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Chalona Drive at 20 Arpent Canal

St. Bernard Parish, Louisiana

Bridge Replacement

Installation:

Spring 2020

Technical Description:

• CON/SPAN® O-Series® Bridge System
• Span: 34’
• Rise: 7’-2½”
• Length: 43’-1¾"

On August 29, 2005, Hurricane Katrina brought wind and high velocity floodwaters that caused scouring, erosion and material loss to multiple canal crossings throughout St. Bernard Parish, Louisiana. Debris deposits accumulated throughout the Parish waterways, contributing to the excessive sediment deposits at the crossings. After the flood waters receded, the structures were inspected and 51 of St. Bernard Parish’s existing culverts were declared problematic. The Chalona Drive crossing at 20 Arpent Canal was eligible for full replacement under FEMA's Hazard Mitigation Grant Program (HMGP). After a federally declared disaster like this one, the HMGP provides funds to implement hazard mitigation measures.

“In order to meet this requirement, the facility must have been damaged by 50% or more of the full replacement value," added Courtney Kall, P.E., Project Manager, with H. Davis Cole & Associates, LLC, the city's program management team. "Since these crossings were eligible for full replacement, HMGP funds were made available to replace the crossings."

A 34’ x 7’-2½” CON/SPAN® O-Series® Bridge System, 43’-1¾" in length, was selected as the best bridge replacement option because the clear span was able to provide a waterway area sufficient enough to discourage future debris buildup and flooding. Additionally, the buried arch design allows for existing utilities to remain accessible for future maintenance, while the fully precast arch and wall system decreased construction time. The structure itself was installed in a single day.

During the construction process, Contech Engineered Solutions worked with St. Bernard Parish and Hard Rock Construction in order to problem solve a challenge associated with the designed skew in the CON/SPAN system. While skews in a precast structure typically originate from the need to capture the appropriate waterway area, this project solution required a skew for the additional reason of avoiding utility conflicts. Three high pressure gas lines are buried alongside the structure and run parallel to the roadway. The arch units and, more impactfully, the wingwall system would have interfered with these gas lines if not for the skewed design. Relocating these gas lines was not possible because of the strict budget for this project allocated through FEMA funding. As such, a skew was the best solution to minimize conflicts with the existing gas lines and allowing this project to move forward.

In order to remove water from the construction zone, Hard Rock Construction, the project's contractor, utilized a wise tactic. Using excavated material, the contractor was able to shore the inlet and outlet ends of the waterway, effectively blocking the flow of water to keep it from entering the construction zone. To eliminate any damming, the contractor built a drainpipe system on the inlet end that captured the appropriate volume of flow and carried it away from the construction zone. Despite a small investment on the front end, this approach saved the project a lot of time and money.

Overall, the CON/SPAN system provided St. Bernard Parish with a high-quality precast elements and a proven design backed by more than 10,000 successful installations worldwide.

Technical Description:

• CON/SPAN® O-Series® Bridge System
• Span: 34’
• Rise: 7’-2½”
• Length: 43’-1¾"

800-338-1122 | www.ContechES.com

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