Trinity Oaks and Thousand Oaks are residential subdivisions located in Pasco County, Florida which were constructed between 1990 and 2003. Both areas experienced recurrent flooding of streets and residential property as a result of accumulated rainfall or single large rainfall events. Detention ponds within the Trinity Oaks neighborhood, intended to provide attenuation and storage of local runoff from residential lots and roadways, frequently overflow their banks and flood adjacent property. Detention pond storage recovery is also impeded at some locations by prolonged high water levels in the receiving slough system.
The overall purpose of this and other complementary area wide drainage system improvements (including BMPs 1A & 5A, previously permitted) is to improve storage and conveyance of stormwater flows and to decrease the duration and level of localized flooding of streets and residential property in the Trinity Oaks and Thousand Oaks neighborhoods.
DES was contracted by Land & Water Engineering Science, Inc. to provide modeling and permitting support for the design project.
The existing weir at the boundary of Trinity Oaks and Thousand Oaks, located just upstream of Kinsmere Drive, is in disrepair and a significant amount of subsurface flow occurs, effectively bypassing the flow control structure altogether. Replacement of the structure with modifications will serve multiple purposes, not the least of which is to improve structural stability and eliminate undesirable underflows which bypass and further destabilize the structure.
Maintenance of lower water levels in the wetland would also allow for faster storage recovery of connected stormwater detention ponds following rain events. By increasing available surface storage within the wetland system and providing for the system to efficiently recover to that normal water level condition, there may be a flood control benefit, particularly for smaller magnitude, more frequent rainfall events during the rainy season (e.g., back to back 2-inch storms).