This project primarily consisted of testing, rehabilitating and installing a new liner in a 135 m deep by 350 mm diameter bedrock well equipped with a 80 L/s 150 hp lineshaft pump. Extensive hydrogeologic testing was performed to document well hydraulics and aquifer parameters.
Testing included the completion of a standard step test, a pumping video, a flow profile and depth specific sampling. The pumping video and flow profiles were used to quantify water producing zones over the uncased borehole. This included installation of a 125 hp submersible test pump with the video camera and flow tool in the well and operating all simultaneously.
Water samples were collected at depth specific water producing zones identified in the pumping video and flow profile. Multiple sample pumps were installed in the well with the test pump to collect water samples from discrete zones while operating the well at its design flow rate. The lab analyses showed variations in water quality and apparent ground water age with depth.
A new 250 mm liner was installed in the well and grouted into place to seal off the zones of poor water quality identified in the depth specific sampling. In addition, the liner isolated decaying and heavily corroded sections of casing, thereby extending the functional life of the well.
The well was rehabilitated using strong acid and aggressive mechanical agitation. This included isolating specific portions of the well with inflatable packers and injecting the acid solution at high pressures and flow rates. Surging with air displacement methods and mechanical means was used to further develop the wells. Finally the well was airlift pumped to remove spent cleaning solutions, dissolved mineral, biological growth and sediment. These efforts were very effective at improving the performance of the well.
As with all Lotowater projects, detailed reports including graphs, as-constructed drawings and detailed liner and pump installation reports were provided to the client upon completion of the job.
The project was completed on budget and within the time frame and schedule outlined by the client. The work was successful at improving the performance and extending the functional life of the well. The client was very satisfied with Lotowater’s performance on this job.