Question

1. A) Determine the ratio of waste to cover material (volume basis) as a function of the initial compacted specific weight for a solid waste stream of 1000 tonnes/day to be placed in 2m lifts within a progressive cell width of 30m. The slope of the working face is 3h: 1v. Assume that the waste is compacted initially to an average compaction rate of a) 700kg/m3 and b) 800kg/m3. The daily cover thickness is 200mm.

i. Determine the daily volume of the deposited solid waste for a)700kg/m3 and b) 800kg/m3 ii. Determine the length of each daily cell for a) 700kg/m3 and b) 800kg/m3 iii. Determine cell floor area for a) 700kg/m3 and b) 800kg/m3 iv. Determine volume of soil for daily cover for a) 700kg/m3 and b)800kg/m3 v. Determine ratio of waste to cover soil for a) 700kg/m3 and b) 800kg/m3

b)Estimate the landfill airspace required annually for a Regional Council with a population of 420,000. Assume waste generation rate is 800kg/person/year and the compaction rate is 800kg/m3.

C)A landfill must have a leachate barrier system. Draw diagram to indicate the various components of the leachate barrier system and explain the importance of the various components.

D)The volume of sediment - laden stormwater runoff should be minimized as part of a landfill operation. Explain why and provide examples of erosion control measures to be implemented to reduce the sediment load.

Answer 1

SOLUTION:

1. A) Total solid waste of stream per day = 1000 tonnes

= 1000x1000 kg

= 106 kg

Lift of solid waste = 2m

Since cell is a trapezoidal with slope of 3H:1V

Bottom Cell width = 30 m

Top cell width = 42 m (30 + 2x 3x2)

Cross sectional area of cell = area of trapezium = 2x(30+42)/2

= 72 m2

Cover thickness = 200 mm

i) For compaction rate of 700 kg/m3

Daily Volume of Deposited solid waste = 106/700  

= 1428.5 m3

For compaction rate of 800 kg/m3

Daily volume of Deposited solid waste = 106/800

= 1250 m3

ii) Length of cell for 700kg/m3 of solid waste = 1428.5/(72)

=19.8 m =20 m

Length of cell fot 800kg/m3 of solid waste = 1250/(72)

= 17.36 m = 18 m

iii) Cell floor area = Lx B

For 700 kg/m3

Floor area = 20 x30 = 600m2

For 800 kg/m3

Floor area = 18x30= 540 m2

iv) Daily cover volume = L x B' x h'

B' = 42 m (top width)

h' = 200 mm = .2 m (cover thickness)

For 700 kg/m3

Daily Cover volume = 20x42x0.2

= 168 m3 of soil

For 800 kg/m3

Daily Cover volume =18 x42 x0.2

= 151.2 m3 of soil

v) Ratio of waste to cover soil

For 700kg/m3

Ratio = 1428.5/168= 8.5

For 800 kg/m3

Ratio = 1250/151.2= 8.26