State Water Resources Research Institute Program (WRRI)

Details for Project ID 2006LA46B, 2006

Assessment of the Impact of Hurricane Katrinas and Ritas storm surges on the Southern Hills Aquifer System in Southern St. Tammany and Tangipahoa Parishes

Institute: Louisiana
Start Date: 2006-03-01 End Date: 2007-02-28
Total Federal Funds: $19,855 Total Non-Federal Funds: $49,216

Principal Investigators: Thomas Van Biersel, Douglas Carlson, Loyd Milner

Abstract: On August 29th and again on September 21st, the heavily developed areas adjacent to the north shore of Lake Pontchartrain between the cities of Slidell and Madisonville were flooded by hurricane surges moving saline water from the lake onto dry land. Many residences and businesses that were built close to the shore were damaged or destroyed by the surging waters. Most of those residences and businesses obtained their drinking water from wells drilled nearby the buildings. As the structures were damaged or destroyed, the wells were similarly damaged resulting in open conduit between the surging lake water of non-drinking water quality and the aquifer. Saline lake water and surface contaminants were introduced into the aquifer, impacting an important source of drinking water supply. The goal of the proposed research is to assess the short and long-term implications of hurricane Katrinas and Ritas storm surges on the shallow aquifer system along the north shore of Lake Pontchartrain. The proposed research focuses on obtaining information that could be used to assess the existing damage to the aquifer. A further goal would be to as monitor ongoing improvement through property owner pumping, and the risk of possible additional long term contamination from infiltration of lake water in the subsurface. We propose to collect geophysical soundings and profiling, and groundwater samples to determine the depth of the saltwater front in the subsurface. These samples would also assess the direct impact of saltwater intrusion through damaged water supply wells. The geophysical soundings would be used to assess the presence of saline water migrating in the subsurface. Ground water samples collected from water supply wells would be tested for common compounds found in ground water, as well as waterborne bacteria. The proposed research will provide public health officials with information identifying water supply issues that otherwise would not be investigated. They will be able to assess whether a long term regimen of testing private wells may be necessary to protect the public in the portion of their parish that was affected now, and potentially will be affected in the future by storm surges. This information will also be useful in determining whether wellhead protection is needed for these water wells.