On-Site Sewage Disposal Systems (OSDS)
On-site sewage disposal systems (OSDS)
commonly know as septic systems, are waste water treatment systems
that use septic tanks and drainfields to dispose of sewage below
the ground surface. They are typically used in rural or large lot
settings where a sanitary sewer is not available. When a septic
system is correctly located, adequately designed, carefully installed
and properly managed, you will have a waste disposal system that
is simple, economical, effective, safe and environmentally sensitive.
OSDS fail due to a variety of reasons. If not maintained the drainfield
can become plugged with excess solids or from heavy biological growth
that can plug even coarse sand. They fail due to inadequate soil
conditions, lack of proper maintenance, poor drainage or misuse.
Failing septic systems may allow untreated human waste to eventually
be discharged into the Rouge River, causing unacceptable water quality
and presenting a public health risk.
The monitoring data on the Rouge River suggested that OSDS were
contributing to high bacteria counts during dry weather in several
parts of the watershed. Further water quality testing found consistently
high levels of fecal coliform and E. coli bacteria upstream of locations
that had combined sewer overflows and in several locations where
there were no municipal sanitary systems. A review of the 1990 census
information provided by the Southeast Michigan Council of Governments
(SEMCOG), showed that there were 18,242 OSDS in the Rouge River
watershed. Using dye tests and visual inspections, Oakland County
Health Department found failure rates of 39% in 1995 and 52% in
1994 while the Wayne County Health Department found failure rates
of 21%. Because of the potential threat to public health, a great
deal of effort is being placed on regulating these systems.
Based upon the above findings, the Rouge Project and the Counties
initiated an OSDS management program. A model regulation was developed
that could be used by counties or local units of government to address
management of OSDS. The model regulation was used by Washtenaw and
Wayne Counties to develop county regulations to inspect OSDS at
the time of sale of a property. Those regulations are now being
Wayne County has developed a training program to assist local communities
and counties implementing their OSDS management program. New training
modules and other educational material are also under development.
On-Site Sewage Disposal Systems (OSDS) Management Program