Protecting Public Health and the Environment.

Technical Guidance Manual for Individual and Subsurface Sewage Disposal Systems

This document 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.

Public Comment Opportunity: September 6 to October 6, 2016

DEQ is seeking public comment on proposed revisions to the Technical Guidance Manual for Individual and Subsurface Sewage Disposal Systems (TGM) that address soil design groups and subgroups, gray water, and composting toilet approval conditions.

Current Year's Updates to the Manual

Note: Based on changes to section numbers and page numbers it is recommended to update and replace all of Section 4 of the Technical Guidance Manual.

2016
Description
September
Section 1.9. Managed Operation, Maintenance and Monitoring. Revised guidance to update the management of Operation, maintenance, and monitoring (OMM). (pp. 1-22 to 1-35)
Section 3.3. Wastewater Flows. Revised guidance to update information on the assigning of wastewater flow projects and applicant allowance to propose wastewater flows through other appropriate measures to adequately size the subsurface sewage disposal facility (3.3.1 and 3.3.2) (pp. 3-20 to 3-21)
Section 4.5. Drip Distribution System. Revised guidance to clarify drip distribution system description, approval conditions and design requirements. (pp. 4-24 to 4-35)
Sections 4.8. Extended Treatment Package System and 4.9 Extra Drainrock Trench. Revised guidance to clarify extended treatment package system and extra drain rock trench approval conditions. (pp. 4-53 to 4-62)
Sections 4.12. Grey Water Sump and 4.13. Grey Water System. Revised guidance to clarify grey water sump and 4.13 grey water system approval conditions. (pp. 4-69 to 4-76)
Section 4.15. Individual Wastewater Incinerator. Revised guidance to clarify Individual Wastewater Incinerator approval conditions. (pp. 4-79 to 4-80)
Section 4.18. Portable Sanitation Units. Revised guidance to clarify portable sanitation units approval conditions and unit requirements. (pp. 4-87 to 4-104)
Sections 4.21. Recirculating Gravel Filter, 4.22. Intermittent Sand Filter, 4.23. In-Trench Sand Filter, 4.24. Sand Mound, 4.25. Seepage Pit/Bed, 4.26. Steep Slope System, 4.27. Subsurface Flow Constructed Wetland, and 4.28. Two-Cell Infiltrative System. Revised guidance to update the information in each section. (pp. 4-107 to 4-171)
Section 5.4. Extended Treatment Package Systems. Revised guidance to update and clarify extended treatment package system considerations. (pp. 5-13 to 5-16)
Section 5.14. Proprietary Wastewater Treatment Products. Revised guidance to update the table of Proprietary wastewater treatment products approved by DEQ for individual/subsurface wastewater/sewage disposal. (p. 5-29)
Section 6. Complaint Investigation and Enforcement. Revised guidance to provide for complaint investigation and enforcement and formalize an open sewage complaint investigation protocol. (p. 6-1)
Section 7. Rules and Codes. Updated guidance to provide the Individual/Subsurface Sewage Disposal Rules location at the Idaho Department of Administration website and a current copy of the Individual/Subsurface Sewage Disposal Rules. (pp. 7-1 to 7-45)
June
Section 2.1. Soil Texture and Group Determinations. Revised guidance to update soil texturing and group determinations with current USDA standards and guidance. (pp. 2-1 - 2-7)
Section 2.2.4.2. Reduction in Separation Distance to Surface Water with a Variance. Revised guidance to shorten acceptable phosphorous sorbing lifespan of site soils and to incorporate an equivalency determination for TMDL listed surface water bodies. (pp. 2-10 - 2-12)
Section 2.3. to 2.6. 2.3 standard percolation test was deleted and subsequent sections moved up one number. (pp. 2-16 - 2-36)
Section 4.19.3.1. Pressure Distribution System Piping. Revised guidance to provide a specific orifice spacing on sand mound, intermittent and in-trench sand filter, and recirculating gravel filter piping, include access riser restrictions in drainfields, and require all manifold and distribution lateral drainage to drain to the drainfield or drain back to the dosing chamber if not retained in the transport piping below frost levels. (pp. 4-100 - 4-102)
Section 4.21. Recirculating Gravel Filter. Revised guidance to include additional design elements for nitrogen reducing gravel filters and to allow for additional flow splitting designs. (pp. 4-116 - 4-133)
Section 4.23. In-Trench Sand Filter. Figure caption numbers and callout changes. (pp. 4-141 - 4-146)
Section 4.24. Sand Mound. Figure caption numbers and callout changes. (pp. 4-147 - 4-157)
Section 4.26. Steep Slope System. Figure caption numbers and callout changes. (p. 4-162)
Section 4.27. Subsurface Flow Constructed Wetland. Figure caption numbers and callout changes. (pp. 4-163 - 4-174)
Section 4.28. Two-Cell Infiltrative System. Figure caption numbers and callout changes. (p. 4-180)
Section 5.2. Approved Septic Tanks. New septic tank approvals for Bonner Concrete Products 1,500 gallon, one or two-piece, two-compartment tank and LarKen Precast, LLC 2,000 gallon, two-piece, one or two-compartment, HS20 rated septic tank. (pp. 5-2 - 5-10)
Section 5.6. Individual Wastewater Incinerator. ECOJOHN WC Series incinerator products added. (pp. 5-20 - 5-21)
March
Section 1.5. Installer's Registration Permit. Updated list of systems that require a complex installer's registration permit to install. (pp. 1-9 - 1-10)
Section 1.8. Easement. Revised easement section to outline surveyor requirements and created a consistent reference to real property and dominant and servient estates. (pp. 1-18 - 1-20)
Section 3.3. Wastewater Flows. Minor technical editing. (p. 3-19)
Section 4. Alternative Systems. Updated list of systems that are required to be designed by a professional engineer licensed in Idaho. (p. 4-2)
Sections 4.2 - 4.30. Addition of the type of installer's registration permit required for system installation and professional engineer design requirements under each section title. (p. 4-8, p. 4-18, p. 4-21, p. 4-23, p. 4-32, p. 4-47, p. 4-49, p. 4-65, p. 4-71, p. 4-75, p. 4-77, p. 4-79, p. 4-85, p. 4-87, p. 4-89, p. 4-93, p. 4-95, p. 4-98, p. 4-113, p. 4-115, p. 4-126, p. 4-133, p. 4-139, p. 4-150, p. 4-152, p. 4-169, p. 4-172, and p. 4-174)
Section 4.22.3.3. Intermittent Filter Dosing. Revised the dose volume percentage of the daily design flow. (p. 4-128)
Section 4.27. Subsurface Flow Constructed Wetland. Added new section/guidance for the design, installation, operation, and maintenance of subsurface flow constructed wetlands. (pp. 4-154 - 4-168)
Section 5.1. Approved Installers and Pumpers. Updated contact information for the health districts. (p. 5-1)
Section 5.2. Approved Septic Tanks. Revised contact information for Everlasting Concrete Products. (p. 5-4)
January
Section 5.2. Approved Septic Tanks. Extended Treatment Package System Approvals. Added a table footnote to address non-hydraulically isolated septic tanks as STEP stations and changed a manufacturer name to Larken Precast, LLC (p. 5-5 and p. 5-10)
Section 8. Rules and Codes. Changed title to Section 8 to reflect the movement of previous policies to different sections of the TGM. (p. 8-1)

