Current through Register Vol. 54, No. 7, April 4, 2022
of permeability by the soil permeability class rating technique is based upon a
hydrometer analysis performed as prescribed in (f) below, and a sieve analysis
performed as prescribed in (g) below, together with evaluation of soil
morphological properties as prescribed in
7:9A-5.2 and 5.3. As an alternate
to the hydrometer analysis procedure prescribed in (f) below, the hydrometer
analysis procedure given in ASTM STANDARD D 422, published by the American
Society for Testing and Materials, may be used to determine the percent by
weight of sand and the percent by weight of clay in the sample.
The following equipment is required:
1. A two-millimeter sieve, with an eight inch
or larger diameter frame;
of two sieves, with five inch or larger diameter frames, with covers and pans.
The sieves shall meet the following specifications:
i. The first sieve shall be 0.25 millimeter,
60-mesh, Bureau of Standards, phosphor bronze wire cloth; and
ii. The second sieve shall be 0.045
millimeter, 325-mesh, Bureau of Standards, phosphor bronze wire cloth (0.0015
3. A wooden
rolling pan or mortar with rubber-tipped pestle;
4. An oven;
5. A scale (0.1 gram accuracy);
6. Distilled water;
7. A sodium hexametaphosphate solution of 50
grams of the salt dissolved in one liter of distilled water;
8. The electric mixer (see section 2.1.1 of
ASTM Standard D 422) or mechanical shaker;
9. A 1000 milliliter graduated cylinder with
10. A soil
hydrometer calibrated to read in grams per liter at 68 degrees Fahrenheit (ASTM
12. A clock with
second hand; and
13. A sieve
(c) A loose
sample of soil, 200 grams or more, shall be collected from the soil horizon or
substratum to be tested.
soil sample shall be prepared as follows:
Pass the soil sample to be tested, which has been allowed to air dry, through a
two millimeter sieve to remove coarse fragments. Use moderate pressure with a
wooden rolling pin or mortar with rubber-tipped pestle to break soil aggregates
(but not soft rock fragments) which are larger than two millimeters.
2. Weigh both the material retained and the
material which passes through the sieve. This method shall not be used where
the weight of coarse fragments retained on the sieve exceeds 75 percent of the
total sample weight.
3. Discard the
Dispersion of the soil sample shall be accomplished using a motor-mixed or a
reciprocating shaker as prescribed below. This procedure shall be followed for
each replicate sample tested.
1. Step One:
Place 40 grams of air dry soil which has been passed through a two millimeter
sieve into a mixing cup or one liter shaker bottle together with 100
milliliters of sodium hexametaphosphate solution and 400 milliliters of
distilled water. Weigh out an additional 40 gram sample for determination of
oven dry weight. Re-weigh the latter sample after keeping it in an oven at 105
degrees Centigrade for 24 hours. (Only one sample is required for determination
of oven-dry weight regardless of the number of replicate samples used for the
2. Step Two:
If a motor mixer is used, allow the soil to soak in the cup for 10 minutes,
place the cup on the mixer and mix the sample for five minutes. Next, transfer
the suspension completely to the cylinder. Rinse the mixing cup with distilled
water and pour the rinse water into the cylinder so that none of the suspension
is left in the mixing cup. Bring the volume of the suspension in the cylinder
up to the 1000 milliliter mark with distilled water. Allow the suspension to
reach room temperature.
Alternate Step Two: If a reciprocating shaker is used in lieu of the mixer,
shake the sample for 12 hours, at a rate of approximately 120 strokes per
minute, and transfer to the cylinder rinsing the shaking bottles with distilled
water. Bring the volume of the suspension in the cylinder to the 1000
milliliter mark with distilled water. Allow the suspension to reach room
following procedure shall be used for the hydrometer analysis:
1. Step One: Calibrate the hydrometer as
follows: Add 100 milliliters of sodium hexametaphosphate solution to a 1000
milliliter cylinder and fill to the 1000 milliliter mark with distilled water.
Place the stopper in the cylinder and shake vigorously in a back and forth
motion. Place the cylinder on the table and lower the hydrometer into the
solution. Determine the scale reading at the upper edge of the meniscus
surrounding the hydrometer stem. This is the hydrometer calibration, Rc. Record
the temperature in degrees Fahrenheit ([degrees]F).
