13.20.230 Ground water determination.
An adequate number of observations, excavations, or borings shall be made by the onsite wastewater system installer to clearly establish the elevation of the ground water table in accordance with the procedure outlined above. The ground water table determination should be made when the ground water table is at its highest level. The results of each observation and pertinent information shall be recorded on the onsite wastewater system construction permit application. The location of the ground water table observations shall be indicated on the preliminary site plan.
A. Wet season determinations. The ground water table elevation determination shall be made when the water table is highest; this occurs usually during the months of April through July. In making this determination, it is necessary to bore or dig an adequate number of holes of convenient size in the proposed disposal area to a depth of 8 feet below the surface. All water table observations should be made no sooner than 24 hours after excavation, and shall be witnessed by the Director unless otherwise waived.
B. Dry season determinations. Although the ground water table is more accurately measured in the wet season, data may be available to predict the maximum ground water table elevation during the wet season. To make a dry season determination, the applicant shall dig a 10-foot observation pit in the location of the proposed absorption area. All water table observations should be made no sooner than 24 hours after excavation, and shall be witnessed by the Director unless otherwise waived.