Which soil condition would indicate that a bed installation is not advisable due to proximity to groundwater?

Which soil condition would indicate that a bed installation is not advisable due to proximity to groundwater?

• A. Bed installed less than 90 cm from the high groundwater table
• B. Bed installed more than 2 meters from the groundwater table
• C. Bed installed in very sandy soil
• D. Bed installed with a thick organic layer between bed and soil surface

Answer: (A)

The main idea here is that there must be enough vertical separation between the bed and the groundwater to protect groundwater and give the soil a chance to treat the effluent. When a bed sits within about 90 cm of the high groundwater table, there isn’t enough unsaturated soil to filter and biologically treat the wastewater before it reaches groundwater. This shallow separation allows contaminants to move more quickly through the soil and into the groundwater, increasing the risk of groundwater contamination and potential system failure, especially during periods when groundwater rises. Being more than 2 meters away would provide a safe buffer, so it’s not a sign of proximity to groundwater. Very sandy soil or a thick organic layer affect drainage or heat and moisture dynamics, but they don’t specifically indicate the critical issue of insufficient vertical separation from groundwater.

The main idea here is that there must be enough vertical separation between the bed and the groundwater to protect groundwater and give the soil a chance to treat the effluent. When a bed sits within about 90 cm of the high groundwater table, there isn’t enough unsaturated soil to filter and biologically treat the wastewater before it reaches groundwater. This shallow separation allows contaminants to move more quickly through the soil and into the groundwater, increasing the risk of groundwater contamination and potential system failure, especially during periods when groundwater rises.

Being more than 2 meters away would provide a safe buffer, so it’s not a sign of proximity to groundwater. Very sandy soil or a thick organic layer affect drainage or heat and moisture dynamics, but they don’t specifically indicate the critical issue of insufficient vertical separation from groundwater.