Landcom Book 4 Maintenance - WSUD

www.landcom.com.au 

Water Sensitive Urban Design 

Book 4 | maintenance 

Draft


Book 4 | MAINTENANCE 

Table of Contents 

1 | Introduction 4 

2 | Key Operational and Maintenance Issues 

Identified By Stakeholder Local Councils 6 

3 | WSUD Elements 8 

3.1 Bioretention Basins 8 

3.2 Constructed Wetlands and Ponds 9 

3.3 Sedimentation Basins 11 

4 | Life Cycle Costing 12 

4.1 What are the Life Cycle Costs of WSUD Elements 13 

4.2 How does the LCC of WSUD development compare 

with that of conventional drainage infrastructure 17 

5 | Monitoring and Maintenance of WSUD Elements 18 

5.1 Performance Monitoring Requirements 20 

5.2 Maintenance Requirements 21 

5.2.1 Predictive maintenance 21 

5.2.2 Regular inspection and maintenance 22 

5.2.3 Bioretention mystems 22 

5.2.4 Constructed wetlands and ponds 27 

5.2.5 Sedimentation basins 31 

5.3 Waste Management and Disposal 35 

5.3.1 Dewatered silt 36 

5.3.2 Filter media 36 

5.3.3 Liquid waste (from dewatering activities) 37 

5.3.4 Equipment requirements 37 

6 | Construction Requirements 38 

6.1 Staging 38 

6.1.1 Stage 1: Civil construction (or functional installation) 40 

6.1.2 Stage 2: Building phase protection 

(or sediment and erosion control) 42 

6.1.3 Stage 3: Operational establishment 

(civil and/or landscaping) 44 

6.2 Construction Tolerances 46 

6.3 Construction Certification and Compliance 47 

6.4 Filter Media Specifications 48 

Appendix A – Construction Inspection and Sign off sheets 49 

A.1 Bioretention Systems 50 

A.2 Constructed Wetlands 58 

A.3 Sedimentation Basins / Ponds 68 

Appendix B – Regular Maintenance Checklists 75 

B.1 Bioretention Basins 76 

B.2 Constructed Wetlands 78 

B.3 Sedimentation Basin 80 

B.4 Ponds 82 

Appendix C – Asset handover sheets 84 

Appendix D – References 85 

Book 4 | MAINTENANCE 3


1 | Introduction 

Landcom has 

implemented a 

range of innovative 

Water Sensitive 

Urban Design 

(WSUD) initiatives 

since 2003. 

Since 2003 Landcom has embarked on 

ensuring that all its projects have a strong 

sustainability underpinning, as reflected 

in its annual Triple Bottom Line reporting. 

Landcom prepared a Water Sensitive 

Urban Design Policy in 2003 and published 

its Water Sensitive Urban Design Strategy 

in 2004. Since that time Landcom have 

progressed steadily towards attaining the 

best practice objectives of urban water 

management in all its projects. Landcom 

has implemented a range of innovative 

Water Sensitive Urban Design (WSUD) 

initiatives since 2003, which build upon 

and extend elements of the original 

WSUD strategy. 

This document forms part of a 4-book set 

that updates and revises the Landcom 

Water Sensitive Urban Design Strategy 

of 2004 as published. Recent advances 

in integrated water cycle management 

and WSUD, such as the release of 

Australian Runoff Quality 1 , the BASIX 

scheme, MUSIC (v3) and wider 

implementation have seen the stormwater 

industry evolve over the last three 

years. During this period the NSW 

Government has also revised its statewide 

water management objectives for new 

developments. 

1 

Engineers Australia (2006), Australian Runoff 

Quality: A Guide to Water Sensitive Urban Design, 

Wong, T H F (ed), ISBN 0 85825 852 8, Engineers 

Australia, Canberra, Australia, 2006 

4 Book 4 | MAINTENANCE


Landcom’s Water Sensitive Urban Design Strategy (2009) is contained in the 

following 4 books: 

Book 1 | Landcom’s WSUD Policy and Urban Water Management Objectives consisting of: 

•• 

an overview of Water Sensitive Urban Design 

•• 

a revision of the WSUD Targets and Mandatory WSUD Requirements to ensure appropriateness 

and relevance, including proposed realistic and appropriate “Stretch Targets” which Landcom may 

consistently apply in projects where warranted, and linkages to TBL reporting criteria 

•• 

key components of a project-specific WSUD strategy 

Book 2 | Attaining Landcom WSUD Objectives consisting of descriptions and discussions on urban water best 

planning and management practices applicable to Landcom projects including information on: 

•• 

how to meet the water conservation targets, including information on BASIX and information on 

wastewater and greywater technologies 

•• 

how to meet the stormwater quality targets, including proposed changes to ensure consistency with 

Landcom’s Street Design Guide 

•• 

how to meet the flow management targets 

Book 3 | Case studies and discussions on how water sensitive urban design could be integrated into Landcom 

Development Projects, including examples of: 

•• 

WSUD in the planning phase – Renwick 

•• 

WSUD in the implementation phase - Prince Henry Hospital and The Ponds 

•• 

WSUD after years of operation – Victoria Park 

Book 4 | Operation and maintenance guidelines of key WSUD elements including: 

•• 

life cycle costing of bioretention systems, constructed wetlands and ponds 

•• 

monitoring and maintenance practice and associated checklist 

•• 

construction considerations and associated checklist for construction inspection and asset handover 

This document (Book 4) describes operational and maintenance practices of a number of key WSUD elements 

commonly adopted in Landcom projects. Book 4 was prepared in response to a recurring set of enquiries from 

local government on the topics of construction, and ongoing operation and maintenance of WSUD elements. 

There was a clear desire to have a common set of understanding of the various considerations on these issues. 



2 | Key Operational And Maintenance Issues 

Identified By Stakeholder Local Councils 

Bioretention system in the public domain | Prince Henry 

6 Book 4 | MAINTENANCE 

In preparing the booklet on WSUD 

Operation and Maintenance, two half-day 

workshops with invited Local Government 

representatives were organised. The 

first of these half-day workshops was 

held in December 2008. That workshop 

served as a platform for Council’s to 

present their considerations in approving 

WSUD elements in land development 

projects, concerns with the maintenance 

and operation of WSUD elements and 

information gaps in maintaining and 

operating WSUD elements. 

Representatives from the following 

Councils were present at one or both 

workshops: 

•• 

Auburn Council 

•• 

Bankstown City Council 

•• 

Blacktown City Council 

•• 

Camden Council 

•• 

Campbelltown City Council 

•• 

City of Sydney 

•• 

Fairfield City Council 

•• 

Hills Shire Council 

•• 

Hunters Hill Council 

•• 

Ku-ring-gai Council 

•• 

Liverpool City Council 

•• 

Penrith City Council 

•• 

Pittwater Council 

•• 

Sydney Metropolitan Catchment 

Authority 

•• 

Western Sydney Regional Organisation 

of Councils 

•• 

Wingecarribee Shire Council 

•• 

Wollongong City Council 

Following this first workshop, the issues 

identified were grouped into three 

categories: 

1) Life cycle cost considerations of WSUD 

strategies 

2) Monitoring and maintenance of WSUD 

elements 

3) Construction considerations of WSUD 

elements


Woolwash Park Biofiltration | Victoria Park 

The booklet is 

structured to 

address frequently 

asked questions 

regarding 

construction, 

maintenance and 

operational issues 

of WSUD elements. 

A draft response was compiled for 

specific issues within the three categories 

identified. The responses reference 

current best practice guidelines and 

industry experience. These were then 

discussed and reviewed in a second 

half-day workshop held in March 2009 

involving participants on the first 

workshop. This second workshop was 

also attended by representatives from a 

wider group of local councils. 

The 4 th booklet in the Landcom WSUD 

booklet series addresses operation and 

maintenance concerns of select WSUD 

elements. The booklet is structured 

to address frequently asked questions 

regarding construction, maintenance and 

operational issues of WSUD elements as 

identified from a focus group of Councils. 

The booklet does not aim to recreate or 

reiterated current best practice guidelines 

for the purpose of Councils. Rather the 

booklet provides a consolidated response 

to the issues raised, with information 

supported by appropriate references/ 

links to where additional information can 

be sourced. 

The responses compiled have been 

limited to the following WSUD elements: 

•• 

Constructed wetlands 

•• 

Bioretention basins 

•• 

Sedimentation basin / ponds 

The responses, in particular to monitoring 

and maintenance requirements, assume 

that the WSUD strategy has been 

designed and constructed to meet best 

management practice objectives and 

design guidelines. 



3 | WSUD Elements 

Examples of bioretention systems in streetscapes 

3.1 Bioretention Basins 

Bioretention 

systems can 

provide a degree 

of flow attenuation 

and hence reduce 

the volume and 

frequency of 

runoff delivered 

to downstream 

waterways. 

Bioretention systems are vegetated filter 

systems designed to allow water to pool 

temporarily before percolating through 

the filter media. The filter media controls 

the flowrate of water through the system, 

as well as providing a growing media for 

the plants. The filtered water is directed 

via perforated pipes to the existing 

stormwater system, natural waterways or 

a detention basin for reuse. Bioretention 

systems can provide a degree of flow 

attenuation and hence reduce the volume 

and frequency of runoff delivered to 

downstream waterways (ARQ, 2006). 

Critical to the performance of a 

bioretention system is the filter media 

and vegetation. The filter media needs 

to provide a hydraulic conductivity that 

ensures sufficient contact time is available 

for pollutants to be taken up by biofilms. 

Vegetation root systems provide the 

surfaces for the epiphytic biofilms that 

take up dissolved pollutants. Vegetation is 

also critical in maintaining the porosity of 

the soil media of the bioretention system. 

Bioretention systems can be integrated 

into open space areas and streetscapes 

(for example, parking stations and traffic 

calming devices). The systems can take 

the form of a basin or a swale. A basin is 

typically employed for relatively flat areas. 

Swales provide a stormwater treatment 

and flow conveyance role and are suitable 

for long linear sites with a grade ranging 

between one and four percent. For some 

sites, a combined bioretention basin and 

a conventional swale may be required. 



Examples of constructed wetlands 

3.2 Constructed Wetlands 

and Ponds 

The deep open 

water bodies 

typical of ponds 

provide larger 

detention volumes 

as compared 

to constructed 

wetlands. 

Constructed wetlands use enhanced 

sedimentation, fine filtration and biological 

uptake processes to remove pollutants 

from stormwater. The wetland processes 

are engaged by slowly passing runoff 

through heavily vegetated areas where 

plants filter sediments and pollutants from 

the water. Biofilms that grow on the plants 

can absorb nutrients and other associated 

contaminants. 

Ponds also provide physical, biological 

and chemical mechanisms for pollutant 

uptake. The main physical difference 

between a pond and a constructed 

wetland is the ratio of surface area to 

volume and the coverage by vegetation 

(ARQ, 2006). Typically ponds have a depth 

exceeding 1.5 meters as compared to 

constructed wetlands, which have an 

average depth in the macrophyte zone of 

0.3 metres. Furthermore, a regular water 

level fluctuation regime is promoted in a 

constructed wetland through the design 

of the outlet structures. Combined, the 

high surface area to volume ratio and 

the promotion of regular water level 

fluctuation through the design of the 

outlet structure in a constructed wetland, 

supports a densely vegetated system 

and hence a greater biological uptake of 

pollutants as compared to a pond. 

The deep open water bodies typical of 

ponds provide larger detention volumes 

as compared to constructed wetlands. 