Previous Years' Updates to the Manual

Note: Based on changes to section numbers and page numbers it is recommended to update and replace all of Section 4 of the Technical Guidance Manual.

2015
Description
December
Section 1.4.2.2. Extended Treatment Package System Approvals. Updated policy for extended treatment package systems approval and creation of two-tiered product approval process. (pp. 1-6 - 1-8)
Section 1.4.2.4. and 1.4.2.5. Proprietary Wastewater Treatment Product Approval Policy and All Other Product Approvals. Added new policy for proprietary wastewater treatment products approval and made a heading change. (pp. 1-8 - 1-9)
Section 5.4. Extended Treatment Package Systems. Revised table and created a new table to reflect the product approved as provisional and general ETPSs respectively. (p. 5-13 - 5-18)
Section 5.5-5.12. Composting Toilets through Frainfield Remediation Components. Added new table heading numbers. (pp. 5-19 - 5-28)
Section 5.13. Total Nitrogen Reduction Approvals. Moved table from this section to replace section 8.6. (p. 5-29)
Section 5.14. Propriety Wastewater Treatment Products. Added new section and table to list products approved as proprietary wastewater treatment products. (p. 5-30)
Section 8.1. Individual/Subsurface Sewage Disposal Rules (IDAPA 58.01.03). Made a non-substantive change to wastewater flow table. (p. 8-13)
August
Section 1.4.2.3 and 1.5. Gravelless System Product Approvals and Installer's Registration Permit. Added new policy for gravelless trench product approval and at-grade soil absorption system to list of systems requiring a PE's design. (p. 1-7)
Section 2.2.5 and 2.2.5.2. Method of 72 to Determine Effective Soil Depths and In-Trench Sand Filters and the Method of 72. Updated Method of 72 to include determination of effective soil depths to impermeable layers. (p. 2-10 and p. 2-12)
Section 4.1. General Requirements. Added new guidance addressing the requirement for a PE to design all public systems per Idaho Code 54-1218. (p. 4-1)
Section 4.1.3. Multiple Alternative Systems Combined into One System. Added at-grade soil absorption system to Table 4-1. (pp. 4-6 and 4-7)
Section 4.2. At-Grade Soil Absorption System. Added new guidance for the design, construction, and installation of at-grade soil absorption systems. (pp. 4-8 - 4-17)
Section 4.3. Capping Fill System. Revised capping fill systems guidance. (pp. 4-18 - 4-20)
Section 4.23. In-Trench Sand Filter. Revised in-trench sand filters guidance. (pp. 4-133 - 4-138)
June
Section 2.5.2.1. Permanent Monitoring Wells. Updated design parameters for permanent monitoring wells. (p. 2-20)
Section 3.2.8.1.4. Pit Run. Amended sizing specifications for pit run material. (pp. 3-17 - 3-18)
Section 4.1.3. Multiple Alternative Systems Combined into One System. Added guidance addressing the combination of multiple alternative system designs into one system design. (pp. 4-3 - 4-6)
Section 4.9. Floating Vault Toilets and Boat or Vessel Sewage Disposal. Added guidance addressing design, construction, and operation/maintenance of floating vault toilets and requirements for vessel sewage disposal. (pp. 4-60 - 4-63)
Section 4.12.4. Other Requirements. Changed format in Tables 4-10 and 4-11. (pp. 4-70 - 4-71)
Section 4.20.5. Drainfield Trenches. Added hydraulic application rate for A-2a and A-2b soils to Table 4-18. (p. 4-112)
Section 4.21.4. Drainfield Trenches. Added hydraulic application rate for A-2a and A-2b soils to Table 4-20. (p. 4-118)
Section 5.2. Approved Septic Tanks. Changed Infiltrator Systems, Inc. to Infiltrator Water Technologies, LLC (p. 5-4)
Section 5.3. Approved Dosing Chambers. Changed Infiltrator Systems, Inc. to Infiltrator Water Technologies, LLC (p. 5-11)
Section 5.4. Extended Treatment Package Systems. Added Norweco TNT ETPS model. (p. 5-16)
Section 5.7, Gravelless Trench Components. Changed Infiltrator Systems, Inc. to Infiltrator Water Technologies, LLC (pp. 5-20 - 5-21)
Section 5.12. Drainfield Remediation Components. Changed Infiltrator Systems, Inc. to Infiltrator Water Technologies, LLC (p. 5-27)
