Lake Seminole Weir Replacement

The scope of work required at this Lake Seminole emergency response project in Pinellas County involves construction of a new temporary weir to restrict southern water flow from the lake through bridge culvert 150063 under Park Boulevard and thereby maintain the elevation of the lake. Failure of the existing weir, brought on by the impacts of Hurricane Helene, had resulted in unrestricted flow through the culvert that has been slowed but not eliminated by the exceptional emergency response of Pinellas County construction staff who placed numerous temporary 2’x2’x6’ concrete blocks and additional broken concrete riprap to temporarily obstruct the northern exterior openings of culvert. An improved and reliable method to control the lake elevation is currently in design and is planned for immediate installation. The temporary weir will be comprised of steel sheet piling, 50’ in vertical length, installed with a vibratory hammer supported by a crane working behind the shoreline. The worksite will be leveled in the vicinity of the crane usage for stability during its use. The top elevation of the proposed weir will match the elevation of the intact remnants of the existing weir. The new northernmost wall segment of the temporary weir will be installed parallel to the shoreline and approximately 10 feet north of the northernmost remnants of the existing damaged weir (at its approximate midpoint). Two new segments of sheet piling will extend from each end of the northern segment and taper outward back into the shoreline immediately beyond the wingwalls of the culvert. Floating turbidity barrier will encapsulate the worksite to minimize any buildup of silt from the installation. Once the emergency project is complete, the concrete blocks and riprap at the north end of the culvert will be removed and the leveled area on the shoreline will be restored and sodded. A permanent installation is currently being considered by the County and will be a separate project from this temporary emergency measure. Removal of the temporary sheet piling will occur upon the completion of the future permanent weir.