Higher detention times promote improved 

sedimentation; however the risk of large 

open water bodies is short circuiting, 

redox potential conditions and elevated 

levels of nutrients. These processes can 

have a reverse effect on stormwater 

treatment causing release of pollutants 

from the sediment into the water. High 

nutrient concentrations can also lead to 

nuisance macrophyte growth or algal 

blooms that can be toxic and aesthetically 

unpleasant. 

For these reasons, ponds are commonly 

designed in combination with constructed 

wetlands, providing polishing of 

stormwater quality, attenuation of flows 

and protection of downstream waterways, 

and storage for reuse applications. 



Wetland | Koala Bay 

Table 1 | Stormwater treatment processes of constructed wetlands and ponds 

Constructed Wetlands 

Physical – Sedimentation 

•• 

Traps suspended solids – vegetation in the 

wetland facilitates enhanced sedimentation of 

particles down to the fine fractions 

•• 

Traps adsorbed pollutants – traps a higher 

proportion of adsorbed pollutants through 

higher capture of fine particles 

Biological and Chemical Uptake 

•• 

Traps dissolved pollutants – vegetation 

provides surfaces for epiphytic biofilms, which 

take up dissolved pollutants 

•• 

Chemical adsorption of pollutants to fine 

suspended particles which are trapped through 

enhanced sedimentation and surface filtration 

facilitated by macrophytes and biofilms 

•• 

Promotes rapid biodegradation of organic 

material 

Pollutant transformation 

•• 

The regular wetting and drying cycle 

progressively leads to less reversible sediment 

fixation of contaminants in the substratum 

Ponds 

Physical – Sedimentation 

•• 

Traps ‘readily settleable solids’ – settling of 

solids down to coarse and medium sized silt 

fractions 

•• 

Traps adsorbed pollutants – silt particles 

trapped in the pond system may also retain 

adsorbed pollutants 

•• 

Promotes flocculation of smaller particles 

Biological and Chemical Uptake 

•• 

Biological uptake of soluble pollutants 

predominately by phytoplankton, which remains 

in the water column and is susceptible to washoff 

during the next storm event 

•• 

Chemical adsorption of pollutant to fine 

suspended sediment which remains in the water 

column for extended periods and is susceptible 

to washoff during the next storm event 

•• 

UV disinfection of waterbody by sunlight 

Pollutant transformation 

•• 

Pollutants adsorbed to deposited sediment are 

susceptible to release under conditions of low 

redox potential caused by high organic loading 

and pond stratification 

Table taken from Australian Runoff Quality (Engineers Australia, 2006) 



Examples of sedimentation basins and ponds 

3.3 Sedimentation Basins 

Due to the nature 

of a sedimentation 

basin, regular clean 

out and removal 

of accumulated 

sediment is 

required. 

Sedimentation basins are stormwater 

detention systems that promote the 

settling of coarse sediment (defined 

as particles greater than 125 microns 

in diameter). A sedimentation basin 

can be an integral part of a treatment 

train, providing primary removal of 

coarse sediment. Removal of coarse 

sediment is particularly important in 

protecting downstream systems from 

high sediment loading, which can reduce 

the effectiveness of the system. The 

treatment performance of a bioretention 

system is particularly susceptible to high 

sediment loadings: sediment can smother 

vegetation and clog the filter media 

affecting the percolation of stormwater 

through the media. Sediment basins can 

also be employed for temporary sediment 

and erosion control during construction 

activities. 

Due to the operation of a sedimentation 

basin, regular clean out and removal 

of accumulated sediment is required. 

Sedimentation basins are generally 

designed for a clean out frequency of 

five years, which equates to a volume 

half that of the permanent pool (defined 

by the invert of the outlet structure). 

The sedimentation basin design should 

include an access ramp to allow entry for 

a clean-out truck. 



4 | Life Cycle Costing 

Bioswale | Victoria Park 

Indirect tangible 

benefits associated 

with well designed 

and constructed 

WSUD elements are 

the environmental 

outcomes such 

as reductions 

in potable 

water demands, 

downstream 

pollution and 

waterway 

rehabilitation 

works. 

An important part of implementing 

WSUD strategies is the cost the systems 

pose to Councils. There are many 

approaches to computing and accounting 

the cost of infrastructure. In the case of 

land development, the capital cost is 

often borne by the developer with the 

asset subsequently assumed by local 

government with associated maintenance 

and renewal responsibilities. 

The life cycle cost of an asset is made up of 

its capital cost, operational and 

maintenance cost, renewal cost and 

decommissioning cost. Often not 

included in a life cycle cost/benefit 

analysis are the benefits both directly 

accrued to the development, and 

indirectly attributed to the works within 

the development. The benefits directly 

accrued to the development are reflected 

in the increased demand for properties in 

the development as reflected in the sale 

price. Indirect tangible benefits associated 

with well designed and constructed 

WSUD elements are the environmental 

outcomes such as reductions in potable 

water demands, downstream pollution 

and waterway rehabilitation works. 

Organisations are now considering the 

total community costs in evaluating water 

management strategies. 



The impact of 

maintenance and 

renewal costs is 

dependent on the 

expected life span 

of the asset. 

4.1 What are the Life 

Cycle Costs of 

WSUD Elements 

Life cycle costing is a process to determine 

the sum of all expenses associated with a 

product or project, including acquisition, 

installation, operation, maintenance, 

refurbishment, discarding and disposal 

costs (Standards Australia, 1999). The life 

cycle costs (LCC) for WSUD elements 

include the total acquisition cost (TAC), 

the total annual maintenance (TAM), 

renewal, and decommissioning costs. The 

impact of maintenance and renewal costs 

is dependent on the expected life span 

of the asset. The decommissioning cost 

in some WSUD systems, such as 

constructed wetlands, may be irrelevant as 

they are designed to operate in perpetuity. 

All life cycle costs are discounted back to 

a base date (date of installation). 

How is the Life Cycle Costs Calculated? 

The supporting user manual for the Model 

for Urban Stormwater Improvement 

Conceptualisation (MUSIC, version 3) 

developed by the Cooperative Research 

Centre for Catchment Hydrology (CRCCH) 

provides a summary of the life cycle costs 

associated with bioretention systems, 

wetlands, ponds and sedimentation 

basins. A summary of the parameters 

affecting the LCC of these elements is 

given in Table 2. 

In many cases, MUSIC uses an algorithm to 

define a particular life cycle cost element 

in terms of the treatment area. These 

algorithms have been developed based 

on real data collected between 2002 and 

2004. 



Table 2 | Life cycle cost parameters for specified WSUD elements. 

Life Cycle Cost 

element 

Bioretention 

Wetlands 

Ponds & 

Sedimentation Basins 

Life cycle 25 to 50 years 15 to 80 years (with 50 

years used as the default in 

MUSIC) 

Wetlands are designed to 

have an infinite life span. 

However, to determine 

a life cycle cost, a finite 

number needs to be set 

5 year (sedimentation 

basins) 

50 years (ponds) 

Total acquisition 

cost (TAC) 

(per m 2 ) 

387.4 x (A) 0.7673 

$1000/m 2 for first 20 m 2 

($200/m 2 for remaining 

area) 

1911 x (A) 0.6435 

The treatment area 

used in defining the 

total acquisition cost is 

the combined inlet and 

macrophyte zone area 

685.1 x (A) 0.7893 

Total annual 

maintenance (TAM) 

(%TAC) 

48.87 x (TAC) 0.4410 6.831 x (A) 0.8634 185.4 x (A) 0.4780 

The annual maintenance 

cost considers the volume 

of material likely to be 

removed from the basin 

per year (referred in MUSIC 

as the size attribute, V). 

The size attribute is the 

sum of gross pollutants, 

coarse sediment and total 

suspended solids (TSS) 

that are trapped in the 

basin / pond per year 

Renewal period 

(years) 

25 20 

Renewal considerations 

include replanting and 

recontouring of the 

macrophyte zone 

1 year (default in MUSIC 

due to lack of evidence). 

10 years based on 

available data 

Renewal costs 

(%TAC p.a.) 

2.0% 0.52% 1.4% 

Costs associated with 

access ramps and 

contouring 

Limited data available 

Decommisioning costs 

(% TAC) 

38% - only applicable to 

sedimentation basins 



What is the Annualised Life 

Cycle Cost with respect to 

pollutant removal? 

The annualised life cycle cost is simply the 

Net Present Value (NPV) of the life cycle 

cost divided by the life cycle (years) of the 

asset. 

In developing an example of annualised 

life cycle cost, a series of analyses were 

undertaken for an asset life cycle period of 

50 years. Three different WSUD elements 

were assessed: bioretention basins, 

constructed wetlands, and sedimentation 

basins. 

Bioretention basins and constructed 

wetlands were sized to meet best 

management practice pollutant load 

reductions for total nitrogen (TN) removal 

(that is, 45 percent). The sedimentation 

basin was sized to remove 80 percent of 

coarse sediment (greater than 125 microns), 

while also ensuring the associated clean 

out frequency of the basin was a minimum 

of 5 years. The life cycle costs are shown in 

Figure 1 to Figure 3. 

The results are useful in showing the 

relative cost of maintenance to upfront 

capital cost and in particular the relatively 

low cost of maintaining these systems. For 

example, the annual maintenance cost of 

a bioretention basin sized for a 1 hectare 

impervious catchment is approximately 3 

percent of the capital cost. 

In the life cycle cost figures for each 

WSUD element (Figure 1 to Figure 3), the 

annualised cost in terms of pollutant load 

reductions are also reported. Such data is 

useful in: 

•• 

assessing the efficiency of one WSUD 

element against another in removing a 

specific pollutant 

•• 

comparing the cost of WSUD elements 

against other pollutant abatement 

technology 

The annualised cost in terms of pollutant removal for a 1 hectare completely 

impervious catchment are: 

Bioretention Basin: 

− $70 per kg TN removed (45% reduction) 

− $320 per kg TP removed (67% reduction) 

− $1 per kg TSS removed (81% reduction) 

Constructed Wetland: 


− $2,300 per kg TP removed (70% reduction) 


Sedimentation Basin: 


− $800 per kg TP removed (17% reduction) 




$18,000 

$16,000 

$14,000 

$12,000 

Bioretention basin sized to remove 45 percent of TN pollutant 

loads generated from a 1 hectare, 100 percent impervious 

catchment (road) 

Annualised cost of system in terms of pollutant load reductions 

are: 

/ $70 per kg TN removed 

/ $320 per kg TP removed 

/ $1 per kg TSS removed 

Cost ($) 

$10,000 

$8,000 

Decomissioning Cost 

Renewal Cost 

Maintenance Cost 

Capital Cost 

$6,000 

$4,000 

$2,000 

$- 

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 

Time (years) 

Figure 1: LCC for bioretention basins 

$140,000.00 

$120,000.00 

$100,000.00 

Constructed wetland sized to remove 45 percent of TN pollutant 

loads generated from a 1 hectare, 100 percent impervious 

catchment (road) 


are: 




Cost ($) 

$80,000.00 

$60,000.00 


Renewal Cost 


Capital Cost 

$40,000.00 

$20,000.00 

$- 

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 

Time (years) 

Figure 2: LCC for constructed wetlands 



$6,000.00 

$5,000.00 

$4,000.00 

Sediment basin sized to remove 80 percent of course sediment 

(defined as particles greater than 125 microns) for a 1 hectare, 

100 percent impervious catchment (road) 


are: 




Cost ($) 

$3,000.00 

$2,000.00 


Renewal Cost 


Capital Cost 

$1,000.00 

$- 

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 

Time (years) 

Figure 3: LCC for sedimentation basins 

4.2 How does the LCC of WSUD development compare 

with that of conventional drainage infrastructure 

The life cycle costs of water sensitive urban design measures were assessed by Lloyd et al. 

