March 11, 2009
St. Charles Parish East Bank Urban Flood Control Feasibililty Study
Non-Federal Sponsor: Pontchartrain Levee District
Project Description: The Study is the result of recommendations from earlier work by the U.S. Army Corps of Engineers (Corps) and others to evaluate the need and costs for flood control improvements in the area upstream of the new Lake Pontchartrain Hurricane Protection Levee. Alternatives that are currently being evaluated during this study include increasing the effectiveness of existing stormwater conveyance systems and the construction of new stormwater pump stations along the Hurricane Protection Levee.
Status: The work on the Study Report was originally split evenly between the Corps and the Pontchartrain Levee District (PLD). The PLD has completed developing the computer model for the existing conditions hydraulics and hydrology for roughly two thirds of the East Bank, with the remainder of the East Bank model having been developed by the Corps. The team has completed a comprehensive field investigation that includes establishing high order survey control, on the ground surveying of cross sections along conveyance channels and at drainage structures, blending of field survey results with aerial photography and Light Detection and Ranging (LIDAR) data, inventorying of building structures susceptible to flood damage, recording the experience and damage susceptibility of several large strategic industrial facilities that occupy a significant portion of the western end of the Study Area, cataloging the history of flood damage losses, obtaining historical rain and flood gage data, locating and measuring the multiple drainage structures that convey storm water through railroad and highway embankments, and gathering other pertinent information used to evaluate relative costs and benefits derived from the implementation of the various alternatives recommendations.
Pump Stations: The PLD has begun preparing Detail Design Reports and construction documents for each of four or five separate drainage pump stations on the East Bank of St. Charles Parish.
Trepagnier Pump Station: PLD completed hydraulic and hydrologic modeling of the Norco Basin at the west end of the Parish to determine the required capacity of the first major pump station. Working closely with St. Charles Parish Government, the Corps of Engineers, and private industry in the community, the 0.5 billion gallon per day Bayou Trepagnier Pump Station was designed, and constructed in less than eighteen months. The geotechnical components of the cofferdam and foundation were intensely analyzed due to the close proximity of this station to the Lake Pontchartrain Hurricane Protection Levee and the Bonnet Carre’ Spillway East Guide Levee. The station consists of three 160 million gallon per day diesel driven vertical drive pumps and one 35 million gallon per day constant duty electric pump. Mechanical bar screen cleaners are located at each intake basin. This station was designed and constructed in full adherence with Corps design criteria. The design was reviewed by the Corps technical and administrative branches to ensure compliance for inclusion in federal cost-sharing programs and as required by the current 404-B permit under which all of the pump stations are being constructed. Total cost on the Trepagnier Pump Station project was $8,500,000.
Cross Bayou Pump Station: PLD is obtaining the final Corps approval of the Plans and Specifications for the second of the four or five pump stations that will be built along the Lake Pontchartrain Hurricane Protection Levee. Hydraulics and Hydrologic modeling conducted under this East Bank Study validated programmatically the earlier work done by the Corps in determining flood flow rates to the pump station location. Local funding has been arranged to pay all costs associated with the pump station construction, in compliance with “work-in-kind” agreements between the PLD and the Corps. Using the advantage of a major connecting canal between the Cross Bayou Pump Station location and that of the next pump station to be developed to the east, the Corps was able to provide a range of acceptable capacity values for Cross Bayou, with the residual to be handled by the easterly pump station. This afforded the PLD the opportunity to design the station prior to the final version of the East Bank Study being accepted, while not over-building nor under-sizing the Cross Bayou Pump Station. The pump station and its related levee and floodwall work is being closely coordinated with the Corps during the design and construction of an adjacent drainage structure. All designs are in strict adherence with current Corps design and construction standards. A strong partnering relationship between the PLD and the Corps is ongoing and continues developing.
Conveyance Improvements: As the East Bank Study is completed, strategic drainage structures and canals that feed the various Hurricane Protection Levee pump station and drainage structure sites are being evaluated for needed improvements, additions, or replacement. PLD and the Corps are coordinating efforts by the Louisiana Department of Transportation and Development, the Louisiana Department of Natural Resources, St. Charles Parish Government, and local citizen organizations to provide the most effective plan for improving conveyances to the Hurricane Protection Levee.
Schedule: The St. Charles Parish East Bank Urban Flood Feasibility Study is scheduled to be completed in FY09. The Pontchartrain Levee District has completed its commitment to the initial phase of the Study, and has funds earmarked for completion of its tasks when released to do so by the Study team at the Corps. Funding has been secured at the Corps to complete the Study, and work is currently underway to complete this phase of the project. The second of the five pump stations is nearing design completion and is scheduled to be bid, along with its respective levee and floodwall improvements, in third quarter of FY2009. Currently the last details of the floodwall foundation design are being reviewed by the Corps for compliance with the newest Corps Design Guidelines. Construction is scheduled to begin in the third quarter of FY2009 and completed in the third quarter of FY2010. The Corps has continued its policy of support and assistance. Although all the funding has been procured locally to pay for the Cross Bayou Pump Station construction, the cost share for this and other East Bank Study construction is currently 65% Federal and 35% Non-Federal.
