Page 36 - Materials Chemistry, Second Edition

Site Assessment and Remedial Investigation 19

Step 3: Determine the number and volumes of the USTs removed.
Step 4: Subtract the total volume of the USTs from the volume of the
tank pit.
Step 5: Multiply the value from Step 4 with a soil fluffy factor.

Information needed for this type of calculation

• Dimensions of the tank pit (from field measurements)
• Number and volumes of the USTs removed (from drawings or
field observation)
• Bulk density of soil (from measurement or estimate)
• Soil fluffy factor (from estimate)

Example 2.9: Determine the Mass and Volume of
Soil Excavated from a Tank Pit
Two 5,000-gallon USTs and one 6,000-gallon UST were removed. The excava-
tion resulted in a tank pit of 50′ × 24′ × 18′. The excavated soil was stockpiled
on site. The total bulk density of soil in situ (before excavation) is 1.8 g/cm
3
and that of soil in the stockpiles is 1.5 g/cm . Estimate the volume and mass
3
of the excavated soil.
Solution:
Volume of the tank pit = (50′)(24′)(18′) = 21,600 ft 3
Total volume of the USTs = (2)(5,000) + (1)(6,000) = 16,000 gal
= (16,000 gal)(ft /7.48 gal) = 2,139 ft 3
3
Volume of soil in the tank pit before removal
= (volume of tank pit) − (volume of USTs)
= 21,600 − 2,139 = 19,461 ft 3

Volume of soil excavated (in the stockpiles)
= (volume of soil in the tank pit) × (fluffy factor)
= (19,461)(1.2) = 23,353 ft 3
= (23,353 ft )(yd /27 ft ) = 865 yd 3
3
3
3
Mass of soil excavated = (volume of the soil in the tank pit)(total bulk
density of soil in situ)
= (volume of the soil in the stockpile)(total bulk
density of soil in the stockpile)