Reusing rainwater for irrigation while cleaning the LA River Basin. By Jonas Sipaila.
On July 7, 2010, United States EPA Administrator designated all of the Los Angeles River a ‘Traditional Navigable Water,’ strengthening environmental regulation not only for the river, but also for the tributary streams and wetlands that comprise the Los Angeles River watershed. Developers and businesses that operate along the mostly 82-kilometre cement lined river, as well as those that impact water in the 216,000 hectares of the river’s watershed, will have to consider the implications of compliance with the Clean Water Act (CWA).
LA River during droughts
In anticipation of the ruling and at the same time, showing the foresight to adopt cutting edge technology, the Los Angeles Bureau of Engineering’s Project Manager Ahmed Iftekhar sought the assistance of the design staff at EPIC Green Solutions, an International, UAE-based water management company focusing on irrigation, storm water and environmental solutions. Together, they embarked on a first-of-its-kind Best Management Practice (BMP) to construct the Westside Park Rainwater Irrigation Project.
LA river during rains
Construction efforts for the $2.9 million Proposition O-funded project are currently underway and runoff from 3,700 acres of land adjacent to South Fairfax Avenue will be targeted in an effort to reduce storm water pollution that currently flows into Ballona Creek and Santa Monica Bay. On November 2, 2004, the voters of Los Angeles overwhelmingly passed Proposition O, which authorised the City of Los Angeles to issue a series of general obligation bonds for up to $500 million for projects to protect public health by cleaning up pollution, including bacteria and trash, in the City’s watercourses, beaches and the ocean, in order to meet Federal Clean Water Act requirements.
Once completed in July 2011, this project will help to reduce beach closures, increase tourism, benefit marine habitat and enable the city to meet storm water pollutant reduction goals while using storm water to irrigate the park’s landscape.
Installation of the EPIC sub-surface irrigation and filtration system at Westside Park
According to the study ‘Characterisation of Water Quality in the Los Angeles River’ conducted in 2000 that sought to identify sources of potential pollutants and measure water quality along the river, there are three primary sources of pollution in the Los Angeles River flow: discharge from three water reclamation plants, outflow from river tributaries into the river, and storm drain outfalls.
Conducted in what would be considered a fairly dry month, the study found that, “the three water reclamation plants discharged the majority (72%) of the volume flowing in the Los Angeles River during this study.” This discharge was found to contain “the highest concentrations and greatest mass emissions of nutrients including nitrate, nitrite, ammonia, and total phosphate.” The side benefit of storm water re-use is that all of these pollutants are nothing more than nutrients that can be used in the vegetative plant growth in the sub-surface EPIC system without any public health exposure or concerns. It is here that the versatility of the EPIC system is seen as it acts as both an irrigation and bio-filtration system.
“One of the big benefits of the Westside Park Rainwater Irrigation Project is how it will reduce the need for outside water sources for irrigation in this park,” said Wing Tam of the City of Los Angeles Storm water Program. “In a drought year, using rainwater for irrigation will drastically reduce potable water use in the area and cut our expenses significantly.”
Irrigation water source for Westside Park
Working in different environments wet to arid the multiple applications of the EPIC system are seen to be the solution for water management, conservation and reuse. The EPIC System combines the world’s most efficient irrigation and drainage system through non-pressurised, gravity driven capillary physics of washed sand via direct interface of the EPIC subsurface pipe that never clogs. The entire system is lined with a 45 mil EPDM liner meaning no water is lost and only used when taken up by the plant. The system is also very well suited to dryer climates, as when used for irrigation, it has been proven to use 50-80% less water and relies on sand as its growth medium.
Irrigation water
Reusing rainwater is at the heart of the Westside Park Rainwater Irrigation Project. Off-site surface runoff will be diverted from an existing storm drain to a lift station that will filter water through a screen, removing floatable waste and heavy sediments. A filtration system consisting of a two-acre network of EPIC sub-surface irrigation pipes in a sand profile will provide water to the park’s natural vegetation through root uptake. Excess filtered storm water will be stored in a series of underground chambers. Once these chambers reach their capacity, the surplus water is discharged towards a dry creek and back into a storm drain significantly cleaner.
A closer look at the EPIC System below the ground
In addition, the Westside Park will benefit the surrounding neighbourhood. A playground, which will be financed through sources other than Proposition O, will be developed providing children and their families with a universally accessible playground to enjoy during a sunny weekend afternoon. An outdoor fitness centre featuring exercise equipment will draw health-enthusiasts of all ages. Lastly, a new solar-powered lighting system and fencing will make the surrounding community a safer place for the Angelenos who call the La Cienega/Fairfax area their home.
“It is multi-beneficial projects like this that make our communities better,” says Cynthia Ruiz, president, Board of Public Works. “It is exciting that we are moving forward with this important storm water improvement project that will not only affect Westside Park, but the neighbourhood at large.”
Water flowing from the drainage channel is intercepted and pumped into the EPIC System below the park for irrigation and after bio-filtration is released back into the drainage channel
