Street maintenance
The City of Perth manage and maintain more than $670,000,000 worth of assets within and under the road reserve.
Roads
Most roads within the city are managed and maintained by the City of Perth. Some roads, including freeways, freeway entries and exits, and Mounts Bay Road (west of the Narrows Bridge) are managed and maintained by Main Roads WA. The City manages 113 kilometres (or 1,030,000m2) of roadway with 95 per cent asphalted. The balance consists of other aesthetic surfaces such as brick paving. The City undertakes condition inspections of roads every three years.
Footpaths and kerbs
The City manages and maintains over 400,000m2 of footpaths, 51,000m2 driveway crossovers and 150 kilometres of kerbing. The City also manages 43,000m2 of dual use paths and cycleways while other stakeholders including Main Roads WA and Public Transport Authority manage dual use pathways and cycleways in specific areas such as rail and freeway reserves.
The City undertakes condition inspections on its footpath and kerb assets every three years. For more information, view the City's policy for Upgrading of footpaths and Vehicle crossovers.
Stormwater drainage systems
The City manages over 117 kilometres of stormwater piping together with 6,507 associated assets including manholes and gully pits. All pits within the city are cleaned at least once per annum. Based on asset age, the City undertakes programmed CCTV inspections of pipes to ensure the network is in good condition and to identify possible risks. The City’s Policy Stormwater Drainage Connections can be found in Policy 21.1.
Streetlights and switchboards
The City manages a wide range of lighting assets including light poles, up-lights, wall lights and bollards along with more than 100 switchboards. Not all street lighting is managed by the City, with large sections owned and managed by other stakeholders including Main Roads WA, Western Power and Public Transport Authority.
The City undertakes fortnightly fault inspections of streetlights. Faults to assets other than those owned by the City are reported to the relevant authority. Electrical assets are inspected for condition every three years.
For more information, view the City’s Street lighting policy.
Civil structures
These incorporate various structures including Jacobs Ladder, Trafalgar Bridge and all jetties within Claisebrook Cove. Bridges, overpasses and underpasses are all condition inspected on various schedules based on construction type and use while jetties are inspected above water every three years and below water every five years.
River walls
The City currently manages 8,124 metres of hard landscape along the Swan River frontage. Condition inspections are undertaken either every two years or six years, based on the known condition.
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Graffiti
The City of Perth has a comprehensive Graffiti Management Plan with five focus areas:
- prevention
- reporting
- recording and analysis
- treatment and rapid removal
- response and enforcement.
The whole community can contribute to graffiti management and reduce the impact this criminal offence has on our city.
The City of Perth remove graffiti from private properties where it is visible from the street, in line with Council policy and procedures. Property owners and managers are asked to remove graffiti where it does not fall under Council policy and procedures.
Graffiti vandalism is a crime, unsightly and makes people feel unsafe. You can report graffiti online via the Goodbye Graffiti website. This website is an online information service to assist the community with graffiti management and reduction strategies within Western Australia.
If you see anyone committing any act of graffiti vandalism, report it directly to WA Police by calling 131 444. -
Drainage and dewatering
If a proposed building project involves dewatering or has any impact on the City’s storm water system then approvals need to be in place prior to commencement of works. The City of Perth can provide specialised advice on these matters to ensure that all drainage and dewatering have been addressed and have the appropriate approvals prior to the issue of a Building Permit.
City of Perth drainage connection guidelines
Disposal of stormwater generated on properties shall be as follows:
1. Stormwater to be retained on site.
2. Where (1) above is not possible, an approved onsite detention system must be provided prior to connection to the City’s drainage system.
2.1 If exceptional circumstances exist where stormwater cannot be detained onsite then direct disposal to the City’s drainage system may be approved.
2.2 If an adjoining street drainage system does not exist, or where the existing system is not capable of handling the flow from the property, an application may be made by the owner of the property for an extension or upgrading of the City’s stormwater system.
2.3 Water to be discharged to the City’s drains must be adequately treated onsite to comply with the requirements of the Manual for Stormwater Management Manual for Western Australia as published by the Department of Water 2004-2007.
2.4 The cost of connecting onsite drainage to the City's drainage system shall be the responsibility of the owner of the property being connected, including the cost of any necessary extensions or upgrading to the City's drainage system.
Onsite detention systems
Onsite detention systems are used to counteract the effects of development within a catchment by reducing the peak discharge resulting from storms. This is done by storing the stormwater onsite and slowly releasing it to the street drainage system. Onsite detention systems are installed in conjunction with property development and building works. The construction and maintenance of these systems is the responsibility of the property owner.
Design criteria
There are accepted criteria for the design of onsite detention systems to reduce the peak run-off rate from the developed site. The system is normally designed to cater for a high intensity, short duration, once-in-50-year storm. Storage is used to reduce the outflow rate to that which would have been produced by a longer, but lower intensity once-in-20-year storm on the original undeveloped property. However, this premise is not based on inner city areas and it is considered that adequate provision should be made to cater for a once-in-100-year storm.
In designing onsite detention systems, consulting engineers may use the limiting criteria given or may undertake a detailed analysis of the relevant catchment system. The criteria for storage is meant as a guide only and would be the minimum that the City would accept in approving detention systems. In the case of high rise buildings, it would be advisable to make allowance in designing the storage tanks, for the equivalent extra property area created by the facade.
It should be noted that provision may be made for an overflow from the detention system to the road drainage system to provide some relief from a larger storm than these criteria allow or from temporary problems in storage systems. Therefore, the allowable site discharge should be set at 0.12 cubic metres/second per hectare or 120 litres/second per hectare.
