Construction and demolition waste strategy
An island generates about 800,000 tonnes of construction and demolition waste each year. Only 45% is recycled; the rest goes to landfill or is dumped illegally in valleys. The remaining landfill void is 2.5 million m3, and at current input rates it will last six years. The government has a 70% recycling target for 2030. A gate fee of €60/tonne applies at landfill, but enforcement is weak and the illegal dumping fine is €500. Recycled aggregate sells for €8/tonne, while virgin quarry aggregate sells for €12/tonne. Several quarries have exhausted voids suitable for inert backfilling. Residents near a proposed mobile crusher site complain about dust and noise. The regulator must design a policy package that raises recycling, reduces illegal dumping and extends landfill life without simply shifting the burden to communities.
1. Calculate the annual mass flows and the landfill life under business-as-usual and under the 70% target. State assumptions.
Read the worked answer
Under business as usual, 800,000 t/yr is generated and 45% is recycled, or 360,000 t. The residue is 440,000 t to landfill, ignoring illegal dumping and quarry backfill. The void is 2.5 million m3. Assuming compacted construction and demolition waste at 1.2 t/m3, the void is 3.0 million tonnes. Life is 3.0 million divided by 440,000, or about 6.8 years, close to the stated six years. At 70% recycling, recycled material is 560,000 t and residue is 240,000 t, giving a life of 12.5 years. If illegal dumping is 100,000 t/yr and is eliminated, landfill input rises to 540,000 t under business as usual, giving 5.6 years, and to 340,000 t at 70%, giving 8.8 years. If 150,000 t/yr is diverted to quarry restoration as inert backfill, landfill life extends further. Assumptions must be stated: constant generation, constant density, and no illegal dumping in the baseline. The mass balance shows recycling is necessary but not sufficient; new void or backfill capacity is still needed.
2. Evaluate a policy package of gate-fee increases, mandatory source separation, mobile crushers and green public procurement. Which instruments address which failure?
Read the worked answer
The failures are: illegal dumping is cheap because enforcement is weak and the €500 fine is lower than the gate-fee saving on a truckload; recycling is not economically attractive because recycled aggregate sells at €8 versus €12 for virgin aggregate, and the price may not reflect externalities; source separation is poor because sites lack space and incentives; and there is insufficient demand for recycled material. A package should raise the gate fee to €90/t and earmark revenue for enforcement; require mandatory source separation for sites above a threshold, with site waste management plans; license mobile crushers with dust and noise conditions; and require 30% recycled aggregate in public works through green procurement. Each instrument addresses a different failure: the gate fee internalises landfill cost; separation reduces contamination; procurement creates demand; enforcement raises the expected cost of dumping. A deposit or bond for large projects could cover illegal dumping. A single instrument will be gamed: a higher gate fee without enforcement increases dumping, so the package must be phased and evaluated.
3. Explain why illegal dumping may persist and propose indicators to monitor the package.
Read the worked answer
Illegal dumping persists because it is a rational response to weak detection, low penalties and inconvenient legitimate recycling capacity. Fly-tipping in valleys has a low probability of prosecution and high environmental harm to habitats and hydrology. Indicators should include the number of permitted sites and their throughput; recycling rate by material; landfill input; number of illegal dumping reports and prosecutions; average fine and recovery of costs; dust and noise complaints; recycled aggregate sales; public procurement share; and water quality at valley dump sites. Monitoring should use remote cameras, weighbridge data and drone surveys. Targets should be specific, measurable and published, and the 70% target should specify whether it is by mass and whether backfill counts. The package should be adaptive: if dumping rises after the gate fee, increase enforcement before raising the fee further. Convenient drop-off points and community engagement are also needed.