Ground Water and Well Microbiology Testing: Coliforms and ^way Beyond
Stuart A. Smith, MS, CGWP OTCO Water Microbiology Workshop May 2011 © 2011 all rights reserved
Why am I here? I’ve been studying and advising on well problems for over 30 years – not to mention the pumps I pulled and set with my dad
It’s a living planet…
Coliforms Yes, but Life Beyond Coliforms • All aquatic environments (including aquifers – and not just the cavernous ones) are home to microorganisms • Some are home to things with legs • To at least 1000 meters in depth • Well into the stratosphere • In large numbers • Only a few interested in humans
Beyond coliforms, microbes … • Strongly influence overall water quality • Completely alter the aquifer matrices themselves • Corrode metal • Clog screens, intakes, orifices
Water Borne Diseases/Pathogens • Viruses: most commonly – Rotaviruses - gastroenteritis – Norwalk Viruses - gastroenteritis
• Bacterial pathogens – direct fecal contact • Protozoan pathogens (nonpathogenic ciliates, yes, pathogens rare) • Toxin generators (e.g., cyanobacteria) – rare in ground water
Bio-geo-physico-chemical …
All sedimentary rocks are subject to biological weathering activity… And are laced with microbes
Ordovician limestone, Springfield, Ohio
There is not much keeping bacteria from moving in the earth
Earth matrix
Pore spaces – conditions affect bacteria size, types, attachment
Microbe Transport
USGS
Head changes and catastrophic flooding can have serious effects, in this case, Hurricane Floyd, 1999, which severely affected North Carolina megafarm operations
Cape Fear River, Pender County, NC
1999 Floyd flood height
Karst: Cavernous rock allowing rapid movement and little filtration
Wittenberg University Speleological Society
Standing on a rock aquifer, which is protected from the surface by the clay glacial till visible in the background
In ground water, as elsewhere, most bacteria are growing attached in biofilms, some are in suspension as biocolloids, relatively few are freely “swimming” or planktonic in the water
Biological Attachment and Accumulation • Microorganisms tend to live in biofilms • Biofilms serve to accumulate materials • Think of obsessive-compulsive Uncle Fred who collects old car parts, papers, rare coins, rocks and coyote pelts – that’s a biofilm
Theoretical Drawdown
Observed Drawdown
Static WL Pumping WL
“backwater” “backwater” (hiding (hiding places) places) Long and narrow: stratification, sample representative?
Well Pumping WL
“rapids”: high velocity, biofilm buildup
Well as aquatic environment:
Bad Things Happening to Wells
Requirements of Indicator Organisms • present when pathogens present in water • absent in uncontaminated water • present in higher numbers than pathogens in contaminated water • better survival in water than pathogens • easy to analyze
Coliform Bacteria – Traditional Indicators of Fecal Contamination • bacteria in the family Enterobacteriaceae • generally include the genera Enterobacter, Klebsiella, Citrobacter, and Escherichia • present in the intestinal tract of numerous organisms but also native to aquatic
environments and soil
• gram negative, non-spore forming rods • ferment lactose with acid and gas production in 48 hours at 35 °C or having specific enzyme expressions
Biofilms and Biological Fouling
Types of Biofouling Boreline Inc.
Influenced by local environment: Sulfur slime (biofouling)
Efficient cloggers and accumulators
Can result in biofouling – sufficient accumulation to cause adverse effects
Iron Related And Manganese Bacteria (IRB)
Primitive Life Forms?
Rusticles: Examples of complex 3-D structures formed by microbes
Pump cannot pump water well
Biofouling in Seeps and Outfalls
Sulfur oxidizing bacteria Boreline Inc.
Oxidized zones fed by sulfide ground water (thorough biofuling)
Sulfate Reducing Bacteria, Heterotrophic Aerobic Bacteria, Slime forming Bacteria…
Sulfate Reducing Bacteria SRB are a group of anaerobic bacteria that generate hydrogen sulfide (H2S) This product can cause a number of significant problems in water systems Problems range from “rotten egg” odor to blackening of equipment, slime formations and the initiation of corrosive processes
Corrosion pump damage
Yellow Springs, Greene County, Ohio
Well sampling and analysis
Coliform sampling: Why do it? • Required legally! • Required why? Demonstrated indicator of hygiene and sanitation • On new wells: Has development (and later disinfection) effective? • Time to clean a well
Total Coliforms, Fecal Coliforms & E. Coli Total coliforms include bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste. Fecal coliforms are the subset of the total coliforms that are considered to be present specifically in the gut and feces of warmblooded animals. However, some can be found on vegetation.
Escherichia coli (E. coli) Of the groups of bacteria that comprise the total coliforms, only E. coli is generally not found growing and reproducing in the environment. Consequently, E. coli is a POSITIVE INDICATOR of fecal pollution and the possible presence of pathogens.
Source or Housekeeping? • TC and no E. coli : No confirmation of any dangerous condition – Could be sample issue, need to clean well, pathway for “dirt” (diagnose, fix, clean, chlorinate) • E. coli present: Look for a source and fix it! Chlorination may mask an issue • Occasional more subtle problems: TC, no E. coli, viruses or protozoa
Changes in Coliform Testing • Switch in the 1990s to enzymatic methods from previously used multiple-tube fermentation and membrane filtration • Preference (method-driven) for presence absence vs. enumeration • P/A and enzymatic methods mean that a technician, not a credentialed microbiologist, can run the test. • Loss of numerical information
Changes in Coliform Testing • Remorse A: Distribution system defined total coliform rule applied to raw water from water wells • Remorse B: Desire to recover numbers as a way of judging progress in disinfection actions • Commercial multiple well methods offer an option
Changes in Coliform Testing • Commercial multiple well methods offer an option: • Ohio Department of Health private well rules: return to 4 CFU/100 mL standard for private well sanitation (from < 1/100 mL (absent in P/A test) • Balloting of new Standard Methods Section 9225 “Differentiation of Coliform Bacteria” under way as we speak
Heterotrophic Interference Non-coliform bacteria which are better than coliforms at surviving in the environment may be present in the sample. Given a chance to grow, they may out-compete coliforms during analysis and may limit the analysts ability to detect coliforms or count them correctly.
Coliform Sample Holding Times • drinking water - 30 hours [40 CFR 141.21(f)] • surface/source water - 8 hours [40 CFR 141.74 (a)(1)] • greater chance of heterotrophic interference in untreated source water - hence, shorter allowable holding time ( so the reasoning goes … )
Are Coliform Tests “for real”? (Word to well drillers) • Sorry Charlie – Don’t blame the test • False negatives rare (
