Referenced Document - MCU30/0030 · MCU13/0030

                                        Construction Phase
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Objective           The Contractor will install the Bioretention System in accordance with the 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 inspections, watering and other actions.

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

                    Bio-retention designer I 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 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.

                    Replace geotextile where used, check and if necessary replace sand media with
                    coarser sand. Check that slottedpipe is not blocked and outlet free draining.
                    Replace and repair where necessary.