Treatment efficiency in private sewage systems for other

chemical constituents may be less than ideal or simply unknown in

the present.    Because nitrate, a breakdown of organic nitrogen

compounds, is very soluble and does not adsorb to soil, it often

reaches groundwater from what are considered well functioning

septic  systems.     When  used  on  sandy   soils, many   properly

functioning septic systems have been shown to result in significant

nitrate-N concentrations in groundwater.

1.2 Project Justification and Goals

     This project was initiated due to increasing concern regarding

the  impact   private  on-site  waste  disposal   systems  have  on

groundwater quality. The major quantifiable contaminant that has

been shown to impact groundwater from private sewage systems is

nitrate-N.    This concern has led to a number of ordinances

restricting lot sizes to two or more acres to allow for adequate

dilution of septic system waste. Increased lot size cause a number

of problems related to urban sprawl.    Interest in alternative or

improved waste disposal systems has increased with a number of

innovative systems being used in many areas.

     This project was designed to evaluate a denitrification

system's ability to reduce nitrogen loading to groundwater from on-

site sewage disposal systems. This will be done by installing two

systems in the sand plain areas of central Wisconsin. The systems
used have been installed on sites where we already had groundwater

monitoring wells in place and contaminant plumes well identified.