Minor Change Report MCU18 0120.01 · MCU18/0120.01

APPLICATION FOR A MINOR CHANGE TO A DEVELOPMENT APPROVAL
Author	Development Planner, Billy Glover/Nadine Kirley
Development Assessment

APPLICATION DETAILS
Application No.	MCU18/0120.01, OPW18/0197.01 and RAL18/0013.01
Development Approval	Development Permit for Material Change of Use - Industrial Type 2 Production, Alteration, Repackaging & Repairing (39 Industrial Tenancies) Development Permit for Reconfiguration of a Lot (Access Easements) Operational Works (Roadworks, Drainage Works, Landscaping, Stormwater, Earthworks, Car Parking & Access)
Applicant	Hass Holdings Pty Ltd TTE
Request Received On	29 September 2020

PROPERTY DETAILS
Property Address	5, 12 & 18 Taylor Ct Cooroy
RP Description	Lot 5 SP197517, Lot 1 SP235189 & Lot 2 SP 197517
Land Area	1.0530 ha, 1.324 ha & 2.016 ha
Existing Use of Land	Approved Industrial Type 2 Production, Alteration, Repackaging & Repairing (39 Industrial Tenancies)

STATUTORY DETAILS
SEQRP Designation	Urban Footprint
Locality	Cooroy
Zone	Low Impact Industry
Overlays	Bushfire Hazard (Potential Impact Buffer) Landslide Hazard Regional Infrastructure (Water Resource Catchment & Water Supply Buffer Area)
Assessment Type	Minor Change to Development Approval

PROPOSAL
The applicant seeks to change the existing development approval. The applicant has proceeded to construct the bioretention basin for the approved development the subject of combined approval for MCU18/0120, RAL18/0013 & OPW18/0197, using a design and methodology that is contrary to the approved plans.  Site inspection by Council’s development compliance officer revealed the inconsistency and the applicant has subsequently lodged a change application to seek approval for the altered design of the bioretention device.  The submitted application seeks approval to change the approved plans for the development identified in Condition 36 of the decision notice.
The applicant seeks approval of amended engineering plans which illustrate a retaining wall to the perimeter of the bioretention basin near the eastern boundary of Lot 5.
background
A development approval was issued on 28 November 2018, for the following:
Development Permit for Material Change of Use - Industrial Type 2 Production, Alteration, Repackaging & Repairing (39 Industrial Tenancies)
Development Permit for Reconfiguration of a Lot (Access Easements)
Operational Works (Roadworks, Drainage Works, Landscaping, Stormwater, Earthworks, Car Parking & Access).
assessment
Statutory Process
The applicant has requested to make a minor change to a development approval under s78 of the Planning Act 2016. An application for a minor change to a development approval can only be made in circumstances where a change would constitute a ‘minor change’.
The proposed change to the development approval requested by the applicant is determined to constitute a minor change on the grounds that:
the development would not result in substantially different development;
the change does not include prohibited development;
the change would not require the application to be referred to an additional referral agency or cause a referral agency to have regard to new matters prescribed by regulation;
where the original application was code assessable, the change would not cause the application to become impact assessable.
Statutory Instruments – Planning Scheme
The applicant seeks to change Condition 36 specified in the decision notice for the combined application relating to OPW18/0197 which identifies the approved plans for the development.
Condition 36
36. 	Development works undertaken in accordance with this approval must generally comply with the approved plans of development. The approved plans are listed in the following table unless otherwise amended by these conditions.
Plan/Drw No.	Rev.	Plan Title	Date
250660-CI-001	01	Title Sheet and Drawing Schedule,  prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-002	01	Site Plan,  prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-003	01	Layout Plan, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-004	01	Detail Plan Sheet 1, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-005	01	Detail Plan Sheet 2, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-006	01	Pavement Jointing Plan, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-007	01	Pavement Jointing Details, prepared by HR Design Consulting Engineers	06/06/2018
			
