N.J. Admin. Code § 7:9A-6.1 - General provisions for permeability testing
(a) The design
permeability is the basis for determining the minimum required area of the
disposal field. Tests shall be required at the site of each proposed disposal
field in native soil or rock material to demonstrate an adequate zone of
disposal as required at
7:9A-10.1(e).
Tests shall be required in those areas demonstrating an adequate zone of
disposal for determination of the design permeability. Design permeability
tests shall be conducted as follows:
1.
Design permeability tests for conventional disposal fields shall be conducted
at the level of infiltration at a depth one to three feet below the ground
surface within the soil horizon where the bottom of the disposal field will be
placed;
2. Design permeability for
all mounded disposal fields or soil replacement disposal fields where native
soil will remain above the identified zone of disposal shall be determined from
the remaining least permeable native soil material above the identified zone of
disposal;
3. Design permeability
for all soil replacement disposal fields, including mounded soil replacement
systems, using fill material that meets the requirements of
7:9A-10.1(f) from
the top of the zone of treatment to the top of zone of disposal shall be
between six and 20 inches per hour; and
4. The permeability of all fill material
shall be confirmed after installation to be greater than six inches per hour at
the level of infiltration. A percolation test shall be conducted within the
fill material after it has been emplaced and compacted, or a tube permeameter
test shall be conducted using samples of the fill material which have been
compacted to a bulk density equivalent to that achieved in the construction of
the disposal field. An additional test shall be required at the top of each
separate type of fill, should the fill material in the zone of treatment differ
from the fill material being used in the zone of disposal, to confirm each type
of fill material has been installed with a permeability rate greater than six
inches per hour.
(b) The
administrative authority may require additional types of tests, or additional
tests at additional locations or alternate depths other than the depth of
infiltration, when doubt exists regarding the presence or the type of a
limiting zone or the soil conditions present.
(c) The type of tests which may be used shall
be determined based upon the purpose of the test and the soil conditions at the
depth of the test as shown in Table 6.1 below.
Table 6.1 Type of Test | |
Test Options: | 1--Tube Permeameter Test |
2--Soil Permeability Class Rating Test |
|
3--Percolation Test | |
4--Basin Flooding Test | |
5--Pit-bailing Test | |
6--Piezometer Test |
Purpose of Test and Soil Conditions | Acceptable Test Options | |
at Depth of Test | ||
I. | Determination of Design Permeability at Level of | |
Infiltration, Identification of Hydraulically | ||
Restrictive or Excessively Coarse Horizons or | ||
Substrata Above the Water Table | ||
A. Sands and loamy sands with single grain | 1, 2 or 3 | |
structure | ||
B. Other soil textures | ||
1. Undisturbed sample can be taken | 1, 2 or 3 | |
2. Undisturbed sample cannot be taken | 2 or 3 | |
II. | Identification of Massive Rock Substrata Above | 4 |
the Water Table | ||
III. | Identification of Hydraulically Restrictive | 5 or 6 |
Horizons or Substrata and Massive Rock Substrata | ||
Below the Water Table | ||
IV. | Design of Seepage Pits | 3 |
(d) The
number and location of permeability tests required shall be as follows:
1. When the tube permeameter test or the soil
permeability class rating test are used to determine the design permeability at
the level of infiltration, a minimum of one test shall be conducted within each
disposal field and each test shall consist of a minimum of two test replicates.
The administrative authority shall require additional tests or more than two
replicates per test where the variability of test results exceeds the limits
allowed in 7:9A-6.2(i)2, or
where the results of soil profile pits or borings, made as prescribed in
7:9A-5.2, indicate the presence of
more than one soil type within the area of the disposal field. When soil tests
taken in different parts of the disposal field yield different results, the
system shall be designed based upon the most restrictive conditions found
within the area of the disposal field.
2. When the basin flooding test, the
pit-bailing test or the piezometer test are required for identification of
limiting zones, a minimum of one test shall be required within or no further
than 15 feet beyond the boundaries of each disposal field. The administrative
authority may require more than one test where conditions vary from one part of
the disposal field to another.
3.
In cases where a pit-bailing or basin flooding test pit or part of a test pit
has been excavated within the boundaries of the proposed disposal trench or
bed, the pit shall be backfilled after use in a manner that will not result in
a major discontinuity with respect to soil horizonation, density, or
permeability in the soil below the disposal bed or trench.