(2002) for one of the original WSUD strategies implemented in Victoria (that is, Lynbrook 

Estate). The assessment considered three stormwater management scenarios: 

Conventional Approach: 

Downstream 

Stormwater Treatment: 

Distributed Stormwater 

Treatment: 

Stormwater is piped to the downstream waterway. No treatment of 

stormwater is considered. 

An end-of-pipe treatment system is employed to ensure the 

quality of discharged stormwater meets best management 

practice (BMP) objectives for pollutant load reductions. 

A series of WSUD elements are employed to remove pollutants at 

source, such that a greater volume of stormwater can be treated to 

BMP objectives. 

The assessment found the capital cost of a distributed system to be 22 percent greater 

than the conventional approach, while a downstream stormwater treatment cost an 

additional 47 percent. It should be noted that the cost of drainage infrustructure represents 

approximately 10% of the total cost of development. 

The range of annualised maintenance cost from the study was reported as: 

Approach 

Annualised Maintenance 

Cost 

Annualised Maintenance 

Cost per hectare 

Conventional Approach: $737 to $1,672 $27 to $62 

Downstream Stormwater Treatment: $2,336 to $6,371 $87 to $236 

Distributed Stormwater Treatment: $1,723 to $6,512 $64 to $241 



5 | Monitoring and Maintenance 

of WSUD Elements 

Watersteps | Victoria Park 

The information provided in this section will help Councils understand the 

monitoring and maintenance requirements of WSUD elements and assist 

in generating and/or assessing maintenance plans such that the associated 

monitoring and maintenance plan addresses: 

•• 

inspection frequency 

•• 

maintenance frequency 

•• 

data collection/ storage requirements (i.e. during inspections) 

•• 

detailed cleanout procedures (main element of the plans) including: 

–– 

equipment needs 

–– 

maintenance techniques 

–– 

occupational health and safety 

–– 

public safety 

–– 

environmental management considerations 

–– 

disposal requirements (of material removed) 

–– 

access issues 

–– 

stakeholder notification requirements 

–– 

data collection requirements (if any) 

•• 

design details 

The performance of WSUD elements 

is dependent on the maintenance 

considerations incorporated during their 

design. Maintenance personnel need 

to be involved during the design to 

ensure their requirements (for example, 

access) are addressed, they understand 

the functionality of the systems and the 

role of maintenance in ensuring design 

performance criteria are met, and to 

ensure appropriate maintenance budget 

is allocated. 




Routine monitoring 

checks the status 

of key functional 

elements to 

ensure they meet 

specified design 

requirements and 

include ensuring 

that inlet and outlet 

structures are free 

of debris, and that 

well distributed 

vegetative cover 

of the system is 

maintained. 

Unlike traditional engineered structures, 

WSUD elements will only require minimal 

routine maintenance and these are 

generally of a landscape maintenance 

nature. For example, regular weeding 

should only be required during the 

establishment phase of a well designed 

and constructed system with appropriate 

planting density limiting the ‘free’ area 

available for weed growth. Removal of 

debris and siltation is the most common 

activity. Maintenance activities should 

primarily be prompted through predictive 

and routine monitoring. Predictive 

monitoring activities occur following 

significant storm events and are directed 

at assessing the performance of the 

system (for example, flow distribution 

and ponding duration). These activities 

help identify potential deviations in 

performance and initiate corrective 

maintenance actions. 

Routine monitoring checks the status of 

key functional elements to ensure they 

meet specified design requirements and 

include ensuring that inlet and outlet 

structures are free of debris, and that well 

distributed vegetative cover of the system 

is maintained. 

It is recommended that vegetated WSUD 

elements are monitored by personnel 

with bush regeneration qualifications (as 

approved by Australian Association of 

Bush Regenerators). Bush regenerators 

are well equipped at identifying evasive 

species within a native landscape 

typical of vegetated WSUD systems. 

Furthermore, personnel in charge of 

monitoring should have a good idea and 

understanding of the layout and functional 

design of the treatment system. The 

maintenance activities prompted through 

monitoring activities will generally require 

coordination between landscape and civil 

services. 

The following section documents 

the monitoring and maintenance 

requirements for bioretention basins, 

constructed wetlands and sedimentation 

basins/ponds. The information given can 

be used to guide development of site 

specific maintenance plans for WSUD 

developments. The plans will be used 

by maintenance personnel and asset 

managers to ensure the bioretention 

system functions as designed for its entire 

life cycle. 



5.1 Performance Monitoring 

Requirements 

Surrogate methods 

can often be 

equally effective 

in evaluating the 

adequacies of the 

operation, and thus 

performance, of 

WSUD elements. 

Performance monitoring of WSUD 

elements can be undertaken through 

detailed water sampling and laboratory 

analyses for contaminant concentrations or 

through the use of surrogate performance 

indicators. With the former, it will be 

necessary to set up field monitoring sites 

to undertake the water quality sampling at 

inlet and outlet of systems. The following 

points should be considered when setting 

up a sampling program: 

•• 

Auto-sampling with partial or full 

composite samples is most cost 

effective 

•• 

Monitoring should be accompanied by 

continuous flow and depth observations 

•• 

Design of monitoring set up and 

sampling intervals is site dependent 

•• 

20 events should be monitored as a 

minimum to obtain typical performance 

•• 

The following key water quality 

parameters should be analysed in 

registered laboratories:- 

–– 

TSS analysis should be 

undertaken 

–– 

TP (with occasional filter of 

sample on-site with 0.45um filter 

to test for Orthophosphate) 

–– 

TN (with occasional speciation to 

organic and inorganic nitrogen 

An implicit assumption made when water 

quality improvements are measured by 

comparing observed water quality at the 

inlet and outlet of the system, is that these 

water qualities represent the same ‘parcel’ 

of water. Occasionally, especially with 

wetlands and ponds, negative or very low 

pollutant removal results for a system are 

observed. These results are common when 

the volume of an inflow event is less than 

the permanent pool volume of the wetland 

or pond. In the case of bioretention 

systems, accurately accounting for the 

volumetric balance of inflow, outflow, 

and soil moisture replenishment, is the 

main analytical problem that may lead to 

erroneous performance assessment. 

Surrogate methods can often be equally 

effective in evaluating the adequacies of 

the operation, and thus performance, of 

WSUD elements. They are often more cost 

effective and involve the monitoring of the 

hydrologic and hydraulic performance of 

these systems. The implicit assumption 

with surrogate methods is the premise 

that if the WSUD elements operate in 

accordance to the design hydrologic and 

hydraulic characteristics, it follows that 

these systems can be reasonably expected 

to deliver the pollutant reduction as 

determined from laboratory and field 

experiments. 

Key hydrologic and hydraulic operation 

characteristics define the detention 

time of WSUD elements. Monitoring of 

the following operation of bioretention 

systems, wetlands and ponds, can 

provide important insights on the likely 

performance of these WSUD elements in 

pollution reduction: 

•• 

Flow pattern (most relevant to wetlands 

and ponds), to identify the presences 

of short-circuiting that may inhibit the 

uniform distribution of inflow to this 

system 

•• 

Duration of inundation (most relevant 

to wetlands and bioretention systems) 

to assess the operating detention 

time of these systems and to highlight 

potential clogging of soil media 

(bioretention systems) or the outlet 

structure (wetlands) that would have 

a direct impact on its performance in 

water treatment 

•• 

Turbidity of inflow and outflow which 

are good surrogates for suspended 

solids, total phosphorus, and metal in 

urban stormwater 



WSUD 

infrastructure 

requires ongoing 

inspection and 

maintenance 

to ensure they 

establish and 

operate in 

accordance with the 

design intent. 

5.2 Maintenance 

Requirements 

WSUD infrastructure requires ongoing 

inspection and maintenance to ensure 

they establish and operate in accordance 

with the design intent. Potential problems 

associated with WSUD infrastructure as a 

result of poor maintenance include: 

•• 

Decreased aesthetic amenity 

•• 

Reduced functional performance 

•• 

Public health and safety risks 

•• 

Decreased habitat diversity (dominance 

of exotic weeds) 

The most time-intensive period of 

maintenance for a vegetated system 

is during plant establishment (which 

typically includes two growing seasons), 

when supplementary watering, plant 

replacement and weeding may be 

required. Generally, WSUD elements are 

brought online through stages such that 

the functional elements are protected from 

elevated pollutant loads generated from a 

developing catchment. More information 

regarding staged construction is given in 

the next section of this booklet. 

Once WSUD elements are established 

and operational, on-going inspection, 

monitoring and maintenance will be 

required. Maintenance activities fall 

into one of two categories; predictive 

maintenance or regular maintenance. 

5.2.1 Predictive Maintenance 

Predictive maintenance is scheduled 

based on inspections conducted after 

a significant storm event (defined 

qualitatively as an event likely to mobilise 

sediment and coarse material). Predictive 

inspections are critical to assessing the 

performance of the treatment system, 

in particular the hydraulic function and 

flow distribution of the system. Items 

that should be considered during the 

inspection are included over the page. 



Ponding time 

Detention of flows above the design intent could indicate a blockage 

in the outlet structures. Typical drainage times for treatment systems 

are: 

•• 

72 hours for a constructed wetland 

•• 

6 to 24 hours for a bioretention basin 

•• 

24 hours for a sedimentation basin 

Surface 

distribution 

of flows 

Flow should pond evenly within the treatment system 

Additionally, the absence of ponding after a significant storm event 

may indicate a blocked inlet (that is, flows are being prevented from 

entering the treatment system) 

Scouring 

Scouring can be indicative of a blocked inlet 

5.2.2 Regular Inspection and 

Maintenance 

Generally, WSUD elements should be 

inspected every three months, with 

particular reference to: 

•• 

Structures, such as overflow weirs, 

bypass and inlets 

•• 

Erosion 

•• 

Sediment build-up 

•• 

Weeds 

•• 

Algal blooms 

•• 

Litter (anthropogenic and nonanthropogenic) 

•• 

Oil slicks 

The following tables in the next three 

sections further explore the above issues 

as related to constructed wetlands, 

bioretention systems or sedimentation 

basins / ponds. In particular, the tables: 

•• 

articulate monitoring requirements 

•• 

suggest graded targets for optimal 

performance 

•• 

suggest scheduling of maintenance 

and immediate action 

•• 

propose a general approach to 

maintenance activities 

5.2.3 Bioretention 

Systems 

The routine maintenance of a bioretention 

basin is required to ensure diverted storm 

water: 

•• 

Ponds evenly across the basin surface 

•• 

Percolates through the filter media such 

that the ponding time does not exceed 

the design specifications (typically 6 to 

24 hours) 

To ensure the functionality of 

the bioretention basin is retained, 

maintenance activities will typically 

involve: 

•• 

Routine inspection of the bioretention 

profile to identify any areas of obvious 

increased sediment deposition, 

scouring of the basin or swale invert 

from storm flows, rill erosion of the 

batters from lateral inflows, damage 

to the swale profile from vehicles and 

clogging of the bioretention trench 

(evident by a ‘boggy’ swale invert) 

•• 

Routine inspection of inlet points, 

surcharge pits and field inlet pits to 

identify any areas of scour, litter build 

up and blockages 



Boardwalk | Victoria Park 

•• 

Removal of sediment, especially where 

it is impeding the conveyance of the 

bioretention swale and/or smothering 

the vegetation, and if necessary, reprofiling 

of the system and re-vegetating 

to original design specification 

•• 

Repairing any damage to the system 

profile, especially in the case of a 

bioretention swale, resulting from 

scour, rill erosion or vehicle damage 

•• 

Tilling of the bioretention trench surface 

if there is evidence of clogging 

•• 

Clearing of blockages to inlet or outlets. 

