ESSENTIAL ENGINEERING FOR PLANNERS

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1 ESSENTIAL ENGINEERING FOR PLANNERS Presented By Graham Coles, Urban Development Manager (Qld), Arcadis Australia Pacific 7 th March, 2017

2 Why Me? Biography A ground up background with over 17 years experience in shaping the form of Urban Green Field Developments and optimizing Infill Brown Field Developments Project involvement from Pre-purchase Due Diligence Investigations and Financing Assessments through construction to Project completion Successfully delivered Single stage through to Multi-Stage and Multi-Use Master Planned Communities within all of the SEQ Region Local Authorities. Currently manage a team of +45 staff in our Brisbane and Gold Coast offices and responsible for the mentoring of all levels of engineering staff to understand the principles of sustainable engineering design as part working within the Bigger Picture. 07 March

3 Target Session Outcomes Improve on your understanding of the fundamentals of engineering in a site due diligence investigations process Be able to relate these fundamentals into early concept planning of developments at varying levels of scale and location Take your existing understanding of authority overlay mapping and be able to apply these with context Improve on your ability to identify site constraints, identify how to respond to them and maximize the development potential of each site Have an understanding of common engineering acronyms 07 March

4 What is Essential and Why? Macro Engineering Design Elements that, At a Community Level Elements that impact on the Urban Design or Structure Plan of a Community, At a Site and Allotment Level Elements that impact on the Development Footprint, Outer Boundary and Road/Allotment Orientation. Demonstrate Compliance with the relevant State and Local Authority Statutory town planning requirements 07 March

5 Critical Engineering Design Elements Due Diligence Considerations & Site Constraint Mapping How will the development access Essential Infrastructure Road Access A Lawful Point of Discharge for site storm water runoff A point of discharge for site Sewer Reticulation Access to Potable Water Supply, at the right pressure Access to Electrical and Communications services How will the development respond to Site Constraints Flood & Storm Water Management Site grade impacts on allotment benching and retaining Integration of Public Spaces into the community movements 07 March

6 Essential Infrastructure Access to Road Network Road Hierarchy Understand Road Hierarchy planning to differentiate trunk roads that are used to move residents through a community as opposed to estate roads which function to provide access to each allotment. Be aware that the road corridor width and the internal pavement widths will vary with each level of the hierarchy. Traffic Planning engineers will typically provide the advice on the suitable hierarchy of the roads within larger greenfield estates based on traffic counts. Direct allotment access vs non-direct allotment access Access Places through to Collector Streets provide direct allotment access with the road pavement and corridor widths increasing to cater for on street parking and wider verges for pedestrian and cyclist paths as traffic volumes and catchments increase. Major Collector and Sub-Arterial Roads are typically inter suburb roads and direct allotment access is generally not permitted. These roads are typified by high traffic volumes and often higher speed environments. Identified Bus Routes will often require a specific road corridor design to cater for indented bus stops and turning maneuvers. 07 March

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8 Essential Infrastructure Access to Road Network Safe Intersection Design Critical to the location of road intersections for new estate entry roads and major internal intersections in greenfield developments is the consideration of Sight Distance and Pedestrian/Cyclist movement. All intersections need to be designed to ensure that they achieve the AUSTRoads requirements for Safe Intersection Sight Distance (SISD) and Approach Sight Distance (ASD) Pedestrian & Cyclist Movement Determine if the hierarchy of the road makes provision for on-road or in verge cycle movement as this will inform your urban design linkages between parks and open spaces with the proposed allotments. Consider the context of the actual development against the standards and challenge how the requirement can be achieved but in a more sustainable outcome. 07 March

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10 Essential Infrastructure Lawful Point of Discharge There is no prescribed legal meaning but The Queensland Urban Drainage Manual (QUDM) defines a two part test to determine if a development achieves this requirement, 1. The location of the discharge is under the lawful control of the local government or other statutory authority from whom permission to discharge has been received. This will include park, drainage or road reserve or a stormwater drainage easement. 2. In discharging to that location, the discharge will not cause an actionable nuisance (i.e. a nuisance for which the current or some future neighbouring proprietor may bring an action or claim for damages arising out of the nuisance), or environmental or property damage. How will the development receive storm water runoff from upstream adjoining properties without changing the way in which it leaves, i.e. does not cause ponding or constriction that results in extended inundation. Can the pipe drainage achieve an outlet to the ground surface or connect to an existing pipe system and will it leave the site in the same regime as it did in the predevelopment case. How will bulk earthworks cut and fill, road pavements and onsite overland flow paths change the site flows 07 March

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12 Essential Infrastructure Sewer Reticulation Design and Discharge Where is the closest gravity discharge option to the site Request a Services Advice Notice (SAN) or equivalent from the Water Authority to identify site servicing and infrastructure planning issues. Check the path of the connecting sewer to determine if it needs to cross gullies, pass through steep ridges or traverse private property. If there is a significant separation between the site and the existing sewer and is there any Trunk Infrastructure planned in or around the site? Water Retail Authorities such as Queensland Urban Utilities, Unity Water and then Logan Water, Redland Water and Gold Coast Water have Priority Infrastructure Plans (PIP s) that identify the location of planned infrastructure. Typically Trunk Sewer is categorized as 300mm diameter, however occasionally 225/250mm diameter can apply 07 March