(e) When the percolation test is used the
following requirements shall be met:
1. When
the percolation test is used to determine the design permeability at the level
of infiltration, the administrative authority shall require a minimum number of
percolation tests based upon the size of the proposed disposal field, as
follows:
Size of Disposal Field | Minimum |
(Square feet) | Number of Tests |
Less than 1500 | 2 |
1500-3000 | 3 |
3000-4000 | 4 |
4000-6000 | 5 |
2.
When the accuracy of a percolation test is questioned, one or more replicate
tests may be performed at the same location within the disposal field as a
means of better defining the true soil conditions at that particular location.
The average of the results obtained from replicate tests at a given location
within the disposal field shall be used for design purposes or for
determination of soil suitability at that location.
3. The results of percolation tests taken at
different locations within the disposal field shall not be averaged.
4. When a percolation test is abandoned due
to lack of measurable percolation, this test may be disregarded provided that a
minimum of three replicate tests taken at that same location yield acceptable
results and provided that all subsequent test replicates taken at that location
yield measurable percolation rates.
5. All percolation tests shall be located
within the boundaries of the proposed disposal field and only the most
restrictive percolation rate obtained within the disposal field shall be
utilized for design purposes.
6.
Percolation tests shall be uniformly spaced within the area of the disposal
field. Acceptable patterns of percolation test placement are shown in Appendix
C.
7. When a seepage pit is
proposed, as allowed in
7:9A-7.6, a minimum of one
percolation test shall be performed within each soil horizon or substratum
between the invert of the inlet and the bottom of the seepage pit. The
administrative authority may require additional tests below the bottom of the
seepage pit where the presence of a limiting zone is in question.
(f) The administrative authority
or its authorized agent shall witness permeability tests in accordance with the
requirements of
7:9A-3.6.
(g) When the results of a permeability test
or a percolation test are questionable, the administrative authority or its
authorized agent may require that the test be repeated. When the tube
permeameter test or the soil permeability class rating method is used, the
administrative authority may collect and test replicate samples for
verification of soil permeability. In cases where the results obtained by the
applicant differ from those obtained by the administrative authority, the
results obtained by the administrative authority shall be used for design or
determination of soil suitability.
(h) Except as provided in
7:9A-6.3, only unadulterated water
to which no foreign substances or chemical additives have been added shall be
used to conduct permeability or percolation tests. The addition of foreign
substances or chemical additives to water used for permeability testing shall
be considered as a falsification of data subject to penalties as outlined in
7:9A-1.7.
(i) The results of all permeability tests or
percolation tests, complete or incomplete, including all test replicates, taken
within the disposal field or less than 150 feet beyond the boundaries of the
proposed disposal field shall be reported to the administrative authority using
data submission forms as provided in Appendix B. Results shall be reported
regardless of whether or not they are acceptable and regardless of whether or
not they are used as a basis for the disposal field design. Failure to report
test results shall be considered a falsification of data and may subject the
violator to penalties as outlined in
7:9A-1.7.
(j) The administrative authority may allow
the use of test methods other than the standard test options outlined in
7:9A-6.1(c),
subject to review and approval of the test method by the Department.
(k) A septic system designer shall carry out
or directly supervise and certify all soil testing procedures and results
relied upon as a basis for the design of an individual subsurface sewage
disposal system and determine the permeability of fill material on site as
determined by the tests required in (a) above.
(l) Where test sampling
indicates inadequate permeability in a specific soil horizon to comply with
this chapter, the test location(s) established both horizontally and vertically
and an area 15 feet around the test location(s) in that same soil horizon shall
not be utilized as disposal area unless three additional replicate tests are
performed within that area and horizon, each of which demonstrate acceptable
permeability.
Notes
See: 24 N.J.R. 1987(a), 25 N.J.R. 2704(b).
Amended by R.2012 d.066, effective
See: 43 N.J.R. 478(a), 44 N.J.R. 1047(a).
Rewrote the introductory paragraph of (a); added (a)1 through (a)4; in (b), inserted "types of", ", or additional tests", "additional locations or alternate", a comma following "infiltration", and "or the soil conditions present"; rewrote (k); and added ( l).
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