Results of analysis for potential beach renourishment on Manasota Key expected to be delivered to Sarasota County administrator in April

County commissioners continuing to explore potential of collaborating with Charlotte County on initiative

A graphic shows facets of the shoreline on part of Manasota Key. Image courtesy Sarasota County

The president of a consulting firm that has been working with Charlotte County leaders on a beach renourishment project said this week that he expects to have a report finished by mid-April on an analysis for a potential project on Manasota Key in Sarasota County.

“All the field work is completed,” Michael E. Poff of Coastal Engineering Consultants in Naples, added during a March 21 update that was part of a joint meeting of the Sarasota County and Charlotte County commissions.

Early this year, the Sarasota County board agreed to ask for that analysis with an eye toward potentially partnering with Charlotte County on a project that would run from 7250 Manasota Key Road all the way south to Stump Pass Beach State Park. Even though each local government would be responsible for its own portion of the expense, Poff pointed to a number of benefits from the potential collaboration.

A graphic shows the degree of erosion on one segment of the Manasota Key shoreline, near the area designated R-174. The lines on the graph show the changes in the beach’s profile. Image courtesy Sarasota County

“The more sand you put up there [on the beach],” he said, the better the renourishment project will perform. If the Sarasota County Commission works with Charlotte County, he added, the new sand would be expected to stay in place longer, which also would “save a lot of money.”

The report he will deliver to Sarasota County next month will include information about the estimated cost of its part of the project, he noted.

Initiating one mobilization process for dredging the offshore sand and piping it ashore would be considerably less expensive than two separate operations, he indicated.

He put the total estimated expense of the Charlotte County renourishment at $28,572,000. However, $4.7 million of that is for an extra undertaking on South Beach in Charlotte County, he pointed out.

Photos show conditions before and after Hurricane Irma’s strike in September 2017 at a property on Manasota Key. Images courtesy Sarasota County

In 2016, Sarasota County’s renourishment of South Siesta Key cost about $21.5 million. The county is assessing property owners along the affected part of the shoreline to cover part of that expense. Commissioners have indicated that the only way they would undertake a renourishment project on Manasota Key would be to require those affected property owners to help pay for it.

Several times over the past two years, a number of Manasota Key residents have pleaded with the Sarasota County Commission to renourish the beach because of severe erosion and threats to their property. At the beginning of the joint meeting on March 21, several representatives of the Englewood Chamber of Commerce pointed to the beach’s value to the community’s economy.

“Englewood’s business owners know that the beaches are our top draw,” said Keith Farlow, president of the Englewood Chamber. His family owns Farlow’s waterfront restaurant, he noted.

Without beach renourishment, “Englewood would be a ghost town,” added Mary Smedley, managing broker for Michael Saunders & Co. in Englewood and president-elect of the Englewood Chamber.

Englewood straddles the Sarasota County-Charlotte County line.

After the results of the Manasota Key beach analysis are provided to Sarasota County Administrator Jonathan Lewis next month, Poff told the boards, another joint meeting of the commissions can be scheduled, so they can decide how to proceed.

If all goes as he hopes, he noted, Charlotte County will have its permit in hand by the end of this summer, so it can pursue its renourishment project. “In a perfect scenario,” he said, the initiative start in November 2019, after turtle nesting season ends, and conclude before the next nesting season begins on May 1, 2020.

Current conditions

Poff proceeded to explain some of the findings of the analysis of the Sarasota County segment of shoreline. For example, he said, “there are rock revetments” that residents of the area did not know about until the structures were uncovered by storms over the past three to five years.

A ‘dog-bone groin’ is a structure used decades ago to try to keep sand on a beach. Image from Beaches in Space and Time by Richard A. Davis Jr.

Additionally, the surveyors found “old ‘dog-bone’ concrete groins” that probably were put in place in the 1960s, he continued. They are “crazy concrete pilings,” he explained, with “hammerhead things on top of them.” They were designed to slow the downdrift action of sediment and, thus, keep more sand in place.

The surveyors, he continued, also encountered rock when they waded out into the Gulf of Mexico. “They actually hit a very shallow point,” he said. It is an area “where the rock is literally at the waterline … We have never seen that in the Southwest Florida coastline, where the rock is that close to shore and exposed,” he told the commissioners.

It could be the remnants of an old groin, he said, indicating that the project team might undertake more research into that potential.

Additionally, Poff said, the survey had found near-shore hard bottom, similar to the situation along the Charlotte County portion of the Manasota shoreline. Any dredging pipeline would have to be routed around that hard bottom, he said.

A 2000 article in the Journal of Coastal Research, written by Magnus Larson and Nicholas C. Kraus, explains that hard bottoms “can consist of natural materials such as limestone, coral, shell, work rock, sedimentary rock, and clay, as well as … material such as rip rap. A hard bottom may be covered or uncovered by sand at various times during a storm, and it imposes a constraint on the sand transport rate. … Hard bottom provides habitat for marine life and is, therefore, considered to be a resource that must be protected.”

The data analysis regarding the nearshore hard bottom is underway, Poff said. The survey team has been using “very sophisticated equipment” to scan the area, he added. “We expect in the next week or two to have that information.”

Referencing an offshore monument system used to denote specific areas of shoreline, Poff also noted that the shoreline at R-174 probably is the worst area of erosion. The foundation of the beach remains, he said, but slightly more than 130 feet of beach has eroded there over the past 18 years. “It’s the highest rate we saw in the study area.”

3 thoughts on “Results of analysis for potential beach renourishment on Manasota Key expected to be delivered to Sarasota County administrator in April”

  1. Reading your article and checking satellite details:
    They will be hard pressed to place sand where finding any hard bottom (rock,coral, etc.) We cannot nourish around Point of Rocks for the same reason.
    I also spotted many large rock revetment areas on gulf front properties and wondered about the impact of those on down drift beach areas… who permitted those? Any remaining groins should be removed while accessible to remove that impediment to sand nourishment stabilization. What’s happening with the ‘temporary’ placement of sand bags for up to 3 years? Unless they are biodegradable, the bag fabric will break down, snag and become environmental hazard as the sand moves out. How do you evaluate the status of those bags over time?

    • We have heard nothing to-date. We will check with county staff. Thanks for the reminder.

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