Department of Public Works

Marina del Rey Projects

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Oxford Basin Multiuse Enhancement Project
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Frequently Asked Questions
  1. What is Oxford Retention Basin?
    Oxford Retention Basin is a man-made flood control basin located at the intersection of Washington Boulevard and Oxford Avenue. It was built in 1959 to provide flood risk management to surrounding communities. Although the entire area had long ago been part of the Ballona Marsh, the site on which Oxford Basin was constructed had been used for several purposes in the prior century, including agricultural use and, ultimately, as a municipal dump for many years. In January 1963, after Oxford was already in operation, the Los Angeles County Board of Supervisors gave the site a secondary designation as a Bird Conservation Area, at the request of the Audubon Society and other local environmental advocates. From the 1960s through the 1980s the site was commonly known as the "Duck Pond", and there were large numbers of domesticated ducks introduced and kept on the site. During this time the site was also occupied with up to several hundred abandoned dogs, cats, rabbits, and chickens, causing significant environmental disruption, which led County officials to call for removal of these animals in 1989. Extensive studies documented a clear need for improvements to the site’s biodiversity.
  2. What is the Oxford Basin Multi-Use Enhancement Project?
    The Oxford Basin Multi-Use Enhancement Project is a multi-benefit project, developed over a six year period in consultation with stakeholders and the community, to enhance Oxford Basin’s flood control functions, to improve the habitat and water quality of the Oxford Basin, and to provide new recreational and safety amenities. Due to wear and tear and the accumulation of contaminated sediment, major work at Oxford Basin is required to maintain the site’s flood risk management function. The project will reduce the risk of flooding to the surrounding neighborhoods and provide multiple benefits to the community.
  3. What is the construction schedule for the Oxford Basin Multi-Use Enhancement Project?
    Major project construction is scheduled to commence in June 2015 and conclude by spring 2016.
  4. What are the anticipated construction impacts?
    Working hours are scheduled for 7 AM to 4 PM, Monday - Friday. The project’s construction impacts will include minimal increases in noise, dust, truck traffic, and potential temporary increases in odors. Construction best management practices will be implemented to minimize all of these potential impacts. Construction traffic will primarily be routed along Washington Boulevard to minimize impacts to Admiralty Way. Washington Boulevard and Admiralty Way may experience temporary daytime lane closures. The Marvin Braude Bike Trail will be temporarily closed for one day in late February to replace pavement and striping.
  5. Will construction have any impact on the Marvin Braude Bike Trail?
    To minimize construction impacts to the Marvin Braude Bike Trail, the bike trail will remain open during construction. However, there will be minimal temporary closure of one day to allow for resurfacing and new striping. Once complete, the bike path through the site will be enhanced by the addition of a separate walking path, allowing cyclists and pedestrians to more conveniently share the bike trail in this location.
  6. Will construction produce odors? Will the project reduce odors coming from Oxford Basin?
    Excavation of the accumulated sediment within Oxford Basin may temporarily produce odors originating from decomposing organic matter in the sediment, but any increase in odors will be temporary. The Oxford Basin Project, when complete, will reduce potential sources of unpleasant odors in the vicinity through increased tidal exchange, increased circulation, and removal of accumulated sediment.
  7. How will wildlife be protected during construction?
    All construction will take place under the direction and supervision of a biological monitor, who will ensure all necessary precautions are taken to avoid harming wildlife during construction. As required by the project’s permit from the California Department of Fish and Wildlife, all wildlife encountered on site during construction will be unharmed or relocated as permitted.
  8. How is Public Works engaging and educating the community?
    Public Works is committed to an ongoing relationship with the community to ensure the project’s construction and operations are consistent with the project’s goals to enhance the community. Some of these efforts include the circulation of revised project renderings, a project mailer to approximately 35,000 neighbors, and extensive face-to-face conversations with residents at the Marina del Rey 50th anniversary celebration. For a comprehensive list of engagement and outreach efforts conducted by Public Works over the past six years in developing this project, see the Oxford Basin section of the Community Outreach Efforts website.
  9. How will the project improve flood risk management for the surrounding communities?
    Several streets and properties in the area surrounding Oxford Basin are near or below the level of high tides in the marina. Without Oxford Basin, these areas would potentially flood during a rain event. Prior to a storm, Public Works crews operate Oxford Basin’s tide gates to empty Oxford Basin at low tide, creating a storage capacity that allows surrounding streets to drain into Oxford Basin during high tide. These storm flows are then emptied into Marina del Rey at the subsequent low tide. The Oxford Basin Project will improve flood risk management by removing approximately 3,000 cubic yards of sediment that has accumulated since Oxford Basin was constructed in 1959; replacing the existing tide gates, which have deteriorated due to wear and tear; constructing a 2-foot high parapet wall along Washington Blvd.; and modifying catch basins along Oxford Avenue.
