The Alligator Bayou Pump Station and current expansion is a critical component of the Jefferson County Drainage District #7’s (DD7) hurricane and coastal flood protection system. The Jefferson County DD7 covers 110 square-miles including the cities of Port Arthur, Groves, Nederland, and Port Neches, and unincorporated areas of Jefferson County. The DD7 oversees maintenance and operation of 281 miles of earthen and concrete lined ditches and outfalls, 36 miles of levee and seawall, and 20 pump stations with a combined capacity of 8.2 million gallons per minute (gpm).
The Alligator Bayou Pump Station project is an innovative approach tointerior drainage pump stations designedfor the Orange CSRM and located within the same geologic and coastal setting. The pumping station is rated at 1.5 million gpm (3,300 cfs) for interior drainage and to mitigate impacts of coastal flooding behind levees. The project encompasses modifications to existing levees and floodwalls, new levees and floodwalls, revetment and earth retention systems, erosion control, site access and levee crossing roadways, closure structures, a precast bridge and the pump station building. The pump station houses six 250,000 gpm (550 cfs) rated pumps and associated piping, control valves and gates, primary and backup power, electrical and SCADA systems.
LJA provided complete project management, planning, investigations, surveying, site layout, detailed hydrology and hydraulics, civil, geotechnical, structural, mechanical and electrical engineering analyses and design, cost estimating, and developed plans and specifications. LJA also provided FEMA and TDEM grant coordination, USACE Section 408 permitting, and environmental investigations and clearances. A value engineering study was conducted at 60% design. The project has been successfully procured and construction is on schedule for completion in mid-2020. LJA is currently providing construction management and inspection services for the project. A comprehensive project execution plan, quality management plan, safety plan, design analysis reports, plans and specifications, cost estimating for levees, floodwalls, intake, pump station, and other site improvements including a fuel storage building, and security systems.
Constructability challenges of building structures within coastal environment and adjacent to wide fluctuations in water levels required a temporary perimeter retention system to maintain the line of protection throughout the construction period. Stakeholders coordination included multiple local, state, and federal agencies, and local community representatives.
LJA supported the DD7 to leverage federal and state funding opportunities successfully expedited and secured the USACE Section 408 permit, and designed and competitively bid the project on schedule and within budget.
Contact Allen Sims, PE for more information.