•• 

Regular watering/irrigation of 

vegetation until plants are established 

and actively growing 

•• 

Mowing of turf or slashing of vegetation 

(if required) to preserve the optimal 

design height for the vegetation 

•• 

Removal and management of invasive 

weeds 

•• 

Removal of plants that have died and 

replacement with plants of equivalent 

size and species as detailed in the plant 

schedule 

•• 

Pruning to remove dead or diseased 

vegetation material and to stimulate 

new growth 

•• 

Litter and debris removal 

•• 

Vegetation pest monitoring and control 

Resetting (i.e. complete reconstruction) 

of bioretention elements will be required 

if the available flow area of the overlying 

basin is reduced by 25 percent (due 

to accumulation of sediment) or if 

the bioretention trench fails to drain 

adequately after tilling of the surface. 



Table 3 | Routine monitoring requirement for bioretention basins. 

Item to be 

Monitored 

Purpose of 

Monitoring 

Performance 

Target 

Schedule 

Maintenance or 

Investigation 

Immediate 

Action Required 



Structures 

The inlet and outlet structures of a 

bioretention system should be free of 

debris, litter and sediment to ensure 

flow is not impeded. Large storms (or 

flood) events and vehicles can also 

damage or block these structures 

and prevent the system working 

as designed. The main structural 

elements of a bioretention system are: 

- GPT / trash rack/s GPT clear of litter GPT 10 percent full greater than 30 

percent full 

Contact cleaning service. 

Generally a GPT will require clean-out 

four times per year. For proprietary 

GPTs it is recommended that a vacuum 

based cleaner be used on at least one 

occasion per year, or when frequent 

overflow of litter from the GPT is 

evident. For all other clean-outs, a 

mechanical grab is sufficient. 

- Inlet structures Clear and undamaged Partially Blocked 

Observed damage 

Mostly blocked 

Severe damage 

Schedule removal of debris or contact 

relevant authority within Council for 

structural damage. 

- Overflow pits 

- Underdrains Free flowing Trickle flow while 

basin ponding is 

observed 

No outflow while 

basin ponding is 

observed 

Inspect the bioretention system for 

scour or erosion damage and fix 

accordingly (refer to maintenance line 

item “bioretention system profile” for 

advise). 

- Sediment Forebay Sediment absent Sediment 

accumulation appears 

excessive 

Sediment 

accumulated to half 

the basin depth 

Schedule removal of sediment from 

forebay area. 

Erosion 

Erosion impairs bioretention systems 

by changing the bed profile and 

preventing uniform distribution of flow 

across the system. 

If left untreated, small sites of erosion 

can quickly spread over large areas 

becoming costly to repair. 

Erosion absent 

Erosion damage 

visible, but function 

not impaired 

Severe erosion. 

Damage impairing 

function of device 

Schedule investigation to identify 

cause of profile damage. 

Once source of damage is rectified, 

scour holes should be replaced with 

appropriate filter media. 

Lightly spread and compact replaced 

filter media using either hand tools, an 

excavator bucket or a pozitrack bobcat 

(DO NOT drive over the media with any 

vehicle but a pozitrack bobcat). 

Replace any damaged plants to meet 

the design plant schedule. 



Item to be 

Monitored 

Purpose of 

Monitoring 

Performance 

Target 

Schedule 


Investigation 

Immediate 




Sediment 

build up 

The accumulation of sediment in the 

sediment forebay of the bioretention 

system is a prescribed function of 

this zone. However, sediment must be 

regularly removed to ensure that the 

sediment trapping performance of this 

zone is sustained. 

If sediment accumulates on the 

bioretention surface, percolation 

of water into the media may be 

reduced, resulting in poor treatment 

performance. 

Sediment absent 

Sediment 

accumulation 

appears excessive in 

sediment forebay 

Fine sediment 

accumulation 

apparent on 

bioretention media 

surface 

Sediment 


the forebay depth 

Coarse sediment 

or large volumes 

of sediment 

accumulation 

apparent on the 

bioretention media 

surface 


sediment source. 

Once sediment source is stabilised, 

remove accumulated sediment and 

replace the top 100 mm of filter media 

from the bioretention system. The filter 

media specifications should be as per 

the design intent. 

Common sense should be exercised 

in deciding if plantings need to be 

replaced as part of maintenance work. 

If the sediment build-up is extensive 

and smothering vegetation, it may be 

easier and less costly to remove the 

plantings and replant once the filter 

media has been replaced. Conversely, 

if the sediment build-up is small and 

isolated or the system is planted 

with trees, it may only be necessary 

to scrape away the accumulated 

sediment and the top 100mm of filter 

media and replace without disturbing 

the plants within the bioretention 

system. 

Lightly spread and compact replaced 

filter media using either hand tools, an 

excavator bucket or a pozitrack bobcat 

(DO NOT drive over the media with any 

vehicle but a pozitrack bobcat). 

Replace any damaged plants to meet 

the design plant schedule. 

Compaction 

Percolation into the media may be 

reduced if the media surface has been 

compacted, i.e. by pedestrian traffic, 

poor construction methods. 

No compaction 

evident 

Localised compaction 

or subsidence 

evident. Localised 

ponding longer than 

24 hours after storm 

event 

Water remains 

ponding longer than 

24hours after storm 

event 


cause of compaction. 

If compaction is localised, remove top 

500 mm of filter media with auger. 

- Break-up removed filter media so 

that it is no longer compacted. 

- Refill hole with uncompacted filter 

media (that is, there is no need to 

replace with new filter media). 

If compaction is extensive, seek expert 

advice. 

Weeds and 

invasive 

plants 

The growth of weeds can impair a 

bioretention system’s performance by 

- Changing flow paths across the 

bioretention system 

- Shading and out-competing plant 

species that are important for water 

treatment, or filter media stability. 

Weeds can spread to downstream 

environments, compromising 

ecosystem health. 

No weeds present Weeds present Noxious or 

environmental weeds 

present, or weed 

cover more than 25 

percent 

Hand removal or targeted herbicide 

treatment (herbicides registered for 

use around waterways). 

Note: Herbicides should not be 

routinely used to maintain edges and 

batter slopes. General spraying of 

batter slopes should not be undertaken 

without follow up revegetation with 

native species. 

Weeds compromise the visual amenity 

of the bioretention system. 



Item to be 

Monitored 

Purpose of 

Monitoring 

Performance 

Target 

Schedule 


Investigation 

Immediate 




Plant 

Condition 

Plants are crucial to the performance 

of a bioretention system. 

Healthy vegetation 

Poorly growing or 

visibly stressed 

Die back / dead 

plants 

Schedule an investigation into the 

cause of plant die-back or poor health. 

During dry periods: Plants help 

maintain the structure and porosity of 

the filter media. 

During rainfall events: Vegetation 

aboveground acts to retard and 

distribute flows, and provides scour 

protection if the bioretention system 

is designed as a swale. Below ground 

the roots provide an important media 

for trapping or absorbing pollutants as 

they percolate through the media. 

Maintenance action will depend on the 

cause of die-back or poor plant health. 

Once the problem is rectified, infill 

planting may be required, especially if 

more than 1 square meter of plantings 

has died. Infill planting must be as per 

the original planting schedule. 

The accumulation of dead plant 

material can detract from the visual 

amenity of the bioretention system. 

Litter 

(organic) 

Organic litter can provide an additional 

source of nutrients to the bioretention 

system, introduce non-native species, 

which out-compete native plants and 

block the filter media. 

Accumulated organic matter / litter 

can also cause offensive odours 

(such as methane gas and hydrogen 

sulphide, i.e. rotten egg gas) and can 

reduce percolation of water into the 

filter media. 

No litter visible Litter visible Litter thickly covers 

filter media surface or 

detracting from visual 

amenity 

Identify source of organic litter and 

address with appropriate response 

action: e.g. change of landscape 

maintenance practices; community 

education re: litter dumping 

(appropriate for repeat incidences). 

In the interim, all litter must be 

removed by maintenance crews. 

Litter 

(anthropogenic) 

Litter can potentially block the 

inlet and outlet structures of the 

bioretention system resulting in 

flooding, as well as detract from the 

system’s visual amenity. 

No litter visible Litter visible Litter blocking 

structures or 

detracting from visual 

amenity 

Identify source of rubbish: e.g. from 

catchment (commercial precinct); 

overflow of rubbish bins; accumulation 

in backwater area and schedule 

general maintenance to remove 

rubbish. Where required address 

source of rubbish (e.g. increase in 

frequency of rubbish bin emptying; 

gross pollutant traps in high load 

generation land uses). In the 

interim, all litter must be removed by 

maintenance crews. 

WARNING: Contact with sharp objects, 

including hypodermic needles is a 

risk when removing litter. All workers 

must be made aware of this risk, wear 

appropriate protective gear and use 

caution. 

Oil slicks 

Oil spills / inflows are not necessarily 

an impedance to bioretention system 

function. Bioretention systems 

are designed to remove oils from 

stormwater; hydrocarbons decompose 

relatively quickly in the presence 

of soil microbes and water. It is 

expected that fuel or oil trapped in the 

bioretention basin would decompose 

within two to three weeks, depending 

on the size of the oil spill. 

No visible oil 

Persistent but limited 

visible oil 

Extensive or localised 

thick layer of oil 

visible 

Do not isolate bioretention system 

in the case of an oil spill - it is better 

that the oil is contained within the 

system than allowed to flow to the 

downstream water course. 

Notify the EPA of the spill and clean-up 

requirements 

NOTE: do not add any fertiliser, or 

other nitrogen based product to the 

system. The microbes within the filter 

media are capable of decomposing 

hydrocarbons. 



5.2.4 Constructed Wetlands 

and Ponds 

A pond treats 

runoff by providing 

extended detention 

and allowing 

sedimentation to 

occur. 

NOTE:- 

A separate 

maintenance 

checksheet has 

been developed 

for ponds as 

provided in the 

appendix to this 

booklet. 

Wetlands treat runoff by filtering it through 

vegetation and providing extended 

detention to allow sedimentation to occur. 

In addition, they have a flow management 

role that needs to be maintained to 

ensure adequate flood protection for 

local properties and protection of the 

wetland ecosystem. Ponds are frequently 

designed downstream of a wetland to 

provide further polishing of stormwater 

as well as detention (either to meet reuse 

requirements or attenuation of flows). A 

pond treats runoff by providing extended 

detention and allowing sedimentation 

to occur. This same principle applies for 

ponds designed for primary treatment. 

To ensure the functionality of the system, 

routine monitoring and maintenance of 

constructed wetlands will require: 

•• 

Checking flow paths in and out of the 

system are unobstructed 

•• 

Ensuring vegetation is healthy and is 

sufficiently dense 

•• 

Preventing undesired vegetation from 

taking over the desirable vegetation 

•• 

Removal of noxious plants or weeds 

•• 

Re-establishment of plants that die 

•• 

Removal of accumulated sediments 

•• 

Litter and debris removal 

Of the above items, debris removal 

should be the only action requiring 

ongoing attention. Debris, if not removed, 

can block inlets or outlets, and can be 

unsightly if located in a visible location. 

Inspection and removal of debris should 

be done regularly, but debris should be 

removed whenever it is observed. 

The monitoring and maintenance 

requirements of ponds are similar to 

constructed wetlands in maintaining 

flow into and through the system, 

ensuring healthy vegetation, minimising 

establishment of evasive and noxious 

plants and removal of accumulated 

sediment, litter and debris. The guidance 

given for monitoring and maintaining 

constructed wetlands can in general be 

adopted for ponds, (refer to note) noting 

the following: 

•• 

Artificial turnover of the lake may be 

required (because of long residence 

times). A mechanical system will need 

to be employed and will require specific 

maintenance 

•• 

Ponds designed to provide primary 

treatment will typically be more 

maintenance intensive due to the 

higher loads of nutrients delivered and 

captured 



Table 4 | Routine monitoring requirement for constructed wetlands. 

