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HomeMy WebLinkAbout15-01-14 Item 1 - BIIA_Committee_Report_to_Harbor_Commission To: The Harbor Commission From: Jamshed (Jim) Dastur Chairman, BIIA Committee on Seawalls Subject: Status report on Balboa Island Seawall replacement Date: January 14, 2015 The official position of BIIA on the issue of Balboa Island Seawalls was presented in writing to the Harbor Commission at its last meeting on November 17,2014. The following narrative summarizes this writer's understanding of the current status of discussions and issues as deliberated in several meetings of the Tidelands Management Committee and in personal meetings and correspondence with the City staff. The two islands, of what is called Balboa Island, are protected from erosion and flooding by approximately 13,200 linear feet of concrete seawalls and adjoining public boardwalks, built, maintained and owned by the City of Newport Beach. Over several decades since they were first built, these seawalls and the adjoining board walks have been periodically repaired, raised in some cases and generally kept in decent shape by the City, to serve the purpose for which they were built. Some segments of the seawall are now nearing the end of their projected useful life and are in need of significant repairs or replacement. New walls would have a life expectancy of 75 to 100 years whereas structural repairs to the existing walls, where necessary, would possibly add another 25 years to their remaining life. Of the 13,200+/- linear feet of seawall, approximately 8,780+/- feet (about 2/3) are currently in good shape and have a remaining useful life of 25 years with normal routine maintenance. The remaining 4,420+/- feet (about 1/3) are in need of replacement or major structural repairs in the immediate future. The segments in need of replacement or structural repairs are — (1) the walls of the Grand Canal (approximately 3250 feet) and (2) the walls at the West End of the big island (approximately 1170 feet). The currently identified structural repair fix for the Grand Canal walls is estimated to cost approximately 40% of what a new wall would cost. Other less expensive structural repair options are also under consideration for the Grand Canal walls. The structural fix for the West End walls is estimated to cost approximately 76% of what a new wall would cost. Decision making would be relatively uncomplicated if the only parameters under consideration were those discussed above. The complicating issue is that the current walls are not high enough to prevent flooding from a combination of king tides, ocean swells, EI Nino, heavy rainfall and wind generated surf. (The City's study titled Assessment of Seawall structural integrity and potential for Seawall over-topping—April, 2011). Add to that the issue of predicted ocean rise in the future, estimates for which range from 17" to 66" by the year 2100. This wide range is not the result of competing scientific theories, but the result of variations in the estimate of carbon emissions over the coming decades, particularly by emerging nations such as China, India, Brazil, etc. This does not seem to be the appropriate forum to debate whether the oceans are rising and at what rate. California Coastal Commission Sea-Level Rise Policy Guidance (currently in draft form) when finalized, will be used in the future to obtain permits for construction of waterfront structures. So, any new waterfront construction will require the designers to allow for some reasoned measure of rise in ocean levels. However, it may take a year or two (or more) before the above Policy Guidance is finalized. The average prediction of sea level rise by the California Coastal Commission is 7" (2" to 12" range) by 2030, 14" (5" to 24" range) by 2050 and 41" (17" to 66" range) by the year 2100. The current height of the seawalls is woefully inadequate for the predicted rise by 2030. So, regardless of the physical condition of the sea walls, they need to be raised in the very near future. In addition, the City needs to start looking at options for protecting some 20+/- miles of other waterfront property inside the harbor for the dire 2100 projections. Any decision regarding the Balboa Island seawalls, should take into account holistic long-term planning for the rest of the inner harbor. Building higher and higher walls is not the ideal solution. Higher walls prevent water from coming over the top, but do little to suppress the rising water table in highly pervious soil. The infrastructure of roads, sidewalks, utilities, and grounds surrounding residential properties cannot be adequately protected from rising ground water by walls alone. One strategy currently being considered by the City is to do the bare minimum to protect Balboa Island over the next 25 years. During this time frame, more reliable data would become available regarding the actual sea level rise. This time span would also be used in studying various options for protecting the entire inner harbor. Under this strategy, the action items boil down to the following. 1. Determine the wall height necessary to protect Balboa Island from flooding over the next 25 to 30 years. In this task, a balance needs to be drawn between providing assured flood protection and maintaining the essential charm and soul of Balboa Island — open and easy public access to the beaches, preserving the views from waterfront properties, protecting property values, etc. 2. For 2/3'd of the wall length (8780'+/-) that does not require any repairs, add a functional concrete cap to the top of the wall to bring it to the elevation determined in (1) above. 3. For the Grand Canal walls (3250'+/-) evaluate the pros and cons of spending money on a new wall with a 75 to100 year life versus repairing the existing wall to extend its life by 25 to 30 years. In either case, the top elevation would be raised to the level determined above. 4. For the West end walls (1170'+/-) make the same evaluation as (3) above. Since the structural wall construction for the West End is quite different from that of the Grand Canal, it may possibly result in a different conclusion than (4) above. 5. Layout a sophisticated plan, to monitor sea level rise over the next 15 to 20 years with a view to zero in on future sea level trends. 6. Commission a study to look at various options, their feasibility and cost for protecting the harbor beyond the year 2040. An innovative method being used by some of the other cities having similar issues is to have several competitive solutions offered by different pre-qualified teams, for a small fixed fee for each participant. We need to put the best and brightest brains to work on this issue. Last, but not the least, it is imperative that the issue of who pays for this construction is put to rest. This started off as a financially daunting $75,000,000 project; it has slowly been whittled down to a financially manageable project, of the order of magnitude of 20 to 25 percent of that amount. The Citizen's Advisory Panel that works with the Tidelands Management Committee has had some impact in clearly defining the issues and reining in the costs. The walls of Balboa Island are City owned and City maintained. The Board Walk is accessible to the public at large. It has been hinted in several forums that the City may be looking to the property owners of Balboa Island to pick up a portion of the cost for fixing the seawalls. This is a non-starter. For the City and the property owners of Balboa Island to work as a homogenous team, working towards the most cost effective solution, it is important for the City to unequivocally accept the financial responsibility for fixing the seawalls.