Effectiveness of a Mobile Chlorine Gas Generator as a Treatment for Biofouling in Relief Wells

Abstract

Dams and levees are a critical component of the contingency plans required to provide sufficient potable water to support the population during episode of droughts. However, microbial growth and subsequent encrustation that builds on the relief wells have been shown to build unwanted pressure within dams and levees when left untreated. This biofouling can lead to malfunctions of the wells, especially in dams that are under stress from drought-induced low water levels. Oxalic acid has been used as the most common alternative to alleviate hydrostatic pressures when encrusted biofouling occurs. The Water on Wheels (WOW) Cart Relief Well Sustainment (RWS) system was designed to function as a more cost-efficient and targeted alternative by allowing the use of a portable chlorine generator. It electrochemically converts sodium chloride to sodium hypochlorite, in a controlled and monitored manner, allowing for the use of either chlorine gas or chlorine gas dissolved in water. The Grenada Dam is a man-made dam that supplies Mississippi, as well as a habitat to various local species. A previous study in the area showed how the effects of drought and biofouling altered the coastline and performance of the dam, affecting the local ecosystem and water supply. Scheduled treatments in this area are conducted to upkeep the dam, as well as monitor the water levels that might indicate a rapidly emerging drought event. Various relief wells in the Grenada Dam region were treated using either oxalic acid or the chlorine produced by the WOW Cart RWS system alternatively. Initial field test results have shown that the WOW cart system reduces the microbial growth just as effectively as current conventional methods of treatment, while minimizing the associated costs. When tested against oxalic acid, it was found that the relief wells treated with the cart reported no detected level of growth for a lesser cost and adequately relieved the pressure on the relief wells to allow proper water-flow and usage. Therefore, the WOW cart provides an easier and more efficient alternative to maintain the functionality and ecosystem of the dam, making it readily prepared for any dry spell that might affect the area. Future studies will be developed to determine Standard Operating Procedures (SOP) that will focus on treatment time and condition.