The impact of climate change on septic systems is a topic that has come up a couple of times in the past year during the workshops we’ve conducted. This is a difficult question, because neither of us has a crystal ball and can predict what will happen in the future. However, we can discuss a couple of long-term trends being talked about and provide some insight to what may happen if they continue.

Overall temperature on a global scale is increasing. This is melting polar ice and raising the sea level. This will continue if the current trend continues. For us in Minnesota, this seems far off both in distance and in time, so we are more worried about how cold it is this winter and how much snow we will receive. This is related to the day-to-day weather challenges we always have to deal with. However, if we lived in a coastal area, the threat of overall sea level rising would get our attention.

COASTAL THREAT

Onsite systems are numerous in low-lying areas along the East Coast and Gulf Coast. Conventional gravity-to-drainfield or pressure-to-drainfield systems assume a certain separation distance between the bottom of the drainfield trenches and the seasonal high-water level to provide for treatment. As the water table rises, the separation distance will diminish, so these systems will operate less efficiently and, in the extreme cases, become inundated by the high water levels and flood out. As providing separation distance becomes more difficult, other technologies will be considered to either raise the level of the system or provide more treatment before being discharged to the environment.

Another aspect of overall warming is that it will change not only the amount of precipitation but also how that precipitation occurs. It is projected that precipitation in humid regions will not only increase but will involve more large precipitation events; think intense summer storms and large snowfall events in the winter. If this occurs, even we in Minnesota are not off the hook from the consequences.

With increased amounts of water, lake levels rise, both on inland lakes as well as the Great Lakes, and the issue with seacoast areas plays itself out on our lakeshores. Rising water tables interfere with our onsite systems, making it necessary to move to other technologies to provide adequate wastewater treatment.

THE COMING FLOODS

Another aspect of increased precipitation events is a corresponding increase in localized flooding events. So systems located in or near floodplains would likely be subjected to an increase in flooding frequency and homeowners needing to deal with fixing or repairing flood damage. Similarly, larger flood events will probably mean more damage to the systems, requiring total system replacement. In any event, the cost of the systems would increase and probably drive a move again to different technologies to address the problems.

Research is underway to determine the impact of overall increasing temperatures on soil treatment of different contaminants of concern. As temperature increases, overall respiration of soil organisms increases, so less oxygen is available in the soil profile. Here the researchers feel the effects may be mixed in nature.

Less oxygen would mean the potential for more denitrification, which would be good from a nitrogen standpoint, but there would be less treatment potential for pathogens and some other contaminants. Then, of course, how does this change with the interaction with precipitation? So it is a difficult research problem. This too would indicate the need to move to more advanced technologies, though, to handle more of the treatment on the front end rather than relying solely on the soil.

RAINWATER REUSE

In addition to Minnesota, we do quite a bit of work in Arizona and New Mexico. In the desert regions, the picture is different, but the way we deal with the change may be similar. Under the current climate change scenario, the Southwest will have more and prolonged periods of drought along with temperature increases. In addition, precipitation events when they occur are likely to be more severe; large amounts of localized rainfall in a short period of time.

Prolonged drought periods will push the move already underway in these locations to capture, treat and reuse water leaving the house as sewage. This includes separating out not only the toilet waste from the laundry and bath, but also separating urine from the component that includes the feces. Initially the treated water will be used for things like landscape irrigation. But if conditions persist or worsen, we will probably see the use of more systems that recycle water back into the house to flush toilets. Again, the conditions will make a move to more advanced technologies more likely and more prevalent.

Additional intense precipitation events will also put stress on treatment systems from washouts and flooding. Additional precautions will be needed to protect systems from excess water running onto the site and taking the systems out.

We cannot say how quickly these conditions will occur. But no matter your role in the industry, planning now in anticipation of the problems is not only prudent but good business. Being educated and informed about advanced technologies and being able to work on them is a sound track to take for the future. If none or only some of what is projected actually happens, you will be in a position to react and anticipate the needs of your clients.