RTRP MR76 Waterfall Way Crystal Falls to Maynards Plains and Woodchip Corner Slope Works

⁠⁠⁠Construction of slope treatments on Waterfall Way Crystal Falls to Maynards Plains and Woodchip Corner.

Scope:

Transport proposes to remediate a timber crib wall on slope 94428 within segment 4100 of Waterfall Way (MR76) approximately 8 km west of Thora. The existing timber crib wall is about 14 m long by 3.1 m high and occurs between a recently remediated project identified as slope 93784 to the west (installed 2019) and an existing anchored pile wall to the east (installed 2011). Remediation works for the timber crib wall would occur over an area of about 30 m in length by 10 m width. For the purposes of this MWREF, the entire length of road corridor between slope 93784 and the existing anchored pile wall has been included within the area of assessment. The area is approximately 160 m long by 10 m wide and is hereafter referred to as ʻthe siteʼ.

All work is within the nominal road reserve of Waterfall Way, which as per a Memorandum with National Parks and Wildlife Service (NPWS) is “assumed to be 1 chain (100 links or 20.115 m) wide”. This equates to about 10 m measured from either side of the centreline. 

The proposal is anticipated to involve the following work methodology:

• Implement traffic control.

• Site establishment and use of existing Transport compound and stockpile sites located within the road reserve along Waterfall Way.

• Install erosion and sediment controls.

• Clear vegetation within the work area.

• Infill table drain with rock and push single traffic lane over to cut side.

• Install movable barriers.

• Remove old w-beam guardrail and posts.

• Locate small excavator on top of crib wall area/ east bound lane.

• Sawcut through the thick patch 1 m behind the new barrier, at approximately the differential line in the east bound lane.

• Excavate with small machine down to 1 m depth in the outside of the east bound lane. Make a level bench to use much of the verge area and work from.

• Install row 1 soil nails (temporary) and apply temporary facing. Run small excavator mounted rig behind the barrier working on the bench. Use an observational approach to manage risk of slope movement (the Factor of Safety [FoS] would be <1.2 for this area).

• Once facing has reached 30 MPa, excavate row 2 (row 1 permanent nails). Install nails and temporary facing. Leave nail plates on the outside of the facing and leave room to extend the bars later. Cut out bench towards timber crib wall.

• Excavate down to next row.

• Repeat previous two steps until four rows of nails are installed (1 temporary and 3 permanent rows).

• Once the temporary facing is completed, remove the remainder of the timber crib if any remaining is left in the verge. Form a level bench to work on, ensuring the bench drains to the downslope side of the road.

• Extend 3 lower rows of soil nails, and hang a form for spraying the final shotcrete facing at the permanent location, with the hinge point out 1.1 m behind the guard rail line at the crest.

• Spray the permanent facing against the form and backfill the void between the two facings with controlled fill or no fines concrete. Colour the permanent facing appropriately.

• Work up the facing/ backfilling until at subgrade level – allow 1 m lifts to limit forces on the formwork.

• Install pavement, guard rail strip footing and crest of wall turn back detailing.

• Remediate pavement and dish drains.

• Finalise erosion and sediment controls, and revegetation works prior to demobilisation from site.

Additional details/instructions

Any Price and Non price percentage published under Evaluation/Weighting as part of this Opportunity advertisement is the default setting of a mandatory field, and does not apply to this Opportunity.

Please see attached files in the link for more information