Longitudinal Structures

CASE HISTORY Rev: 03, Issue Date 15.01.08 CLIVE RIVER Clive, Hawkes Bay Contractor: HAWKES BAY REGIONAL COUNCIL WORKS GROUP Subcontractors: ROCKCAGE NZ LTD, BURGISS CONTRACTING PVC GABION, RENO GALMAC PVC, BIDIM Construction date: Product used: MAY- SEPTEMBER 2006 CLIVE RIVER STOPBANK PROTECTION WORK Product: Galmac + PVC Coated Reno Mattresses, Gabions & Bidim Geotextile Problem The Clive River acts as the main outlet for two other rivers on the Heretaunga Plains, which under flooding conditions backs up from the sea. Residential properties along the saline sections of the Clive River were at risk from flooding. Solution Maccaferri Galfan + PVC coated gabions and Reno mattresses were chosen as the most environmentally friendly and cost effective option. The contractors involved also had previous experience with this system being a recognised installer of the Maccaferri mesh products. Constructed parallel to river, gabion and Reno mattress structures correct and control the flow of water helping to prevent flooding of property, and preventing erosion of stream beds and edges of banks. Reno mattresses were assembled on the stop bank and lifted into place using Maccaferri’s Reno frame onto the soft marine silt. A layer of Bidim was placed on the underside of the gabion and Reno mattress units to act as a filter preventing sediment loss through the stone infill. Once the Renos were installed, the stepped gabion wall was then constructed on top with the first layer using Maccaferri’s gabion lifting frame. The use of gabion and Reno mattress lifting frames offers contractors the ability to rapidly construct gabion walls and revetments in difficult terrain with poor access. A crane with lifting capacity to support approximately 4.5 tonne with sufficient reach is required for these applications. This method of construction has been used in New Zealand and worldwide and has been well documented in various Maccaferri brochures. Gabion and Reno mattresses offer environmentally enhanced retaining and revetment structures, a fact supported by the World Wild Life Fund research and publications on various stream and river protection system. Installation of Reno mattresses Date: May 2006 Gabion installation in process Date: July 2006 Completed project with vegetation Date: January 2007 Maccaferri NZ Ltd. 14 Goodman Place, P.O. BOX 12536, Penrose, Auckland, New Zealand Tel. (+64) 9 6346495 - Fax (+64) 9 6346492, FREEPHONE 0800 60 60 20 E-mail: sales@maccaferri.com - Web site: www.maccaferri.co.nz Quality System AS/NZS ISO 9001:2000 The information presented herein is, to the best of our knowledge and belief, correct and is subject to periodic review and revision. The validity of the information relative to the subsoil, hydraulic and other engineering conditions must be ascertained by a suitably qualified person. No warranty is either expressed or implied. Unauthorised reproduction or distribution is prohibited. Copyright is vested in Maccaferri or Maccaferris’ Principal where applicable. The use of fresh concrete structures in waterway protection is to be discouraged and has shown to raise local pH concentration to a pH of 10 or more, which is very detrimental to local species that habitate the waterway. The voids in the stone infill of gabions and Reno mattresses or purpose made recesses in the wall itself that maybe designed and constructed, provide a safe habitat for the various marine species that live in these waterways. Gabions structures can also allow water to re-oxygenate and this helps improve water quality and biodiversity in the waterway. In addition, vegetation is able to regrow within sediment deposits that accumulate or soil and plants may be deliberately included in the gabion works. The mesh allows plants to entangle and become one with the structure and provides additional resistance to damage during flooding. The use of Galmac + PVC coating (a Zinc / Aluminum 5% alloy Mischmetal) on the units provides enhanced erosion resistance of three to four fold over normal galvanised wire, providing optimum longevity to the structure. Landscape of Completed Project Date: January 2007