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.
- Technical Guidance Manual for Individual and Subsurface Sewage Disposal Systems (Last updated: August 2024)
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Current Updates to the Manual
Date | Description |
|---|---|
August 2024 | Section 3.2.3 Septic Tank and Dosing Chamber Installation Appendix D – DEQ Memorandums List |
April 2024 | Section 4.23 In-Trench Sand Filter Section 1.5 Installer’s Registration Permit Section 4.5 Drip Distribution Appendix C – uncommon wastewater flows |
January 2024 | Section 4.26 Steep Slope System Section 2.2.3 Effective Soil Depths |
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