Onsite Site Plan Requirements
Link to Onsite wastewater treatment systems - Setbacks, Sewage Flows and Soil Information
Prior to drawing any site plan or planning out the location of your project please review the link above.
📐 Site Plan Requirements
Throughout your septic project, you’ll likely need to create more than one site plan. Use this guide to help you meet the requirements for each stage, from the Site Evaluation to the Onsite/Septic Permit.
📝 Why Different Site Plans?
Each phase of your project requires a slightly different site plan.
- For example, during a Site Evaluation, the Onsite Specialist identifies the approved area where your septic system can be placed.
- That approved area must be clearly shown on the site plan submitted with your Onsite Permit application.
✅ Standard Requirements (Apply to All Site Plans)
Your site plan must include the following:
- Entire property drawn proportionally
- Label all structures as either “Existing” or “Proposed”
- Identify structure uses (e.g., residence, garage, shed)
-
Distances from proposed structures to:
- Property lines
- Existing structures
- Sizes of all buildings, decks, patios, outbuildings, driveways, and access roads
-
Location of major features, such as:
- Waterways
- driveways
- Slope Changes
- Easements, including utility lines and power poles
- Property line dimensions
- Location of wells and water sources on the subject property
- North arrow
- Street names and road locations adjacent to the property
⚠️ Additional Requirements by Permit Type
🏢 Commercial Construction Permits
In addition to the standard requirements:
- Site plan must be to-scale
- Label commercial use of each structure
- Show any required EV infrastructure with quantity calculations
-
Exit Discharge Route to:
- Public Way, or
- Safe Dispersal Area (include size calculation and distance from building)
🧪 Site Evaluation (for New Septic Installations)
Include the following in addition to the standard items:
- 3 to 5 test pits, spaced 60'–75' apart
- Wells on adjacent properties, if within 100' of property line
🚽 Onsite/Septic Permits
In addition to the standard site plan items:
- Location of approved test pits
-
Distance:
- From septic tank and drainfield to the structure served (minimum 5’)
- From septic tank to distribution box/drop box
- From septic drainfield to property lines (minimum 10’)
- From septic tank to well and water sources, or 50’ radius from well and water sources
- From septic drainfield to well and water sources, or 100’ radius from well and water sources
- From septic drainfield to driveway and/or parking areas
- Drain field layout and replacement reserve area
- Length and spacing of trenches
- Elevation changes from tank to drain field (uphill/downhill)
-
Soil elevation differences:
- At septic tank
- At each end and center of all proposed trenches
- Wells on adjacent properties, if within 100' of property line