"Pollutants to the Remedied by the Reed Bed

• Hydrocarbons - many types of oils and fuels from the North Circular Road and surrounding neighbourhood streets;
• Detergents and organic matter - from both residential and industrial sources discharging into the surface water system through misconnections;
• Heavy metals - discharging into the Reservoir from commercial properties and from road/urban run-off;
• Sediments - discharging into the Reservoir from road/urban run-off and misconnections;

Note: The concentration of copper and zinc are phytotoxic at the concentrations shown. As the vegetation is not currently affected, it is unlikely that they will cause a problem in the future as long as the type and hardiness of the vegetation does not change. Otherwise, mitigation may be required. Most likely this would involve the addition of the topsoil or the introduction of plants resitant to elevated copper and zinc concentrations."

Technical Reason for the Task. Welsh Harp Reservoir Reed Bed Feasibility Study, Halcrow, May 2001

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