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Planning for public landing to heed sea level rise

By Susan Mustapich | Feb 10, 2020
Photo by: Susan Mustapich Waterfront infrastructure vulnerable to flooding, and what to do about it, is a focus of planning and budgeting in Camden.

CAMDEN — Sea level rise and flooding risks for Camden's public landing, compiled in a new state report, will factor into the town's capital improvement planning, with an eye towards shovel-in-the-ground projects beginning in 2024.

Report recommendations include elevating the town pier and moving the harbor master's office and public restrooms to higher ground.

The report is very helpful because it "gives us more specifics on what needs to be fixed," Town Manager Audra Caler-Bell said Feb. 5.

It also "gives the community the broad assumptions by which to do some detailed planning and figure out what we want to invest in," she said. It will help voters decide what and how they want to invest for the short-term as well as mid-and long-term, she said.

Caler-Bell said that by 2023, municipal government will have paid off a significant amount of debt for prior capital improvements.

Leading up to 2023, planning will take place for new capital improvements to the public landing, Harbor Park and stormwater systems. Caler-Bell hopes this will produce plans to make the town's infrastructure resilient to sea level rise and increased rainfall over a long-term period.

The first step involves budgeting for needed engineering and design work. This involves the town's Budget Committee, the Select Board and residents who ultimately make spending decisions by voting at town meeting, she explained.

Preparing to undertake major construction projects in 2024 also involves completing engineering and design, making decisions on construction projects and financing, and bidding out the work.

To best way to plan these long-term improvements to vulnerable infrastructure is for the town to hold off spending for new infrastructure projects within the next few years, Caler-Bell said.

In the short-term, the town will complete six projects already budgeted for and approved by voters. These projects include the Mechanic St. parking lot paving and drainage, Ragged Mountain recreation area (Snow Bowl) access road culvert replacement, Pearl Street drainage, road bed and paving, Norwood St. drainage and substructure improvements, Sand Street stormwater project and Opera House building repairs.

State report

The Public Landing and Harbor Park, Vulnerability Assessment and Resilience Planning report, was conducted by Wood Environment and Infrastructure Solutions of Portland. The Maine Coastal Program of the Department of Marine Resources funded studies of working waterfront infrastructure in 10 coastal Maine towns, including Camden.

To understand the vulnerability of Camden's 1.4 acre public landing site to sea level rise and flooding, engineers measured the topography of the site, elevations of the town pier, harbor master's office and public restrooms, and the condition of those structures. The four, town-owned floating dock systems in Camden Harbor and the sea wall at Harbor Park were also reviewed.

Flood risk due to sea level rise, tides, storm surge and wave affects is reported for current conditions, and projected for short-term (2030), mid-term (2050) and long-term (2085) conditions.

Sea level is predicted to rise in Camden, 1 foot by 2030, 2 feet by 2050 and 4 feet by 2085. These sea level increases are intermediate-level predictions generated by the National Oceanic and Atmospheric Administration.

The predictions “are within the range of the sea-level-rise scenarios recommended by Maine Department of Transportation for design of transportation infrastructure,” according to the report's authors. They state that the probability these levels will be exceeded is “rather low (17%).”

Engineers measured the elevations of the harbor master's shack at 8.21 feet, the pier's wooden walkway elevation at 8.07 feet and the public restroom at 9.68 feet. The granite wall at the base of Harbor Park was measured, at the request of town officials, though not part of the public landing study. It measures 8 feet at its highest elevation.

The highest average tide in Camden Harbor is 4.8 feet, according to the report. There are two high tides each day, with one higher than the other. The average of the highest tides each day over approximately 19 years is used to calculate this measurement.

The current 100-year flood level is 9.1 feet, and accounts for storm surge and tide, but not wind-driven waves. This flood level, plus a 1% wave-crest elevation, is 10-11 feet. Flood levels are calculated and predicted by the Federal Emergency Management Agency.

The highest annual tide in Camden Harbor is 7.1 feet, based a 20-year observation period, established by NOAA, last updated in 2012-16. Twice a month, the high tide level exceeds normal high tide levels, due to the alignment of the sun, moon and earth in a straight line. The highest annual tide measurement is the average of these twice a month highest tides.

Another tide measure is a mean of high waters. In Camden Harbor, this measurement is 4.8 feet. There are two high tides every day, one with a higher elevation than the other. This high tide measure is the mean of the highest tide each day, over a 20-year period.

Harbor Master Steve Pixley, who was interviewed for the report, told the authors the tide rises to just below the pier elevation two to three times a year, causing failure of electrical supply around the pier area.

The combination of predicted sea level rise with twice monthly highest annual tides will most likely flood infrastructure on the public landing within 30 years.

With 1-foot of sea level rise predicted by 2030, comes a highest annual tide prediction of 8.1 feet. With no wind or waves this inundates the deck of the pier and comes close to flooding the harbor master office.

By 2050, a predicted 2-foot sea level rise coincides with a highest annual tide of 9.1 feet. By 2085, a predicted 4-foot sea level rise, coincides with a highest annual tide of 11.1 feet.

Flooding of the harbor master's office is predicted within 10 years, and within 30 years, flood levels could exceed the window height, according to the report. Moving the office to higher ground, such as the 15-foot elevation of Commercial Street is recommended. The restrooms need to be elevated by 2 feet, or moved to the 15-foot elevation.

Elevating the pier above the 4-foot sea level increase predicted by 2085 is recommended to address mid- and long-term sea-level-rise predictions. Recommendations for the wall at Harbor Park are not within the scope of the study, according to its authors.

The report can be accessed from the home page of the town website, camdenmaine.gov.

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Comments (1)
Posted by: Mary A McKeever | Feb 10, 2020 14:59

Man can not defeat Mother Nature, no matter how hard one tries!



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