were used on Maui prior to 1991 for individual home wastewater disposal
in rural areas where there was no municipal sewer service.
In its most basic and traditional
form a Cesspool is a hole in the ground to receive sewage: sometimes the walls of
the "hole" are lined with stone or concrete to form a pit into which
sewage is discharged. Solids remain in the pit, effluent (liquid) is
absorbed into soil below and at the sides of the Cesspool. Solids settle
to the bottom, floating grease and scum collect at the top, and liquid
seeps into the ground, most of the time through the bottom of the Cesspool. The problem with Cesspools is that the
liquid seeping into the ground has the potential to contaminate the
ground water. The
Hawaii State Dept of Health has required the use of septics after 1991
to protect Mauiís ground water resources where most of our drinking
water originates. A few septics were installed on Maui prior to 1990.
These were mostly in Kihei and Maui Meadows. It was easier to install a
shallow septic than it was to blast through rock to put in a Cesspool.
Many of the early septics used an injection well for effluent disposal
instead of a seepage pit. An injection well is simply a water well that
has water going into it rather than being pumped out. More information
on septic systems can be found by clicking on the "Septic Systems" tab
to the left.
County Public Works standard detail illustrated Cesspools to be six feet
in diameter and 20 feet deep (there is an illustration in the back of
the Maui County Public Works publication). This was a hole in the earth
with a concrete cover on it. I must interject at this point, that I have
never in 30 years seen a "standard" Cesspool. They are all
different shapes and sizes. Most are excavated with a backhoe whereas
the Public Works Cesspool was dug with a crane and a clamshell bucket. If the
sewer pipe between the house and the Cesspool is two feet deep at the
cover leaving an 18í depth, the volume will then be 3,800 gallons.
Back in the 80ís everyone had a backhoe in their carport and they were
all digging Cesspools. Some used precast concrete covers, others were
poured in place. A typical poured cover had eucalyptus logs or railroad
ties/rails laid over the excavated hole and roofing metal over that. The
concrete was poured on top of that. Some, but not many, had the
foresight to make a plug from which to pump. These are the Cesspools where
we typically need a jackhammer to break through the concrete and then,
if we are lucky, the logs have rotted and fallen into the Cesspool so we
donít have to cut them with the chain saw. Of course, by the time we
break the concrete, sewage is flowing out so a saw can be a lot of "fun".
placed in sand or loose soil usually had concrete liners or hollow tile
supporting the cover. I used liners at my house and placed filter rock
around the liners to insure I would never have a problem. You get what
you pay for.
many different soil types which determines how well a Cesspool is likely
to perform. Porous rocky soil in Hana will allow water to percolate at a
rate of one minute per inch where Haiku clays may require 300 minutes
per inchÖwhen it is not raining. Some locations may vary from lot to
lot. Take Pukalani Terrace, for example. Some Cesspools are dug and only
dirt is encountered. But, blue rock (Basalt) required many to be
blasted. Sometimes cinder was found under the blue rock, in which case
the water flowed out easily. Others have to rely on fractured rock to
allow any seepage at all. Another place to look at Cesspools is Maui
Meadows. Most Cesspools there are only 10í-12í deep, resulting in a
very small capacity. The prevailing thought must have been that beneath
the blue rock that was blasted out is a cinder layer, which is capable
of absorbing a lot of flow. Driving on Piilani Highway in the cut below
Maui Meadows, the rock and cinder layers are evident.
you enjoy our frequently asked questions. Please call me at 242-5692 and ask if you
donít see your question answered.
to FAQ's About Cesspools