Septic leachate surveys for lakeside sewer needs evaluation

The rising costs of structural wastewater treatment systems and the realization of the limited capabilities of even the massive Section 201 funding prompted the 1977 amendments to the Clean Water Act (PL 95-217). In particular, the amendments attempted to recognize the great potential of redirecting attention to individual on-lot systems and to provide for a higher level of fed eral funding. A review of facilities planning for rural lake communities highlighted several major areas of deficiencies:1 Facilities plan proposals often viewed the existence of shoreline septic facilities as a priori evidence of water quality problems. Where water quality problems existed, only casual efforts were made to determine if any cause-and-effect relationships existed between individual systems and perceived problems. The responsibilities of local public health officials for existing on-site systems are generally limited to en forcement actions for system failures identified by the homeowner or his neighbors. Public health officials, with notable exceptions, are unprepared to provide com prehensive information on actual water quality and the effect on public health from shoreline septic systems. To demonstrate how the effectiveness of evaluation of septic systems could be increased, a specially de signed survey was conducted along the shoreline of Crystal Lake in the glacial deposits of northern Mich igan.2 Using a newly developed septic leachate detec tor3,4 and a groundwater flow meter, a surface and groundwater sampling program, and mathematical techniques for evaluating the condition of groundwater plumes, the performance of shoreline on-lot treatment systems was analyzed. The survey identified three dif ferent types of discharges from malfunctioning shore line systems: erupting groundwater plumes, dormant (seasonal) groundwater plumes, and surface-water plumes. The position and density of plumes were related to the observed flow of shoreline ground water.