Section 8.1. Individual/Subsurface Sewage Disposal Rules (IDAPA 58.01.03). Revised IDAPA 58.01.03.005.11 to reference correct Idaho code (p. 8-9)
April
Section 1.6. Nonprofit Corporations. Moved from Section 4. No content changed. (pp. 1-10 - 1-13)
Section 1.7. Existing and Approved Systems, Abandoned and Undocumented Systems, and Nonconforming Systems. Replaced entire section to provide clarification on different system classifications, their allowed use, and permit requirements. Moved from Section 4. (pp. 1-13 - 1-16)
Section 1.8. Easement. Moved from Section 4. No content changes. (pp. 1-16 - 1-17)
Section 2.1.3. Soil Design Subgroup Corrections. Made subgroup corrections optional at the discretion of the permitting health district and provided an example of how subgroup corrections are made. (p. 2-6)
Section 4.15. Pit Privy. Updated to include new construction and maintenance standards. (pp. 4-74 - 4-75)
Section 4.16. Portable Sanitation Units. Updated to include new construction and maintenance standards and unit requirements based on event use and event attendance. (pp. 4-76 - 4-78)
Section 4.26. Vault Privy. Added new construction and maintenance standards. (pp. 4-137 - 4-138)
Section 5.2. Approved Septic Tanks. Corrected a tank description for Infiltrator Systems, Inc. (p. 5-4)
March
Section 3.2.8.1.2. Medium Sand. Corrected an error in the percentage of material passing the #30 sieve for medium sand. (p. 3-17)
Section 5.2. Approved Septic Tanks. Added Infiltrator Systems, Inc. 475-gallon and 1,500-gallon septic tank. (p. 5-4)
Section 5.3. Approved Dosing Chambers. Added Infiltrator Systems, Inc. 552-gallon dosing chamber. (p. 5-11)
January
Section 4.22.5. Drainfield Trenches. Corrected label in Figure 4-27. (p. 4-110)
2014
Description
December
Section 1.4.2.1.1. Initial Septic Tank Approvals. Added description of the approval process for new septic tank models for manufacturers. (pp. 1-3 -1-5)
Section 1.4.2.1.2. Transfer of Septic Tank Approvals Between Manufacturers. Added description about the process a manufacturer must complete to transfer approval of an existing septic tank model from another manufacturer to the new manufacturer's approved list. (p. 1-5)
Section 3.2.3. Septic Tanks and Dosing Chambers. Updated installation requirements for septic tanks and dosing chambers and removed design criteria that was included in section 1.4.2.1.1. (pp. 3-5 - 3-8)
Section 4.10.3. Extended Treatment Package System Operation, Maintenance, and Monitoring. Updated to include an allowance of sampling from a common dosing chamber for multiple systems from the same manufacturer. (pp. 4-43 - 4-47)
Section 4.11. Extra Drainrock Trench. Updated to amend approval conditions and multiplication factors used in the extra drainrock trench design. (pp. 4-58 - 4-63)
Section 4.16. Incinerator Toilets. Updated to amend approval conditions, design, and operation and maintenance requirements for incinerator toilets. (pp. 4-75 - 4-76)
Section 4.22. Recirculating Gravel Filter. Updated to amend approval conditions, design, construction, inspection, and operation and maintenance requirements for recirculating gravel filter systems. (pp. 4-102 - 4-112)
Section 4.23. Intermittent Sand Filter. Updated to amend approval conditions, design, construction, inspection, and operation and maintenance requirements for intermittent sand filter systems. (pp. 4-113 - 4-119)
Section 4.24. In-Trench Sand Filter. Updated to reflect new figure numbers. (pp. 4-120 - 4-124)
Section 4.25. Sand Mound. Updated to reflect new figure numbers. (pp. 4-125 - 4-135)
Section 4.27. Steep Slope System. Updated to amend approval conditions and construction requirements for steep slope systems. (pp. 4-138 - 4-139)
Section 4.28. Two-Cell Infiltrative System. Updated to reflect new figure numbers. (pp. 4-140 - 4-142)
Section 5.7. Gravelless Trench Components. Updated to reflect the new approval of Infiltrator Systems, Inc.'s Arc 36 LP gravelless chamber product. (p. 5-19)
Section 6.1. Septic Tank Pumping and Septage Disposal. Updated throughout to describe current septic tank pumping recommendations, describe septage classification, permit requirements, and septage storage and disposal. (pp. 6-1 - 6-10)