13 Essential Infrastructure Sewer Reticulation Design and Discharge What options are available? Conventional Gravity connection with a pipe size of 150mm/160mm diameter that can achieve minimum cover Private / Temporary or PIP Sewer Pump Station (SPS) and Rising Main Low Pressure Sewer and external Rising Main Implications of system on extent of development Will a conventional gravity system restrict how much of the site can be serviced. Will an Odour Control Unit on the SPS vent pole reduce the development setback requirement (100m radius) Will the market accept a non conventional sewer system and the additional costs to the buyer for a Low Pressure Sewer System. 07 March

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15 Essential Infrastructure Water Reticulation Connection Where is the closest connection option to the site Request a Services Advice Notice (SAN) or equivalent from the Water Authority to identify site servicing and infrastructure planning issues. Check the path of the connecting water main to determine if there is available service corridors in the road verge. Will the development scale and location require a network assessment be completed to determine if the Desired Level of Service criteria can be achieved for Fire Flow (25L/s) and minimum mains pressure of 15m Head and maximum of 80m Head? If there is a significant separation between the site and the existing water, is there any Trunk Infrastructure planned in or around the site? Water Retail Authorities such as Queensland Urban Utilities, Unity Water and then Logan Water, Redland Water and Gold Coast Water have Priority Infrastructure Plans (PIP s) that identify the location of planned infrastructure, Typically Trunk Water is categorized as 300mm diameter, however occasionally 225/250mm diameter can apply 07 March

16 Essential Infrastructure Water Reticulation Connection Identify if the site is located in Low Pressure or High Pressure Demand Management Area (DMA) Water networks can operate as a Low Pressure or High Pressure Network. Check if the site requires one or the other or both in order to provide a connection to each allotment. Will the development require a water main booster on the public main Can a low level network be temporarily boosted to provide the Desired Level of Service at each allotment. Implications of system on extent of development Typical reticulation pipe sizes are 100mm/150mm diameter. Can the staging of the development take into consideration the level boundaries and delay the expenditure of dual networks? 07 March

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18 Essential Infrastructure Electrical & Communications Services What Allowances need to be made for these services? Every allotment requires a Low Voltage (240V) connection through the design of an underground reticulated network Most developments over 30 allotments will require a Pad Mount Transformer (PMT) to be located within the development footprint, typical footprint of 4.8m x 5.0m. PMT s are typically supplied by a High Voltage (11kV) network. Lots can not be connected to this network as it is similar to a trunk supply. Large Developments with significant Power Demand may require a Zoned Sub Station which is supplied by a 32kV connection. Is there an existing overhead network on the site frontage that needs to be undergrounded? Estates with 100 proposed allotments will need to seek a connection agreement with a NBN network provider, otherwise a Telstra Supply agreement to the current network will be required. 07 March

19 Internal Site Constraint Mapping Flood & Site Based Storm Water Management Regional Flooding Constraint from Water ways or Creeks and Crossings Confirm what the Defined Flood Level (DFL) is relevant to the site as this sets various engineering design control levels within the site, e.g. minimum allotment and habitable floor levels and minimum road crown levels for road trafficability. Where the extent of development encroaches on flood prone areas of the site an assessment on the impact on flood storage and Flood Levels will need to be completed. What is the Flood Hazard designation across the site and does the development layout provide sufficient setback or management of the High Hazard Areas? Localized Overland Flow The development proposal needs to identify locations on site boundaries where pipe, surface and channelized flows are received at upstream boundaries. 07 March

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22 Internal Site Constraint Mapping Flood & Site Based Storm Water Management On site Storm Water Detention Storm water detention basins are typically required in instances where the post development rate of runoff (m3/s) is greater than that of the pre development. Land Area required will vary from 2.5% of site area for site slopes up to 5% and increase to 4-5% for site slopes around 10% Minimize the impact on development footprint / yield by integrating with a landscape solution? Can the works be considered trunk works and therefore creditable against the Infrastructure Charges? On site Storm Water Quality Treatment A Storm Water Quality Management Plan is required under State Planning Policy 4/10 to address pollutant loads from the change in land use and enforced by all councils. In isolated cases, sites can demonstrate a suitable Best Practice Management solution. Land Area required will vary from 2.5% of site area for site slopes up to 5% and increase to 4-5% for site slopes around 10% 07 March

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24 Internal Site Constraint Mapping Site Grading, Allotment Benching & Retaining Orientation of Roads and Storm water Channels The grading of the natural terrain of the site will always dictate road orientation unless significant cut and fill is intended across the site. Roads with allotment access to be directed longitudinally perpendicular to contours where possible Narrow allotment frontages allow for smaller retaining walls on boundaries Retaining walls less than 1m in height do not need to comply with the Structural Retaining Wall design codes, therefore cheaper to construct. Retaining Wall heights should be limited to 2.0m in height maximum, but can be agreed to 3.0m with landscape support Limit retaining walls to side and rear allotment boundary and avoid them fronting road reserve and public open space Ensure layout makes sufficient provision for overland flow at the low point of the road Avoid Acid Sulphate Soil earthworks below RL5.0mAHD 07 March

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