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Reservoir pavements for drainage attenuation (formerly HD 221/18). Version 0.1.0

DMRB: Drainage CD 531

Reservoir pavements for drainage attenuation (formerly HD 221/18). Version 0.1.0

Document Status



Civil & Structural Supplement


DMRB: Drainage


Provides guidance for selection, design, installation, application and construction of reservoir pavements used as drainage attenuation. Covers hydraulic and structural design principles and includes a worked example and design configurations.


Drainage. Design. Supersedes CD 531. Reservoir pavements for drainage attenuation (formerly HD 221/18) (HE, 2020). Design manual for roads and bridges (DMRB). Version 0 dated Mar 2020 - replaces HD 221/18. Version 0.1.0 dated November 2021 - changes made to core document.


Publisher History

National Highways is a government company, with responsibility for operating, maintaining and improving motorways and major A roads in England. It works with the Department for Transport and was previously known as Highways England and Highways Agency.



NBS has produced specification systems and information products for construction industry professionals for more than 40 years. The National Building Specification is the recognised UK national standard and is used by over 5,000 organisations. NBS is part of RIBA Enterprises Ltd.


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