November
Section 4.2.1. Required Nonprofit Incorporation Elements. Corrected cross-reference number for Line 23. (p. 4-5)
Section 5.2. Approved Septic Tanks. Clarified bury depths for tanks only listed as HS20 load rated. (p. 5-10)
Section 5.7. Gravelless Trench Components. Corrected product ownership and model names. (pp. 5-19 and 5-20)
October
Section 1.5 Installer Registration Permit. Guidance added on what is required to obtain an installer's registration permit and requirements necessary to renew the permit. (pp. 1-4 - 1-7)
Section 2.2.4.2.3 Nutrient Evaluation Model Outputs for a Reduced Separation Distance to Surface Water. Clarified site life requirements. (p. 2-10)
Section 3.2.3.1 Conversion of a Septic Tank to a Lift Station. Guidance added on recommended practices for the conversion of a septic tank to a lift station. (pp. 3-7 - 3-8)
Section 4.1 General Requirements. Added description of plan requirements, operation and maintenance documents, and as-built plans and specifications for engineering of subsurface sewage disposal systems. Description of plumbing and electrical permit requirements for subsurface sewage disposal systems also added. (pp. 4-1 - 4-3)
Section 4.7.7 Drip Distribution. Corrected error in system design example. (p. 4-21)
Section 4.17 Individual Lagoon. Updated requirements for design, installation, and operation and maintenance of an individual lagoon. (pp. 4-73 - 4-76)
Section 4.20.3.2 Pressure Distribution. Revised equation number. (pp. 4-86 - 4-87)
Section 4.25.3.2 Sand Mound. Revised equation number. (p. 4-114)
Section 5.2 Approved Septic Tanks. Added new 1,000 gallon Wilbert Precast, Inc. septic tank to Table 5-1. (p. 5-10
August
Section 4.25.3.2 Sand Mound - Medium Sand Fill Design. Table 4-22 corrected to reflect correction factor for 20% slope. (p. 4-111)
June
Section 2.1.4 Medium Sand. Section removed and replaced with section 3.2.8.1.2.
Section 2.2 Separation Guidelines. Revised to include provisions for the reduction in the separation distance to surface water from a drainfield with and without the use of a variance. (pp. 2-7 - 2-13)
Section 3.2.7 Drainfield Cover. Updated to provide further clarification for both soil barriers and soil cover over drainfields. (pp. 3-13 - 3-17)
Section 3.2.8 Drainfield Excavation Backfilling Materials and Alternative System Construction Media. Added to provide descriptions on what backfilling materials are allowed for use in drainfields, how drainfield aggregate and construction media sources must be approved, the specifications for the various aggregate and construction media, and the process to substantiate aggregate and construction media sources and volumes. (pp. 3-13 - 3-17)
Section 4.5 Capping Fill System. Updated to provide clarification in the construction techniques used depending on the installation depth of the drainfield. (pp. 4-9 - 4-11)
Section 4.7 Drip Distribution. Updated to provide a revision in section formatting and clarification of required system components. (pp. 4-14 - 4-22)
Section 4.9 Experimental System. Updated to clarify approval conditions and add recommendations on operation and maintenance requirements. (pp. 4-39 - 4-40)
Section 4.10.3 Extended Treatment Package System Operation, Maintenance and Monitoring. Updated to include additional effluent testing methods, extend the deadline for resampling upon initial effluent sampling failure, and include regulatory provisions for property owners that fail to resample upon initial sample failure. (pp. 4-44 - 4-45)
Section 4.10.8 Extended Treatment Package System Construction. Updated to include the requirement that the O&M entity or service provider will submit information on the manufacturer, product, model number, and serial number of each ETPS installed prior to health districts providing final approval of the system installation. (p. 4-55)
Section 4.20 Pressure Distribution System. Updated throughout to meet the most current design research on pressure distribution systems. (pp. 4-78 - 4-92)
