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.
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 its
watershed, there are 500 WWTS.
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 waste water 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 waste water. 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 know 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 waste water. Some of reasons for
this failure to treat are age, design, hydraulic limitations, location, and
ground water characteristics.
were installed in locations of marginally seasonal water table. 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.
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
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
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 Power Point
presentation at last year’s North American Lake Management Society meeting in
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 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 associations
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 will improve
the lake and property values and would greatly improve the enjoyment of a
healthy lake. Details of the system design are described on this website