  10. How will the project improve habitat and water quality?
    The project will substantially improve habitat and water quality through several project elements. These include removal of approximately 4 acres of existing non-native vegetation along the perimeter of the basin and replacement with more than 45,000 native plants and trees; removal of approximately 3,000 cubic yards of contaminated sediment and soil within the basin and along the perimeter of the basin; building a circulation berm within the basin to improve dissolved oxygen levels; a more natural tidal exchange; and construction of three bioretention water filtration systems.
  11. How will the project improve public safety at Oxford Basin?
    The project includes several features which will improve public safety, including a new 6-foot-wide, ADA-compliant walking trail; wildlife-friendly lighting to improve security at night; re-alignment of the walking trail along Admiralty Way with the construction of a landscaped parkway to separate pedestrians from traffic; construction of a separate walking trail along the Marvin Braude Bike Trail to reduce potential conflicts between pedestrians and cyclists; and new fencing.
  12. What is the cost of the project?
    The total project estimate is approximately $14.5 million.
  13. Is the project fully funded? How is it being funded?
    The project is fully funded. The Los Angeles County Flood Control District is primarily responsible for funding the design and construction of this project. Because of the significant enhancements the project will provide to native habitat, water quality, flood risk management, and community recreational opportunities, the project has also been awarded $2 million under the Proposition 84 Santa Monica Bay Grant Program and $1.5 million under Round 2 of the Proposition 84 Integrated Regional Water Management Grant Program. Los Angeles County Supervisorial District 4 has also committed $1 million of its discretionary funds to project construction.
  14. What kind of trees and plants will be planted?
    The basin was planted with approximately 750 native trees, including California sycamore, coast live oak, Fremont cottonwood, lemonade berry, California laurel, mulefat, Mexican elderberry, and narrowleaf willow. Over 45,000 drought tolerant plants were planted around the basin including over 200 milkweed plants that are a food source for Monarch Butterflies. The project planting palette can be viewed at the following link: Project Planting Plans.
  15. Why were the non-native trees removed?
    The 648 trees removed were all non-native species. One of the primary goals of the Oxford Basin project is to maximize the site’s habitat value to native wildlife. During our multi-year planning and evaluation process for this project, several biologists recommended that the site’s non-native vegetation, including trees, be removed and replaced with native vegetation. This recommendation is included under item 5.1.4 in the 2010 Oxford Basin Biological Report. Additionally, many of the trees removed were diseased, including the majority of the 540 myoporum. As stated in 3.5.1 of the 2010 Conservation & Management Plan for Marina del Rey "[Oxford Basin was] landscaped extensively with non-native trees and shrubs, especially small flowered myoporum (Myoporum laetum), a practice now recognized as being contrary to sound ecological principals. The myoporum landscaping is now in poor health, presumably due to an infestation of the myoporum thrip (Klambothrips myopori), which is taking a heavy toll on this plant across the region."
  16. Why were the non-native trees removed between the months of December 2014 and January 2015?
    As part of the multi-year planning and evaluation process for this project, it was determined, based on biologist recommendations, that removal of the trees should be scheduled to avoid the bird nesting season (January 1 through September 30, per the Marina del Rey Local Coastal Plan) to the greatest extent possible. In order to ensure potential impacts to wildlife are minimized, the removal process was overseen by a biologist, consistent with all permit requirements.
  17. Why was there a delay between the tree removal and construction resuming within the basin?
    Tree removal was conducted during December 2014 and January 2015 to avoid nesting season (see previous question for more details), but further work was halted to avoid storm season. Because the primary purpose of Oxford Basin is to provide flood protection to the surrounding neighborhood, major construction must take place outside of the storm season, which runs from October 15 to April 15. This also reduces the potential for erosion from the site to adversely impact water quality in the area.
  18. What are the benefits of replacing non-native plants with native plants?
    California’s native plants are uniquely adapted to thrive in local climate, soil types, and to support native wildlife. In addition to their ability to provide the best possible habitat for native wildlife, there are many other benefits to planting native plants including reduced irrigation requirements and lowered maintenance needs. According to the California Department of Fish and Wildlife: "California’s native plants should be conserved not only because of their beauty and intrinsic value, but also because they are essential components of ecosystems and natural processes..." You can read more about these benefits on the CDFW Native Plant Program Website.
