Water Well Journal
Issue link: http://read.dmtmag.com/i/705618
B acteria occur naturally in the bot- tom of the deepest part of the ocean and at the tops of the tallest mountains—they are a universal entity. So despite what you or your cus- tomers have read online, bacteria are naturally occurring within the subsur- face and in groundwater. There is no specific geographical occurrence. Mi- crobial problems and impaction of wells can be an equal opportunity problem worldwide—there are no bacteria-free sources of groundwater. Why am I bringing this up in an arti- cle on rig disinfection? The well indus- try is filled with myths and legends, and one of the common misapplications of science is iron bacteria are transferred from one well to another by the well driller. The almost universal occurrence of iron bacteria has not helped this argu- ment, nor have we as an industry ade- quately responded. Aside from equipment used on envi- ronmental sites or wastewater-related sites, there is a limited potential for the infection or transference of bacteria from one site to another. Research in our lab shows us the bulk of the biofouling problems develop from bacteria native to the site, aggravated by inadequate development or by poor maintenance practices. As a borehole is drilled, there is a lot of co-mingling of different soil and rock layers, water qualities, as well as intro- duced fluids and resulting heat, energy, and pressure from the drilling activity. Couple this with the fact the borehole is offering an increased amount of surface area for attachment and a "mixing bowl" for concentration of water chem- istry and microbiology. Add in flow, aeration, and even minor variations in water chemistry (within the producing zones) during pumping and you have quite a recipe for problems. This is where strong, effec- tive, and multiple development tech- niques help to set the stage for good well health by flushing the influences out of the well while stabilizing flow into and through the well system to reduce the potential for impeded flow or stagnant zones. Iron Bacteria One of the most common bacterial contaminants mistakenly attributed to "contamination" by drill rigs is iron bacteria. Iron bacteria are a ubiquitous problem in our industry and there are a lot of myths and misunderstandings about its occurrence. Iron oxidizing bacteria, commonly referred to as iron bacteria, are a natu- rally occurring, generally aerobic group of bacteria that use iron as an energy source. Typically these bacteria secrete an iron-oxy-hydroxide byproduct that can cause fouling of well screens and pump intakes, and affect water quality, impacting both color and total iron content. Of the group of iron bacteria, the most common is Gallionella. Over the past five years, our lab has identified Gallionella in 47% of troubled well samples. Although there are "iron re- lated bacteria" presence/absence tests, Gallionella are stalked bacteria easily identifiable microscopically. The presence of iron bacteria is not a regular water quality test although it is a common fouling mechanism. Often, iron bacteria are identified more from their byproducts, including the organi- cally mobilized iron found in long stalks and iron oxide entrained biomass. The term "IRB" or iron related bacteria stems from the BART test for iron bac- teria presence and not iron reducing bacteria, a common misunderstanding. Iron reducing bacteria are, in fact, rare in groundwater. Gallionella are a naturally occurring bacteria found in a variety of aquatic en- vironments, including aquifers. They are known to migrate beyond the well sys- tem and can foul transmission lines and filter systems. Iron bacteria are common to shallow alluvial well systems, even though they can be found in deeper settings. Wells completed with or containing low carbon steel are more vulnerable to iron bacteria problems, although stainless steel completions can be impacted as well. Areas of active cor- rosion, aeration, or cascading water can help to stimulate growth and propaga- tion of these organisms. The common occurrence of iron bac- teria aids the myth of contamination. Its occurrence is often used as an indication of contamination, although in reality few states go after the real problem: use of cheaper materials for completion and poor or inadequate maintenance. Best Practices Aside from improving the under- standing of bacteria in groundwater, how should we as an industry respond? The simple answer is to take a more proactive stance, removing ourselves from the conversation of blame. Develop a "best management practice" for your team and ensure all equipment is properly maintained with an active housekeeping program. As a first step, power-washing all well-related equipment with potable water is necessary. The goal of such ef- forts is the removal of "bulk material." SCHNIEDERS continues on page 20 PVC casing and stainless steel screen awaiting installation at a job site. The materials are banded together and kept off the ground to limit influence. Photo courtesy of Ned Marks, Terrane Resources, Stafford, Kansas. Twitter @WaterWellJournl WWJ August 2016 19 It averts risk while increasing the professionalism of the industry. By Michael J. Schnieders, PG, PH-GW RIG DISINFECTION