Dwg No: C01 Job No: 18-0165	D	General Notes & Details, prepared by HR Design Consulting Engineers	0711/2018
Dwg No: C02 Job No: 18-0165	D	Driveway Details, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C03 Job No: 18-0165	D	Stormwater Drainage, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C04 Job No: 18-0165	D	Stormwater Drainage Details, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C05 Job No: 18-0165	D	Block Stormwater Tank 1 Details, prepared by HR Design Consulting Engineers	0711/2018
Dwg No: C06 Job No: 18-0165	D	Block Stormwater Tank 2 Details, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C07 Job No: 18-0165	D	Block Stormwater Tank 3 Details, prepared by HR Design Consulting Engineers	07/11/2018

Applicant’s Request
The applicant seeks to change the construction method of the proposed bioretention basins.  The approved drawings indicate the bioretention basins are bounded by batters.  The applicant proposes to replace the batters on the eastern side of the bioretention structure with retaining walls and argues that the filter media surface area is greater if the retaining wall design can be used.  The applicant also asserts that the filter media can be moved further away from the retaining wall that separates the bioretention basins and the car park areas which maximises the batter distance and reduces the potential for the car park retaining wall exerting pressure and compacting the filter medium.
The applicant acknowledges that maintenance access to the lower basin 3, would be prevented by a retaining wall around its perimeter.  It has been argued that the access to the lower basin can be gained from Bio Basin #1 which has the lowest height retaining wall being closest to the road, or from the drainage reserve land along the southern boundary of all 3 basins.

Figure 1: Section showing proposed retaining wall construction bounding bioretention basin

Assessment of Request
The proposed minor change involving placement of retaining walls in lieu of vegetated batters on the sides of the proposed bioretention basin has been considered in context of the proposed development overall.  Specific Outcome O8 of the Water Sensitive Design Code seeks to ensure that retaining walls are not used in the design and construction of stormwater devices.  The solution proposed is in direct conflict with the Specific Outcome with the applicant’s argument for the change being that the retaining wall design allows for the bioretention basin to have a larger filter medium area due to the lesser amount of batter required.  The applicant also argues that the removal of the batter on the eastern side near the property boundary pushes the filter medium further from the retaining wall separating the device from the carparking area, thus reduces the potential for the wall to settle and place pressure on the filter media, compacting it and thus reducing its conductivity ability.  It has also been argued that this arrangement will reduce potential scour of the filter medium at the base of the batter and retain the ability for the system to function properly.
Council’s Development Engineer has identified that some sections of the retaining wall along the boundary have relatively low finished levels to top of wall which will easily allow overland flows, mulch and debris to overflow and wash-down into the bio-basins and compromise their function and operation, and create significant maintenance problems and issues. These sections need to be raised or suitable vegetation buffer/strip provided along this boundary to mitigate the effects of this potential problem.  This could be addressed through a condition of approval.
The use of retaining walls around bioretention devices is not encouraged by the planning scheme.  It is understood through discussion with the Development Engineers that this related primarily to the added maintenance issues with repairing and maintaining retaining walls and the effects of scouring and other soil disturbance resulting from their placement in the device.
With respect to the stability of the walls, the applicant’s RPEQ has signed off on the design and the strength of these walls for the given situation is difficult to dispute.  To address the maintenance issue, it is therefore, recommended that the ownership and management of the retaining walls is retained by the applicant.  As a result, it is recommended that Condition 77 of the original approval be changed on the decision notice which makes it clear that the ownership of the bioretention basin will not be handed over to Council as an asset, ensuring that maintenance obligations for the infrastructure, in particular the retaining walls, are met by the property owner/ body corporate so that Council is not left with a potentially undesirable maintenance burden.
Initial information provided by the applicant indicated that the proposed change would prevent compliance with Condition 69(d) and (e) of the original approval.  Subsequent discussion with the applicant and further information provided demonstrates that with the parking removed from the swale area, Condition 69(d) can be met and Condition 69(e) is not necessary.   As a result Condition 69(e) can be deleted.
The proposed retaining walls are located generally within the bounds of Lot 5 and are not excessively visible from the street and surrounding areas (refer site inspection photographs at Figures 2 & 3).  From a visual amenity perspective, the proposed retaining walls are not considered intrusive and are located behind planting which is also a requirement of the original approval conditions.  Assessment of the proposed design by Council’s development engineer and environment officer concludes that in this instance, with some modifications, the proposed retaining wall design has the capacity to maintain the overall outcomes for the Water Sensitive Design Code and could be conditioned accordingly despite the conflict with the Specific Outcome.

