Cesspool or Septic System, Neither are Appropriate

Cesspool or Septic System, Neither are Appropriate

Part One:  History, Nutrients, and Pathogens

  

Richard H. Bennett Ph.D

Applied Life Sciences LLC

Cesspools and septic systems are antiquated and inappropriate waste management technologies.  Both enjoyed the nod of the Department of Health since 1915!!  It is more than incredulous that the EPA (Environmental Protection Agency) and the Hawai‘i Department of Health consider these holes in the ground to be acceptable waste management in 2018.  Given the vast scientific literature and public information, one would expect that in 103 years, we would have made the initiative, akin to putting a man on the moon to clean up our, ah…wastes. Instead, we bury the tank or the pit placing the matter "out of sight and out of our political minds." 

The development of Hawai‘i since 1915 was “greased” by simple ignorance, that in effect said, "it's ok it's all underground."   This naive attitude ignored the wet stinky areas surfacing just over the buried tanks.  It was Irma Bombeck who famously titled her book “The grass is always greener over the septic tank” (1995).  Septic system failure was so common that it made its way into our urban folklore.

According to research by University of Hawai‘i Professor Roger Babcock, about one-third of the onsite waste systems on Oahu have failed (1).  Cities in Florida will spend millions of dollars to close septic systems because they contaminate ground waters and the ocean.  So why pray tell, is the State of Hawai‘i advocating a waste system the is hundreds of years out of date and known to pollute? 

Like ignoring the termites in the wood foundation, the State and the Federal Government allowed this happen.  The problem is not new by any means.  Ultimately State Policy is to blame, as are the people who administer it.   No wonder the homeowner is livid at the specter of the high cost of conversion to a septic system.  For many the state told them less than ten years ago it was perfectly ok to install a cesspit.  We watched an "approved” cesspit installation just a year ago and if they sell the home tomorrow, they may be forced to upgrade.

Old Technology

The Frenchman Mouras invented the first septic system in 1881.   The history timeline notes US septic systems became very popular and inexpensive in the post-WWII era.  Septic failures after a decade of use were common the 1960ʻs.  The 50ʻs and 60ʻs was a time of the enormous population growth in the West and septic systems were the cheapest option for developers.  It was then groundwater contamination tainted water all over the country and sewer systems advocated to protect water resources. 

In high-density urban areas, cities began building wastewater treatment plants.  The plants are expensive and without, the assistance of large grants and loans from the EPA, more homes might still be on septic systems.

Schematic cesspool (left), water, and constituents leach downward.  Septic leach field (below) works similarly depending on soil type and depth (3) (a).

Waste Treatment Plants

The modest size wastewater treatment plant Kealakehe in Kailua-Kona processes about two million gallons of sewage per day.  It was constructed with EPA funds to bring sewer service to the multitude of homes and businesses along the oceanfronts of Alii Drive.   After Los Angeles and San Francisco spent over four billion federal dollars for municipal waste treatment systems in the 1990ʻs, the attitude in Congress was “no more, let the states fend for themselves”.  That brings us full circle back to our conundrum.

In the ensuing years, the septic system became the only option for regions that did not have or afford centralized wastewater treatment plants.  Today approximate 25% of US homes use this 19^th-century technology.

Indeed, the upfront cost was the primary concern, but the downstream costs of surface water and groundwater pollution require expensive mitigation to remain in compliance with the US Clean Water Act, were largely ignored.  Furthermore, the state failed to acknowledge the cost to the stateʻs economy as tourists encounter polluted beaches, microbial hazards, algal blooms and murky waters.

Under pressure from local activists and the EPA, the state has prioritized high-risk areas targeted for septic system installation.  Many of these regions are near the shore such as Puako, Hawai‘i or Hanalei Kauai and upslope from drinking water wells in Makawao, Maui.

We only need look back in time, to the shores of California and see that septic systems are not the solution.   Near Stinson Beach California, very high-value homes dot the hillsides.   Most of the locations have soils for the installation of a septic system and leach field. Standford University conducted near shore groundwater research at Stinson Beach and found nitrate and fecal indicator bacteria in the water contained in soils and sand (2).  Simply stated the septic systems removed some fecal indicator bacteria, but the nitrate was largely not mitigated.   This California problem is yet further documentation that this magical attribute some officials call "soil treatment” cannot be assured.

The graph shows as more water is added to the wastes the more constituents like virus move through toward groundwater. The effect is profound on well-drained ground.

In fact, the research community published a multimillion-dollar study that says, we cannot predict how soil treatment will work.   We cannot provide predictive evidence that any given system will remove or attenuate microbes and chemicals of concern. The variables are too complicated and site-specific to allow for accurate performance predictions. They state, “hydraulic loading rate appears to be more important than soil texture or soil depth within the first 30-60 cm (1-2 ft.), although both soil depth and texture remain important variables” (3,16).  In regions of the state where the soil is rare, and wastewater loading rates are reasonable to high, septic systems will fail to provide even modest treatment and allow rapid leaching to groundwater and the sea.

