Development Application - Part 2 of 2 - Report & Plans · OPW11/0116

                                                                                                                        HAT



                Scour                                                                                Scour

                                                                                                                Seabed [varies]



Figure 48: Preliminary design of groynes

The groyne has been designed as an emergent structure. The crest height has been nominated as approx. 1 m above HAT
to allow for wave action without significant overtopping. The base of the structure is variable to reflect changing surface
levels along the length of the structure. As a minimum the base containers should be 0.7m below the surface level [greater
at the head of the groyne] with scour containers to accommodate greater erosion.

Preliminary estimates have been prepared [Table 9]. It is noted that this is based on existing surface levels and could vary if
levels change.

Table 9: Preliminary cost estimate for 2 groynes
                                                                       Qty                  Rate                Amount
                                                                                                                [ex-GST]
Establishment                                                                                                   $100,000
Supply of 2.5m3 containers [standard]                                  175                  $300                 $52,000
Supply of 2.5m3 containers RP                                          260                  $185                $48,000
Dredging to provide suitable sand stockpile                          1,087 m3                $12                 $13,000
Fill & placement of 2.5m3 containers                                    435                 $280                $122,000
Project mans ement                                                                           5%                 $15,000
TOTAL                                                                                                           $350,000

     6.5.   Dredging

There is an existing secondary southern channel [Figure 13] which is proposed to be deepened slightly to provide adequate
navigation after closure of the primary southern channel by the proposed works. Existing depths are presently approx. -0.5m
AHD. It is proposed to deepen this channel to approx -2m AHD (-1m LAT). The proposed deepening will require the
removal of approx. 10,000m3. Material is to be placed as foreshore nourishment and/or backfilling adjacent to structures as
required.

Table 10: Preliminary cost estimate for dredqin
                                                                       Qty                  Rate                Amount
                                                                                                                ex-GST]
Establishment                                                                                                   $100,000
Dredging / Nourishment                                              10,000m3                $12                 $120,000
Project management                                                                          5%                   $10,000
TOTAL                                                                                                           $230,000



     6.6.   Total Strategy

Preliminary costs associated with the complete strategy [Figure 39] are as per Table 11.

Table 11: Summary of costs
                                                                       Amount
                                                                      [ex-GSTJ
Submerged closure                                                    $1,280.000
Training Wall                                                        $ 407.000
Revetment Wall                                                       $ 665.000
2 Groynes                                                            S 350.000
Dredging / Nourishment                                               $ 230.000