Figure 2: Bioretention basin with retaining walls viewed from within the drainage reserve on eastern boundary of Lot 5.

Figure 3: Bioretention basin at northern end facing Taylor Court.

cONSULTATION
Other Referrals
The application was forwarded to the following internal Council specialists whose comments are incorporated into the above assessment:
Environment Officer, Environment & Sustainable Development
Development Engineer, Development Assessment
conclusion & reasons for decision
The applicant has submitted a change application in response to Council’s request to rectify works that have been undertaken that are inconsistent with the approved plans for OPW18/0197.  The proposed use of retaining walls is inconsistent with Specific Outcome O8 of the Water Sensitive Design Code which seeks to avoid retaining walls in bioretention devices.  The ability for the device to function as expected, incorporating the minor change, is generally consistent with the overall outcomes of the code with some minor modifications being required via conditions to ensure consistency with other outcomes of the code.
The proposed retaining walls are low to the ground when viewed from outside the site and situated behind planting which is conditioned as part of the original approval. From a visual amenity perspective the design results in a low visual impact to the surrounding locality.  Including retaining walls on the perimeter of the stormwater bioretention device has the potential for increased maintenance as walls have the potential to fail, crack or result in unwanted scour or erosion that can negatively impact on the proper functioning of the bioretention basin.  It is therefore recommended that the ongoing maintenance obligations of the bio-basin infrastructure be retained by the property owner and the device is not handed to Council at the end of the maintenance period.
In context of the development overall, the proposed minor change is still able to achieve the overall outcomes for the code and appropriate conditions can be applied to address any remaining concerns.
Due to a clerical error in the original Decision conditions have been re-numbered.
The application is recommended for approval subject to appropriate conditions.

RECOMMENDATION
With regard to Application No. MCU18/0120.01 MCU18/0120, OPW18/0197, OPW18/0197.01, RAL18/0013, RAL18/0013.01, to make a minor change to an existing approval (Retaining Wall Around Bioretention Basin) situated at 5, 12 & 18 Taylor Ct Cooroy Qld 4563 described as Lot 5 SP197517, Lot 1 SP235189 & Lot 2 SP 197517, Council on 1 February 2021 decided to:
Approve the change
B.	Amend administrative errors in the numbering of conditions
C.	Amend re-numbered Operational Works conditions 1 & 42
Condition 1
1. 	Development works undertaken in accordance with this approval must generally comply with the approved plans of development. The approved plans are listed in the following table unless otherwise amended by these conditions.
Plan/Drw No.	Rev.	Plan Title	Date
250660-CI-001	01	Title Sheet and Drawing Schedule,  prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-002	01	Site Plan,  prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-003	01	Layout Plan, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-004	01	Detail Plan Sheet 1, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-005	01	Detail Plan Sheet 2, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-006	01	Pavement Jointing Plan, prepared by HR Design Consulting Engineers	06/06/2018
250660-CI-007	01	Pavement Jointing Details, prepared by HR Design Consulting Engineers	06/06/2018
Dwg No: C01 Job No: 18-0165	D	General Notes & Details, prepared by HR Design Consulting Engineers	0711/2018
Dwg No: C02 Job No: 18-0165	D	Driveway Details, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C03 Job No: 18-0165	D	Stormwater Drainage, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C04 Job No: 18-0165	D	Stormwater Drainage Details, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C05 Job No: 18-0165	D	Block Stormwater Tank 1 Details, prepared by HR Design Consulting Engineers	0711/2018
Dwg No: C06 Job No: 18-0165	D	Block Stormwater Tank 2 Details, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No: C07 Job No: 18-0165	D	Block Stormwater Tank 3 Details, prepared by HR Design Consulting Engineers	07/11/2018
Dwg No. R01 Job No 1941	A	Locality Plan and Schedule of Drawings, prepared by Barlow Shelley Consulting Engineers	04-11-19
Dwg No. R08 Job No 1941	A	Bioretention Basin Layouts, prepared by Barlow Shelley Consulting Engineers	28-09-2020
Dwg No. R09 Job No 1941	A	Bioretention Details, prepared by Barlow Shelley Consulting Engineers	28-09-2020

