Q3: Oral Presentation C Friday, 9:30 � 10:00 am C French River Room
GIS as a Tool to Manage Northern Minnesota's On-site Wastewater Treatment
Richard J. Otis, Timothy Barnett
2445 Darwin Road
Madison, WI 53704
Over 25% of existing homes in the U.S. rely on
onsite systems to treat and disperse the household wastewater into the
environment. Traditionally, these onsite systems have been prescriptive designs
that protect public health by discharging partially treated wastewater below the
ground surface in infiltration trenches located some distance from private
wells. Because of the reliance of the system on the soil to accept the
wastewater, these systems can be used only on lots with suitable site and soil
Increasingly, there is pressure to develop beyond
the reach of existing sewer systems because of the high costs of conventional
sewerage. Today, approximately 37% of new homes in the U.S. use onsite systems.
With this increased development pressure, the availability of suitable sites is
becoming limited and more marginal lands are used where onsite system failures
are more frequent. The failures create environmental as well as public health
Federal, state, and local governments are
recognizing that sewers are not the wastewater solution for many small
communities and rural areas. However, onsite system practices must change if
public health and the environment is to be protected adequately. Conversion from
prescriptive onsite system codes where suitable sites must be available to use
the approved designs to performance codes where suitable systems must be
designed to build on the available sites is occurring. But this change increases
the complexity of administering onsite system permitting programs substantially.
Performance standards for the onsite systems will depend on the environmental
sensitivity of sites to wastewater discharges, proximity wellhead protection
zones, densities of homes, etc. Better tools are needed by the counties to
assist in the consistent administration of a performance-based program.
This paper will describe a GIS based tool to evaluate environmental sensitivities, establish performance standards for systems, plan for future development, assess performance of existing systems with respect to site conditions, and track permits and maintenance records. This is an essential tool if onsite wastewater systems are to be sustainable substitutes to central sewerage.