- Feb. 5, 2019
- 15 min read
The Future of Lakes & How the Application of Alum Wastewater Conditioning Would Improve Lake Water Quality
My comments that follow are in the context of lake communities served by septic systems, aka Waste Water Treatment Systems (WWTS). The numerous posts on this website discuss how lakes are negatively impacted by cultural eutrophication – a term used by D. Schindler – to describe the effects on a water body (lake) as a result of man’s presence and activities. Man’s altering the watershed has proven to cause drastic changes to the ecology of the lake in terms of increased inputs of solids and nutrients. Lakes are plagued by algae blooms and low clarity. Some blue green algae can cause toxicity.
A major dynamic in altering the watershed relates directly to the intensity of development and the effect of decade’s long presence of WWTS that process each household’s waste water. Small lot sizes result in housing density far exceeding current regulations for present day septic codes. Because lot size is fixed, older systems are grand-fathered on small lots.
If a lake has 500 homes in it's watershed, there are 500 WWTS.
Typically people view WWTS systems as a necessary evil. They serve a critical function but most people just don’t want to know the details. Some may not know where their WWTS is located. Out of sight out of mind. More recently, awareness of proper maintenance and timely pumping has reached home owners. Some understand the relationship WWTS have on their lake and thus do not ignore them. Still, it seems the majority of folks either don’t want to know or simply ignore the whole issue failing to understand their connection to their lake.
Maybe it’s unfortunate that WWTS seem to function successfully without visible sign of failure. A sign of failure occurs when there is untreated wastewater emerging on the surface or strong noxious odor in the vicinity of the system. Absent this, people commonly believe their WWTS is adequately treating the wastewater. Other posts on this website describe how the soil disposal field treats both bacteria and inorganic chemicals. The fact surrounding the inability of the soil disposal field to adequately treat are less known and more difficult to prove. The proof lies in the condition of the lake. Take a look at your lake in the middle of August.
Can a WWTS fail to treat as it ages?
Studies say yes and I describe this condition associated with older systems as failing to treat completely. What do they fail to treat? Failure to treat is associated with the disposal field’s inability to react with the components contained in the wastewater. Some of reasons for this failure to treat are age, design, hydraulic limitations, location, and ground water characteristics.
Many WWTS were installed in locations of marginally seasonal water tables. The soil components of the disposal system need oxygen to carry out the reactions with the minerals of the soil. A saturated condition will result if untreated wastewater reaches the ground water. The untreated wastewater will cause a plume to the lake and result in non-point source pollution – a condition that causes unhealthy conditions, algae blooms and weed growth.
In studying a 500 member lake community, I estimated the total amount of phosphorus produced by WWTSs in the watershed. The phosphorus in the disposal field, the amount of phosphorus escaping the disposal field, and the amount of phosphorus entering the lake becomes a surprisingly large amount. Each home will produce approximately 3 grams of phosphorus each day primarily from human waste products. The 500 homes if lived in full time would produce 547 KG of phosphorus per year. Over the long time spans that WWTS have been used in older lake communities, the total phosphorus could be as much as 5,470 KG. per every 10 years!
The dispersed phosphorus does not stay in the septic field forever! Older WWTS begin releasing phosphorus and develop a downstream ground water plume after several years. Twenty to thirty years is the useful life given for WWTSs. The older a WWTS is, the greater percentage of phosphorus enters the ground water and to the lake. This realization is not well understood nor admitted to exist by health regulators. When enough “leakage” of phosphate reaches the ground water entering the lake, dramatic changes begin to develop in the lakes response to the nutrient input. Increased algal populations and reduction in clarity, and the color of the water are the most noticeable changes.
The question remains- What can lake communities do to counter degradation of their lake's water quality?
After significant phosphorus loading over many years and obvious complaints registered by lake community residents’ water consultants will recommend in-lake measures to counter the nutrient loading. They will recommend septic management programs, management of storm water and promote awareness and education to enlist voluntary help. However, the WWTS problem will not go away unless sewers are installed, or everyone with a septic system of questionable condition chooses to replace the disposal field and by adding pretreatment units. Expensive lake side pretreatment units can remove some phosphorus (unless you have an electrolytic precipitation device) and most of the nitrogen. They will lessen the loading on the disposal field and increase its useful life. But the phosphorus will remain the problem as most lakes are phosphorus limited.
Sewers and advanced pretreatment units are expensive! Both cost tens of thousands of dollars to have installed. Homeowners are not going to voluntarily spend this kind of money on their property unless mandated by the health department or the lake association. This is where we are now. It becomes a quandary for those wrestling with the lake’s problem and frustrated with only partial improvements that result from in-lake management approaches and other measures.
Lakes are a valuable resource. To not do everything possible to restore this resource will ultimately effect property values. After closing beaches due to harmful algae blooms, a lake’s reputation as a great place to live is damaged. Lake associations need to act proactively. The most practical and economic measure that can be taken is to equip every WWTS with an in-house alum system that conditions the wastewater before it reaches the septic tank. An alum system will prevent 90% of the phosphorus and 99% of the coliform from reaching the field. I have tested my alum system over 6 years and the results of my tests are posted on the PowerPoint presentation.
The alum system developed by Clear Lake Technology has the same effect as alum used in municipal waste treatment. Importantly, for a lake community, it removes the damaging phosphorus before it gets to the watershed and then to the lake. The septic tank retains 90 % of the phosphorus and 99 % coliform bacteria and when the tank is pumped (every 2-3 years), all these pollutants are trucked away from the lake and its watershed.
How does the cost of adding and operating an alum system for your WWTS compare to sewers or adding advanced pretreatment systems?
To replace an existing septic field and upgrade to a 2 compartment tank – it costs $30-60,000 depending on size and site restrictions. A sewer connection requires the cost of hook-up estimated at $10-15,000 including retirement and disposing of existing system and rearranging plumbing within the house. A fee for sewer service varies between $75-125/mo. Water consumption based cost could be added. Cost of an alum conditioning system installation is estimated between $1700 -2000. The install cost would be about the same as the cost of a chlorination sanitizer system because the same equipment is repurposed for use with the alum system. The monthly operating cost including pumping the tank at a 2 year interval, purchase of alum and providing this service to the homeowner would be approximately $24/mo. There is a tremendous saving over many years and the disposal field life will be longer if not indefinite.
If a lake association’s promoted this system, it would result in less overall expense to the association members while slowly restoring the lake’s water quality. An incentive reduction in dues would provide a shared cost paying arrangement and result in the motivation to install the alum systems. Why help pay for someone else’s system. The overall cost to improve your lake through expensive in-lake treatment measures would gradually be reduced. The use of an alum wastewater conditioning system for every home would not only be a wise investment, but it would improve the lake and property values and would greatly improve the enjoyment of a healthy lake.
