O129-00-00-X002 Headwall Replacement

O129-00-00-X002 Headwall Replacement
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PROJECT DESCRIPTION 

In August 2019, the Flood Control District will remove and replace a failed headwall structure on the downstream end of a pipeline corridor channel crossing along HCFCD Unit O129-00-00, a tributary of Goose Creek. 

The project will repair 30-year old infrastructure and restore conveyance to the drainage channel as originally designed. The completed project will also ensure that the buried refinery pipelines remain functional across the channel. The project is expected to take up to 4 months to complete, weather dependent. 

The structural design of this sixteen foot tall headwall requires 12' wide continuous footings x 1.5' thick along the entire 146' of the headwall. For a two-month period following the demolition effort of the old wall, the project site will have a 16' deep by 30' wide hole in the ground extending the full 200' distance between East and West Hutto Blvds. This temporary excavation has been carefully designed with a safe layback slope and a protective shotcrete overlay that serves to protect both the workers and the integrity of the active pipelines buried in the crossing behind the new wall. Pedestrian and bicycle traffic will be routed to the far sides of East and West Hutto Boulevards as a safety measure during construction. 

Construction equipment for the demolition phase will operate from a temporary earthen dam constructed a safe distance downstream of the failed headwall. Ramps will be cut into the existing channel banks to allow from heavy equipment to access the earthen dam. Excavation equipment will operate from a position on the upstream edge of the excavation. Heavy timber mats will be placed on the ground to protect the buried pipelines from potential equipment track/wheel damage.