Rapid growth in St. Tammany Parish in the past 20 years has led to a number of challenges related to public infrastructure including water, sewer, and drainage. Rapid urban sprawl during this time period coupled with decentralized and private sewer collection and treatment facilities contributed to a significant decline in surface water quality. As water quality in the Parish declined, flood risk increased as areas were developed without adequate stormwater controls (i.e., detention) or best practices for floodplain management. Lack of detention and loss of floodplain storage caused the capacity of existing infrastructure to be exceeded and flooding increased.
In 2014, DDG led a flood risk assessment of St. Tammany Parish waterways as part of a comprehensive watershed management study. DDG completed an analysis of repetitive loss / severe repetitive loss data from FEMA as part of identifying and prioritizing needed drainage improvements in the area. Thirteen different project concepts were developed that totaled more than 5,000 acre-feet of storage. For each project, conceptual designs and cost estimates were prepared along with estimates of flood risk reduction.
In addition, estimates of water quality benefits associated with these features were provided. Several of these projects are currently in the design phase and moving toward implementation.
As part of this project, DDG reviewed St. Tammany Parish’s drainage ordinance and made recommendations related to design criteria for new detention ponds. DDG also developed funding concepts for regional detention ponds that would include special taxing districts to curtail the effects of development.
The following is a list of each project:
• Abita River Sub Basin (Tammany Hills Drainage Improvements)
• French Branch (internal subdivision improvements)
• Labarre Street and Little Bayou Castine
• Meadow Brook Subdivision Improvements
• Bayou Chinchuba
• Cypress Bayou
• Sharp Road/Century Oaks Drainage Improvements
• Lapin Street/Quail Creek/Forest Brook Drainage Improvements
• Ben Thomas Road Regimen Detention Pond
• Eddins Canal/Whisperwood Subdivision/Northwood Village Drainage Improvements