Agenda Item Name:
Title
SW 8th Avenue and Tomoca Hills Stormwater Maintenance Project.
End
Presenter:
Ramon D. Gavarrete, P.E.
Description:
Staff has developed plans for a stormwater maintenance project at SW 8th Avenue and in Tomoca Hills. The purpose is to reduce flooding and improve drainage.
Recommended Action:
Recommended Action
Direct Staff to proceed with the SW 8th Ave and Tomoca Hills Stormwater Maintenance Project. Adopt the resolution authorizing the acceptance and execution of two drainage easements.
End
Prior Board Motions:
None
Fiscal Consideration:
Fiscal Consideration
The work for this project will be performed by the stormwater maintenance crew under the scope of their existing duties. Additional funding is not needed for this project.
End
Background:
After Hurricane Irma, County Staff began looking for opportunities to reduce flooding that has occurred as a result of large rainfall events including flooding over SW 8th Avenue and downstream at several residences near SW 12th Avenue west of SW 91st Street. Staff researched the existing easements in the drainage basin and located several that can, with maintenance or improvement, function to reduce flooding at said location.
During the same period of time a drainage issue arose on SW 8th Avenue that affected the multi-use path just west of SW 91st Street. Changes to the property adjacent to the County Right-of-Way caused runoff and sediment to collect on the path. The adjacent property owner has granted a drainage easement to the County that will allow for this issue to be resolved and promote the runoff from the County Right-of-Way directly into an existing drainage easement on an adjacent property.
Staff has developed a plan to maintain an existing basin within Tomoca Hills Unit 2. This basin was created by berming an area where runoff was being naturally collected within the subdivision. The plan includes constructing vehicle/equipment access and excavating 1’-3’ in order to remove accumulated sediment to restore/improve storage and infiltration.
Plans have also been developed for an easement along SW 8th Avenue. These include constructing a berm and adding a control structure onto the cross drain under SW 8th Avenue to provide storage within the easement on the north side of 8th.
The proposed work will be outside of the SW 91st Street Scenic Road buffer. The impact to trees due to the construction of the berm has been evaluated and removal of regulated trees will be mitigated with this project. 30 trees were located within or near the footprint of the proposed berm. Of those 30 trees, sixteen trees will be removed. Of the sixteen to be removed, six are regulated trees, including one 32” Live Oak. A total of 13 trees, including eight 4” trees to mitigate the Live Oak, will be planted as mitigation. Furthermore, the berm will be seeded with native wildflowers as part of its stabilization.
The work along 8th Avenue also includes constructing a paved ditch on the south side of 8th Avenue from the cross drain into the existing drainage easement adjacent to the Right-of-Way. A shallow swale will be constructed in this easement and the property owner has granted additional easement for the paved ditch. This will provide direct conveyance of flow from the cross drain to the proposed swale.