Understanding the PA-Required Process for System Selection
In Pennsylvania, the type of septic system approved for a property is determined through a strict, regulated process overseen by a Sewage Enforcement Officer (SEO) and guided by the Pennsylvania Department of Environmental Protection (PA DEP).
System selection is not optional or based on preference — it depends entirely on soil conditions, site limitations, and state-mandated testing standards under PA Code Chapter 73.
Below is the exact process used in Pennsylvania.
1. Site Evaluation by a PA-Certified SEO or Soil Scientist
Before any testing begins, the SEO evaluates the property to determine:
- Suitable testing areas
- Required setbacks (from wells, property lines, water bodies, buildings)
- Slopes and natural drainage
- Available land for absorption areas
- Physical site constraints
This step establishes whether the lot is capable of supporting any on-lot wastewater disposal system.
2. Pennsylvania Soil Testing Requirements
Deep Probes / Soil Profile Evaluations
PA DEP requires test pits to be dug at the proposed absorption area. The SEO examines:
- Soil horizons
- Texture, structure, & mottling
- Depth to limiting zones
- Bedrock depth
- Seasonal high water table
- Soil color and permeability
Percolation (Perc) Tests — PA Code Chapter 73 compliant
Perc tests determine:
- If the soil can absorb water
- The rate at which wastewater moves through soil
- Required system sizing
- Whether advanced or alternative treatment is needed
These tests must be witnessed and approved by the SEO.
3. Determining Limiting Zones (PA DEP Requirement)
Pennsylvania defines a “limiting zone” as anything that prevents safe wastewater treatment:
- High seasonal groundwater
- Impermeable clay
- Fragipan
- Bedrock
- Hardpan
- Poorly drained soil layers
The depth to the limiting zone is the single most important factor in determining which system type is permitted.
Examples:
- Less than 20–36 inches of natural soil: Sand mound required
- Moderate depth but not deep enough: At-grade system
- Adequate depth: Conventional or trench system may be approved
4. Matching PA Soil Conditions to System Types
Conventional In-Ground System
Allowed when:
- Soil depth > 48 inches
- No limiting zone
- Acceptable perc rate
- Adequate area available
Eljen GSF (PaDEP Approved Alternative)
Used when:
- The lot is restricted in size
- Soil has borderline or inconsistent percolation
- A smaller footprint system is required
At-Grade Bed
Used when:
- Soil is shallow but still meets minimum separation from limiting zones
- There is moderate drainage and structure
Sand Mound (PA’s Most Common Alternative System)
Required when:
- There is a limiting zone within 20–36 inches
- Soil is too shallow for in-ground systems
- Groundwater is high
- Bedrock or restrictive layers are present
Ecoflo / Biofilters
Used when:
- Advanced treatment is needed
- Lot size or environmental restrictions limit system design
- Local ordinances or sensitive areas require high-quality effluent
Aerobic Treatment Units (Jet, Norweco, etc.)
Used for:
- Commercial properties
- High-strength waste
- Poor soil conditions
- Sites requiring supplemental treatment before final dispersal
5. Engineering & System Design (PA DEP Requirements)
A Pennsylvania-certified designer or engineer prepares a full system design including:
- Tank size & type
- System footprint
- Pipe elevations
- Pump requirements (if dosing system)
- Soil absorption area size
- Setbacks required by PA Code Chapter 73
- Type of system permitted by testing results
This design is then submitted to the township SEO.
6. Township / County Permit Approval
The SEO reviews the full system design to ensure compliance with:
- PA DEP regulations
- Chapter 73 standards
- Local municipal requirements
- Environmental protections
No installation can begin without signed permit approval.
7. System Installation by a Licensed PA Installer
Once approved, John’s Septic & Excavation installs the system according to:
- The engineered plan
- SEO directions
- DEP material specifications
- Required elevations and dimensions
Work is inspected at multiple stages before final approval.
8. Final Inspection & As-Built Verification
The SEO returns to confirm:
- System was installed per permit
- Depths and elevations are correct
- Materials meet PA-approved specifications
- All components are in proper working order
Once approved, a final completion certificate is issued.
Summary: How Pennsylvania Decides Which System Goes Where
In PA, system type is determined by:
- Soil depth
- Perc rate
- Limiting zones
- Groundwater elevation
- Slope & topography
- Lot size & usable land
- Environmental setbacks
- Wastewater flow (residential or commercial)
- PA DEP & municipal regulations
This ensures that every property receives the safest, most compliant, and most effective septic system for Pennsylvania soil and environmental conditions.