GSI helped the City of Fairview rehabilitate one of its wells, and then developed a comprehensive and innovative preventative maintenance plan to help keep the well functioning at optimal performance.

Background

The City of Fairview, Oregon, relies exclusively on groundwater as its water supply source. Using five water rights and five operational water supply wells, the City pumps groundwater from two major aquifers within the Portland Basin: the Troutdale Sandstone Aquifer (upper aquifer) and Sand and Gravel Aquifer (lower aquifer). In 2011, one of the City’s wells, Well 9, experienced significant declines in performance.

GSI’s Solution

To assess the cause(s) of the diminished performance, GSI conducted a series of exercises to review aquifer-trend data and water chemistry data, and visual inspections. Reviewing the specific capacity, water level, and water pumping data for Well 9 revealed that well interference was not causing the declined performance. A hydraulic test of Well 9 and two nearby wells verified that Well 9 aquifer conditions were not the cause of the decreased performance. Next, a quantitative and qualitative assessment of water chemistry confirmed that the cause was either biofouling or physical plugging. Further water sampling and laboratory analyses indicated that biofouling was the likely cause of the diminished performance. The analyses indicated water chemistry differences between the shallower and deeper aquifers make the Well 9 more conducive to biofouling. This was verified with a downhole video, prompting a mechanical redevelopment and chemical treatment of the well.

To facilitate downhole video equipment during investigation and during future maintenance activities, GSI installed a 2-inch-diameter PVC access port in the wellhead. This allowed a small-diameter fluid impulse generation tool to be put into the well without removing the pump (but with small adjustments to the pump alignment), saving the City money and time.

Lastly, GSI developed an innovative/comprehensive Operations and Preventative Maintenance Plan (OPMP) to extend the life of the City’s groundwater asset(s). Wells are best maintained by a preventative, rather than a reactive, maintenance program. The OPMP provides criteria that allow the City to evaluate changes in performance of the pump, motor, and well, and to plan for maintenance of the water supply system. It also allows the City to have improved reliability of its water supply and extends the life of the groundwater as a water system asset.

“ The innovative approach developed to allow Interim rehabilitations using Air Shock ™ Fluid Impulse Generation techniques without removal of the pump is endorsed by SWS and is a concept that we will recommend to other clients who wish to economically protect their groundwater assets.  Identifying cost saving approaches to responsibly prolong the period between focused well cleanings for our clients is central to providing outstanding customer service”. – Kriss Schneider, Schneider Water Services (SWS)