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Septic Technical Guidance Committee

The Technical Guidance Committee (TGC) is responsible for maintaining the Technical Guidance Manual, reviewing best management practices for individual and subsurface sewage disposal, and providing recommendations on variances and commercially manufactured wastewater treatment components and systems. The TGC comprises six members: one DEQ representative (chair), three health district representatives, one State of Idaho-licensed professional engineer, and one licensed installer. TGC meetings occur quarterly unless, a special issue warrants a special meeting.

The Technical Guidance Manual provides guidance on the design, construction, alteration, repair, operation, and maintenance of standard individual and subsurface sewage systems, their components, and alternatives. The manual is updated periodically to adapt to the dynamic and complex nature of small wastewater disposal systems. Updates are cited below.

Note: This is a large file. If you have difficulty downloading it, try opening it in a different browser or from your hard drive instead of your browser. Right-click on the link, select “Save link as,” navigate to the file on your hard drive, and double-click to open.

Current Updates to the Manual

Date Description
February 2025 Section 4.26 Steep Slope System Section
4.15 Individual Wastewater Incinerator

Previous Updates to the Manual

Date Description
September  2023 Section 4.20 RV Dump Station Section 5.9 Pipe Material for Specified Uses
June 2023 Section 1.4.2.1.2 Modified or Custom Septic Tank Approvals Section 1.8 Property Access and Use Section 3.2.8 Drainfield Excavation Backfilling Materials Section 3.3 Wastewater Flows Section 4.3.3 Above-grade Capping Fill System Approval Conditions
March 2023 Section 5.2 Approved Septic Tanks Section 5.4 Extended Treatment Package Systems Section 5.13 Proprietary Wastewater Treatment Products Section 4.3.5 Capping Fill System Construction

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Onsite Wastewater Coordinator

Peter Adams
peter.adams@deq.idaho.gov
(208) 954-1438

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