2. Step Two: Place a stopper in the cylinder
containing the dispersed soil sample, shake the cylinder using a back and forth
motion (avoid causing circular currents in the cylinder) and place the cylinder
on the table. Record the time immediately. After 20 seconds carefully lower the
hydrometer into the cylinder and, after exactly 40 seconds, read the
hydrometer. Repeat this step until two successive readings are obtained which
agree within 0.5 gram per liter.
Step Three: Determine the temperature of the suspension and correct the
hydrometer reading as follows:
i. Subtract the
reading obtained in Step One, Rc, from the hydrometer reading.
ii. For each degree Fahrenheit above 68 add
0.2 gram to the reading or for each degree Fahrenheit below 68 subtract 0.2
4. Step Four:
Remove the hydrometer, stopper the cylinder, and shake the hydrometer as in
Step Two. Remove the stopper and immediately place the cylinder on a table
where it will not be disturbed. Take a hydrometer reading after exactly two
hours and correct the hydrometer reading as in Step Three.
Step Five: Using test data reporting forms
provided in Appendix B, record, the following data:
i. Oven dry weight of soil, Wt (from Step One
of (e) above);
calibration, Rc and Temperature ([degrees]F) (Step One);
iii. Hydrometer reading at 40 seconds, R1
iv. Temperature of
suspension (Step Three);
Corrected hydrometer reading, R1' (Step Three);
vi. Hydrometer reading at two hours, R2'
(Step Four); and
hydrometer reading, R2' (Step Four);
Step Six: Calculate the percent of sand
and percent of clay as follows:
i. Percent of
sand = (Wt.-R')/Wt. x 100
Percent of clay = R2'/Wt. x 100
NOTE: The hydrometer analysis may not be carried out in a
room where the temperature varies more than two degrees during the time
required to perform the test.
A sieve analysis shall be performed as
prescribed below for each replicate sample used in the hydrometer analysis
except when the content of sand determined as prescribed in Step Six of (f)
above is less than 25 percent.
1. Step One:
After the completion of Step Four in (f) above, pour the suspension from the
sedimentation cylinder into a 0.045 millimeter sieve and wash the fine material
through the sieve using running water.
2. Step Two: Dry the sieve and its contents
in an oven. Cool the sieve and transfer the sand to a pre-weighed evaporating
dish (or similar heat resistant vessel) carefully, using a soft
3. Step Three: Place the
dish and its contents in an oven at 105 degrees Centigrade, for two hours, to
dry. Cool the dish and its contents and weigh to the nearest 0.01 gram.
Determine the weight of the sand by subtracting the weight of the
4. Step Four: Assemble a
stack of sieves as specified in (a)2 above, consisting of the pan, the 0.045
millimeter sieve and the 0.25 millimeter sieve, from bottom to top,
respectively. Inspect sieves carefully before using to make sure that they are
clean and undamaged. Transfer the sand from the evaporating dish to the top
sieve using a soft brush to complete the transfer.
Step Five: Put the cover on the top sieve,
firmly fasten the sieves to the sieve shaker and shake for three minutes.
Disassemble the stack of sieves, transfer the contents of each sieve to a
weighing dish separately. Weigh the contents of each sieve to the nearest 0.01
gram. Record the following data:
weight of sand fraction, from Step Three;
ii. Weight of sand passing the 0.25
millimeter sieve (retained in the 0.045 millimeter sieve);
iii. Percent fine plus very fine sand: Divide
weight of stand passing 0.25 millimeter sieve by total weight of sand fraction
and multiply this value by 100.
The following procedure shall be used to
determine the soil permeability class:
One: Using the soil permeability/textural triangle, Figure 6 of Appendix A,
determine the soil permeability class of the soil horizon being tested, based
upon the average percentage of sand and the average percentage of clay in the
replicate samples tested as prescribed in (f) above.
2. Step Two: If the average percentage of
fine plus very fine sand in the replicate samples tested, determined as
prescribed in Step Five of section (g) above, is 50 percent or greater, adjust
the permeability class determined in Step One of this subsection to the next
3. Step Three: If
the soil horizon being tested is found to have a massive or platy structure or
a hard, very hard, firm, very firm or extremely firm consistence, determined as
7:9A-5.3, adjust the permeability
class determined in Step One of this subsection to the next slowest