Required Inspections during Installation of OWTS

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Onsite Wastewater Treatment Systems (OWTS; also known as "Septic Systems") Inspections

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What are the different inspections required during the installation of an Onsite Wastewater Treatment System (OWTS)?

The inspection steps required for the installation of an OWTS will vary with the type and complexity of the OWTS installed. The following inspections shall be required unless waived by YCEH. Please consult the approved/issued installation permit - it will indicate which inspections are required. Some of these inspections can be combined: 

Precon Inspection: stake out the OWTS
 precon

 

  1. PRECONSTRUCTION MEETING: The preconstruction meeting shall have the marked layout of the proposed OWTS. If not already existing, include any proposed footprints of buildings, pools, or other structures which could affect the OWTS and replacement area. Minimum horizontal setbacks shall be in accordance with the approved design.


  2. OPEN TRENCH INSPECTION: Open trench inspection shall be performed jointly by the OWTS Designer and Yolo
  3.  Open Trenchopen trench

    County Environmental Health (YCEH). At the time of the open trench inspection, all of the following shall be completed: 
    • All excavations necessary for the OWTS at the designed depth, width and length. This may not be possible with the logistics of installation with the site restrictions, and one trench needs to be dug and rocked at a time. In this situation, consult with YCEH and the first trench shall be inspected prior to rock.
    • All smeared or compacted surfaces shall be corrected.
    • Bottom of the trenches shall be level.

  4. ROCK and PIPE INSPECTION

     Clean Rock Only!rock

    • The connection of the septic tank, all distribution piping and the quality of the rock will be inspected. The rock shall be inspected and approved prior to installation into the trench - this may happen during the open trench.
    • For alternative systems, this inspection will also include inspection of the dosing tank, pump and filter assembly, and hydraulic squirt test for pressure distribution system in conjunction with the qualified system designer.

  5. FINAL INSPECTION: At the time of the final inspection by YCEH, all of the following shall be completed:
    • The trenches filled with rock to the specified level with the filter material in place or the gravel-less chambers installed.
    • Approved distribution boxes, with covers, installed level on undisturbed soil and at the proper elevation and distribution.
    • Approved tank risers and inspection ports.

      Final Inspection
       standard on hill (2)

    • All pipe, other than in trenches, must be installed on grade (1/8"/ft. minimum) and grouted to septic tank or distribution boxes.
    • All pipe in trenches installed level (max drop of 3" in 100 ft std. trench.) in the full length of trenches with ends capped. Watertight sealing around pipe is also to be completed at the distribution boxes.
    • The septic tank set level in place on undisturbed soil.
    • All trenches must be uncovered to the filter material and visible for inspection - do not backfill without YCEH approval. Leave ends of pipes exposed.
    • If required, Service Provider shall be present at the Final Inspection. Because they will be providing on-going monitoring and maintenance to the OWTS, it is important that they understand the system layout and settings prior to use.

  6. OTHER INSPECTIONS: Other inspections may be required as installation permit conditions by YCEH depending upon the type of system proposed. Owner-installed OWTS may require additional inspections to verify workmanship during the construction.

The costs of additional inspections and related services beyond services normally covered by the permit fee may be charged to the applicant at an hourly rate.

YCEH may combine one or more required inspections into a single field visit if possible.

Septic tanks or other primary components may be required to be filled with water to the flow line prior to requesting inspection. All seams or joints shall be left exposed (except the bottom) and the tank shall remain watertight.

A flow test may be required to be performed through the OWTS to the point of effluent disposal. All lines and components shall be watertight and distribution shall be according to the approved OWTS design.

OWTS must be backfilled within ten (10) days of written approval for backfill from YCEH and the OWTS designer (if required), or as specified by the approved system design.

For all inspection requirements, please refer to the Yolo County OWTS Manual and the approved/issued installation permit. 

Does the installation of Alternative OWTS have different inspection requirements?

Yes. Alternative system inspections may include those inspections listed above, but will also include inspections specified for each type of  alternative OWTS, as stated in Section 5 (page 46) of the YCEH OWTS Manual. Please see some of the inspection summaries below:

  1. Supplemental Treatment Systems: These are alternative OWTS designed to produce a higher quality wastewater effluent prior to land dispersal. These systems require specific construction inspections, such as the following:

     QD and contractor reviewing plans at final inspection.qd inspection

    • Proprietary Treatment Units: These manufactured or "package" units/components are specifically designed to provide enhanced treatment, producing a higher quality effluent meeting a predetermined standard prior to dispersal to land. Joint inspections by the Qualified System Designer, installation contractor, and YCEH may be required of the following: preconstruction inspection; water tightness of septic and pump tanks; testing of treatment unit, to include the function and setting of all control devised and alarms; final inspection. The Service Provider shall be present at the final inspection. 
    • Intermittent Sand Filter (ISF) and Recirculating Sand Filter (RSF): These systems consist of packed-bed filter of sand, designed for single pass-through or recirculating treatment of septic tank effluent. Joint inspections with the Qualified Septic Designer, installation contractor, and YCEH may be required of the following: preconstruction inspection; water tightness of septic and pump tanks; sand filter dimensions, structure and liner; underdrain piping and filter rock; sand quality and placement; piping installation and hydraulic ("squirt") test of the distribution system; functioning and setting of all control devices; and final inspection to verify that all construction elements are in conformance with the approved plans and specification, all inspection ports are installed, and erosion control has been completed. The Service Provider shall be present at the final inspection.
  2. Pressure Distribution (PD) System: This is a different method of wastewater dispersal to the land because it uses a pump and

    Hydraulic test of PD OWTS 
    squirt (2)

    small-diameter pressure piping to achieve broad, uniform distribution of wastewater for improved soil absorption and better treatment of percolating effluent. Joint inspections by the Qualified System Designer, installation contractor, and YCEH will be required of the following: preconstruction inspection (recommended); water tightness of septic and pump tanks; hydraulic "squirt" testing of laterals; open trench and rock approval; functioning and setting of all control devices; final inspection to verify that all construction elements are in conformance with approved plans and specification, all performance ports are installed, and erosion control has been completed. The Service Provider shall be present at the final inspection. 
  3. Subsurface Drip Dispersal System: This is a method of wastewater dispersal to land that can be used only after

    Drip Dispersal field 
    drip field (2)

    supplemental treatment. Joint inspections of the supplemental OWTS (see above) by the Qualified System Designer, installation contractor, and YCEH may be required of the following: preconstruction inspection; water tightness of septic and pump tanks; drip field layout, piping materials and installation, and all associated valves and connections; hydraulic testing of system; functioning and setting of all control devices; final inspection to verify that all construction elements are in conformance with approved plans and specification, all performance/inspection ports are installed, and erosion control has been completed. The Service Provider shall be present at the final inspection. 
  4. Mound Systems: These systems usually consist of an elevated sand bed with a gravel distribution bed covered by soil fill. Joint inspections by the Qualified System Designer, installation contractor, and YCEH may be required of the following: preconstruction inspection; water tightness of septic and pump tanks; clearing and ripping/plowing of the mound basal area soils; sand material and placement; pea gravel distribution bed and piping installation; hydraulic testing of system; functioning and setting of all control devices; placement of filter fabric silt barrier and soil cover; final inspection to verify that all construction elements are in conformance with approved plans and specification, all performance/inspection ports are installed, and erosion control has been completed. The Service Provider shall be present at the final inspection. 

For all inspection requirements, please refer to the Yolo County OWTS Manual and the approved/issued installation permit. 

Which Activities DO NOT Require an OWTS Permit or a YCEH Inspection?

Permits are NOT required* for any of the following:

  1. Clearing stoppages in pipes, provided that the OWTS is undisturbed.
  2. Cleaning of each individual septic tank, dosing tank, holding tank, or other wastewater receptacle that is pumped or cleaned by a licensed Yolo County Septage Pumper.
  3. To replace the following components to an approved OWTS provided the property owner or contractor notifies YCEH in writing that the modification was made:
    • Risers and/or lids to a septic tank if the tank is not located in an area that is subject to vehicular traffic. Risers may be added to an existing tank without a permit provided the work is performed by a licensed contractor. Risers shall be sealed so as to be watertight.
    • Effluent filters.
    • Sanitary tees and joints.
    • Solid pipe, including the building sewer. Please know that the building department may require a permit for the building sewer.
    • Distribution boxes.
    • Mechanical components of proprietary treatment systems, that are like-for-like, such as pumps and blowers, provided that YCEH is notified of the work performed.
  4. To replace the following components to an approved OWTS provided that the replacement is like-for-like: float switches, pumps, and electrical boxes. 
  5. To expose a portion of the OWTS for purposes of evaluating its performance or operation provided the OWTS is not damaged, altered, or modified as part of the evaluation.

*Nothing listed above shall provide an exemption from the material, structural, and installation requirements of the YCEH OWTS Manual, or the requirements of other enforcement agencies (e.g., building department).


-  For all inspection requirements, please refer to the Yolo County OWTS Manual and the approved/issued installation permit. 

-  Now that the OWTS is installed, it's important that is works well AND lasts a long time. Please visit the OWTS OM&M Requirements webpage for more information.
-  Please visit the 
OWTS/Septic Systems Types webpage for information about all types of OWTS.