Section 4.25 Sand Mound. Updated throughout to meet the most current design research on sand mounds. (pp. 4-108 - 4-118)
Section 4.28 Two-Cell Infiltrative System. Updated to include revisions to construction, inspection, and operation and maintenance requirements. (pp. 4-122 - 4-124)
Section 5.2 Approved Septic Tanks. Jerome Precast was purchased by Triple C Concrete and is in the process of transferring approval for Jerome Precast's existing models. (pp. 5-4 - 5-9)
Section 5.3 Approved Dosing Chambers. Maximum bury depth included for each dosing chamber. (p. 5-11)
May
Section 5.2 Approved Septic Tanks. Added a new 1,000 gallon septic tank with an integral 500 gallon dosing chamber and a 1,500 gallon septic tank for Kanta Products, Inc. Additional descriptions of bury depths and updated material descriptions provided for all previously approved septic tanks. (pp. 5-2 - 5-10)
Section 5.3 Approved Dosing Chambers. Updated table format and headings. (p. 5-11)
Section 5.11 Vault Toilets. Added two vault toilet manufacturers that were previously listed in the approved septic tank list. (p. 5-25)
Section 8. Updated subsurface rules to include non-substantive revisions to IDAPA 58.01.03.005.16 and 58.01.03.006.07. (pp. 8-9 - 8-10)
March
Section 4.4 Easement. Revised section covering the creation of an easement for the placement of a subsurface sewage disposal system on a property that does not contain the wastewater generating structure. (pp. 4-7 - 4-8)
Section 4.12.2 and 4.12.3. new callout for section and table numbers. (p. 4-56)
Section 4.24. In-Trench Sand Filter. Revised section covering the design, installation, and construction of in-trench sand filters. (pp. 4-97 - 4-101)
Section 4.25. Sand Mound. New figure numbers. (pp. 4-102 and 4-104)
Section 4.27. Steep Slope System. New figure numbers. (p. 4-113)
Section 4.28. Two-Cell Infiltrative System. New figure numbers. (pp. 4-115 and 4-116)
Section 4.30. Drainfield Remediation Components. New section and table callout numbers. (p. 4-119)
Section 5. Addition of new section 5.3 listing approved dosing chambers, amended the section numbers for approved products throughout due to the addition of section 5.3, section 5.8 Pump Vaults only addresses packaged septic tank pump vault units after the removal of the approved dosing chambers to section 5.3. (p. 5-1 - 5-25)
2013
Description
December
Section 2.5.2.2. Updated in-text reference to figure. (p. 2-20)
Section 3.2.4. Updated in-text reference to table. (p. 3-8)
Section 4.2.1. Updated in-text reference to section. (p. 4-3)
Section 4.5.2. Updated in-text references to tables. (p. 4-8)
Section 4.8.2. Updated in-text reference to multiple sections and tables. (pp. 4-20 - 4-21)
Section 4.10.3. Removed certified; updated in-text reference to figure. (pp. 4-40 - 4-41)
Sections 4.11.4, 4.12.1, 4.12.2, and 4.12.3. Updated in-text references to multiple sections and tables. (pp. 4-53 - 4-55)
Section 4.26.2. Created separate paragraph a. under approval conditions. (p. 4-106)
Section 4.28.6. Updated in-text reference to section. (p. 4-111)
November
Section 1.4.2.2. New policy regarding approval procedures for new extended treatment package system technologies. (pp. 1-3 - 1-4)
Section 2.2.3. New method for determining the necessary effective soil depth to porous layers and ground water. (pp. 2-8 - 2-10)
Section 2.5. Expanded description of ground water level determination practices. (pp. 2-17 - 2-23)
Section 3.2.5. New section added describing equal distribution methods for gravity flow systems. (pp. 3-9 - 3-10)
3.2.6. Expanded description of serial distribution methods for gravity flow systems. (pp. 3-10 - 3-13)
3.3. New section describing acceptable methods for documenting wastewater flows that are not included in the subsurface sewage disposal rules. (pp. 3-14 - 3-16)
4.2. Revised section covering amendments and new additions for the requirements surrounding nonprofit corporations setup to manage operation and maintenance of subsurface sewage disposal systems (pp. 4-1 - 4-5)
4.3. Revised section covering vested rights and nonconforming uses to include processes outlined in DEQ program directives. (pp. 4-5 - 4-6)
