It is estimated that about a third of homes in Virginia have
septic systems. There are many different types of septic system designs. The
most common type used for single family homes is still the traditional septic
system that consists of a single chamber septic tank that flows by gravity to a
drain/leach field. However, due to regulatory changes, continued growth in
housing Alternative Onsite Sewage Systems (AOSS) have become popular.
A typical AOSS in Virginia consist of a septic tank, treatment unit, pump
chamber, conveyance line, distribution system, and an absorption field
(trenches, pad, drip tubing, etc.). However, the exact set of components that
make up the system are site and system specific. AOSSs allow homes to be built
on land that “does not perk”- can neither pass the standard percolation test
nor support a traditional septic system.
To protects public health, the waters of the state and the
environment AOSS are regulated in Virginia under 12VAC5-613-140. This
regulation requires all AOSS are designed, meet minimum performance standards
and will be properly maintained and inspected at least once a year with newer
systems required to be sampled regularly. The full text of the regulations can be read at this link.
These non-conventional septic systems include: aerobic tank
or ATU’s, peat filter systems, coir filter systems, single and recirculation
sand filters, mound systems, drip dispersal, spray and low pressure dispersal.
Manufacturers of these systems have gotten their systems approved in the
commonwealth so that they can be bought off the shelf. These systems include
but are not limited to: Advantex, Clearstream, Puraflo, EcoFlo, EZ Treat,
Fujiclean, Microfast Norweco, Bio Coir. All of these systems are approved for
use in Virginia, but may not be optimal for all sites and are also expensive to
build, maintain and replace.All of these systems are approved foruse in Virginia, but may not be optimal for all sites and are also expensive tobuild, maintain and replace.
None of these AOSS systems is ideal, but I’ve always liked the simplicity of
the peat filter systems and the peat is a phenomenal media for absorption. The
peat media filter system is a traditional septic tank with peat filtration
system instead of a leach field. The filtration system is the aerobic portion
of the treatment and is located in tanks which are filled with peat moss over a
gravel base. The filtered septic tank effluent is collected in the pump tank. A
timed dosing system pumps the effluent through an inlet manifold located at the
base of the treatment modules. An orifice plate is located inside the top of
each inlet manifold which allows the flows to be split equally and fed
simultaneously to each biofilter module or modules. (The number of modules is
based on the size or type of the system-the number of bedrooms is how these
systems get sized.) The inlet manifold is connected to the base of the
biofilter module and is fed upwards to a rectangular distribution grid located
6 inches below the top of lid. The effluent percolates laterally and vertically
through the depth of the peat fiber treatment media and emerges as a clear,
innocuous liquid from the base of the system. The treated effluent is then
collected and dispersed. New systems are installed with a sample port.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX5Dhil2xYAp0jFgZm_aWvJFij9Jzhk2NrXtvUAN2su8WqVKyf4cOI2q7EEc7VF958dT5xwBCLSlHU_sQWNBxB6DZNJnyJKQpKpe6sOynymwrDUTZ3qqgxZGMa-RfJRf9rhjy2pSZ8OIH86X_0f_2qWxJUYKKGMv1V-zCnB1gE0SGyePrvLnt_ODGBOin9/w399-h211/AOSS%20Ecoflo.png) |
from EcoFlo |
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ9RswXyfFueIFuZltLXcFguNFR7S5tkQUl2kzh-b8Q9-tta29LXnyL_Z6Bv6jSJHbjrZ2qy-7UI9wW4Ser6KbEJ3C8dnE2ByvWGQd3va3R7jXkGmjYn4jfvnBAgu77cip1mEEuzeJBEIJquPOfpTYuMmqXLrWTd8CpGObwDacFkZdLCDhz6V5fA9LsEGj/w440-h259/puraflo%20layout.png) |
From Anua |
The peat is an excellent media for allowing the natural secondary treatment of
the sewage waste to take place: Absorption and filtration of any impurities chemical adsorption, and microbial assimilation. As a result, these systems are typically capable of removing 90% or more of the polluted mater (characterized as BOD, SS, Coli forms and E. Coli). The life of these systems varies by manufacturer and origin of the peat. For Puraflo systems, peat moss replacement is recommended around every 14 years. For Ecoflo systems they recommend that the peat should be replaced approximately every 7 years. These number assume that the system is properly used and maintained (or less with improper use). The required annual inspection of the system will determine when to replace the peat, and when to pump the tanks.
The problem is that the peat used in these systems came from Canada, Ireland,
or other overseas location (depending on if you have a Puraflo or Ecoflo), and
extraction and removal of the peat can impact natural ecosystems of those
locations. Peat is a limited natural resource and as such expensive. Recently,
the cost of replacing the peat media is $2,250-$3,010 per module for the Puraflo system (depending on
the number of modules) and $5,200-$6,000 for the Ecoflo system. This pricing
includes disposal of the existing peat and labor, but does not include the pump-out
of the tanks which is necessary. This has gone up significantly since I last
checked pricing. The Puraflo prices are down somewhat since the end of the
pandemic. Ecoflo pricing went up during the pandemic and have stayed up.
There is another option. Puraflo has a new media, coir, coconut
fiber. While Anua has a Bio-Coir system that is generally approved in Virginia,
you can also use a coir media as a direct substitute for peat. Unfortunately,
since this substitution of media has not been generally approved, it would
require five rounds of 180 day sampling to prove it’s functioning, new spray
nozzles and an engineer’s stamp on the design. (see the VHD memo.)(see the VHD memo.)
The costs to change
the media would be about the same as the costs for replacing the peat listed
above, the first time. Though coir, which is coconut fiber, is low-cost and a
renewable resource that gets consumed over time, the change from peat media
includes disposal of the existing peat and changing of the spray nozzles to the
ones designed specifically for the coir. Going forward the system would only
require the addition of coir as needed, but that is a long term cost savings
and many do not keep their homes long enough to benefit. Coir is a by-product
of coconut harvesting and is a renewable resource.
The AOSS market in Virginia is dynamic. Things change and it
is likely that steps that need to be taken to replace peat media with coir will
evolve and become simpler. However, for
now though costs are still high.