EVEREST June, 2013 - California Department of Boating and ...

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Orange County Coastal Regional Sediment Management Plan funding sources currently used to fund dredging in the County as well as insurance and labor considerations.” 4.20 Sand Retention Feasibility Study This activity would consist of a study to determine whether a sand retention device would be economically beneficial over existing methods at key erosion hotspots within Orange County. Aspects of the study would include the following: • Update on the Oil Piers and Fletcher Cove reef projects; • Summary of recent state of the art advancements in sand retention devices; • Development of a short list of erosion hot spots that may benefit from sand retention; • Conceptual design of sand retention devices at those hotspots; and • Compare costs between sand retention and existing beach maintenance methods at those hotspots. 4.21 Huntington Harbour Dredging with Beach or Nearshore Placement This activity would be to investigate whether any material from the ongoing maintenance dredging of Huntington Harbour is of sufficient quality for beach or nearshore nourishment and to investigate funding or other mechanisms to encourage placement of this dredged material on Surfside Beach or in the nearshore. The various channels and basins within Huntington Harbour, Sunset Harbor, Anaheim Bay, the Seal Beach Naval Weapons Station, and the Seal Beach National Wildlife Preserve require infrequent maintenance dredging, with the dredged spoils usually being dumped offshore at an ODMDS. Material from the surrounding watershed is causing shoaling within Huntington Harbour navigation channels and marinas, creating channel navigation restrictions, and impairing the use of launch ramps and public and private boat slips. Dredging was previously conducted in Huntington Harbour from 1967 to 1976 during initial construction and in various areas in 1988, 1989, and 1999. Results from a bathymetric survey of Huntington Harbour in May 2000 suggested that approximately 34,000 yd 3 of sediment needed to be dredged. To this end, the City of Huntington Beach and Orange County have proposed to carry out maintenance dredging in the 2012/2013 fiscal year. Much of this sediment originates from urbanized flood control channels and other drainage outlets such as the Wintersburg, Sunset (i.e., Heil), and Edinger (i.e., Bolsa Chica) Flood Control Channels (USACE, 2001). The watershed that drains into Huntington Harbour is large and heavily urbanized. In June 2003, the Federal government added Huntington Harbour to its Everest International Consultants, Inc. 4.15
Orange County Coastal Regional Sediment Management Plan list of impaired water bodies after USEPA found unacceptable levels of polychlorinated biphenyls (PCBs) and dieldrin. Since much of the shoaling identified in 2000 was located near drainage outlets, there is concern that the sediment buildup might be so contaminated with toxic metals, pesticides, and PCB’s that special dredging and other management measures may be required for sediment disposal. It is unknown if or how much of the sediment proposed to be dredged from Huntington Harbour can be placed on the beach or nearshore, so investigation into this matter is recommended. 4.22 Update the Plan The Plan should be a living document that would benefit from periodic updates to add or modify data, information, understanding, and recommended activities. The Plan should be updated using a collaborative approach between the various stakeholders and led by either the new JPA (see Section 4.2) or Orange County and USACE. The update should include a review of the coastal RSM strategies outlined in the current Plan, modifications to activities based on lessons learned, and potential additional activities as appropriate. Much of the updated understanding should come as direct results from the studies recommended within the Plan activities. As with the current Plan, future modifications should be carried out in a transparent fashion with full cooperation and inclusion of the stakeholders and the public in general. 4.23 Update Sediment Budget for Laguna Beach Littoral Cell The most recent sediment budget for the Laguna Beach Littoral Cell was for a time period ending in 1984 (USACE, 2002b). Given the large amount of development occurring in the area in the last 28 years, it is expected that sediment yields and the sediment budget for this area have changed significantly. This activity would be to update the sediment budget for the Laguna Beach Littoral Cell to better represent current conditions. 4.24 Investigate Methods to Assess and Mitigate for Upstream Sand Mining This activity would be to perform a study to identify methods to assess and mitigate for removal of beach sand from upstream creeks, streams and river beds. 4.25 Study Large Grain Size Impacts at East Beach, Seal Beach This activity would be to perform a study to determine if use of larger than native grain sizes for beach nourishment has caused negative impacts to surfing or habitats at East Beach in Seal Beach. The positive effects of using large grain sand in beach nourishments are understood to increase beach width and increase sand retention, thus lowering maintenance costs, but potential negative impacts are less understood. Everest International Consultants, Inc. 4.16
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