Transcript Powerpoint Version - Vann Engineering Inc.

Cochise, Maricopa, Mohave, Navajo,
Pima, Pinal, Yavapai and Yuma
Counties
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Septic percolation testing for the various
counties within Arizona under the direction
of ADEQ are neither consistent nor
uniformly enforced. This has led many firms
such as Vann Engineering, Inc. to conduct
these tests inaccurately.
The most common septic percolation test
we conduct is for single-family homes that
are more than 400 feet away from any
existing sanitary sewer lines. Most of these
systems are either conventional or leach
beds.
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The purpose of this presentation is to review and
become familiar with the requirements of various
counties for septic investigations.
According to the counties testing for disposal
trenches is the same as conventional systems or
leach beds.
Although not as common, seepage pits will also be
covered.
Essentially, we want to start conducting septic
percolation tests everywhere and with 100%
conformance to the local governing standards.
We figure by doing the above we will retain more
clients, gain more new clients and develop strong
relationships with governing agencies.
Note: 7” max
30” deep; does not allow : Cochise, Mohave, Navajo, Yavapai
During Site Investigations for Septic Projects we
shall visually identify and report (on the
Driller’s Report) any of the following limiting
conditions discovered at the subject site:
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Presence of rock outcrops/boulders
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Presence of fill (deep and pervious)
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Presence of visible earth fissures
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Site topography
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Washes
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50’ is needed for a wash
Note: Use ADEQ form
stapled to folder
While advancing exploratory test borings or
conducting test pits for Septic Projects we
shall identify and report any of the following
limiting conditions discovered during the
subsurface investigation:
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Depth to bedrock or other “hard”
stratum which may be impermeable
(slower than 60 minutes per inch)
Presence of groundwater
Presence of free-draining soil layer
(faster than 1minute per inch)
Deep non-engineered fill
Clay
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There is an Arizona Administrative Code requirement of 3
points of exploration for conventional/leach beds/disposal
trench systems: 2 in the primary area and 1 in the reserve
area (in hopes that at least 2 locations will achieve
acceptable results)
The reasoning for this is to assure at least 2 locations will
yield acceptable results
The depth for the test borings/pits is to 12 feet below the
surface
The average depth range for the percs is 3 to 7 feet below
the surface, depending on the average septic discharge
depth and any particular county requirements (to follow)
The exploration depth (12 feet) allows for an examination
of the stratigraphy that exists a minimum of 5 feet below
the discharge depth, which should approximate the
bottom of the perc test
Seepage pits are not a part of the above but are discussed
later in the presentation
Note: 12” deep percolation test hole has a 15” diameter
 Assuming you have chosen an appropriate discharge
elevation for the percolation testing to be conducted………we
move on to:
 Planning and Preparation A.A.C. R18-9-A310(F)(1)
 Tests to be conducted in proposed discharge soil layer (native
undisturbed soils)
 Hand dig 12” x 12” x 12” cube OR 15” diameter x 12” deep test
hole
 Scarify smeared soils within the test hole and remove any
loosened materials from the bottom
 Use buckets with holes in the sides to support the sidewalls, if
necessary (it must be noted in the final report if this method was
used)
Presoaking procedures A.A.C. R18-9-A310(F)(2)
Fill hole with water up to 12”
Observe & record the water level decline in minutes
Repeat
If water drains in less than 60 minutes
 Repeat for a third time and if still draining in less than 60
minutes perform the percolation test
If water drains in more than 60 minutes
 Add water after 60 minutes and maintain a water depth of 9” for
at least 4 hours
 Wait 16-24 hours to perform the percolation test
Seepage Pit Procedures
Planning and Preparation A.A.C. R18-9A310(G)(1)
Drill a test hole at least 18 inches in
diameter and a minimum of 30 feet deep
Scarify smeared soils within the test hole
and remove any loosened materials from
the bottom
Presoaking Procedures A.A.C. R18-9-A310(G)(2)
Fill the bottom 6 inches of the test hole with gravel, if
necessary to prevent scouring
Fill the test hole with water to 3 feet below the surface
Observe the decline of water and determine the amount of
time in hours and minutes for it to completely drain
If water drains in less than 4 hours
 Repeat for a second time and if still draining in less than 4
hours perform the percolation test
If water drains in more than 4 hours
 Add water to the hole to maintain the level at 3 feet below the
surface for at least 4 more hours
 Wait 16-24 hours to perform the percolation test
Field Testing For
Conventional/Leach
Bed/Chamber and
Disposal Trench
Systems – By County
Site Investigation
 3 Test Pits or Test Borings to 12 feet
 2 in the primary, 1 in reserve location
 Pits should be 60 feet apart
 This remains constant no matter the type of septic system to be
used
Percolation Tests
 2 in the primary, 1 in the reserve location
 Assuming that the bottom of the test interval will be at -5 feet
(remember the typical depth range of 3-7 feet), keep in mind that
