Massachusetts
Public Health Inspector Training
Wastewater Certificate Program
(MA PHIT WW)
Session 3:
Site Evaluation and Selection
MA PHIT- Wastewater Certificate Program, Session 3
1
Learning Objectives
After completing this session, you will be able to:
 List design considerations for site evaluation and
selection for onsite systems
 Discuss safety precautions in the field
 Describe requirements for deep observation holes
and percolation tests
 Explain how to witness and document a percolation
test
 Explain how to determine soils layers and seasonal
high groundwater levels
MA PHIT- Wastewater Certificate Program, Session 3
2
Site Evaluation
A conventional septic system has
 a septic tank,
 a distribution box,
and
 a soil absorption
system (SAS)
MA PHIT- Wastewater Certificate Program, Session 3
3
Site Evaluation Criteria
1. Location and position (including topography and condition)
2. Setbacks
3. Soil classification and permeability (deep hole and
percolation tests)
4. Estimated seasonal high groundwater
MA PHIT- Wastewater Certificate Program, Session 3
4
Video
Play these videos
Preliminary research to be
performed in office
MA PHIT- Wastewater Certificate Program, Session 3
Necessary Tools for
Site Evaluation
5
1. Location and Position
Key question:
 Where do we locate the onsite system components?
 For septic tanks, what should we consider?
 For the SAS what should we consider?
MA PHIT- Wastewater Certificate Program, Session 3
6
1. Location and Position
MA PHIT- Wastewater Certificate Program, Session 3
7
Video
Play this video
Site view and assessment of site constraints
MA PHIT- Wastewater Certificate Program, Session 3
8
2. Setbacks
MA PHIT- Wastewater Certificate Program, Session 3
9
2. Setbacks
Why?
MA PHIT- Wastewater Certificate Program, Session 3
10
3. Soil Classification and
Permeability
Deep Observation Holes
and Percolation Tests




Who can conduct the tests?
Who can witness and document
the tests?
What is the purpose of the deep
observation holes?
What is the purpose of a
percolation test?
True/False: the BOH must
witness perc tests and deep
holes.
MA PHIT- Wastewater Certificate Program, Session 3
11
Videos
Play these videos
Safety during soil testing
MA PHIT- Wastewater Certificate Program, Session 3
12
Safety First

What are potential hazards?
MA PHIT- Wastewater Certificate Program, Session 3
13
Safety First

Know your limits

Be cautious around big
equipment

Know confined entry
procedures

Use DigSafe

Go with your “gut”
MA PHIT- Wastewater Certificate Program, Session 3
14
Protective Measures

Develop and use sanitary procedures

Know first aid
MA PHIT- Wastewater Certificate Program, Session 3
15
Deep Observation Hole
MA PHIT- Wastewater Certificate Program, Session 3
16
Videos
Play these videos
Deep Hole Observations
MA PHIT- Wastewater Certificate Program, Session 3
17
Soil Suitability and Profile
 Soil
Suitability and Profile
1.Soil texture
2.Soil structure
3.Pervious material
present
4.Depth and thickness of
layers
5.Groundwater indicators
Image credit:
http://www.soils.wisc.edu/courses/SS325/introduction.htm
MA PHIT- Wastewater Certificate Program, Session 3
18
Field Notes
MA PHIT- Wastewater Certificate Program, Session 3
19
Deep Observation Hole
Summary

Minimum of two test holes in each proposed
SAS including reserve areas for new
construction or an increase in flow

10 feet deep

Minimum of one test hole in proposed SAS and
one in reserve area for repair (remedial)

Additional holes may be required by BOH—ask
for examples
Must be witnessed by BOH and documented if
MA PHITWastewater Certificate
Program, Session
3
requesting
certain
waivers
on design plan

20
Percolation Testing

Minimum of one perc test in each proposed SAS

Additional perc testing may be required by BOH

Use most restrictive area

Witness by BOH

Documented
MA PHIT- Wastewater Certificate Program, Session 3
21
Video
Play this video
Percolation test
MA PHIT- Wastewater Certificate Program, Session 3
22
Steps
1. Dig and confirm depth
2. Add water
3. Soak for 15 minutes (called
4.
5.
6.
7.
pre-soak) keeping water level
at 12”
Let water drop from 12” to 9”
and record time
Let water drop from 9” to 6”
and record time on Form 12
Determine the rate
What if you’re unable to
maintain 12” for pre-soak?
MA PHIT- Wastewater Certificate Program, Session 3
23
Practice
PT 1
12:15 pm
Time at 12”
12:45 pm
Time at 9”
1:30 pm
Time at 6”
Time 9” to 6”
Perc Rate (mpi)
if okay for new
if okay for
repair
MA PHIT- Wastewater Certificate Program, Session 3
PT 2
PT 3
PT 4
9:00 am
10:00 am
1:00 pm
Noon
10:15 am
2:30 pm
5:00 pm
10:18 am
4:30 pm
24
Key Points
 Percolation
Testing is not allowed in:
̶ Frozen, non-naturally occurring, or filled/disturbed soils
̶ Fractured or weathered rock
̶ Soils exposed to air for >3 days
 Additional
Percolation Testing can be required for:
̶ Varying soil conditions or designs over 2000 gpd
 Design
using the slowest rate
 How long are the test results good for?
MA PHIT- Wastewater Certificate Program, Session 3
25
4. Groundwater Determination
Deep observation holes also determine estimated
seasonal high groundwater elevation. Read more:
http://nesoil.com/properties/eshwt.htm
http://maps.massgis.state.ma.us/map_ol/oliver.php
MA PHIT- Wastewater Certificate Program, Session 3
26
System Design Considerations
The onsite system can
now be designed. Design
considerations include:

Site evaluation results

Source of the sewage

Daily flow

Waste
strength/characteristics
MA PHIT- Wastewater Certificate Program, Session 3
27
Session Recap
We discussed:
Design considerations for site evaluation and
selection for onsite wastewater systems
 Safety on the job site
 Requirements for deep observation holes and
percolation tests
 How to conduct and witness a percolation test
 How to determine seasonal high groundwater
levels

MA PHIT- Wastewater Certificate Program, Session 3
28