Bio Retention Basins
Prior to Council accepting water quality treatment device assets as completed, the applicant must provide Council with a Schedule of Maintenance Costs for all activities undertaken to maintain the bio retention basins in accordance with the most current version of Healthy Waterways Bio retention Basin Maintaining Vegetated Stormwater Assets Guidelines. The schedule shall include records of actual costs of maintenance work undertaken.

D.	Delete re-numbered Operational Works condition 34(e)
Stormwater Drainage
The site must be provided with a stormwater drainage system that connects to a lawful point of discharge and the Queensland Urban Drainage Manual, and must include in particular:
A stormwater detention system to ensure  no  increase in peak flow runoff in 1, 5, 50 or 100 ARI events, as per The Stormwater Management Report  for Lot 5 Taylor Court, Cooroy Qld, 4563 report No 18-0165D Dated 7 November 2018 by HR Design
No adverse impact on other properties and the road’s footpath and grassed verge (e.g. by diverting flows and/or blocking flows and causing additional ponding)
The use of gravity stormwater drainage only and not surcharge pits or pumps.
A stormwater quality treatment system in accordance with the with The Stormwater Management Report  for Lot 5 Taylor Court, Cooroy Qld, 4563  report No 18-0165D Dated 7 November 2018 by HR Design   to achieve the following objectives as predicted in MUSIC modelling in accordance with the Water by Design MUSIC modelling guidelines.
	State Planning Policy	SEQ Water Development Guidelines: Development Guidelines for Water Quality Management in Drinking Water Catchments (SEQ Water 2012)
Total Suspended Solids	80% reduction compared to an unmitigated development	No increase in pollutant loads compared to a Vacant Industrial Allotment
Total Phosphorous	60% reduction compared to an unmitigated development	
Total Nitrogen	45% reduction compared to an unmitigated development	
Deleted.
The development must include bins with educational signage material to encourage patrons who purchase items that generate gross pollutants to dispose of such items appropriately, and not where they may enter stormwater systems.
Stormwater quality treatment devices must be routinely checked, serviced and cleaned in accordance with Water by Design maintaining vegetated stormwater assets guidelines. Records of all maintenance activities undertaken must be kept for 5 years and made available to Council upon request.
The ongoing maintenance plan for the development must include the operations and maintenance manual for the water quality device/s and must include the full cost of maintaining the system. This maintenance plan must be provided at the Pre-Start meet
The development must not cause an increase in peak flow runoff in 1, 5, 50 or 100 ARI events. The subsequent application for operational works must include calculations and designs to demonstrate how this condition is achieved.
E.	Include additional Operational Works conditions 56 & 57
Additional Conditions for OPW
Bio Retention Basins – retaining walls
To prevent escape of stormwater and mulch material from the bioretention basins, all perimeter retaining walls must have no less than 250mm clearance below the top of any part of the retaining wall measured to the finished surface of the bioretention filter medium.
Ongoing maintenance obligations of the bioretention basins shall not be transferred to Council and are to remain the responsibility of the applicant/owner/ body corporate of Lot 5.

F.	Note the report is provided in accordance with Section 83(9) of the Planning Act 2016

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