What is the role of groundwater level in determining drainfield performance?

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Multiple Choice

What is the role of groundwater level in determining drainfield performance?

Groundwater level limits how much soil is available to receive and treat effluent. When groundwater is high, the zone of unsaturated soil above the water table is small, so the drainfield can’t infiltrate quickly. Infiltration slows, effluent may pool on the surface or in the trench, and the system ends up operating in saturated conditions with reduced aerobic treatment. That combination lowers the drainfield’s ability to absorb and treat wastewater and may require an alternative design, such as a raised or mound system, or other adjustments to reduce loading. While groundwater temperature and other factors can play a role, the primary concern here is saturation limiting infiltration and causing pooling.

Groundwater level limits how much soil is available to receive and treat effluent. When groundwater is high, the zone of unsaturated soil above the water table is small, so the drainfield can’t infiltrate quickly. Infiltration slows, effluent may pool on the surface or in the trench, and the system ends up operating in saturated conditions with reduced aerobic treatment. That combination lowers the drainfield’s ability to absorb and treat wastewater and may require an alternative design, such as a raised or mound system, or other adjustments to reduce loading. While groundwater temperature and other factors can play a role, the primary concern here is saturation limiting infiltration and causing pooling.

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