4.10. Revised section covering the requirements surrounding the operation, maintenance, reporting, and enforcement requirements and procedures for extended treatment package systems. (pp. 4-37 - 4-51)
5.2. Table 5-1. Addition of a new 1,500-gallon septic tank for Dahle's Red-E-Mix, Inc. (p. 5-3)
5.6. Table 5-5. Added Plastic Tubing Industries, Inc. (p. 5-17)
October
Section 5.2. Table 5-1. Included amendments to the bury depth and materials description for the Oldcastle 1,500-gallon, low profile, two-compartment tank. (p. 5-6)
Section 5.2. Table 5-1. Added a 1,000-gallon septic tank for Robertson Manufacturing, Inc. that was previously approved under Boise Vault. (p. 5-7)
Section 5.2. Table 5-1. Approved Septic Tanks. Approved manufacturers updated and a new septic tank listed for Wilbert Precast, Inc. (pp. 5-2 - 5-9)
Section 5.7. Table 5-7. Septic Tank Pump Vaults. Approved manufacturers updated. (pp. 5-19 - 5-20)
August
Section 5.2. Table 5-1 updated to add septic tank model for Wilbert Precast, Inc. and the revision of a previously approved tank for Wilbert Precast, Inc. (p. 5-10)
July
Section 1. Updated in its entirety to include subsurface product approval policies (pp. 1-1 - 1-4)
Section 2.6.3. Table 2-11 updated to include upper slope limits (p. 2-21)
Section 2.7.2. Additional Application Information Requirement. Section updated to clarify subsurface system installations above unstable landforms. (p. 2-25)
Section 3. Updated in its entirety. (pp. 3-1 - 3-10)
Section 4.1. General Requirements. Section updated to clarify systems that should be designed by an engineer (p. 4-1)
Section 4.6. Composting Toilet. Toilet compost disposal options and waste types added. (pp. 4-8 - 4-9)
Section 4.10.2. Operation, Maintenance, and Monitoring Conditions for Approval. (p. 4-35)
Section 4.17.6. Operation and Maintenance. (p. 4-61)
Section 4.23.6. Operation and Maintenance. (p. 4-88)
Section 4.25.6. Operation and Maintenance. (p. 4-97)
Section 7. Operation and Maintenance content moved to Section 4 under repective systems amended. (pp. 7-1 - 7-2)
June
Section 5.2. Approved Septic Tanks. Added septic tank to the Wilbert Precast listing (1-piece, 2-compartment tank) in Table 5-1. (pp. 5-10 - 5-11)
May
Section 4.15. Emergency Holding Tank. Entire section was updated to reflect the intended use of holding tanks for emergency situations only. (pp. 4-54 - 4-55)
Section 4.20.3.6. Pump to Drop Box. New subsection to section 4.20 providing guidance on pumping effluent to a different elevation for gravity dispersal through the drainfield. (p. 4-76)
Section 4.21. Recreational Vehicle Dump Station. Entire section updated to provide guidance on these installations and separate the requirements from section 4.15 of the TGM. (pp. 4-77 - 4-78)
Section 4.26. Seepage Pit/Bed. Entire section updated to expand guidance regarding the use of seepage pits in health districts 1-6 and provide expanded guidance on seepage bed type installations. (pp. 4-96 - 4-98)
Section 5.9 Pipe Materials for Specified Uses. Section updated to include a new type of pipe allowed for installation in subsurface sewage disposal systems. (p. 5-25)
April
Section 5.3. Added Orenco model AX25-RT3N to approved products list in Table 5-2 (p. 5-16)
Section 4.13. Figure 4.11 replaced due to spelling error (p. 4-46)
Section 4.25. Figure 4.26 replaced due to spelling error (p. 4-86)
Section 5.2. New 4180 gallon septic tank added to Oldcastle Precast (p. 5-7)
Section 8.1. ASTM D-3033 removed because it is no longer manufactured (p. 8-16)
February
Updated to reflect DEQ's style guide for guidance documents. Changes in this document are reflected in section and subsection numbers, table and figure numbers, and page numbers. In addition, sections 2.1.4 Medium Sand Definition, 4.12 Gravelless Trench System, and 4.20.3.5 Pressure Distribution – In-tank Pumps have been updated based on final recommendations by the Technical Guidance Committee from the January 30, 2013 meeting. DEQ encourages users to replace their entire TGM with this update.

