With its picturesque setting, beaches, art galleries and shopping facilities, St Ives Cornwall, is a popular place to work, live and spend holidays. In recent years this has increased the requirement for homes and a support infrastructure designed to welcome the thousands of visitors. The town now extends way up the surrounding hillsides and along the approach roads, particularly the A3074 and B3311. With so much development, a large area of the surrounding countryside has been built on and paved over with buildings, associated access roads and car parks.
St. Ives Town Council became very concerned about the risk of flooding in the lower town. Weather fronts racing in from the Atlantic bring heavy rain fall, particularly during the winter months. This has resulted in rainwater cascading down the steep roads and into the lower town’s narrow streets and passages. The memory of the devastating floods in neighbouring towns and the need to protect valuable real-estate gave extra urgency to the plans for a new road drainage scheme.
Hydraulics experts advised the Council that existing road drainage could be compromised during extreme rainfall events; a new drainage scheme with a very large capacity had become essential. Slotted channels were considered but rejected as it was feared the narrow slots could be easily blocked by debris and in any case the small inlet area could not cope with the predicted large quantities of water that accumulated on the town’s steeply inclined approach roads. Instead, civil engineers were looking for a drainage system with large inlet apertures. In addition, the application called for a particularly robust channel that could take the large volumes of traffic and the many delivery vehicles entering the town. The Local Authority invited tenders for the FASERFIX® SUPER 500 channel made from fibrereinforced concrete because it met all the design criteria: an extremely robust and rugged channel having a large drainage cross section, matched with heavy-duty ductile iron gratings to class E 600 for heavy load applications.
The grating specification chosen featured three parallel rows of slots, each 20mm wide. Careful calculations were undertaken to ensure the installed system could easily cope with the very large quantity of water expected.
The building contractor, Carillion Construction, installed a total of 186 meters of FASERFIX® SUPER 500 channels across various roads leading down to the lower town in order to ensure effective flood prevention. Single, double or triple channel runs were installed across the carriageways depending on the volume of run-off water to be diverted.
The project was supported by Hauraton’s project managers, Andy Beirne and Steve Wiseman who provided hydraulic calculations and engineering advice during the design and installation phases. The local Building Control department, planners and the building contractor were impressed with the design support received from Hauraton and full of praise for the company’s excellent cooperation and flexible service. Happily, now the new scheme is operational, even when there is heavy rainfall, all the run-off is safely diverted.