Funding History: The cost sharing for the original Feasibility Study was 50% Federal and 50% Non-Federal. Funding available for FY05 was approximately $1,000,000 ($500,000 Federal and $500,000 Non-Federal). Funding available for FY06 was approximately $2,000,000 ($1,000,000 Federal and $1,000,000 Non-Federal). Total funding for the Study is $5,400,000 ($2,700,000 Federal and $2,700,000 Non-Federal). In the aftermath of Hurricane Katrina, large portions of the Study were used in other projects, most notably by the Interagency Performance Evaluation Taskforce (IPET), with additional Federal funding being allocated to support those projects.
The cost sharing for the design and construction of the next major pump station, the Cross Bayou Pump Station is 65% Federal and 35% Non-Federal. At this time, no Federal funding has been earmarked specifically for the construction of any of the East Bank pump stations. The current estimated design and construction cost for the Cross Bayou Pump Station is $20,000,000.
Funding Requirements for FY 09: Funding for the original feasibility phase of the East Bank Study was to be 50% Federal and 50% Non-Federal. The Non-Federal funding for the original project has been allocated by the Pontchartrain Levee District for the effort through and including the Feasibility Study, although these funds will not all be spent until the Corps has completed its current task on the Study, which consists of developing the alternative conditions hydraulics and hydrology model and developing, modeling, and evaluating various alternative mitigative efforts. The expected funding requirements from last year for FY08 (not verified) and from this year for FY09 are:
FY08
Federal
Original $ 0
Special $ 500,000
Non-Federal $ 200,000
Total $ 700,000
FY09
Federal
Original $ 700,000
Special $ 0
Non-Federal $ 500,000
Total $ 1,200,000
Funding Requirements Outside the East Bank Study: During FY09, the Corps should complete the alternative mitigation portion of the East Bank Study. Upon release of that evaluation, work scheduled for FY09 will include survey, geotechnical investigation and engineering design of the recommended mitigation projects. The Non-Federal funds associated with this effort are allocated and ready to be spent as the Corps completes its alternative mitigation analysis. Upon completion of the analyses and design, funding will be required for construction of the mitigation projects. The expected cost of the mitigation construction is $ 40,000,000 total over the next five years.
Funding for the design and construction of the Cross Bayou Pump Station will be 65% Federal and 35% Non-Federal. In conjunction with the pump station construction, existing drainage conveyances will require hydraulic improvements. The extent of these improvements will be forthcoming from the Corps alternatives analysis. The schedule for this portion of the work on the project is the third or fourth quarter of FY09. Some of the key components of the analysis are available in advance of the formal completion date. The funding demands of the Cross Bayou Pump Station are $ 20,000,000.:
One additional major pump station is planned for the East Bank, dependent on the outcome of the East Bank Study. One or two minor pump stations will likely be necessary in the extreme east end of the Hurricane Protection Levee near the New Orleans Armstrong Airport. The funding requirements for all of these pump stations will begin in the fourth quarter of FY09 and run through the third quarter of FY10. The estimated total funding requirements for all these pump stations is $ 30,000,000.
Cross Bayou Mitigation Additional
Pump Station Alternatives Pump Stations
FY09
Federal $ 13,000,000 $ 500,000 $ 0
Non-Federal $ 7,000,000 $ 0 $ 0
Not Allocated $ 0 $ 2,000,000 $ 2,000,000
Total $ 20,000,000 $ 2,500,000 $ 2,000,000
FY10
Federal $ 0 $ 0 $ 6,000,000
Non-Federal $ 0 $ 0 $ 12,000,000
Not Allocated $ 0 $ 7,500,000 $ 0
Total $ 0 $ 7,500,000 $ 18,000,000
FY11
Federal $ 0 $ 0 $ 2,000,000
Non-Federal $ 0 $ 0 $ 4,000,000
Not Allocated $ 0 $ 12,000,000 $ 0
Total $ 0 $ 12,000,000 $ 6,000,000
FY12
Federal $ 0 $ 0 $ 2,000,000
Non-Federal $ 0 $ 0 $ 2,000,000
Not Allocated $ 0 $ 10,000,000 $ 0
Total $ 0 $ 10,000,000 $ 4,000,000
FY13
Federal $ 0 $ 0 $ 0
Non-Federal $ 0 $ 0 $ 0
Not Allocated $ 0 $ 8,000,000 $ 0
Total $ 0 $ 8,000,000 $ 0
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