Item to be 

Monitored 

Purpose of Monitoring 

Performance 

Target 

Schedule 


Investigation 

Immediate 


Maintenance Action Required 

The purpose of the inspection is to 

check that the structures associated 

with the constructed wetland 

(macrophyte zone cells and inlet 

zone) are not damaged and function 

as designed. Examples of causes of 

structural damage include sediment 

and/or litter accumulation and large 

storms (flood events). 

Structures 

- GPT / trash rack GPT clear of litter GPT 10 percent full GPT / trash rack 

for than 30 percent 

full 

Notify Cleaning Services 

NOTE: If the wetland substrate has 

been disturbed during maintenance 

activities, ensure bed profile 

re-established as designed. 

Irregularities in bed profile may have 

the potential to act as mosquito 

breeding habitats. 

- Inlet pipe Clear and 

undamaged 

- Pipes connecting macrophyte 

cells 

- Outlet pit 

Partially Blocked 



Severe damage 

Schedule removal of debris, or notify 

relevant authority within Council for 

structural damage. 

Inspect for associated erosion and 

scour damage within the wetland 

and associated structure, and 

schedule repair work as required by 

Council. 

Erosion 

Erosion impairs wetland function by 

- Changing flow paths through the 

wetland 

- Smothering wetland vegetation 

and biota 

- Creation of mosquito habitat 

- Contributing to poor water quality 

by adding additional sediment 

If left untreated, small sites of 

erosion can quickly spread over 

large areas becoming costly to 

repair. 



visible, but structure 

functional 




Schedule investigation into cause 

of erosion. Action appropriate 

stabilisation response. 

Any erosion damage of the 

macrophyte zone batters, berms, 

and around the inlet and outlet 

structures should be noted on the 

Inspection Form and remediation 

measures undertaken immediately. 

Remediation measures may include 

surface reinforcement and revegetation. 

Sediment 

build up 

The accumulation of sediment 

in the inlet pond of the wetland 

is a prescribed function of this 

zone. However, sediment must be 

regularly removed to ensure that the 

sediment trapping performance of 

this zone is sustained. 


Sediment 

accumulation 

appears excessive 

Sediment 

accumulated to 

half the basin 

depth 

Schedule an investigation into 

source of sediment: e.g. localised 

erosion or catchment based runoff. 

Sediment build up can affect 

the hydraulics of the wetland, 

and smother aquatic plants, 

compromising plant growth. 



Item to be 

Monitored 


Performance 

Target 

Schedule 


Investigation 

Immediate 



The growth of weeds can impair a 

wetlands performance by 

- Changing flow paths through the 

wetland 

- Shading and out-competing plant 

species that are important for water 

treatment, or bed / bank stability. 

Weeds can spread to downstream 



Weeds compromise the visual 

amenity of the wetland. 

Invasive plants in constructed 

wetlands take the following forms: 

Weeds 

- Aquatic weeds (submerged, 

emergent and floating) 


environmental 

weeds present 

Emergent Plants (e.g. Typha): 

schedule hand weed removal or 

herbicide treatment. 

Floating Plants (e.g. Salvinia) with 

30% cover: removal with harvester 

- Terrestrial weeds (e.g. within the 

batter slopes) 


environmental 

weeds present 


treatment (herbicide registered for 



routinely used to maintain edges 

and banks. General spraying of 

banks should not be undertaken 

without follow up revegetation with 

native species. 

Algal 

blooms 

Algal blooms are easily detected: 

the water colour becomes green, 

the water clarity is poor and there 

is an offensive odour. Although an 

algal bloom can be a sign that the 

wetland is working as intended (as 

wetland organisms such as algae 

remove nutrients from the water 

column), algal blooms can be toxic 

to aquatic organisms and humans. 

Algal shading can kill macrophytes. 

No algae apparent Algae visible Algal growth 

prominent or 

extensive 

Schedule water quality testing: 

e.g. cyanobacterial community 

composition and cell count. When a 

potentially toxic bloom is identified, 

notify residents to avoid contact 

with the water and continue 

monitoring until the bloom subsides. 

Notify the Environment Branch 

Waterways Project Officer so the 

lakes priority for management/ 

retrofit works can be reviewed. 



Item to be 

Monitored 


Performance 

Target 

Schedule 


Investigation 

Immediate 



Plant 

Condition 

Vigorous plant growth is important 

in ensuring good water treatment. 

The plants take up nutrients and 

provide surface area for biofilms to 

form (another important mode of 

nutrient removal). 

The accumulation of decaying 

vegetation can create mosquito 

breeding habitats and inhibit 

seasonal growth of plants. 





plants 

Schedule an investigation of 

cause: e.g. is the observed 

changes in health and cover due to 

inappropriate water level or water 

level variation; disease; competition 

by weeds; damage (e.g. by birds or 

flood) or poison contaminant. 

Maintenance action will depend 

on the cause of die-back or poor 

plant health. Once the problem 

is rectified, infill planting may be 

required, especially if more than 3 

square meters of plantings has died. 

Infill planting must be as per the 

original design planting schedule. 

Dead vegetation may need to be 

removed as part of ensuring good 

plant condition. 

Litter 

(organic) 

Organic litter can provide an 

additional source of nutrients to 

the constructed wetland, and 

introduce non-native species, which 

out-compete native plants (both 

terrestrial and aquatic). 




sulphide, i.e. rotten egg gas). 


structures or 

detracting from 

visual amenity 









Litter can potentially block the 

inlet and outlet structures of the 

constructed wetland resulting in 


wetland’s visual amenity. 


structures or 



Identify source of rubbish from 

catchment, for example, overflow 

of rubbish bins. Target areas of 

litter accumulation, for example, 

backwater areas. Schedule general 

maintenance to remove rubbish. 

Litter 


Where required, address source 

of rubbish (e.g. increase in 

frequency of rubbish bin emptying; 

gross pollutant traps in high load 

generation land uses). In the 

interim, all litter must be removed by 

maintenance crews. 

WARNING: Contact with sharp 

objects, including hypodermic 

needles is a risk when removing 

litter. All workers must be made 

aware of this risk, wear appropriate 

protective gear and use caution. 



The frequency of 

litter and debris 

removal may be 

high, but will 

depend on the 

land use within the 

systems catchment. 

5.2.5 Sedimentation Basins 

Sedimentation basins are designed to 

retain coarse sediment by providing 

sufficient extended detention (and hence 

settling time). Furthermore, sedimentation 

basins are designed to allow sediment 

to accumulate to half the basin depth 

before clean out is necessary. The design 

of sedimentation basins is critical in 

preventing coarse sediment to carry over 

and smother vegetation in downstream 

treatment systems such as bioretention 

basins and constructed wetlands. 

The majority of maintenance associated 

with sedimentation basins concerns the 

inlet zone (and GPT if installed). Inlets can 

be prone to scour and build up of litter. 

Litter removal and potential replanting 

may be required as part of maintaining 

an inlet zone. The frequency of litter 

and debris removal may be high, but will 

depend on the land use within the systems 

catchment. 

Weed removal and replanting of edge 

vegetation will also be required. 



Table 5 | Routine monitoring requirement for sedimentation basins. 

Item to be 

Monitored 


Performance 

Target 

Schedule 


Investigation 

Immediate 



Structures 

The inlet and outlet structures of 

a sedimentation basin should be 

free of debris, litter and sediment 

to ensure flow is not impeded. 

Large storms (or flood) events 

and vehicles can also damage or 

block these structures and prevent 

the system working as designed. 

The main structural elements of a 

sedimentation basin are: 

- GPT / trash rack/s GPT clear of litter GPT 10 percent full greater than 30 

percent full 

Contact cleaning service. 

Generally a GPT will require 

clean-out four times per year. For 

proprietary GPTs it is recommended 

that a vacuum cleaner be used on 

at least one occasion per year, or 

when frequent overflow of litter 

from the GPT is evident. For all other 

clean-outs, a mechanical grab is 

sufficient. 

- Inlet structures Clear and 

undamaged 

Partially Blocked 



Severe damage 

Schedule removal of debris or 

contact relevant authority within 

Council for structural damage. 

- Overflow pits 

Inspect the sedimentation basin for 

scour or erosion damage and fix 

accordingly. 

Erosion 

Erosion will affect the distribution of 

flow across the sedimentation basin. 

If left untreated, small sites of 

erosion can quickly spread over 

large areas becoming costly to 

repair. 



visible, but function 

not impaired 





cause of profile damage. 

Once source of damage is rectified, 

scour holes should be replaced with 

appropriate filter media. 

Replace any damaged plants to 

meet the design plant schedule. 

Sediment 

build up 

The accumulation of sediment 

is a prescribed function of a 

sedimentation basin. However, 

sediment must be regularly removed 

to ensure that the sediment trapping 

performance of this system is 

sustained. 


Sediment 

accumulation 

appears excessive 

Sediment 


the sediment basin 

depth 


sediment source. 

Once sediment source is stabilised, 

remove accumulated sediment. 

Replace any damaged plants to 

meet the design plant schedule. 



Item to be 

Monitored 


Performance 

Target 

Schedule 


Investigation 

Immediate 



Weeds and 

invasive 

plants 

Weeds should be removed from the 

sedimentation basin: 

- Weeds can spread to downstream 



- Weeds compromise the visual 

amenity of the sedimentation basin. 


environmental 

weeds present, or 

weed cover more 

than 25 percent 


treatment (herbicides registered for 



routinely used to maintain edges 

and batter slopes. General spraying 

of batter slopes should not be 

undertaken without follow up 

revegetation with native species. 

Plant 

Condition 

Plants are crucial to bank stability 

and visual amenity 





plants 

Schedule an investigation into the 

cause of plant die-back or poor 

health. 

Maintenance action will depend 

on the cause of die-back or poor 

plant health. Once the problem 

is rectified, infill planting may be 

required, especially if more than 1 

square meter of plantings has died. 

Infill planting must be as per the 

original planting schedule. 

Litter 

(organic) 

Organic litter can provide an 

additional source of nutrients and 

on-native species which have a high 

likelihood of being transferred to 

downstream treatment systems and 

waterways. 

No litter visible Litter visible Litter thickly covers 

filter media surface 

or detracting from 











sulphide, i.e. rotten egg gas). 



Litter 


Litter can potentially block the inlet 

and outlet structures resulting in 


system’s visual amenity. 


structures or 



Identify source of rubbish: e.g. 

from catchment (commercial 

precinct); overflow of rubbish bins; 

accumulation in backwater area 

and schedule general maintenance 

to remove rubbish. Where required 

address source of rubbish (e.g. 

increase in frequency of rubbish 

bin emptying; gross pollutant traps 

in high load generation land uses). 



WARNING: Contact with sharp 

objects, including hypodermic 

needles is a risk when removing 

litter. All workers must be made 

aware of this risk, wear appropriate 

protective gear and use caution. 



Item to be 

Monitored 


Performance 

Target 

Schedule 


Investigation 

Immediate 



Oil slicks 

Oil spills / inflows are better 

trapped and isolated within 

a sedimentation basin 

than allowed to flow to the 

downstream waterway. 

No visible oil 

Persistent but 

limited visible oil 

Extensive or 

localised thick 

layer of oil 

visible 

Do not isolate sedimentation 

basin in the case of an oil 

spill - it is better that the oil is 

contained within the system 

than allowed to flow to the 

downstream water course. 

