The ground in Portland
Portland sits on the Highland Rim in northern Sumner County, running into Robertson County. Rim soils are different from the Basin’s: silty loams over cherty limestone, and many of them have a fragipan, a dense, brittle layer a foot and a half to three feet down that water passes through very slowly.
A fragipan can hold water up near the surface in winter and spring. A drain field above it may work fine in August and struggle in February, which is why permits on the Rim can call for shallower trenches, bigger fields or an alternative system design.
Permits and records
Septic permits in Portland come from TDEC’s Division of Water Resources, through the Nashville Environmental Field Office. Homes just across the line in Robertson County are handled by the same field office.
Calls we get from Portland
- Fields that struggle in wet seasons
- Pumping before wet-season trouble starts
- Inspections on rural homes north of town
- Repairs on lines and baffles
Portland septic questions
Questions from Portland.
Why does my Portland drain field only act up in winter and spring?
Many Highland Rim soils around Portland have a fragipan that slows water moving down. In wet seasons, water perches on top of it and the field has nowhere to send effluent. Keeping the tank pumped, fixing leaky fixtures and spreading out laundry helps a field get through the wet months.
What is a fragipan?
A fragipan is a dense, brittle subsoil layer, common on the Highland Rim, that roots and water pass through very slowly. It’s one of the main things a TDEC soil evaluation looks for when sizing a drain field.
Can a Portland home need an alternative septic system?
Yes. When the soil is shallow, wet or slow, TDEC can require an alternative design rather than a conventional trench field. Which design depends on the soil evaluation for your lot.
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