For updates made 2000-2012, contact the On-Site Wastewater Coordinator.

Negotiated Rulemaking

An individual/subsurface sewage disposal rulemaking has been initiated to create an effective and useful means of approving and overseeing service providers for DEQ and the health districts and will expand choices of service providers for private property owners. Learn more.

Technical Guidance Committee

Next Scheduled Meeting Date

Thursday, November 3, 2016, 8:30 a.m. - 4:30 p.m.
DEQ State Office
Conference Room C
1410 N. Hilton, Boise

Meeting Minutes

For previous meeting minutes, contact the On-Site Wastewater Coordinator.

Extended Treatment Package System Subcommittee

Meeting Minutes


Page Subscription

Staff Contacts

Wastewater Engineering Manager
Larry Waters
DEQ State Office
Water Quality Division
1410 N. Hilton
Boise, ID 83706
(208) 373-0151
larry.waters@deq.idaho.gov

On-Site Wastewater Coordinator
Clark Weaver
DEQ State Office
Water Quality Division
1410 N. Hilton
Boise, ID 83706
(208) 373-0144
clark.weaver@deq.idaho.gov

DEQ Resources

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Individual/Subsurface Sewage Disposal Rules

Related Pages

On-Site Wastewater Systems (Septic Systems)

Extended Treatment Package Systems (Aerobic Treatment Units)

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