Solving Total Coliform Failures with Well Rehabilitation and Maintenance

As water systems age deterioration is an almost inevitable consequence resulting in loss of production and water quality deterioration. In groundwater systems water wells will experience biofouling and deposit buildup depending upon many factors. Total Coliform occurrences in water systems including water wells are not uncommon. Total Coliforms are recognized as being naturally occurring in subsurface environments and become part of biofilm growth that is enhanced when wells are operated. As wells become significantly clogged it is often evidenced by loss of production and deterioration of water quality. Monitoring specific capacity does not detect the early growth of bacteria until the clogging material is extensive and hardened.  It is very important to establish “Time Based” removal of deposited material. Deterioration of water quality is often manifested by discolorations, elevated HPC’s, Detection of Total Coliforms. Pumped water samples from water wells are subject to the limitations of percentage attached (sessile) vs. detached (planktonic) when performing bacterial tests. The problem with putting confidence on bacterial numbers is the variable nature of percentage attached vs. detached. While operating water wells and water systems many factors can contribute to detachment of normally attached material resulting in discolorations, taste and odors and increases in bacterial numbers.  During the past 15 years a time based approach has been very effective at maintaining wells capacity and quality since deposits in water wells are much more effectively managed by removing them when they are soft and not very extensive. Effective rehabilitation and maintenance can be very effective at maintaining peak efficiency as well as maintaining more consistent water quality and minimizing the detection of Total Coliform during sampling from pumped water samples. Reducing total lifecycle costs can be significant with proactive preventive well maintenance.