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"Two techniques were evaluated for rehabilitating failing septic tank/soil absorption systems - water conservation and absorption bed resting. These techniques may offer less costly alternatives to complete replacement of the soil absorption area. Eleven homes with failing soil absorption areas were identified in the Centre County, Pennsylvania, region. At each home, the soil and site were characterized, and baseline data were collected on household water flow and septic tank effluent quality. Water conservation devices were then installed at one of three levels of predicted water reduction capability - maximum, moderate, or minimum. At three of the minimum water conservation homes, effluent was also diverted to a specially designed alternative trench for 10 months to permit the main absorption area to rest. After conservation measures were applied, water flow and effluent quality were measured for periods comparable with the baseline data collection period. In addition, the soil absorption areas were characterized by weekly measurements of surface conditions and effluent ponding levels for up to 2 years. Median in-house water use reductions were statistically significant and ranged from 9.8% to 42.5%. The water use reductions were in accord with the increased concentrations of most effluent quality parameters. Maximum levels of water conservation generally succeeded in restoring failing absorption beds, but lower levels of conservation did not. Absorption bed resting also restored failing systems. None of the three rested systems malfunctioned in the 16 months after effluent was redirected to them. However effluent was ponded in them, and the level continues to rise, suggesting that the effluent will have to be directed to the alternative trench at regular intervals." |