The Nitrate is Ours

Rest assured groundwater contamination with nitrate is a concern.  Drinking water with elevated nitrate is simply not good for public health, especially for infants.  Septic systems and cesspools add human waste nitrate to the ground and underlying ground waters.  Nationwide,  agricultural fertilization of irrigated farms is the primary source of nitrate.  In rural areas without irrigated agriculture or animal feedlots, the nitrate source in groundwater is home wastewater systems.

Until relatively recently we have not had to tool to look at groundwater nitrate with greater refinement.  The work of Dr. Meghan Dailer at UH Manoa is compelling. Dailer and coworkers collect nearshore limu or marine plants and measure the isoptic forms of nitrate to arrive at what is called the delta 15 N (δ 15N). The assay measures the stable isotopes of nitrogen. The expression is the ratio of the two isotopes.  Marine plants near the more urban shores on Maui and Hawai‘i Island have a higher value.  These signatures are indicative of human sourced nitrogen.  The most of the undeveloped beaches of N. Maui have a much lesser signal (4).

For a couple of decades, people have openly speculated about nitrogen in groundwater and nearshore oceans.  Since there was no apparent source like a feedlot or dairy, the conclusion erroneously drawn is the elevated nitrogen was the natural background state.  This assumption makes little sense in the light that nitrogen is a limiting nutrient in most ecosystems and highly conserved (5).  The nitrogen isotope studies confirm the nitrogen is not spilling from the ecosystem.

A Better Smoking Gun

For some time we have been looking for better tracers in human wastewater.  Researchers explored testing for caffeine, nicotine, and pharmaceutical drugs.  All have limitations, and many degrade too quickly in sewage and the environment and thus not reliable.  However recently a nearly ubiquitous household compound emerges as a valid chemical indicator of human wastewater pollution.  The nonnutritive sweetener Splenda or sucralose is a sucrose or table sugar reacted with chlorine.  It is very sweet but wholly indigestible and very stable throughout sewage treatment.  The Yale researchers declared it an ideal tracer and as we might expect it is an excellent marker for wastewater tracer in the environment (6).   Field research validates Sucralose as a tracer for groundwater contamination from septic systems (7). Analysis of sucralose in water is complicated, and few labs have the instrumentation.

What about the germs?

This next statement will come as complete heresy. Human fecal waste from healthy persons is not teaming with pathogens just lingering for an opportunity to start the next epidemic or for that matter put a household at risk.

The Human Microbiome Consortium (8) stated in 2014, “This overall absence of particularly detrimental [fecal] microbes supports the hypothesis that even given this cohort’s high diversity, the microbiota tends to occupy a range of configurations in health distinct from many of the disease perturbations studied to date.”  In simple terms, the feces of a large cohort of healthy persons is NOT populated with disease pathogens.

 Just because governments monitor something called Fecal Coliform and document its presence does not mean it indicates genuinely hazardous pathogens are present.  The fecal coliform is a 100 plus-year-old and arbitrary distinction that does not correlate with the presence of pathogens. Many agencies no longer use this test.  A more appropriate measure of microbial water quality is the typical bacteria E.coli.  Most E. coli are harmless, yet some strains like O157:H7, the infamous Jack in the Box undercooked hamburger strain is potentially lethal.   It is a typical resident in feedlot cattle feces and not humans.

 Science validates the monitoring of E. coli for drinking water safety assessment. Since we drink volumes of water, this allows the consumption of millions of bacteria at a time.  The “bad” E. coli have a minimum infective dose of about one million.  Consume less than that and disease is not likely.  

It is not the bacteria that is a concern; it is the virus. For example the infamous Cruiseship Virus, Norwalk has a minimum infective dose of less than 10.  Moreover, victims of this "24-hour stomach flu" will shed trillions of virus particles every day for a week or more.  It is the enteric virus that presents the real hazard in drinking and recreation waters. (9,10).

The graph to left depicts virus fecal shedding in a person infected with Norwalk virus. Maximum shedding about one trillion virus per day.

The question remains, how well do septic systems remove or otherwise attenuate virus? This question is exceptionally complicated .question.  It depends on the soil type, its pH, the ionic charge of the virus and the soil, the number of virus and the volume of water flushing through the system daily and significant pulses of water, as on laundry day.  The big picture answer is virus do breakthrough (11).  The risk to drinking water is more likely when the density of septic systems exceeds a few homes per acre of land in a square mile. (12). In West Hawai‘i, housing densities range from one to 5 home waste systems per acre and far away exceed the EPA recommended density.

