Which soil condition would preclude installing a bed?

Which soil condition would preclude installing a bed?

• A. Bed installed in soils with a T-time of less than 1 min/cm
• B. T-time greater than 50 min/cm
• C. Bed installed more than 1 meter from the high groundwater table
• D. Bed installed in sandy soil with good drainage

Answer: (A)

Soil percolation rate, or T-time, shows how quickly the soil will absorb effluent. For a septic bed to function properly, the effluent needs enough contact time with the soil to be filtered and treated by soil organisms. If the T-time is extremely fast—less than 1 minute per centimeter—the water passes through too quickly for adequate treatment, increasing the risk of contaminants reaching groundwater. That condition would preclude installing a bed. By comparison, a very slow T-time (like greater than 50 min/cm) signals poor drainage and would require a different design, but isn’t automatically disqualifying on its own with the right adjustments. Being more than a meter away from the high groundwater table and having sandy, well-drained soil are favorable conditions and support installation, not preclusion.

Soil percolation rate, or T-time, shows how quickly the soil will absorb effluent. For a septic bed to function properly, the effluent needs enough contact time with the soil to be filtered and treated by soil organisms. If the T-time is extremely fast—less than 1 minute per centimeter—the water passes through too quickly for adequate treatment, increasing the risk of contaminants reaching groundwater. That condition would preclude installing a bed.

By comparison, a very slow T-time (like greater than 50 min/cm) signals poor drainage and would require a different design, but isn’t automatically disqualifying on its own with the right adjustments. Being more than a meter away from the high groundwater table and having sandy, well-drained soil are favorable conditions and support installation, not preclusion.