N.J. Admin. Code § 7:9A-6.3 - Soil permeability class rating

(a) Determination 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.

(b) The following equipment is required:

1. A two-millimeter sieve, with an eight inch or larger diameter frame;

2. A set 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 wire);

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 rubber stopper;

10. A soil hydrometer calibrated to read in grams per liter at 68 degrees Fahrenheit (ASTM # 152H);

11. A thermometer;

12. A clock with second hand; and

13. A sieve shaker

(c) A loose sample of soil, 200 grams or more, shall be collected from the soil horizon or substratum to be tested.

(d) The soil sample shall be prepared as follows:

1. 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 coarse fragments.

(e) 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 hydrometer analysis).

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.

3. 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 temperature.

(f) The 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.

3. 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 gram.

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.

5. 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);

ii. Hydrometer calibration, Rc and Temperature ([degrees]F) (Step One);

iii. Hydrometer reading at 40 seconds, R1 (Step Two);

iv. Temperature of suspension (Step Three);

v. Corrected hydrometer reading, R1' (Step Three);

vi. Hydrometer reading at two hours, R2' (Step Four); and

vii. Corrected hydrometer reading, R2' (Step Four);

6. Step Six: Calculate the percent of sand and percent of clay as follows:

i. Percent of sand = (Wt.-R')/Wt. x 100

ii. 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.

(g) 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 brush.

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 dish.

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.

5. 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:

i. Total 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.

(h) The following procedure shall be used to determine the soil permeability class:

1. Step 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 slowest class.

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 prescribed in 7:9A-5.3, adjust the permeability class determined in Step One of this subsection to the next slowest class.

Notes

N.J. Admin. Code § 7:9A-6.3

Amended by R.1999 d.314, effective 9/20/1999.
See: 31 N.J.R. 1416(a), 31 N.J.R. 2741(a).
Substituted "0.045 millimeter" for "0.047 millimeter" throughout; and in (b)2ii, substituted "325-mesh" for "300" following "millimeter,".
Amended by R.2012 d.066, effective 4/2/2012.
See: 43 N.J.R. 478(a), 44 N.J.R. 1047(a).
In (f)5ii, inserted "and Temperature ([degrees]F)".