains. Borboa says they are always looking for more commercial customers.

SMRRF has a dual function to educate the public about the need to prevent pollution. It is located near the beach and the Santa Monica Pier in a highly trafficked tourist area with attractive landscaping and architecture. The facility is designed such that visitors can walk through and view the results of the water cleansing process.

The recycling process begins with the dry weather runoff being screened in a continuous deflective separation unit located across the street from SMRRF where large floating debris and trash is removed. The runoff is then pumped to the recycling facility where it is run through a rotating drum screen to remove fine floating particles—greater than 0.04 inches in size—that escaped the course screening.

Next the water flows through the cyclone-type grit chamber, which removes grit and sand, to the raw water storage tank to dampen the influent flow fluctuations. This allows the downstream filtration and disinfection processes to operate at a steady, more efficient rate.

The water is then pumped to the dissolved air flotation unit where compressed air is injected into the water at the unit inlet. As the water reaches the surface of the open tank, atmospheric pressure creates fine air bubbles which rise to the top of the water and carry the oil and grease to the surface where it is skimmed off.

The water next flows to the microfiltration treatment units where it is forced through membranes to filter out the turbidity and moves on to ultraviolet disinfection where the UV light kills bacteria and viruses.

Now clean, the water is stored in the clean water tank where it will be pumped into the distribution system and sent to irrigation systems in the parks, and to the commercial buildings.

SMRRF is operated and maintained by city staff, says Borboa.

Weather Defeats Recycling
In a final note, the failed attempt by West Sound Utility District in Port Orchard, WA, to develop a reclaimed water distribution program illustrates how important water scarcity is as a driver in such a program at least for the West. Randy Screws, plant manager at the South Kitsap Reclamation Facility, which the utility district owns, says they distributed 1 million gallons to one irrigation customer during the whole season from 2014–2015.

“The drivers are not there for us. There’s no water shortage,” says Screws. And there is no industry in Port Orchard. It’s all light commercial, he explains.

Reclaimed water became a competitor for potable water, says Screws, and it was more costly to distribute than potable water. “Everyone wanted to be on the bandwagon [for reclaimed water] until the trigger was pulled,” he says. The amount of public education was not there, he explains, but he expects there will be more education in the future.

The utility district invested $1 million in the project, which treated wastewater with a membrane bioreactor and an ultra-filtration system. “We don’t want to put money into it while we’re not breaking even,” says Screws.