Notify the EPA of the spill and 

clean-up requirements 

NOTE: do not add any fertiliser, 

or other nitrogen based product 

to the system. The microbes 

within the filter media are 

capable of decomposing 

hydrocarbons. 



Water sensitive 

urban design 

elements are 

designed to detain 

pollutants from 

being discharged 

to the downstream 

watercourse. 

5.3 Waste Management 

and Disposal 

Water sensitive urban design elements 

are designed to detain pollutants from 

being discharged to the downstream 

watercourse. Vegetated WSUD elements 

such as constructed wetlands and 

bioretention basins use pollutants such as 

nitrogen and phosphorus in plant growth, 

minimising the build up of nutrients in 

the system. Conversely, suspended solids 

and gross pollutants cannot be used by a 

vegetated treatment system and hence 

accumulate and will eventually require the 

intervention of maintenance crews. 

Three types of waste are associated with 

WSUD elements: 

•• 

Contaminated silt (sedimentation 

basins, constructed wetlands and 

ponds) 

•• 

Spoiled filter media (bioretention 

basins) 

•• 

Liquid waste from dewatering activities 



5.3.1 Dewatered silt 

The NSW Department of Environment 

and Climate Change (DECC) has recently 

amended the rules governing waste 

disposal. Silt collected from sediment 

basins is now defined as general waste 

(non-putrescibles). For general waste 

(non-putrescibles), there is no requirement 

for the silt to be tested, unless the Council 

(or owner of the asset) believes that the 

nature of the catchment could cause the 

silt to have: 

•• 

A Specific Contaminant Concentration 

(SCC) higher than the guideline values 

given by DECC; and/or 

•• 

A leachable concentration of any 

chemical contaminant (as determined 

through the Toxicity Characteristics 

Leaching Procedure (TCLP)) higher than 

the guideline values given by DECC 

Guideline values for General Solid 

Waste for both measures are given in 

the following document http://www. 

environment.nsw.gov.au/resources/ 

waste/08202classifyingwaste.pdf 

Disposal of dewatered silt is accepted 

by WSN Environmental solutions, but 

only at their Eastern Creek and Lucas 

Heights locations. WSN Environmental 

solutions classify General Solid Waste as 

Special Waste, which has a disposal cost 

of $220 per tonne. The waste service 

facility at Belrose will also accept General 

Solid Waste; however due to a limited 

capacity, it will only accept waste from the 

surrounding LGA (Ku-ring-gai). 

Although in theory general waste (nonputrescibles) 

can be accepted by private 

waste disposal operators, very few facilities 

within the Sydney Metropolitan actually 

have the capacity to accept sludge / silt 

type material. One of the few exceptions 

is Blacktown Waste Service who accepts 

general solid waste (non-putrescibles) at a 

cost between $75 and $110 per tonne. 

5.3.2 Filter media 

The filter media for bioretention basins 

may need replacing in the following 

situations: 

1) Filter media has reached full capacity 

for retaining metals as identified 

through pollutant breakthrough. 

2) Surface of filter media is clogged. 

Recent research conducted by FAWB has 

shown for a bioretention basin sized at two 

percent of the impervious catchment area 

and a filter media depth of 0.5 metres, 

pollutant breakthrough will occur within 

15 years. The results were considered 

conservative (ie lower estimate) as the 

soils had a low pH. Soils with a neutral 

pH will have a greater capacity to attract 

metal pollutants, hence further delaying 

breakthrough from occuring. When 

breakthrough occurs, the entire filter 

media will need replacing. 

Surface clogging can be observed 

through poor plant growth, or when 

ponding times exceed the design 

specifications. The replacement of filter 

media is not required if plant growth is 

poor. The clogging of the surface media 

could be remedied by re-establishing 

plants to ensure density is sufficient in 

maintaining surface porosity. If, however, 

plant growth is adequate, clogging 

is related to failure of the filter media 

and the top 200 to 300 millimetres of 

filter media will require replacing. 

Removed filter media may be 

contaminated and should be tested 

accordingly. Filter media classified as 

contaminated should be disposed of 

at a certified waste disposal centre. 

Alternatively, there may be options to 

bio-remediate the soil and reuse it. 



Detention pond | Garden Gates 

Open space | Victoria Park 

The location of the 

dewatering facility 

should consider 

existing site 

constraints. 

5.3.3 Liquid waste 

(from dewatering activities) 

Prior to discharge, the silt removed must 

be dewatered such that it does not 

contain any free liquid (that is, the density 

is 1.5 to 3 times the density of the material 

if completely dry (Collins, 2006)). 

The dewatering of collected silt can 

be accommodated in the design of 

the sedimentation basin, whereby free 

liquid is directed back into the treatment 

train. Alternatively, collected silt can be 

stockpiled within designated bunded 

areas offsite or stored in skip trucks 

brought into the site. The location of 

the dewatering facility should consider 

existing site constraints, DECC regulatory 

requirements, health and safety issues, 

odours and other community concerns 

(WBM and Ecological Engineering, 2005). 

Liquid removed during dewatering is likely 

to be classified as either Group A liquid 

waste or non-controlled aqueous liquid 

waste, depending on the concentration 

of suspended or dissolved chemicals 

(WBM and Ecological Engineering, 

2005). The level of contamination should 

be confirmed by laboratory testing; 

however it is likely that dewatered water 

will classified as non-controlled aqueous 

liquid waste. 

The decantered water must be treated 

prior to discharge to a receiving 

waterbody. Treatment can be achieved 

through many mechanisms, including: 

•• 

Pumping decantered water to a settling 

tank to remove elevated levels of 

suspended solids. This may require the 

addition of a flocculent such as gypsum. 

•• 

Decanting liquids to pervious areas, 

ensuring liquids are appropriately 

treated to meet reuse requirements. 

Potential implications of reusing 

decanted water from stormwater 

treatment measures include high 

pollutant (in particular heavy metal) 

concentrations and health risks posed 

by trapped pathogens. 

•• 

Decanting liquids back into the 

stormwater treatment system. 

5.3.4 Equipment requirements 

For a sediment basin, wetland or pond, 

cleaning will generally require a backhoe, 

excavator or eductor / vacuum truck, 

requiring service from one to two vehicle 

operators and one to three labourers 

(HSC, 2001). 

The removal of waste from a bioretention 

basin must be done by hand to protect 

the bathymetry and compaction of the 

filter media. 



6 | Construction Requirements 


The ultimate aim 

of each option 

is to protect the 

functional elements 

of the WSUD 

element. 

This section provides advice on the 

construction of WSUD elements. In 

particular, the advice concentrates on 

the staging of construction in association 

with other development in the catchment. 

The construction advice is supported by 

a series of checklists, which have been 

developed to ensure critical design 

elements are checked and signed off 

as completed; hence minimising the 

potential for expensive re-work. 

6.1 Staging 

The construction of WSUD elements 

should be coordinated with other 

construction activities within the 

catchment. Construction activities 

will generate greater loads of coarse 

sediment and gross pollutants, for which 

the WSUD treatment element is unlikely 

to be designed for. High loadings of 

coarse sediment and gross pollutants 

can be particularly detrimental during 

plant establishment for a vegetated 

system, smothering infant vegetation and 

changing the bathymetry of the element 

(which in turns affects the hydraulic 

function and the distribution of flow within 

the treatment element). 

The Water Sensitive Urban Design 

Construction and Establishment 

Guidelines (version 1) developed by Water 

by Design (2009) a program of the South 

East Queensland provides guidance 

on the staged construction of WSUD 

elements. Multiple options are presented 

for each WSUD element, which assess: 

1) The location of the WSUD element 

(that is, streetscape, parkland); 

2) The level of environmental protection 

the system provides during staged 

construction; and 

3) The landscape amenity of the system 

during staged construction. 

The ultimate aim of each option is to 

protect the functional elements of the 

WSUD element. This is achieved by either 

isolating the functional elements by 

diverting stormwater flows or increasing 

the capacity for sediment capture either 

upstream or within the WSUD element. 

For each option, construction and 

establishment of WSUD elements is 

divided into three stages: 

Stage 1: Civil construction 

(or functional installation) 

Stage 2: Building phase protection 

(or sediment and erosion 

control) 

Stage 3: Operational establishment 

(civil and/or landscaping) 

These are illustrated in Figure 7 together 

with a list of corresponding management 

forms contained in Appendix A. 



Stage 1: Civil Construction 

Pre start construction meeting 

Subdivision 

Construction 

FORM A 

Earthworks and hydraulic / 

Functional Structures 

FORM C (bioretention basin) 

Filter media and finished levels 

Stage 2: Building phase protection 

FORM B 

Erosion and Sediment Control 

Allotment 

Building 

(up to 30 percent 

completion) 

Stage 3: Operational establishment 

FORM C 

(wetland and sedimentation) 

Top soil and finished levels 

FORM D 

Landscape Planting 

Allotment 

Building 

(greater than 

80 percent 

completion) 

Asset handover 

Asset handover checklist 

Completion 

of construction 

activities 

Figure 7: Staged construction of WSUD elements and the timing of relevant forms 



6.1.1 Stage 1: Civil construction (or functional installation) 

Stage 1 requires the construction of the functional components for the WSUD element. 

The functional components for the WSUD elements addressed in the booklet are: 

Bioretention basin Constructed wetland Sedimentation basin 

Bulk earthworks to 

establish bunds and system 

batter slopes 

Detailed profiling of bunds, 

batters, sides and base 

of system to meet design 

requirements (given 

allowed tolerances) 

Construct all hydraulic 

structures, for example, 

inlet pipes and headwalls, 

bypass weir, outlet riser and 

rock protection* 

Install system lining, 

underdrainage, clean out 

points and various layers 

(that is, drainage layer, 

transition layer and filter 

media) 

Survey wetland layout in 

accordance with the design 

Remove ground cover and topsoil 

as indicated from the survey 

Stockpile topsoil designated for 

reuse in construction, noting 

that the soil must be tested 

and screened to remove coarse 

sediment and weed seeds 

Bulk earthworks to establish the 

inlet and macrophyte zone, high 

flow bypass and surrounding 

bunds and batters 

Detailed profiling of bunds, 

batters, sides and base of system 

to meet design requirements 

(given allowed tolerances as 

well as 300 mm of topsoil and 

impervious liner, if specified) 

Install impervious liner (if required) 

Construct bunding between the 

inlet and outlet zone, as well as 

between the wetland and lake (if a 

lake is included in the design) 

Construct all hydraulic structures, 

for example, inlet pipes and 

headwalls, bypass weir, outlet riser 

and rock protection* 

Topsoil placement and profiling to 

within accepted tolerances 

Bulk earthworks to 

establish bunds and system 

batter slopes, as well as 

maintenance access (e.g. 

ramp) 

Installation of outlet 

structures (for example, 

overflow pit / weir and 

spillway) 

Installation of inlet 

structures including inlet 

pipe and headwall. 

For a sedimentation basin, 

install the inlet energy 

dissipater and primary 

treatment measure (for 

example, gross pollutant 

trap) 

Detailed profiling of 

bunds, batters, system 

base, access points and 

spillway to meet design 

requirements (given 

allowed tolerances) 

Install system lining 

Stabilise system batters 

and base with sterile grass 

NOTE: 

* This is not a complete list of hydraulic, functional and structural elements of a constructed wetland – the 

reader is referred to the Water by Design documents for complete details. 

Immediately following completion of stage 1, sediment fences should be installed at the 

top of the system batter. Bioretention basins will also require sediment fences installed 

around the filter media. 



