Vadose Zone Penetration
Environmental Engineering · FE Reference Handbook section
Handbook notes for this section
Definitions and conditions exactly as the handbook states them.
- Soil Gasoline Kerosene Light Fuel Oil
- A constant value representing capacity of soil and viscosity of product
- Data from Shepherd, W. D. No date. Practical Geohydrological Aspects of Groundwater Contamination.
- Dept. of Environmental Affairs, Houston: Shell Oil, as published in Underground Storage Tank
Core formulas for this FE topic
Definitions, applicability, units, assumptions and worked examples for each relation.
Worked exam-style examples
The four ways this section is written on the real exam — thoughts first, then equations, then substitution.
vadose zone penetration time for a spill migrating to groundwater Given depth to water table (d) = 26.5000 m; field capacity (FC) = 0.3900; infiltration rate (I) = 0.0250 m/day, determine the time to reach water table (t) in day.
Given
Find
time to reach water table (t), in day
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except t is given, so isolate t symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for t:
Step 3 — List the givens: depth to water table (d) = 26.5000 m, field capacity (FC) = 0.3900, infiltration rate (I) = 0.0250 m/day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning t = 413.4 day to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 826.8 — kept a factor of two that cancels in the correct rearrangement.
- 206.7 — dropped that same factor in the other direction.
- 454.7 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration estimate given field capacity and infiltration rate Given field capacity (FC) = 0.1600; infiltration rate (I) = 0.0300 m/day; time to reach water table (t) = 4,455 day, determine the depth to water table (d) in m.
Given
Find
depth to water table (d), in m
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for d:
Step 3 — List the givens: field capacity (FC) = 0.1600, infiltration rate (I) = 0.0300 m/day, time to reach water table (t) = 4,455 day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning d = 835.3 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1,671 — kept a factor of two that cancels in the correct rearrangement.
- 417.7 — dropped that same factor in the other direction.
- 918.8 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration analysis above the water table Given depth to water table (d) = 18.5000 m; field capacity (FC) = 0.1800; time to reach water table (t) = 4,275 day, determine the infiltration rate (I) in m/day.
Given
Find
infiltration rate (I), in m/day
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except I is given, so isolate I symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for I:
Step 3 — List the givens: depth to water table (d) = 18.5000 m, field capacity (FC) = 0.1800, time to reach water table (t) = 4,275 day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning I = 0.0008 m/day to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0016 — kept a factor of two that cancels in the correct rearrangement.
- 0.0004 — dropped that same factor in the other direction.
- 0.0009 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration time for a spill migrating to groundwater Given depth to water table (d) = 24.5000 m; field capacity (FC) = 0.1500; infiltration rate (I) = 0.0030 m/day, determine the time to reach water table (t) in day.
Given
Find
time to reach water table (t), in day
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except t is given, so isolate t symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for t:
Step 3 — List the givens: depth to water table (d) = 24.5000 m, field capacity (FC) = 0.1500, infiltration rate (I) = 0.0030 m/day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning t = 1,225 day to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 2,450 — kept a factor of two that cancels in the correct rearrangement.
- 612.5 — dropped that same factor in the other direction.
- 1,348 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration estimate given field capacity and infiltration rate Given field capacity (FC) = 0.3600; infiltration rate (I) = 0.0540 m/day; time to reach water table (t) = 225.0 day, determine the depth to water table (d) in m.
Given
Find
depth to water table (d), in m
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for d:
Step 3 — List the givens: field capacity (FC) = 0.3600, infiltration rate (I) = 0.0540 m/day, time to reach water table (t) = 225.0 day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning d = 33.7500 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 67.5000 — kept a factor of two that cancels in the correct rearrangement.
- 16.8750 — dropped that same factor in the other direction.
- 37.1250 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration analysis above the water table Given depth to water table (d) = 9.5000 m; field capacity (FC) = 0.4000; time to reach water table (t) = 1,971 day, determine the infiltration rate (I) in m/day.
Given
Find
infiltration rate (I), in m/day
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except I is given, so isolate I symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for I:
Step 3 — List the givens: depth to water table (d) = 9.5000 m, field capacity (FC) = 0.4000, time to reach water table (t) = 1,971 day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning I = 0.0019 m/day to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0039 — kept a factor of two that cancels in the correct rearrangement.
- 0.0010 — dropped that same factor in the other direction.
- 0.0021 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration time for a spill migrating to groundwater Given depth to water table (d) = 24.5000 m; field capacity (FC) = 0.1700; infiltration rate (I) = 0.0050 m/day, determine the time to reach water table (t) in day.
Given
Find
time to reach water table (t), in day
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except t is given, so isolate t symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for t:
Step 3 — List the givens: depth to water table (d) = 24.5000 m, field capacity (FC) = 0.1700, infiltration rate (I) = 0.0050 m/day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning t = 833.0 day to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1,666 — kept a factor of two that cancels in the correct rearrangement.
- 416.5 — dropped that same factor in the other direction.
- 916.3 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration estimate given field capacity and infiltration rate Given field capacity (FC) = 0.2200; infiltration rate (I) = 0.0700 m/day; time to reach water table (t) = 4,253 day, determine the depth to water table (d) in m.
Given
Find
depth to water table (d), in m
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for d:
Step 3 — List the givens: field capacity (FC) = 0.2200, infiltration rate (I) = 0.0700 m/day, time to reach water table (t) = 4,253 day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning d = 1,353 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 2,706 — kept a factor of two that cancels in the correct rearrangement.
- 676.6 — dropped that same factor in the other direction.
- 1,489 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration analysis above the water table Given depth to water table (d) = 13.5000 m; field capacity (FC) = 0.2000; time to reach water table (t) = 63.0000 day, determine the infiltration rate (I) in m/day.
Given
Find
infiltration rate (I), in m/day
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except I is given, so isolate I symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for I:
Step 3 — List the givens: depth to water table (d) = 13.5000 m, field capacity (FC) = 0.2000, time to reach water table (t) = 63.0000 day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning I = 0.0429 m/day to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0857 — kept a factor of two that cancels in the correct rearrangement.
- 0.0214 — dropped that same factor in the other direction.
- 0.0471 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration
vadose zone penetration time for a spill migrating to groundwater Given depth to water table (d) = 4.0000 m; field capacity (FC) = 0.3700; infiltration rate (I) = 0.0840 m/day, determine the time to reach water table (t) in day.
Given
Find
time to reach water table (t), in day
Start with the thinking
- The governing relation printed in this handbook section is Vadose Zone Penetration.
- Everything except t is given, so isolate t symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Vadose zone penetration estimates travel time for an infiltrating contaminant to move through the unsaturated zone to the water table.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for t:
Step 3 — List the givens: depth to water table (d) = 4.0000 m, field capacity (FC) = 0.3700, infiltration rate (I) = 0.0840 m/day.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning t = 17.6190 day to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 35.2381 — kept a factor of two that cancels in the correct rearrangement.
- 8.8095 — dropped that same factor in the other direction.
- 19.3810 — rounded an intermediate value before the final step.
Reference: FE Handbook — Vadose Zone Penetration