---
title: "Douglas J. Hartnett, Title 5 System Inspector SI #339 | Title 5 Roster"
description: "Douglas J. Hartnett is a MassDEP-approved Title 5 System Inspector (SI #339) based in Franklin, MA. Approval expires June 30, 2028 per the NEIWPCC list."
canonical: https://title5roster.com/inspectors/douglas-j-hartnett-si339/
---

# Douglas J. Hartnett, Title 5 System Inspector (SI #339)

Douglas J. Hartnett is on the NEIWPCC list of MassDEP-approved Title 5 System Inspectors dated October 2, 2026.

* **SI number:** #339
* **Approval expires:** June 30, 2028
* **Approved by:** Massachusetts Department of Environmental Protection (MassDEP); list published by NEIWPCC
* **Business listing:** Listed under own name
* **Based in:** Franklin, MA
* **County:** Norfolk County

Source: https://neiwpcc.org/wp-content/uploads/2026/10/SI-Instate-10.2.2026.pdf (retrieved 2026-10-12)