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Auburn, CA 95603

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Perc & Mantle

What is a Perc and Mantle?


Soil test pits or soil mantles are excavations done with a backhoe to verify effective soil depth. Effective soil is considered soil that will treat or filter sewage. For a standard sewage disposal system (in our counties) a minimum 6 feet of effective soil is required, 4 feet of effective soil below the trench bottom. The standard trench depth is 24-inches.


Percolation test are used to determine how fast or slow water will filter through the soil. A perc hole is dug to the anticipated trench bottom or to the limiting horizon. The hole is pre-soaked to simulate winter time or wet weather conditions. Readings of how quickly water leaves this hole are taken the following day. These reading are then averaged to calculate your average percolation rate.

What is an O.S.S.E.

Before applying for a new septic system, it is necessary to have a valid soils testing (On Site Soils Evaluation - OSSE) done. An OSSE includes soil tests that determine the effectiveness of soil to filter sewage through leach lines, as well as observations of required setbacks, constraints and possibilities for an individual, “on-site” septic system. The Soils Evaluation Report produced by the consultant (navo) of the particular site tested on a parcel is reviewed and evaluated by an Environmental Health Specialist who generates a findings report. An OSSE must be conducted by a County approved Soil Testing Consultant (navo).

Quick steps to apply for an OSSE/ Perc & Mantle

1) Hire a County Approved Soils Testing Consultant (Navo)

2) Your Consultant (navo) will Apply for the OSSE using some forms you will fill out from ""

  1. Septic Health Site Evaluation (PDF-fillable form)
  2. Fee Disclosure Form (PDF-fillable form)

3) Consultant (Navo) schedules an OSSE (see below)

4) Consultant (Navo), Backhoe operator (Typically Navo) and County Specialist meet on site for soils testing

5) Consultant (navo) submits Soils Evaluation Report to County

6) County Specialist generates Findings Report to approve what type of septic system to install

7) AFTER This a design can be created by your Consultant (Navo) to apply for the permit and get an install estimate

8) You may then proceed to apply for a Septic Permit 

Process To Install The Average Septic System in Placer County
Time Completed Description Anticipated Cost
1-3 days

Download forms from County Website, Fill out and Submit to
Placer County Environmental Health Dept. website
(P.C.E.H.D) and go into PCEH and apply/pay the Perc & Mantle
(P&M) (see below)

2-7 weeks

To schedule the P&M apply and pay the County and then CALL us


5-7 days

Because we are one stop shop we provide the backhoe,
operator, designer for 2 mantles and 3 perc test -
(A Standard P & M).The designer will complete
the P & M paperwork.

The County supervises Navo & Sons Inc. (ie designer,
backhoe, and operator) performingthe P& M Please note:
It is recommended to have owners or owners representative present on this first day


1-2 weeks

If a design is needed: The designer will quote a firm price
to perform the specific design and time to complete said design

Please note: Upon approval and completion of the design
we can provide a firm installation cost for the system

1-6 weeks

Once the design is completed, the 2 design
originals will need to be taken to P.C.E.H.D. to
apply for the installation permit of system

1-5 weeks Once a permit is issued we can usually start installing the system. Depends on the system