Poplar Farm, Grantham

THE CHALLENGE

Grantham was awarded Growth Point Status in 2006 following a successful bid by South Kesteven District Council and Lincolnshire County Council for additional funding from the Department of Communities and Local Government. The Spitalgate Heath expansion, latterly badged as one of the ‘garden village’ schemes at the start of 2017, aims to provide up to 3,700 new homes and 11ha of commercial development.

The land was formally allocated for development under SKDC’s local plan in 2012. The area is dominated by the high limestone country typical around Grantham and by the River Witham’s valley, sheltering a highly-valuable riverine habitat. Water quality is key both in the river for its habitat value and for the underlying aquifer in the limestone that supports water-supply abstractions to the east.

SYSTRA’s Role

SYSTRA provided infrastructure investigation and design services to the landowners, commencing in 2007 with work on an outline planning application and corresponding technical documents. This included investigating the existing land drainage arrangements and identifying a suitable surface drainage approach to serve the site in accordance with requirements of the relevant drainage authorities. The site spreads across a hillside and the ground is generally clayey in nature with a widespread agricultural field drain network. The ground conditions would not support infiltration drainage as an effective site-wide solution and an alternative drainage approach would be needed.

SYSTRA consulted extensively with SKDC, LCC, the Environment Agency and with the local Internal Drainage Board who controlled the stream draining the site. A large attenuation lagoon had been formed as part of the earlier development phase but changes to drainage performance standards and to the development scale meant that this was no longer sufficient for the whole site. SYSTRA devised a series of additional attenuation features to provide additional capacity that would allow a site-wide storm drainage system to serve the development parcels. The strategy was presented as part of the Flood Risk Assessment and Drainage Strategy reports and outline planning permission was granted in 2009.