Constructed wetlands in UK urban surface drainage systems

Area of Science:

• Environmental Engineering
• Urban Hydrology
• Sustainable Drainage Systems (SuDS)

Background:

• Constructed wetlands emerged as "soft engineered" solutions for surface runoff treatment following UK Environment Agency recommendations.
• Reports by the UK Construction Industry Research and Information Association (CIRIA) highlighted benefits of vegetated systems for developers and communities.
• UK Environment Agency and Highways Agency (HA) have established specific design criteria for managing road runoff using vegetation.

Purpose of the Study:

• To conduct an inventory of planted wetland systems in the UK, categorized by land use.
• To evaluate the design and performance of constructed wetland systems for road runoff treatment.
• To compare and evaluate differing design approaches in UK guidance documents.

Main Methods:

• Inventory and classification of planted wetland systems across various land use types in the UK.
• Case study analysis of a constructed wetland system designed for road runoff treatment.
• Performance assessment based on design criteria, runoff loads, and maintenance procedures.

Main Results:

• The paper details the inventory outcomes and presents a case study on a constructed wetland's performance.
• Performance is assessed against established design criteria, considering runoff volumes and maintenance.
• Analysis includes an evaluation of the varying design approaches recommended by key UK agencies.

Conclusions:

• Constructed wetlands are viable sustainable drainage systems for managing surface runoff, particularly road runoff.
• Performance is influenced by design, loading, and maintenance, necessitating adherence to specific criteria.
• Discrepancies in guidance documents from the Environment Agency, CIRIA, and HA require evaluation for consistent application.