The City of Los Angeles Department of Public Works plans to construct a $15.9-million diversion system along Temescal Canyon Road that will be used solely for rainstorm runoff from October through April, if it obtains local city coastal approval and Coastal Commission approval. Ideally, stormwater will one day drain into a diversion tank that feeds into a hydro-separator, which separates out pollutants such as trash and oil. The debris remains in the hydro-separator and the water flows into a 1.3-million-gallon cement-reinforced holding tank at the bottom of Temescal Canyon Park (just north of Pacific Coast Highway), where it will stay for up to three days before being sent to the Hyperion Treatment Center in El Segundo. The LADPW plans to finance construction from Proposition O, which passed in 2004 and allowed the city to issue up to $500 million in general bonds for watershed projects that clean up and prevent pollution of waterways and beaches. The diversion system will filter rain from the 1,600-acre watershed area that encompasses El Medio on the west, Via de la Paz on the east, and the ridge line of the Santa Monica Mountains to the north, which means a great deal of the runoff comes from parkland. That area does not have a high concentration of trash and toxins such as used motor oil, antifreeze, fertilizers, pesticides and pet waste, which are the most common stormwater pollutants, according to Michelle Vargas, spokesperson for the Department of Public Works. Despite being a low-pollution site, the Temescal location was selected for the facility because it is on city-owned property. The diversion system will be housed underground at three sites in the canyon. The first stop for the stormwater will be the diversion tank (16 ft. by 12 ft. and 24 ft. deep). From that tank the water drains into the hydrodynamic separator, while the cleaned water continues towards the beach to the holding tank. The separator is 16 ft. in diameter and will be buried 25 ft. below ground, with a 5-ft. by 5-ft. hatch being the only visible feature at the surface. The holding tank will be buried under a playing field and playground area. This tank is 166 ft. by 66 ft. and 30 ft. deep. After construction, the field and playground will be reinstated. Construction is expected to start next September and take about a year. Temescal Canyon Road, of course, is a major artery in and out of the Palisades. At a December 5 public hearing at the Palisades Branch Library, Bureau of Engineering Temescal Stormwater Project Manager Andy Flores said that the bike lane and sidewalk on both sides of the road would remain open, but that traffic could be reduced to one lane each way. Community activist George Wolfberg asked that a traffic study be presented to the Pacific Palisades Community Council. ’The traffic plans for this project are currently being developed in compliance with L.A. Department of Transportation requirements,’ Vargas said. ‘The project team will be able to inform residents about it when it is finalized, sometime towards the end of project design in the spring of 2009.’ At the public hearing, several audience members wondered if there were sensors in the system in order to alert that the hydro-separator needed to be cleaned. Although the audience was told that there are no other existing systems like this, and that it is state-of-the-art, the hydro-separator and the holding tank would have to be visually inspected to see if they need cleaning. ’Maintenance will be done on a routine scheduled basis per manufacturer’s indication,’ Vargas told the Palisadian-Post on Tuesday. ‘The [1.3-million-gallon] tank will also be maintained on a regular scheduled basis.’ He sadded, ‘As in any bond measure, the Prop. O funds passed by L.A. voters and approved by the L.A. City Council only cover the cost of construction.’ Unfortunately, ‘All of the Prop. O money has been committed,’ said Alex Fey, the Legislative and Environmental Officer for Councilman Bill Rosendahl’s office on Tuesday. ‘We’re looking for an ongoing funding source, maybe a property assessment. We’re looking at different options.’
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