VCSA BOD MEETING May 2, 2017: LAKE BANK RESTORATION STATUS – E. Johnson
In May 2013 the Southwest Florida Water Management District (SFWMD) lake permit officially converted the lake(s) to Operation Phase with VCSA and VLII as permittees. The permit established these two entities with the responsibility for correcting any erosion while maintaining a maximum 4:1 slope to a depth of 2 feet below the control elevation. According to SFWMD everyone in the community is responsible for maintenance of the Water Management System, including the lake bank. Discussions with Steve Nagle of SFWMD require bank escarpments exceeding 9” to 10” to be remediated with a maximum 4:1 slope. Escarpments greater than this limit do not provide bank sustainability. There are many areas along the shoreline with bank erosion exceeding SFWMD guidelines.
A Lake Bank Restoration Committee (the Committee) was formed one and a half years ago by the VCSA BOD with Hank Fox and Eric Johnson as members. Their directive was to determine the extent of lake bank erosion and determine methods for remediation. Paul Croteau replaced Hank on the Committee a year ago. At the beginning of 2017 the Committee was expanded to include Paul, Eric, the entire Commons VLCA Board and Hank Jones of VLII. Over the last year and a half the Committee has interviewed seven contractors who have presented a half dozen different solutions; visited lake bank restoration projects at six offsite communities; and reviewed best practices described in Land Development Codes of SFWMD, Lee County and the City of Bonita Springs. At the Committee’s recommendation VLCA contracted bathymetric and sonic tests that provided a contour of the lake bottom.
The interviews and research indicate the lake shore has three distinct bank conditions with the following likely remediation methods.
· Severe Bank Drop off: (Carmel, areas adjacent to commons boat ramp, numerous other locations around the lake). The probable solution for these areas require large riprap. Contractors interviewed all indicated most of the erosion of the Carmel shoreline is caused by water runoff from steep roofs and lanai surfaces during heavy rains. The Carmel community was informed by the VCSA BOD that they are responsible for obtaining and implementing an engineered solution of gutters/downspouts and underground drainage pipes to address this excessive water shedding. Pipes would be directed through the riprap exiting into the lake below the low water line. This work will be required before the bank remediation can be initiated. The Carmel HOA President acknowledged that they are investigating this storm water collection system. The Committee has rejected the use of wood or vinyl seawall as a solution for the Carmel shoreline due to expense, insufficient soil depth above lake bottom cap rock for long term sustainability, and liability issues relating to human egress from the lake along its roughly 600 feet of deep dropoff.
· Shallow Escarpments <or=8 Inches With 4:1 Maximum Slope Extending From Bottom of Escarpment to 2 Feet Below Seasonal Low Water Level: These areas would be supported by planting a littoral shelf of native, aquatic plant species to protect the shoreline from further erosion.
· Escarpments >8 Inches With Shallow Drop off: The majority of our 10,000 foot shoreline falls into this category. The optimum solution based on research of successful installations at numerous other communities and best practice recommended by SFWMD, Lee County, and Bonita Springs Land Development Codes is a compacted aggregate fill from the top of the escarpment extending at a maximum 4:1 slope to 2 feet below the seasonal low water level. A woven biodegradable Turf Reinforcement Mat planted with littoral shelf of native aquatic plant species would cover the slope. The littoral plant root systems will stabilize the bank; littorals will create a wind driven wave break; and provide a protective barrier to prevent fertilizer and other chemical seepage into the lake, while providing an enhanced environment for aquatic life.
The permitting agency for Vanderbilt Lakes Community is the City of Bonita Springs (incorporated Dec 2000). The Land Development Codes of the City of Bonita Springs, SFWMD and Lee County all consider “Restoration of lake shoreline to originally permitted max 4:1 slope to mimic the natural environment and provide sustainability” to be best practice. Areas that require riprap or other hardened solutions are limited to a total of 20% of the shoreline or approximately 2000 linear feet. A variance may be required if excessive rip rap is used. The above three proposed solutions constitute best practice for our lake shoreline situations.
· May 2017: Presidents of Lake Permittees Paul Croteau (VCSA) and Hank Jones (VLII) to schedule onsite meeting with SFWMD to tour and discuss community concerns relating to the Water Management System with emphasis on the excess water entering the system during the height of the rainy season and the restrictions to water leaving the system.
· October 2017: Commons Board to schedule community meeting with SFWMD for presentation on the Water Management System community permit responsibilities and recommendations for course of action
· October – November 2017:
o Acquire three bids for hiring Project Manager to oversee lake bank restoration
o Develop plan to finance the project
· December 2017: Hire Project Manager to oversee the lake bank restoration project
· January – February 2018: Project Manager develops BOD approved Engineering designs of remediation methods, obtains bids on lake bank restoration, establishes contracts, obtains permits and schedules work
· March 2018: Commence first phase of bank restoration prior to start of rainy season.