Environment, Ventilation & Hazards

Land Reclamation (Earthwork & Backfill)

Topsoil and backfill volumes, the truck loads to move them allowing for swell, and balancing spoil against pit volume.

PART 1

Topic Breakdown & Traps

The Engineering Principle

Reclamation re-establishes land after mining: spreading topsoil, backfilling voids and regrading spoil. Volumes are area times depth. Because excavated material bulks (swells), the loose volume to be hauled exceeds the in-situ (bank) volume by the swell factor — which sets the number of truck loads. A cut–fill balance checks whether the available spoil meets the backfill requirement.

The Core Formula Matrix

Layer volume:

V = area \times depth

.

Loose volume / truck loads:

V_{l oose} = V \times swell

; loads

= V_{l oose} / V_{t r u c k}

.

Cut–fill balance: surplus

= \frac{V _{s p o i l, l oose}}{swell} - V_{ba c k f i l l}

The ‘IIT Traps’

⚠
Swell increases hauled volume; multiply bank volume by the swell factor for loose volume.
⚠
Backfill volume is in-situ (compacted); convert loose spoil back to bank volume before comparing.
⚠
Keep area and depth in consistent units before multiplying.

PART 2

Progressive 3-Tier Question Suite

Q1BASIC1 Mark · MCQ

Spreading topsoil

0.3 m

deep over

10, 000 m^{2}

needs a topsoil volume of:

Q2MEDIUM2 Marks · NAT

Hauling that

3000 m^{3}

(swell factor

1.25

) in

15 m^{3}

trucks needs ______ truck loads. (Round off to the nearest whole number.)

Q3HARD2 Marks · NAT

A spoil bank of

60, 000 m^{3}

loose (swell

1.2

) is used to backfill a pit of area

8000 m^{2}

5 m

depth. The surplus in-situ volume is ______ m³. (Round off to the nearest whole number.)

m³