Stage 1 – Functional Installation 

Civil construction 



6.1.2 Stage 2: Building phase protection (or sediment and erosion control) 

Stage 2 involves the construction of temporary measures to protect the functional elements 

of the system. As stated, two options are typically considered, either diversion of flows 

away from the functional elements to allow plant establishment, or the establishment of 

temporary sedimentation basins (within or upstream of the main functional part of the 

WSUD element). 

The main activities required as part of stage 2 are: 

Bioretention basin Constructed wetland Sedimentation basin / pond 

Bypass of stormwater flows / isolation of functional design 

Install bypass structure. The 

system will typically involve 

one of the following: 

1) Completely bypassing 

the inlet pipe around the 

filter media area 

2) Partitioning the systems 

such that the inlet and 

outlet only are engaged 

Isolate macrophyte zone 

from the inlet zone by 

blocking the connection 

pipe between the two zones 

Stabilise the high flow 

bypass either with turf or 

reinforced turf 

Ensure the entire perimeter 

of the wetland is protected 

by sediment fences 

Construct non-wetland 

related hardscapes, such as 

boardwalks and pathways 


Generally not considered for 

sedimentation basins 

Ponds 

Isolate pond from downstream 

treatment devices by blocking 

connecting pipework 

Ensure the entire perimeter of the 

pond is protected by sediment 

fences 

Establishment of temporary sediment protection devices 

Protect the filter media with 

a filter cloth or 25 to 50 mm 

of course sand plus 25 mm 

of topsoil and turf 

The entire constructed 

wetland footprint is allowed 

to operate as a sediment 

basin 


Ensure earthworks are stabilised 

immediately post construction 

(basin profile should be stabilised 

through sterile grasses, while 

terrestrial planting established 

around the basin perimeter) 

Ensure overflow from basin 

disconnected from any 

downstream treatment devices 

(such as wetlands) 

The protective measures identified above should be removed only when 80 to 90 percent of 

construction works in the catchment have been completed. If a distributed water sensitive 

design process has been implemented, treatment systems can be brought online gradually 

without having to wait for all development to cease. 

Landscaping can be established in areas isolated from stormwater flow. For constructed 

wetlands, special attention is required in manipulating the water level during plant 

establishment within the macrophyte zone such that plants are not ‘drowned’. The specific 

plant establishment requirements for constructed wetlands are detailed in the Water by 

Design documentation. 



Stage 2 – Sediment Control Measures 

Sediment Control 



6.1.3 Stage 3: Operational establishment (civil and/or landscaping) 

Stage 3 involves reconnecting the functional elements of the WSUD element to meet 

design specifications. In general, this involves decommissioning erosion and sediment 

control protection devices and replanting of landscape areas. Specific tasks within stage 3 

as they relate the WSUD elements addressed in the Operations and Maintenance booklet 

are: 

Bioretention basin 

Desilt basin if converted 

to a temporary sediment 

basin. 

Remove measures 

protecting filter media, 

for example bunds, filter 

cloth, topsoil and turf. 

Flush out under-drainage 

using potable (mains) 

water 

Flatten filter media 

surface to within given 

tolerance (additional 

media may be required 

to fill in over-excavated 

areas) 

Mulch filter media, 

allowing for planting 

holes 

Dig holes for planting 

Plant nominated species 

Maintain landscaping 

to ensure healthy plant 

establishment 

Constructed wetland 

Remove accumulated sediment 

and gross pollutants from inlet 

zone (and macrophyte zone if 

the wetland has been used as a 

sedimentation basin during stage 

2) 

Assess the condition of the 

impervious liner and hydraulic 

structures (if the wetland has 

been operated as a temporary 

sediment basin in stage 2) and 

amend accordingly 

Install topsoil in basin to a depth 

of 300 mm on batters and 500 

mm below the normal water 

level (this will be required for the 

macrophyte zone only if zone 

used as a sediment basin during 

stage 2) 

Remove disconnection between 

inlet and macrophyte zone (only if 

macrophyte plantings have been 

established during stage 2)* 

Landscape macrophyte zone if 

zone not yet established** 

Landscape inlet zone according 

to the design specifications** 

Sedimentation basin / 

pond 

Desilt basin 

Remove sterile grass from basin 

and establish marsh zone and 

embankment planting as per 

the design specifications 

Install topsoil to a depth of 300 

mm on batters and 500 mm 

below the normal water level 

Landscape basin as per the 

planting specifications*** 

NOTE: 

* If the wetland has been used as a temporary sedimentation basin during stage 2, establish macrophyte 

plantings prior to bringing the macrophyte zone online. Specific requirements for plant establishment in the 

macrophyte zone of a constructed wetland are detailed in the Water by Design documentation. 

** Water levels will need to be manipulated during landscape establishment 

*** Water level manipulation is not required for ponds. The plants specified for the base of ponds will be suitable 

for an environment starved of oxygen. Typically plant establishment in ponds is through anchoring the plants / 

seedlings to the pond base with rocks. 

This task is required regardless of what sediment control measures are instigated as part of stage 2. 

Specific plant establishment requirements including fertiliser application and 

recommended watering schedule (including frequency of watering for terrestrial and 

marsh plantings, and the requirements for water level manipulation in constructed wetlands 

and ponds) are not detailed in this booklet. The reader is directed to the Water by Design 

(2009) documentation for further information. 



Stage 3 – Operational Establishment 

Operational Establishment 



6.2 Construction Tolerances 

The distribution of 

flow within a WSUD 

element affects 

the treatment 

efficiency. 

Important to the design of bioretention 

basins, constructed wetlands, and 

sedimentation basins/ponds is the 

hydraulic function of the system (that is, 

how water is delivered from one part of a 

system to another) and the distribution of 

flow within the system. The distribution of 

flow within a WSUD element affects the 

treatment efficiency. Poor distribution of 

flow and the creation of localised water 

pools can also cause adverse affects such 

as mosquito breeding. 

The WSUD Technical Design Guidelines 

for South-East Queensland (SEQ) 

(Moreton Bay Waterways and Catchments 

Partnership, 2006) identifies key 

construction tolerances for typical WSUD 

elements as related to system hydraulics 

or flow distribution. The revised technical 

guidelines for bioretention systems and 

constructed wetlands produced through 

Water by Design (2009) have seen the 

relaxing of these tolerances. A summary 

of the tolerances stipulated in the revised 

Water by Design documentation are given 

in the following table. The tolerances for 

sedimentation basins and ponds have 

also been updated to ensure consistency 

between similar design elements (for 

example, hydraulic structures). 

Further details on construction details can 

be found in the WSUD Technical Design 

Guidelines for South-East Queensland, 

which can be downloaded online 

from the Healthy Waterways website 

http://www/waterbydesign.com. 

CONSTRUCTION TOLERANCES 

Bioretention Basins Constructed Wetlands Sedimentation basins / ponds 

Profiling of base 

(+50 mm) 

Profiling of surface grades 

(i.e. drainage, transition and 

filter layer) 

(+25mm) 

Relative levels of flow 

control structures* 

(+25 mm) 

Bathymetry of macrophyte 

zone topsoil levels 

(+50 mm) 

Relative levels of flow control 

structures 

(+25 mm) 

Bathymetry of basin 

(+50 mm) 

Relative levels of hydraulic 

structures 

(+25 mm) 

Surface levels 

(+50 mm) 

Minimum slope of drainage 

system 

(0.5 %) 

* NOTE: Control structures are described as inlet connections, bypass weir and outlet structures 



6.3 Construction 

Certification and 

Compliance 

The construction of a vegetated WSUD 

strategy requires coordination between 

the civil and landscaping contractors. 

Civil contractors are responsible for the 

construction of the functional elements 

of a treatment system, while landscape 

contractors are responsible for the 

initial plantings and management of 

the treatment system to ensure plant 

establishment is successful and meets the 

design brief. 

Consequently, construction certification is 

required from both civil and landscaping 

contractors as documented in the revised 

Water by Design (2009) documentation. 

The suggested construction certificates 

for constructed wetlands, bioretention 

systems and sediment basins/ponds are 

described in the table below. 

Additionally for bioretention basins, 

certification is required from the soil 

supplier to ensure the soil specifications 

of the filter media meet the requirements 

documented by the Facility for Advancing 

Water Biofiltration (FAWB) (refer to section 

4.04). 

The certification outlined above should 

form the basis of compliance for WSUD 

elements. However, to minimise rework 

due to non-compliance issues, it is 

suggested that inspections/meetings be 

scheduled as follows (refer column over): 

1) Pre-start meeting: Ensure all 

contractors are aware of the key issues 

for each stage of construction. For 

example, compaction requirements 

for filter media. 

2) Inspection of all functional elements 

(as completed) of the treatment system 

(for example, the under-drainage for a 

bioretention should be inspected prior 

to the gravel being inserted around 

the pipes). 

3) Inspection of sediment control 

structures to ensure vulnerable 

elements within the treatment system 

are isolated from storm flows as 

dictated in the design documentation. 

4) Inspection of plant establishment 

(if required) to ensure species and 

densities are as per the design. 

Continual inspections should 

be scheduled to check plant 

establishment. 

5) Final inspection of plant establishment 

and civil works. 

The scheduling of the above inspections 

within the three main construction stages 

is given below. Example inspection and 

sign off sheets for WSUD elements are 

given in Appendix A. 

Civil Certification 

Designers certification of functional elements 

Civil certification that functional elements have been constructed as 

per the designers certification 

As constructed survey, drawings and photos 

Landscape Certification 

Designers or ecologist sign off of plant species 

As constructed drawings identifying species and plant density 



6.4 Filter Media 

Specifications 

The Facility for Advancing Water 

Biofiltration (FAWB), a joint collaboration 

between Monash University and Ecological 

Engineering Holdings recently updated 

the original filter media specifications 

produced in 2006. Specifications are 

given for the three main layers defined for 

a bioretention basin as described in the 

table below. 

Further details relating to the testing 

of hydraulic conductivity, the specific 

filter media specifications (for example, 

organic matter content, pH, electrical 

conductivity and phosphorus content), 

and particle size distribution can be found 

in the FAWB document Guidelines For 

Soil Filter Media In Bioretention Systems 

(version 2.01). http://www.clearwater.asn. 

au/resources/658_1.FAWB%20Filter%20 

media%20guidelines_revised_March%20 

2008.pdf 

Recently, bioretention basin design has 

evolved to include an anoxic zone. In 2008, 

FAWB conducted a series of workshops on 

biofiltration systems, which included the 

design requirements and performance 

of biofiltration systems with submerged 

zones. The workshop material made the 

following specifications: 

1. Depth of submerged zone – 

approximately 450 mm. 

2. Media specifications – sand 

or gravel, containing a carbon 

source such as hardwood chips 

or sugar cane. The carbon source 

is to account for 5 percent of the 

volume of the submerged zone 

media. 

The workshop manual produced by FAWB 

can be downloaded from the following url: 

h t t p: // w w w.m o n a s h.e d u.au/ f a w b/ 

products/index.html 

Filter Media (typically 400 to 

600 millimetres in depth) 

Loamy sand, with an appropriate hydraulic 

conductivity (100 to 300 millimetres per hour) 

and soil properties given in AS4419 – 2003 (Soils 

for Landscaping and Garden Use) 

Drainage Layer (typically 150 

millimetres in depth) 

Clean, well graded sand / coarse sand material 

(containing no/little fines) 

Transition Layer (typically 

100 millimetres in depth, 

or sufficient to provide 

50 millimetres of cover to 

drainage network) 

Clean fine gravel 



Appendix A – Construction Inspection 

and Sign off sheets 

A.1. Bioretention Systems 



Bioretention Basin Sign-Off Forms 

Development stage: 

Bioretention basin ID: 

Pre-Start Construction Meeting 

Location: 

Date: 

List of Attendees 

Name Discipline (suggested) Company 

1 Developer 

2 Site superintendent (civil) 

3 Site superintendent (landscape) 

4 Civil Contractor 

5 Landscape Contractor 

6 WSUD - Design Engineer 

7 Civil Engineer 

8 Landscape Architect 

9 

Checklist of Sign-Off Forms 

Sign-Off Form 

Date Completed 

Form A 

Form B 

Form C 

Form D 

Earthworks and Hydraulic / Functional Structures 


Filter Material and Finished Levels 

Landscape Planting (Macrophyte and Inlet Zone) 

Construction Tolerances: 

The construction tolerances on the bioretention systems are to be: 

•• 

plus or minus 50 mm on earth works and filter media levels. 