  19. What agencies reviewed and approved the project?
    All aspects of the Oxford Project have been extensively reviewed and approved through a process spanning several years. These review and approval processes included expert biological review and public review and input prior to the Board of Supervisors approval of the project’s Mitigated Negative Declaration (MND) in December 2013, and also prior to the California Coastal Commission’s consideration of a Coastal Development Permit (CDP) in June 2014 and subsequent issuance of the CDP in November 2014.

    The entire project, including removal of existing trees and their replacement with approximately 750 native trees and over 45,000 native plants, was reviewed and approved by biologists and other experts for the County, the Santa Monica Bay Restoration Commission, the California Department of Fish and Wildlife, the Los Angeles Regional Water Quality Control Board, and the California Coastal Commission, as well as many members of the public. Comments and suggestions from all of these biologists and other experts were incorporated into our final plan by the project team. Copies of the project’s permits and other related documents are available on the Oxford Basin Permits Page.
  20. Did Public Works consider a phased approach to tree and vegetation removal?
    Yes, our proposed construction phasing was carefully planned to minimize impacts to wildlife while maintaining continuous flood protection during the storm season (October 15 to April 15). It was determined that extending the tree and soil removal for multiple years would increase wildlife impacts. Additionally, many trees on or adjacent to Parcel P (the parcel containing Oxford Basin) will be left undisturbed, providing adequate roosting sites during construction and establishment of the new landscaping.
  21. Is Public Works aware of monarch butterflies at Oxford Basin?
    Yes, the presence of monarch butterflies at Oxford Basin is documented in the project’s 2010 Entomology Report, which states that monarch butterflies occasionally stop over at the site while migrating south. However, Oxford Basin has never had suitable food sources for monarch butterflies. The project, when complete, will offer substantially improved habitat for native species, including monarch butterflies. The Oxford Basin Project Planting Plan includes over 200 milkweed plants, the host plant for monarch butterfly caterpillars, which were not previously present at the site.
  22. Will there be any change to the amount of freshwater entering Oxford Basin?
    No, there will not be any change to the amount of freshwater entering Oxford Basin as a result of this project. The project team has discussed the inclusion of freshwater features with several ecologists and we have determined that such features would not be consistent with current ecological recommended practices. Oxford Basin’s natural tidal exchange function will be retained and enhanced once the project is complete.
  23. Why is Public Works removing soil, and how are any contaminants being disposed?
    The contaminated soils above the normal water line are being removed to improve water quality, provide clean soil for the native plants, and for grading purposes. The sediment below the normal water line is being removed to restore flood control capacity, but this will also benefit water quality as this sediment is also contains hydrocarbons, nutrients, and other pollutants. All contaminated soils will be disposed at proper facilities. Analysis of the site’s soil and sediment is contained in the project’s 2012 Environmental Soils Report, particularly the agronomical sections of this report which document the high levels of copper, zinc, and other contaminants which impede the growth of plants.
  24. Why does the pump plant on the southeast side of Oxford Basin periodically discharge water into the Basin?
    The Oxford Basin Pump Station, constructed in 1991, provides protection from flood waters for the low-lying surrounding neighborhood. During rain events, its pumps discharge stormwater into Oxford Basin, reducing the risk of flooding in the streets in the surrounding neighborhood.
  25. Will Public Works keep any of the native vegetation on the Oxford Basin site?
    Public Works will continue to work to protect, relocate and replant as much of the native vegetation on the site as feasible.
  26. How will the project improve tidal exchange?
    Oxford Basin’s tidal exchange is controlled by two tide gates on Admiralty Way that connect it to Basin E of Marina del Rey. During the project development process, biologists reviewing the site recommended that the site’s tidal exchange be increased to be made as natural as possible. These recommendations are included in the 2010 Biological Evaluation of Oxford Basin, particularly sections 5.1.1, 5.4.2, and 5.6.1. To fulfill this recommendation, the Oxford Basin Enhancement Project will increase tidal exchange by 1.5 vertical feet. This increase will be enabled through raising the headwall at the outlet of the Project 3872 storm drain on the eastern end of the project.
  27. Who should I contact if I have any other questions or comments?
    Please contact Josh Svensson of Public Works’ Project Management Division at (626) 458-7157 or