 The graph to the right shows that significant virus survives in warm wastewater for over 140 days. Ample transit time to reach the shallow ground and nearshore waters (13).

The research suggests virus in the ground and water survive weeks to months depending on the conditions (13).  A key variable is the rate of movement. Fissures in rock and lava do allow for the very rapid flow of water and all suspended in it(14). However, all drinking water in municipal systems must disinfect to EPA standards. The process virtually eliminates the risk of infection.  Oceanwater, in contrast, appears to be a higher risk of exposure.  Fortunately, it is more hostile to the virus, and the combined influences of temperature, sunlight and predatory marine biota inactivate virus in a period of days to weeks again depending on site conditions.  However, the presence of this virus in urban recreation beaches is frequent (15).

Conclusion Part One.

The science is unequivocal; septic systems offer no substantial improvement of cesspools as both systems are antiquated and were never intended to isolate or attenuate wastewater nutrient or microbial constituents.  In very select sites with true and deep soils, some attenuation may occur but is incidental if not accidental.  In tropical environments with limited or no soils combined with high rainfall, septic leach field performance is a matter of speculation and not science.

 In the current time, it is more than unrealistic to promote expensive transitions to septic systems when the protection of groundwater and nearshore waters are negligible and the costs extreme.  It is most advisable to step back, set goals and apply the objectives of the of state and federal policies.  For the health of the people and their economy, we are compelled to implement human waste control strategies that meet and exceed those goals.  The lowest common denominator may be the least costly, then again we get what we pay for in the long run.

Coming soon Part Two,   Alternatives: Thinking Way Outside the Box

REFERENCES

1.     Babcock, Roger W., et al. “Condition assessment survey of onsite sewage disposal systems (OSDSs) in Hawaii.” Water Science and Technology 70.6 (2014): 1083-1089.

2.     De Sieyes, Nicholas R., et al. “Submarine discharge of nutrient‐enriched fresh groundwater at Stinson Beach, California is enhanced during neap tides.” Limnology and Oceanography 53.4 (2008): 1434-1445.

3.     McCray, J. E., et al. “Quantitative Tools to Determine the Expected Performance of Wastewater Soil Treatment Units.” Water Environment Research Foundation, DEC1R06 (2010).

4.     Dailer, Meghan L., et al. “Using δ15N values in algal tissue to map locations and potential sources of anthropogenic nutrient inputs on the island of Maui, Hawai ‘i, USA.” Marine Pollution Bulletin 60.5 (2010): 655-671.

5.     Vitousek, Peter M., et al. “Nitrogen and nature.” AMBIO: A Journal of the Human Environment 31.2 (2002): 97-101.

6.     Soh, Lindsay, et al. “Fate of sucralose through environmental and water treatment processes and impact on plant indicator species.” Environmental Science & Technology 45.4 (2011): 1363-1369.

7.     Oppenheimer, Joan, et al. “Occurrence and suitability of sucralose as an indicator compound of wastewater loading to surface waters in urbanized regions.” Water Research 45.13 (2011): 4019-4027.

8.     Huttenhower, Curtis, et al. “Structure, function and diversity of the healthy human microbiome.” Nature 486.7402 (2012): 207.

9.     Yates, Marylynn Villinski, Charles P. Gerba, and Lee M. Kelley. “Virus persistence in groundwater.” Applied and Environmental Microbiology 49.4 (1985): 778-781.

10.  Gerba, Charles P., et al. “Failure of indicator bacteria to reflect the occurrence of enteroviruses in marine waters.” American journal of public health 69.11 (1979): 1116-1119.

11.  Scandura, J. E., and M. D. Sobsey. “Viral and bacterial contamination of groundwater from on-site sewage treatment systems.” Water Science and Technology 35.11-12 (1997): 141-146.

12.  Yates, Marylynn V. “Septic tank density and ground‐water contamination.” Groundwater 23.5 (1985): 586-591.

13.  Kauppinen, Ari, and Ilkka T. Miettinen. “Persistence of Norovirus GII Genome in Drinking Water and Wastewater at Different Temperatures.” Pathogens 6.4 (2017): 48

14.  Allen, Martin J., and SMs Morrison. “Bacterial movement through fractured bedrock.” Groundwater 11.2 (1973): 6-10.

15.  Love, David C., et al. “Human viruses and viral indicators in marine water at two recreational beaches in Southern California, USA.” Journal of water and health 12.1 (2014): 136-150

16.  Yates, Marylynn V., Scott R. Yates, and Charles P. Gerba. "Modeling microbial fate in the subsurface environment." Critical Reviews in Environmental Science and Technology17.4 (1988): 307-344.

Photo / Illustration Credits

a.      https://www.aero-stream.com/septic-system-types.html