The site evaluation is the first step in determining if a parcel meets minimum State
mandated requirements for the installation of an individual on-site wastewater disposal
system (septic system). The site evaluation process involves the evaluation of soils
exposed in test pits which have been dug in the area proposed as the installation site for
both the original and repair area septic system absorption fields. Based upon the
characterization or description of the soils exposed in the test pits and detailed mapping
of the proposed development parcel, a determination is made by Tillamook County On-Site
Sanitation Division staff as to the ability of the parcel to support the installation of
an individual septic system. This determination is based upon requirements for the
installation of individual septic systems found in Oregon Administrative Rules, Chapter
340, Divisions 71 and 73.
Site Evaluation Steps
Completion of the site evaluation process involves the following:
A Complete site evaluation application is submitted with the site evaluation fee. The
site evaluation application consists of a Department of Environmental Quality application,
and a Land Use Compatibility form. The site evaluation application fee is currently $601.00.
A minimum of two (2) test pits are dug in the area of the parcel wherein the original
septic system absorption field and the future repair area absorption field are proposed to
be installed. These test pits are typically dug with a backhoe. The test pit minimum
dimensions are two (2) feet wide by three (3) feet long by five (5) feet deep. A step
should be dug on one side of the test pit that will allow easy entry to and exit from the
test pit. The test pits should be separated by a distance of at least seventy-five (75)
The Tillamook County On-Site Sanitation Division must be notified when the test pits are
Personnel from the Tillamook County On-Site Sanitation Division will then inspect the
parcel and, based upon the results of the parcel mapping and the soils characterized in
the test pits, issue a report stating the findings of the parcel inspection. The site
evaluation report will either approve or deny the parcel for the permitted installation of
an approved septic system.
If a site evaluation report is issued that approves a septic system installation on the
parcel, complete specifications for the permitted installation of the approved septic
system will included with the report. At this point, the appropriate septic system
construction installation permit application may be submitted. Once the septic system
construction installation permit is issued, the permitted septic system may be installed.
If a site evaluation report is issued that denies a septic system installation on the
parcel, the reasons for the denial will be specified in the report. Additionally, possible
appeal methods will be specified should you disagree with the findings of the report.