Cesspools and Seepage Pits
Before septic tanks were common, sewage from dwellings was oftentimes disposed of in covered up perpendicular pits called cesspools. It is not rare to hear a seepage pit called a cesspool, or the other way around. Yet, seepage pits and cesspools are two different things. They're alike in structure but serve dissimilar functions. A seepage pit is utilized for disposal of clarified wastewater from a septic tank, whereas a cesspool is both tank and drainfield (the latter being the soil around the cesspool).
The cesspool was an early adaptation of the current-day septic system, offering a belowground arrangement for disposal of waterborne sewage. Usage of cesspools was primarily driven by convenience and their positioning governed chiefly by the closest usable land. In fact, cesspools were even constructed in the basements of urban buildings. This is in obvious contrast to current septic system designs, based on soil and groundwater conditions, and intended for long-term use.
In most regions, cesspools are banned by local health and building codes. Accordingly, new construction of cesspools is relatively uncommon. Nevertheless, numerous cesspools are still in active use, most commonly in
less populated areas, also older homes in suburban communities.
RIGHT A typical stone walled cesspool is a cylindrical hole in deep soil,
several feet in diameter. The outer
surface (between the stone wall and the outer soil wall) is back filled with gravel.
There is a concrete lid and, on top of that, soil backfilled to grade.
Raw wastewater flows into the top of the inner chamber. The inner chamber retains (and partially digests) the solids, and the effluent seeps through to the gravel-filled outer chamber, and then into the surrounding soil.
A large number of cesspools are still in active use, most commonly in rural areas.
Owners of cesspools should be aware, in most areas, cesspools are prohibited by local
health and building codes. If your system fails, you apply for a permit to build an addition,
or you sell your house or some bureaucratic requirement of some sort means you could be
required to replace your septic system with a high-tech, expensive, system costing anywhere
from $8000 to $40,000.
A seepage pit is, in essence, a upright leach or drain field, consisting of a deep hole with a porous-walled inside chamber and a filling by gravel
between the chamber and the encompassing soil. Seepage pits are typically 4 to 12 feet in diameter and 10 to 40 feet deep. Septic tank wastewater
enters the inside chamber and is temporarily stored in that location until it gradually seeps away and passes through into the surrounding sidewall soil.
The wall, along with the surrounding gravel filling, provides structural
support for the pit. The wall is 1 to 2 feet smaller in diameter than the actual pit,
and may be constructed of pre-cast concrete rings or a cylindrical wall of brick or concrete block. For outward seepage of the effluent, concrete
rings have pre-cut holes or notches; bricks or blocks are laid up with staggered joints. In a smaller diameter cavity, the interior chamber may
consist of a large-diameter perforated pipe placing upright . The bottom of the pit is usually covered with 6 to 12 inches of gravel.
LEFT A typical brick or block walled cesspool. As with drain field and leaching field trenches, seepage pits go through progressive biomat growth.
Because the biomat grows thicker in the lower level, the effluent climbs to a higher level, where it permeates through the unclogged sections of the sidewall.
Cesspool Seepage Pit Problems
Because the biomat is comprises of living anaerobic bacteria microbes that grow only in the absence oxygen.
, its balance can be upset. Septic tank troubles can result in an excess of solid waste matter (nutrient) to the
biomat organisms, stimulating excessive growth and, consequently, cutting back the ability of the sewer water
from the septic tank to pass through the biomat and go into the soil. In the supersaturated state the
aerobic qualities no longer exist, and controlled break up of the biomat by aerobic soil bacteria will no longer take place .
RIGHT Cross section of a failing seepage pit / cesspool caused by septic tank problems. The biomat has gotten too dense and impenetrable,
and the wastewater sent to the seepage pit / cesspool will rapidly and easily exceed the amount that can filter out through the biomat.
The consequence is backflow into the septic tank (and possibly also into the house), and surfacing of effluent above ground over the
seepage pit / cesspool or septic tank causing wet spots and rapid grass growth, in other words "a failing septic system."
Cesspool & Seepage Pit Pumping|
Whether you’re putting in a septic aerator or pumping as regular maintenance it is noteworthy to make sure that the cesspool or seepage pit is pumped out right and that you're receiving what you are paying for.
Make an effort to be there while the pumping is performed. Lean over the shoulder and keeping an eye on the pumper is the most effective way to make certain the cesspool or seepage pit is pumped entirely. Likewise have a garden hose accessible with a high-pressure attachment connected.
While the cesspool or seepage pit is pumped, it ought to be cleaned out as thoroughly as possible with a hose. A few pumpers make little or no effort to get rid of the bottom few inches of sludge, especially if it contains a lot of soil or sand. The pumper should hose down the side walls along with the sludge along the bottom once it's exposed so that it will partly liquefy and can then be sucked out.
How Septic Aeration
Septic system that consists of a septic tank and use a seepage pit – cesspool as the soil absorption system
offers a unique arrangement that lends it’s extremely well to septic aeration. Unlike all other tank and soil
absorption system where the septic aerator is added to the tank the aerator is placed inside the
seepage pit. Adding a septic aerator to your seepage pit – cesspool causes aerobic bacteria (microbes) to
come in close and constant contact to the biomat. The aerobic microbes thrive when given the two things
they need, food (biomat) and oxygen(aerator).
To Learn More Visit These Related Topics
• How Septic Aeration Works: Understanding
septic system aeration
principles, how and why septic aeration works fixing septic tank problems and
drain field problems.
• Septic Tank Problems: Understanding
common septic tank problems, signs of septic tank problems and diagnosing them.