For a 100-year return frequency storm on the developed property the minimum storage required is 184.28 m3/ha. Several catchments were analysed and gave similar results. It is therefore considered that the minimum volume of storage required should be set at 185 cubic metres/hectare.
Soakwells
Design criteria (Note: This should be used as a guide only to the minimum number of soakwells and the city takes no responsibility for drainage based on these guidelines).
The design method is based on the basic concept that sumps function by providing temporary storage. While inflow (stormwater runoff) arrives at a high rate, outflow (soakage) occurs at a slower rate. The design method consists of developing very simple inflow and outflow hydrographs, integrating these and determining the difference between them to give the required storage volume.
Shallow Water Table (maximum height of water table less than 1 metre below bottom of soakwell).
1000 sqm runoff requires 31.99 sqm soakage area in Perth sand.
Seven soakwells (1.8 diameter and 1.8 depth).Deep Water Table (maximum height of water table more than 1 metre below bottom of soakwell).
1000 sqm runoff requires 22.85sqm soakage area in Perth sand.
Five soakwells (1.8 diameter and 1.8 depth).Excessive storm conditions can cause flooding therefore an overflow pipe may be required.
Soakwell calculation is based on slotted side soakwells and assuming that soakage area is the base area plus 25 per cent of the side walls area. (It is assumed soakwells has an open base). Additional soakwells may be required in the case of high rise developments. Also, please note that optimal soakage will only occur if the soakwells are regularly maintained.
Note: The City encourages the recycling of the storm water. Where possible, recharging the groundwater system is encouraged.
Dewatering
Dewatering during winter months is not recommended. All dewatering applications must demonstrate that drainage network is not negatively impacted.
All dewatering applications must include:
- Written approval from the Department of Water and Department of Parks and Wildlife.
- Construction Management Plan (lodged with Building License).
- Dewatering Impact Report.
- Demonstrated compliance with Swan River Trust Policy SRT/DE6.
All complex dewatering applications will be referred to the Construction Unit for review and approval.
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Onsite detention systems
Onsite detention systems are used to counteract the effects of development within a catchment by reducing the peak discharge resulting from storms. This is done by storing the stormwater onsite and slowly releasing it to the street drainage system. Onsite detention systems are installed in conjunction with property development and building works. The construction and maintenance of these systems is the responsibility of the property owner.
-
Design criteria
There are accepted criteria for the design of onsite detention systems to reduce the peak run-off rate from the developed site. The system is normally designed to cater for a high intensity, short duration, once-in-50-year storm. Storage is used to reduce the outflow rate to that which would have been produced by a longer, but lower intensity once-in-20-year storm on the original undeveloped property. However, this premise is not based on inner city areas and it is considered that adequate provision should be made to cater for a once-in-100-year storm.
In designing on-site detention systems, consulting engineers may use the limiting criteria given or may undertake a detailed analysis of the relevant catchment system. The criteria for storage is meant as a guide only and would be the minimum that the City would accept in approving detention systems. In the case of high rise buildings, it would be advisable to make allowance in designing the storage tanks, for the equivalent extra property area created by the facade.
It should be noted that provision may be made for an overflow from the detention system to the road drainage system to provide some relief from a larger storm than these criteria allow or from temporary problems in storage systems.
Therefore, the allowable site discharge should be set at 0.12 cubic metres/second per hectare or 120 litres/second per hectare.
For a 100-year return frequency storm on the developed property:
The minimum storage required for these conditions is 184.28 m3/ha. Several catchments were analysed and gave similar results.
It is therefore considered that the minimum volume of storage required should be set at 185 cubic metres/hectare.
-
Soakwells
Design Criteria
(Note: This should be used as a guide only to the minimum number of soakwells and the city takes no responsibility for drainage based on these guidelines).
The design method is based on the basic concept that sumps function by providing temporary storage. While inflow (stormwater runoff) arrives at a high rate, outflow (soakage) occurs at a slower rate.
The design method consists of developing very simple inflow and outflow hydrographs, integrating these and determining the difference between them to give the required storage volume.
Shallow Water Table (maximum height of water table less than 1 metre below bottom of soakwell).
- 1000m2 runoff requires 31.99m2 soakage area in Perth Sand.
- 7 soakwells (1.8 diameter and 1.8 depth).
Deep Water Table (maximum height of water table more than 1 metre below bottom of soakwell).
- 1000m2 runoff requires 22.85m2 soakage area in Perth Sand.
- 5 soakwells (1.8 diameter and 1.8 depth).
Excessive storm conditions can cause flooding therefore an overflow pipe may be required.
Soakwell calculation is based on slotted side soakwells and assuming that soakage area is the base area plus 25% of the side walls area. (It is assumed soakwells has an open base)
Additional soakwells may be required in the case of high rise developments. Also, please note that optimal soakage will only occur if the soakwells are regularly maintained.
Note: City encourages the recycling of the storm water. Where possible, re charging the groundwater system is encouraged.
-
Dewatering
Dewatering during winter months is not recommended. All dewatering applications must demonstrate that drainage network is not negatively impacted.
All dewatering applications must include:
- Written approval from the Department of Water and Department of Park and Wildlife.
- Construction Management Plan (lodged with Building License).
- Dewatering Impact Report.
- Demonstrated compliance with Swan River Trust Policy SRT/DE6.
All complex dewatering applications will be referred to the Construction Unit for review and approval.