the entire test interval must be within the discharge layer
 The results of the pilot boring are key in determining the test
interval above
Exceptions
 If refusal before 12 feet for Test Borings use Pits
 Remember, there must be 4 feet between the bottom of the test hole
and the limiting condition (5 feet if the limiting condition is ground
water)
Site Investigation
 3 Test Pits to 12 feet
 2 in the primary, 1 in reserve location
 Pits should be 50 feet apart from each other
 This remains constant no matter the type of septic system to be used
Percolation Tests
 2 in the primary, 1 in the reserve location
 Assuming that the bottom of the test interval will be at -5 feet (remember
the typical depth range of 3-7 feet), keep in mind that the entire test interval
must be within the discharge layer
 Recommended that percs are conducted at varying depths in the discharge
soil layer (i.e. 3.0’, 4.0’ and 5.0’)
 The results of the backhoe pit are key in determining the test interval above
 Must be observed by a County Official with a 24 hour notice
Exceptions
 Seepage Pits are not allowed
 Hillside lots with greater than 15% grade are not allowed on-site systems
(due to back hoe inaccessibility ) (double check with Civil Engineer)
 Remember, there must be 4 feet between the bottom of the test hole and the
limiting condition (5 feet if the limiting condition is ground water)
Site Investigation
 3 Test Pits to 12 feet
 2 in the primary, 1 in reserve location
 Pits should be 50 feet apart from each other
 This remains constant no matter the type of septic system to be used
Percolation Tests
 2 in the primary, 1 in the reserve location
 Assuming that the bottom of the test interval will be at -5 feet (remember
the typical depth range of 3-7 feet), keep in mind that the entire test interval
must be within the discharge layer
 Recommended that percs are conducted at varying depths in the discharge
soil layer (i.e. 3.0’, 4.0’ and 5.0’)
 The results of the backhoe pit are key in determining the test interval above
 Must be observed by a County Official with a 24 hour notice
Exceptions
 Seepage Pits are not allowed
 Hillside lots with greater than 15% grade are not allowed on-site systems
(due to back hoe inaccessibility) (double check with Civil Engineer)
 Remember, there must be 4 feet between the bottom of the test hole and the
limiting condition (5 feet if the limiting condition is ground water)
Site Investigation
 3 Test Pits or Test Borings to 12 feet (use 15 feet depth test
borings using 4.5-inch auger)
 2 in the primary, 1 in reserve location
 This remains constant no matter the type of septic system to
be used
Percolation Tests
 2 in the primary, 1 in the reserve location
 Assuming that the bottom of the test interval will be at -5
feet (remember the typical depth range of 3-7 feet), keep in
mind that the entire test interval must be within the discharge
layer
 The results of the pilot test hole are key in determining the
test interval above
Exceptions
 If refusal before 12 feet for Test Borings use Test Pits
 A 4 foot separation must exist beneath the base of the perc
test and the limiting condition
Site Investigation
 3 Test Pits or Test Borings to 12 feet (use 15 feet)
 2 in the primary, 1 in reserve location
 This remains constant no matter the type of septic system to be used
Percolation Tests
 2 in the primary, 1 in the reserve location
 Assuming that the bottom of the test interval will be at -4 feet
(remember the typical depth range of 3-7 feet), keep in mind that the
entire test interval must be within the discharge layer
 The results of the pilot boring are key in determining the test interval
above
 A Pinal County representative must be given adequate notice and the
opportunity to inspect the holes prior to perc testing
 Sand in the base of the hole although an ADEQ requirement is
paramount for Pinal County
Exceptions
 If refusal before 12 feet for Test Borings use Pits
 If more than 35% rock fragments must use Test Pits
 A 4 foot separation must exist beneath the base of the perc test and the
limiting condition
Site Investigation
 3 Test Pits to 12 feet (will not require percs)
 OR 3 Test Borings to 12 feet*
 2 in the primary, 1 in reserve location
 Pits should be 60 feet apart from each other
 This remains constant no matter the type of septic system to be
used
Percolation Tests
 Not required when work is supervised or performed by an Arizona
registered Engineer or Geologist
 *Note: If only performing test borings and the county is not
satisfied with the data collected they will require percs to be
performed
Exceptions
 Hillside lots may require trenches to be farther than the
recommended 60 feet apart
Site Investigation
 3 Test Pits or Test Borings to 12 feet (use 15 feet deep test borings)
 2 in the primary, 1 in reserve location
 This remains constant no matter the type of septic system to be
used
Percolation Tests
 2 in the primary, 1 in the reserve location
 Assuming that the bottom of the test interval will be at -5 feet
(remember the typical depth range of 3-7 feet), keep in mind that
the entire test interval must be within the discharge layer
 The results of the pilot hole are key in determining the test interval
above
Exceptions
 If refusal before 12 feet for Test Borings use Test Pits
 A 4 foot separation must exist beneath the base of the perc test and
the limiting condition
Site Investigation for Subdivision:
 A Soils Test Plan must be submitted to the County and
approved prior to testing for the subdivision. The Soils Test
Plan consists of:
 Proposed locations of testing on a plat map
 The method of testing (boring/pit/perc)
 Name of firm
 Depth to seasonal high groundwater
 Site-specific geology
 Site-specific topography
 Information to be included in final report
 A ‘set of tests’ is required for 30% of the lot coverage of the
subdivision.
