Environmental Engineering

Question 1

municipal landfill has available space of 16.2 ha at an average depth of 10 m. Seven hundred sixty-five
(765) m3 of solid waste is dumped at the site 5 days a week. This waste is compacted to twice its delivered
density. Draw a mass-balance diagram and estimate the expected life of the landfill in years.

Answer 1

16.25, or 16 years

Question 2

The Rappahannock River near Warrenton, VA, has a flow rate of 3.00 m3 · s−1. Tin Pot Run (a pristine
stream) discharges into the Rappahannock at a flow rate of 0.05 m3 · s−1. To study mixing of the stream and
river, a conservative tracer is to be added to Tin Pot Run. If the instruments that measure the tracer can detect
a concentration of 1.0 mg · L−1, what minimum concentration must be achieved in Tin Pot Run so that
1.0 mg · L−1 of tracer can be measured after the river and stream mix? Assume that the 1.0 mg · L−1 of
tracer is to be measured after complete mixing of the stream and Rappahannock has been achieved and that
no tracer is in Tin Pot Run or the Rappahannock above the point where the two streams mix. What mass rate
(in kilograms per day) of tracer must be added to Tin Pot Run?