MTD Evaluation Process

The Virginia Department of Environmental Quality (DEQ) has issued guidance that describes a process for approving manufactured treatment devices (MTDs) and assigning pollutant removal credits to them.

Guidance Memo No. 14-2009 — “Interim Use of Stormwater Manufactured Treatment Devices (MTDs) To Meet The New Virginia Stormwater Management Program (VSMP) Technical Criteria, Part II B Water Quality Design Requirements” (pdf)

To have a MTD evaluated by DEQ:

  1. Complete Attachment 1: MTD Registration Form* (Word)
  2. Submit the completed MTD registration form along with supporting documents to DEQ’s Robert Cooper (

Each approved MTD is assigned a total phosphorus (TP) removal efficiency based on best professional judgment and in accordance with DEQ guidance (No. 14‑2009). MTDs approved by DEQ are listed by category:

*All information submitted to DEQ will be made publically accessible to all interested parties. If the MTD is approved, the submitted MTD registration form and other information reviewed by DEQ will be posted on the Virginia Stormwater BMP Clearinghouse website.