Response to Information Request - MCU12/0184

                                                                                               ~
                                                                                           Callaghan & Toth


Objective                   The Contractor will install the Bioretention System in accordance with the
                            Operational Works drawings.

Actions                     Bioretention systems to be constructed at the end of civil works for the
                            development.
                            Bioretention systems used for sediment basins during civil works construction
                            shall have sediments removed prior to layout of bioretention zone.

                            Construct Bioretention systems in accordance with steps as detailed in "Water by
                            Design Construction and Establishment Guidelines: Swales, Bioretention
                                    -




                            Systems and Wetlands" Version 1 dated February 2009.
                            Contractor to conduct regular watering of all planted bioretention systems until
                            such time as plants are established.

                            Contractor to ensure bioretention systems are protected from sediment laden
                            stormwater runoff during construction period or only install once upstream
                            catchment is stabilised.


Monitoring                  The Contractor will carry out weekly inspections of the Bioretention system
                            (Including three monthly during the defects liability period). The following will be
                            examined at each inspection:

                            ~   Sediment build up on the surface

                            ~   Health of vegetation

                            ~   Pondage during major storms not infiltrating into the sand
                            ~   Erosion at the outlet

                            ~   Pondage during minor storms

Reporting                   Contractor to maintain a log of ins ections, watering and other actions.

                            Records are to be logged and kept for verification of compliance on a need basis.

                            Bio-retention designer / Engineer shall perform inspections during construction
                            stage and fill out Water by Design forms for compliance.


Incidents                   ~   Bioretention   systems not installed correctly
                            ~   Sediment builds up on the surface of systems.

                            ~   The vegetation dies off.

                            ~   Pondage of water is in excess of one hour.

                            ~   Erosion occurs.

                            ~   Pondage of water occurs at every minor rainfall event.
                            ~   Weed growth occurs.


Corrective Action           Contractor to amend installation to ensure it complies with Operational Works
                            drawings.
                            The Contractor will check up stream sediment control and fix failures. The
                            sediment build up will be shovelled off the non-woven geotextile of the
                            Bioretention systems. The geotextile will be replaced at the beginning of the
                            defects liability period

                            Unsuccessful plantings will be replaced as required. A normal allowance of 10%
                            should be made for unsuccessful plantings. Ensure watering rates are adequate
                            and increase if necessary.


                                                                                                               B

1209 Animal Husbandry   Top Forestry Rd, Ridgewood
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                                                                                               SWQMP
April 2013