Widespread flooding of a dense urban area is a rare event in North America. Thus, little information is available regarding the impact of such natural disasters on buried infrastructure systems. In the aftermath of the 1997 Red River flood, which resulted in the flooding of Grand Forks and portions of the city of Winnipeg, Canada, it was suggested that the effect of surcharge on the internal pressure loading in vitrified clay gravity pipes resulted in extensive cracking. When the water receded, loss of bedding support also was suspected to occur. However, when attempts to collect data were undertaken more than a year after the water receded, the actual impacts of the flood on the deterioration of the sewer collection system were difficult to clearly identify. Hurricane Katrina brought the most severe flooding in modern US history, including the submergence of the City of New Orleans, a one million strong major metropolitan area. At present, there are no proven tools for assessing the damage sustained by buried infrastructure networks in the 90,000 sq. mile hurricane-struck area.
This award will focus on collecting time-sensitive data in areas where the water has receded such as Slidell, Louisiana and Biloxi, Mississippi. Data to be collected includes visual inspection of the current condition of underground piping systems using closed-circuit television (CCTV), damage to surrounding above ground structures and infrastructure, maximum height and velocity of the wave front, the depth and the length of time the water flooded the impacted area, and the condition of vertical buried structures such as manholes. Other data to be collected include the type, diameter, material and age of the pipeline networks that will be inspected and information regarding recent rehabilitation activities such as pipe lining. The award seeks to identify damage mechanisms due to non-traditional loading associated with hurricane flood waves and long term flooding. Studied areas will be carefully chosen to include areas recently CCTVed (or subjected to other condition assessment survey methods) to allow the condition before and after the hurricane to be quantified. While physical inspection will be limited to sanitary and storm sewer collection systems, data will be also collected on the water and natural gas distribution systems in the studied areas.
The time-sensitive data collected in this study and the knowledge gained regarding the failure mechanisms associated with hurricane-related loading will serve as a basis for enhancement of current design and construction practices. Quantitative data on the damage suffered by selected underground systems will allow for better assessment of the damage to the wider hurricane-struck area. Thus, the information gathered and the knowledge gained under this study will contribute to the reconstruction efforts of buried infrastructure systems in the Gulf Coast area and to the prevention of flood-related failures in the future.
