Placentia Canal Drainage Improvements

Upgrade the existing two 48” RCP culverts under both North and South Thompkins Blvd to two 10’x5’ box culverts. The length of the proposed double box culvert is 64 linear feet at North Thompkins and 70 linear feet at South Thompkins. The Base Bid includes precast box culverts. Alternate 1 includes cast-in-place box culverts. The pre-cast box culvert must utilize a “watertight” ASTM C1677 joint in lieu of the “soil tight” ASTM C990 joint that has typically been utilized locally. The cast-in place box culvert must utilize expanding waterstop in addition to the GDOT specified exterior waterproofing. The double box culverts will be bear on a geotextile and 12 inches of #57 stone. The project will include cast-in-place wing walls and aprons. New stormwater pipes and manholes as well as modification of existing pipes will be included at each crossing. Stormwater curb inlets will be included at both crossings. Sanitary Sewer will be impacted at South Thompkins where two 10x7’ sections of box culvert will be required to install a 12” ductile iron pipe and 20” steel casing. An additional 12 inch sanitary pipe will be rerouted at South Thompkins. Water lines will be rerouted at each crossing with inserta valves in manholes. The project will include the demolition and replacement of sidewalks and 3 rail wooden fences. Riprap will be provided for channel stabilization. The project will be performed in two phases with North Thompkins being phase 1 and South Thompkins being phase 2. Phase 1 (N. Thompkins) must be substantially complete and opened to traffic before closing traffic for phase 2. Traffic Control must be coordinated with Savannah State.

Division 31 -	Earthwork, Erosion and Sedimentation Controls.
Division 33 -	Utilities, Storm Drainage Utilities, Ponds and Reservoirs.