 Each set consists of 1-50.0 foot pilot test boring and 1
percolation test (usually at 5.0 feet)
 The primary and reserve criteria do not apply at this point
These results are used to determine if on-site septic systems
will be possible or acceptable for the subdivision overall…….
If not……..
The developers will need to make arrangements for sanitary
sewer system throughout the subdivision.
If the results are acceptable….
Then the individual homeowners will be responsible for
individual lot testing (3 pits/3 percs-primary/ reserve
criteria). They have the option of relying partly on the report
generated for the subdivision and my be able to have less
septic testing done for the individual lot. This depends on
the test locations (primary/reserve) versus their septic system
location.
Site Investigation for an Individual Lot:
 3 Test Pits or Test Borings to 12 feet. For conventional / leach field and
disposal trenches, the test hole depth is required to reach at least 5 feet
below the discharge depth (resulting in a 10 foot boring usually-15 feet will
be assumed by Foree and Vann so we have one less variable to mess with).
12 feet is the maximum depth attainable with a conventional backhoe. If
borings are used it makes perfect sense to use 15 feet (3 sections of auger).
Borings shall be small diameter auger i.e. 4.5 inches.
 2 in the primary, 1 in reserve location
 Pits or Borings should be 10 - 25 feet apart
Percolation Tests
 2 in the primary, 1 in the reserve location
 A 1 cubic foot test hole is excavated in the test pit, while a minimum of 15
inch diameter auger is used for drilling efforts
 Assuming that the bottom of the test interval will be at -5
feet (remember the typical depth range of 3-7 feet), keep in mind that the
entire test interval must be within the discharge layer
 The results of the pilot boring or test pit are key in determining the
percolation test interval above
Exceptions
 A 4 foot separation must exist beneath the base of the perc test and the
limiting condition if encountered shallower than 12 feet
Field Testing For
Seepage Pit
Disposal Systems –
By County (where
accepted)
Seepage Pits are No
Longer Allowed in this
County
Seepage Pits are No
Longer Allowed in this
County
Seepage Pits are No
Longer Allowed in this
County
Site Investigation for an Individual Lot:
 Using 4.5 inch diameter continuous flight auger, complete a
pilot test boring to a minimum depth of 50 feet
Percolation Tests
 One in the primary area only
 One 18 inch diameter test hole to a minimum depth of 30
feet
 Typically the bottom of the test interval will be from 3 feet
below the current grade to the bottom of the test (keep in
mind the entire perc test must be within the discharge layer
for the seepage pit system)
Exceptions
 A 4 foot separation must exist beneath the base of the perc
test and the limiting condition
Site Investigation for an Individual Lot:
 Using 4.5 inch diameter continuous flight auger, complete a
pilot test boring to a minimum depth of 50 feet
Percolation Tests
 One in the primary area only
 One 18 inch diameter test hole to a minimum depth of 30
feet
 Typically the bottom of the test interval will be from 3 feet
below the current grade to the bottom of the test (keep in
mind the entire perc test must be within the discharge layer
for the seepage pit system)
Exceptions
 A 4 foot separation must exist beneath the base of the perc
test and the limiting condition
Seepage Pits are No
Longer Allowed in this
County
Site Investigation for an Individual Lot:
 Using 4.5 inch diameter continuous flight auger, complete a
pilot test boring to a minimum depth of 50 feet
Percolation Tests
 One in the primary area only
 One 18 inch diameter test hole to a minimum depth of 30
feet
 Typically the bottom of the test interval will be from 3 feet
below the current grade to the bottom of the test (keep in
mind the entire perc test must be within the discharge layer
for the seepage pit system)
Exceptions
 A 4 foot separation must exist beneath the base of the perc
test and the limiting condition
 Required to maintain a 60 foot separation between the
bottom of the proposed pit and aquifer
Site Investigation for an Individual Lot:
 Using 4.5 inch diameter continuous flight auger, complete a
pilot test boring to a minimum depth of 50 feet
Percolation Tests
 One in the primary area only
 One 18 inch diameter test hole to a minimum depth of 30
feet
 Typically the bottom of the test interval will be from 3 feet
below the current grade to the bottom of the test (keep in
mind the entire perc test must be within the discharge layer
for the seepage pit system)
Exceptions
 A 4 foot separation must exist beneath the base of the perc
test and the limiting condition
Report
Major Components of the
Report
 Test
Locations (Site Plan)
 Boring Logs
 Groundwater data
 Field Data Sheet
 Completion of ADEQ forms
 Presentation of SAR
Test
Locations
Typical
Boring Log
Groundwater Map
Field Data
Sheet
Typical
Form
Section
Soil Absorption Rate (SAR)