WAMITAB - Chartered Institution of Wastes Management Landfill Management Operations Questions and Answers

Question 1

A landfill site manager observes that leachate levels in a monitoring well have risen above the maximum permitted level specified in the site's environmental permit. What is the most critical immediate operational action to take?

Accepted Answer

Increase the rate of leachate extraction from the collection system to lower the level.

Answer

The most critical immediate operational action is to mitigate the hazard. Increasing the extraction rate directly addresses the problem of high leachate levels, aiming to bring them back into compliance and prevent uncontrolled release or damage to the liner system. While notifying the Environment Agency is a legal requirement, the first step is always to control the immediate environmental risk.

Question 2

Landfill gas is a natural byproduct of the decomposition of organic waste. Which two gases comprise the vast majority (typically 90-98%) of landfill gas?

Accepted Answer

Methane and Carbon Dioxide

Answer

Landfill gas is produced by anaerobic bacteria breaking down organic waste. The primary products of this process are methane (CH4) and carbon dioxide (CO2), which together typically make up 90% to 98% of the gas by volume. The other listed gases are either trace components (like Hydrogen Sulphide) or the main components of air (Oxygen and Nitrogen).

Question 3

According to UK landfill regulations, which of the following waste types is explicitly banned from being accepted at any landfill?

Accepted Answer

Liquid waste, including wastewater but excluding sludge.

Answer

UK regulations, implementing the Landfill Directive, explicitly ban the disposal of liquid waste in landfills. This is to prevent hydraulic instability and the rapid generation and migration of large volumes of leachate. Specific provisions exist for accepting the other waste types under controlled conditions.

Question 4

An environmental technician detects a sustained, significant increase in methane concentrations at a perimeter monitoring borehole located just outside the engineered containment system. What is this a likely indicator of?

Accepted Answer

Failure or inefficiency of the landfill gas collection system.

Answer

Perimeter monitoring boreholes are designed to detect the lateral migration of landfill gas. A significant and sustained increase in methane outside the containment area indicates that the gas is not being effectively captured by the internal collection system and is escaping. This could be due to blockages, well damage, or insufficient extraction pressure.

Question 5

In the construction of a modern landfill's basal lining system, what is the primary function of a Geosynthetic Clay Liner (GCL)?

Accepted Answer

To provide a low-permeability hydraulic barrier to prevent leachate escape.

Answer

A Geosynthetic Clay Liner (GCL) consists of a thin layer of sodium bentonite clay sandwiched between two geotextiles. When hydrated, the bentonite clay swells to create a highly effective, low-permeability hydraulic barrier, which is its primary function in preventing leachate from migrating into the surrounding soil and groundwater.

WAMITAB - Chartered Institution of Wastes Management Certification Practice Test

WAMITAB - Chartered Institution of Wastes Management Certification Practice Test

WAMITAB - Chartered Institution of Wastes Management Landfill Management Operations Questions and Answers