Case Study

Project Overview

Project Activity: In-situ filter drain refurbishment

Hours of Works: Weekday nights

Overview of Works: The scheme was undertaken on two sections of the A47 located between Trowse to Blofield, and Lingwood to Acle on the outskirts of Norwich, Norfolk. These sections of road were identified by National Highways as flooding hotspots requiring works to improve road user safety.

Crown Plus assumed the works for Eurovia, undertaking just over 3km of in-situ filter drain refurbishment to the east and west bound verges, together with the central reservation.

Principal quantities of works undertaken:

− 2000m3 of filter drain recycling
− 2410m3 of overburden removal
− 500m3 of filter drain excavated and removed for off site recycling

275m3 of filter drain material located around the barriers and near live services was additionally excavated with Vacuum Excavators with this material recycled off site and re-used as part of the permanent works.

As the works were undertaken in a semi-rural environment, we worked closely with Eurovia and the Traffic Management designers to ensure access was maintained to the residential properties and farms along the route.

Following the 10 weeks of filter drain refurbishment works, Crown Plus also undertook 3 weeks of HADDMS Surveys to the refurbished sections of drainage. Having been informed of the importance of alleviating as many potential flooding issues as possible, Crown Plus liaised closely with Eurovia to enable pipes to be cleared of blockages at the time of detection. This was an additional service that Crown Plus undertook, which was not included in the original contract.

Notwithstanding the additional blockage clearance works, the scheme was delivered successfully and to programme by the Crown Plus team.


A47, Norwich


Jan to March 2022

Filter Drain Recycling