|Title||Non-point pollution assessment in northern Michigan: a ground water monitoring approach in evaluating on-site wastewater disposal systems|
|Year of Publication||1979|
|Authors||Tilchin M, Croghan M, Ehlers S, Feeney D, Hughes K, Hummel M, Marshall B, Murray R, Schumaker J, Torf M|
|Institution||University of Michigan Biological Station|
A group of nine investigators at the University of Michigan Biological Station conducted a study integrating research on on-site wastewater disposal with an environmental management program. The objectives of the study were to: 1. assess the ability of several groundwater sampling techniques to monitor on-site wastewater disposal systems. 2. identify soil factors and septic system characteristics that influence nutrient loading to the groundwater. 3. educate lakeshore communities on lake protection and management. The physical and chemical limitation of porous ceramic cup (PCC) lysimeters, sand point wells, silicon carbide lysimeters, and polyvinyl chloride (PVC) membrane lysimeters were assessed on four test plots from a range of soil texture and moisture conditions. Problems with the assembly and installation of silicon carbide and PVC membrane lysimeters rendered them unsuitable for field use. Sand point wells functioned in a severely restricted range of texture and moisture conditions. PCC lysimeters demonstrated substantial variability among samples in several water quality tests, but were the best available method for monitoring groundwater in the subsequent septic system study. Quality of groundwater adjacent to nine lakeside spetic systems was monitored. Concentrations of ammonia, nitrate, phosphorus, and chloride were measured from groundwater samples collected from an array of PCC lysimeters between the septic system drainfield and the lake shore. Excessive nitrogen (greater than 10 mg/l Tot-N) and phosphorus (greater than 1 mg/1 TDP) levels were detected at two sites. At a third site, high nitrogen concentrations but no phosphorus loading were found. Results indicate that septic systems built in undisturbed soils affected groundwater less than those systems constructed in fill materials. Application of large effluent loads (greater than 600 gpd) resulted in measurable deterioration of groundwater quality. Presentations and workshops on wastewater management, septic system monitoring, and wetland ecology were given to lake associations, county commissioners and public health officials. Innovative programs for septic system maintenance and water qualtiy monitoring were implemented.