Installing a new septic system in Tennessee — whether it's a conventional gravity system or an LPP system — requires a permit from the Tennessee Department of Environment and Conservation (TDEC) processed through your county's environmental health office. Skipping the permit isn't an option: unpermitted systems can result in stop-work orders, fines, and required removal of installed work.
Here's exactly how the process works, step by step.
Step 1: Hire a Licensed Soil Evaluator
Before any permit can be issued, your property must be evaluated by a TDEC-licensed soil evaluator or a licensed professional engineer. The evaluator will:
- Dig soil pits (typically 18–36 inches deep) across the proposed drain field area
- Assess soil texture, color, and structure to determine drainage capability
- Identify seasonal high water table indicators (mottling, redoximorphic features)
- Determine the appropriate system type — conventional or LPP
Cost: typically $300–$600 depending on the evaluator and site complexity. Allow 1–3 weeks to get on their schedule.
Step 2: System Design
For a conventional gravity system, the soil evaluator's report may be sufficient to support a straightforward permit application. For an LPP system, a licensed engineer must produce a full system design, including pump sizing, pipe layout, dose calculations, and alarm specifications.
Engineering fees for LPP design typically run $500–$1,500. Budget 2–4 weeks for design completion.
Step 3: Submit the Permit Application
The permit application is submitted to the county environmental health office (part of the Tennessee Department of Health, which administers TDEC septic permits at the county level). Your application package typically includes:
- Completed permit application form
- Soil evaluation report
- System design (required for LPP)
- Site plan showing property boundaries, well locations, setbacks, and proposed system location
- Permit fee (typically $150–$400 depending on county)
In Williamson County, applications go through the Williamson County Environmental Health office in Franklin. For Davidson County, contact Metro Public Health. Each county has its own office and processing timeline.
Step 4: Permit Review and Approval
County review typically takes 2–6 weeks, though timelines vary based on workload. Complex or large systems may require additional back-and-forth with the reviewing engineer. Once approved, you'll receive a permit authorizing the installation as designed.
Do not begin installation before the permit is issued — work done before approval typically must be removed or re-inspected at your cost.
Step 5: Install the System
Installation must follow the approved design exactly. Any field modifications require prior written approval from the county office. Most installations take 1–3 days of active construction.
Site prep — clearing, grading, and access — is typically completed before or concurrent with the installation. Back 40 Land Services handles this phase with our excavation and forestry mulching equipment.
Step 6: Final Inspection
Before the system is covered, a county inspector must conduct a final inspection to verify the installation matches the approved design. Schedule the inspection in advance — inspectors in some counties book out 1–2 weeks. Once approved, the system can be backfilled and the site restored.
Total Timeline
From initial soil evaluation to a permitted, installed system:
- Soil evaluation: 1–3 weeks
- System design (LPP): 2–4 weeks
- Permit review: 2–6 weeks
- Installation: 1–3 days
- Final inspection: 1–2 weeks to schedule
Plan on 6–14 weeks from start to an approved, operational system — longer during busy season or if your county office has a backlog. Starting the evaluation early is the single most important thing you can do to keep a construction timeline on track.
Questions?
Back 40 Land Services coordinates with licensed engineers and county offices on septic projects across Middle Tennessee. We install both conventional septic systems and LPP septic systems and handle all site prep — clearing, grading, and access — so your system can be installed on schedule. Back 40 is actively serving Maury County and Rutherford County. Williamson County installation is pending local licensing. Contact us or call (615) 609-0053 for a free consultation.
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