•• 

plus or minus 25 mm on hydraulic structures (e.g. pit and weir 

crests/ bund heights, pipe and pit invert levels) 

Deviations to be approved only at the discretion of superintendent. 



Form A - Earthworks and Hydraulic / Functional Structures 

Purpose: 

1) To ensure bulking out, trimming and profiling is in accordance with design specifications 

(including allowance for 300 mm topsoil and a minimum 300 mm of impervious liner where required). 

2) To ensure hydraulic structures associated with the bioretention basin are constructed in accordance 

with the design specifications. 

Checklist: 

Items 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Bulking out & hard structures 

As constructed survey of basin base and surrounding 

bunds, pit crests, inlet and outlet pipes 

Base levels are at correct elevation, given the 

minimum allowances for topsoil and impervious liner 

(where required) 

Base at correct grading (0.5 percent) 

Hold Point - Sign off is required from superintendent and bioretention basin designer before proceeding 

Bunds and impervious liner 

Laboratory test results of liner material submitted 

and adequate 

Delivery docket of liner material submitted and 

adequate 

Delivery docket of liner material supplied 

Geotechnical engineer certification of in-situ 

compaction or liner placement 

Geotechnical engineer certification / sign off of key 

bunds 




Functional and hydraulic functions 

Inlet and outlet pipes and headwalls correctly set 

out and at correct level (upstream and downstream 

ends) 

Bypass weir correct width and level 

Overflow pit is correct size and crest is at correct 

level 

Maintenance pipe and valve installed at 

correct location and level 

Maintenance access installed to inlet zone 

Rock or concrete base constructed at 

inlet to bioretention basin 

Rock protection provided at correct locations 

and rock size consistent with design 


Under-drainage 

Base of system free from debris 

Under-drainage pipes laid at required grade 

(verified using level or string line) 



All junctions and connections have 

been appropriately sealed using sealant 

Underdrain pipes correctly connected and 

sealed into overflow pit 

Top of clean out points at design level (i.e. 

approximately 100mm above filter media surface 

level) 

Extension of under-drains out of the 

basin are NOT perforated 

Clean out points capped 


Comments: 

Signed by Superintendent(s): 

Print Name: 

Date: 



Form B – Erosion and Sediment Control 

Purpose: 

To ensure sediment and erosion control measures are correctly installed to protect the bioretention 

basin filter media. 

Checklist: 

Items 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Continuous silt fences installed around all 

elements of constructed wetlands 

If silt fences are deemed inadequate, other sediment 

and erosion control measures installed to ensure 

sediment does not enter basin 

High flow bypass channel protective measures in place 

(that is, turf installed and where required reinforced turf) 

If basin to be used as a sedimentation basin 

during lot development 

Filter media surface protected, either by installing a 

filter cloth or 25 to 50 mm of course sand plus 25 mm 

of topsoil and turf 

If basin is to be isolated during lot development 

Stormwater diverted away from functional elements 

of bioretention basin 


Comments 


Print Name: 

Date: 



Form C – Filter Material and Finished Levels 

Purpose: 

To ensure that the soils to be placed in the basin match the soils that were specified and ordered. To ensure 

soil layers are placed according to specifications prior to any landscape works. 

Checklist: 

Item 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Filter Material 

Drainage layer (fine gravel): 

Supply docket matches gravel specification 

NOTE: Attach Supply Docket 

Transition layer (coarse sand): 

Supply docket matches sand specification 


Filter layer (sandy loam): 

Supply docket matches media specification 


Filter material testing completed and approved 

in accordance with design report 

Drainage layer (fine gravel) installed to 

correct depth (photo and survey) 

Transition layer (coarse sand) installed to 

correct depth (photo and survey) 

Filter media installed to correct depth 

(photo and survey) 

Light, even compaction applied to remove air gaps 

Even flat surface of filter media 



Finished levels 

As constructed survey of basin surface and 

surrounding bunds completed 

Final constructed levels are consistent with 

design levels 

Under-drainage pipes flushed to remove initial 

ingress of material 

All civil construction items are complete and basin is 

ready for planting by landscape contractor 

Geofabric layer + 50mm topsoil (top layer of 

supplied filter material) and turf applied to basin 

surface. 

Suitable batter protection in place 

(e.g. sediment fence or landscape netting) 

HOLD POINT - Sign off is required from superintendent and bioretention basin designer before proceeding 

Comments 


Print Name: 

Date: 



Form D – Landscape Planting 

Purpose: 

To ensure correct plants are supplied and installed. To be used in conjunction with other landscape sign off 

requirements. 

Checklist: 

Item 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Basin desilted and filter media levels reinstated to 

meet design specifications 

NOTE: This action is applicable if bioretention 

basin was converted to a sediment basin during lot 

development 

Supplied plants are correct species 

Changes to species planted must be approved by 

wetland designer/ecologist and marked up on asconstructed 

drawings 

Supplied plants are in correct pot sizes, maturity 

(minimum 300 mm in height) and hardened 

Plants have been installed at correct planting density 

Correct mulch has been supplied and installed to 

batters and bunds above the extended detention 

and secured in place 

As constructed drawings marked up with final plant 

species and densities 

HOLD POINT - Sign off is required from superintendent and bioretention basin designer before proceeding 

Comments 


Print Name: 

Date: 





A.2. Constructed Wetlands 



Constructed Wetland Sign-Off Forms 


Wetland ID:: 


Location: 

Date: 



1 Developer 








9 


Sign-Off Form 


Form A 

Form B 

Form C 

Form D 



Topsoil and Finished Levels 



The construction tolerances on the constructed wetland systems are to be: 

•• 

plus or minus 25 mm on hydraulic structures (e.g. pit and weir crests/ bund heights, pipe and pit invert 

levels) 

•• 

plus or minus 50 mm on earthworks (base of wetland, as measured from the surface of the topsoil). 

•• 

plus or minus 50 mm on embankments and bunds (that is, crest level of the embankment). 

Deviations to be approved only at the discretion of the superintendent. 



Form A – Earthworks and Hydraulic/Functional Structures 

Purpose: 

3) To ensure bulking out, trimming and profiling is in accordance with design specifications (including 

allowance for 300 mm topsoil and a minimum 300 mm of impervious liner where required). 

4) To ensure hydraulic structures associated with the wetland are constructed in accordance with the 

design specifications. 

Checklist: 

Items 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 




Set out of wetlands is correct (including inlet 

zone, macrophyte zone, high flow bypass) 


minimum allowances for topsoil and impervious 

liner (where required) 

Hold Point - Sign off is required from superintendent and wetland designer before proceeding 



and adequate 

Delivery docket of liner material submitted 

and adequate 




Geotechnical engineer certification of in-situ 

compaction or liner placement 

Geotechnical engineer certification / sign off 

of key bunds 



Inlet and outlet pipes and headwalls 

correctly set out and at correct level 

(upstream and downstream ends) 

Inlet zone connection pit or pipe 

correct size, location and level 

Outlet riser connection, location, 

size and levels correct 


Overflow pit is correct size and crest 

is at correct level 

Maintenance pipe and valve installed 

at correct location and level 

Maintenance access installed to inlet zone 

Rock or concrete base constructed to inlet zone 



Rock protection provided at correct locations and 

rock size consistent with design 

Seepage collar(s) installed to all pipe outlets from 

wetland 


Comments 


Print Name: 

Date: 



Form B – Sediment and Erosion Control 

Purpose: 

To ensure sediment and erosion control measures are correctly installed to protect the macrophyte zone of 

the constructed wetland. 

Checklist: 

Items 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Continuous silt fences installed around all elements 

of constructed wetlands 




High flow bypass channel protective measures in 

place (that is, turf installed and where required 

reinforced turf) 

Inlet zone disconnected from macrophyte zone (that 

is, plates placed on overflow pit and secured) 

If inlet zone not disconnected, macrophyte zone 

converted into a sedimentation basin (base and 

batters of macrophyte 


Comments 


Print Name: 

Date: 



Form C – Topsoil and Finished Levels 

Purpose: 

To ensure the topsoil is installed to the correct depth and finished levels of wetland are correct and meet the 

design. 

Checklist: 

Item 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Topsoil meets the requirements of AS4419 and 

laboratory tests provided 

Topsoil has been screened and is free of large debris 

Topsoil applied to wetland (minimum 300 mm depth) 

Final topsoil levels are consistent with design levels 

(CRITICAL in the macrophyte zone) 

Surface is smooth and free of local depressions and 

debris 


Comments 


Print Name: 

Date: 




Purpose: 

To ensure correct plants are supplied and installed. 

Checklist: 

Item 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Macrophyte zone landscape installation 



wetland designer/ecologist and marked up on 

as-constructed drawings 




Water level control is operating appropriately 


batters and bunds above the extended detention 


As constructed drawings marked up with final 

plant species and densities 

HOLD POINT - Sign off is required from superintendent and wetland designer before proceeding 

Macrophyte zone landscape establishment 

Weeds removed as required 



Watering occurring as required 

Macrophyte plants established such that the water level 

in the macrophyte zone can be allowed to reach design 

level (typically 500 mm above the normal water level) 


Comments 


Print Name: 

Date: 



Form D – Landscape Planting (inlet zone) 

Purpose: 


Checklist: 

Item 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Inlet zone landscape installation 


Changes to species planted must be approved by wetland 

designer/ecologist and marked up on as-constructed 

drawings 

Supplied plants are in correct pot sizes, maturity (minimum 

300 mm in height) and hardened 


Correct mulch has been supplied and installed to batters 

and bunds above the normal water level and secured in 

place 

As constructed drawings marked up with final plant species 

and densities 


Inlet zone landscape establishment 

Weeds removed as required 

Watering occurring as required 

Inlet zone plantings established such that the water level in 

the macrophyte zone can be allowed to reach design level 

(typically 500 mm above the normal water level) 


Comments 


Print Name: 

Date: 





A.3 Sedimentation Basins / Ponds 



Sedimentation Basin Sign-Off Forms 


Sediment basin / pond ID: 


Location: 

Date: 



1 Developer 








9 


Sign-Off Form 


Form A 

Form B 

Form C 

Form D 


Sediment and Erosion Control 

Topsoil and Finished Levels 



The construction tolerances on the constructed wetland systems are to be: 

•• 

plus or minus 25 mm on hydraulic structures (e.g. pit and weir crests/ bund heights, pipe and pit invert 

levels) 

•• 

plus or minus 50 mm on earthworks (base of wetland, as measured from the surface of the topsoil). 

•• 

plus or minus 50 mm on embankments and bunds (that is, crest level of the embankment). 

Deviations to be approved only at the discretion of superintendent. 



Form A – Earthworks and Hydraulic/Functional Structures 

Purpose: 

5) To ensure bulking out and key levels of hard structures are in accordance with design specifications. 

6) To ensure hydraulic structures associated with the sedimentation basin or pond is constructed in 

accordance with the design specifications. 

Checklist: 

Items 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 





minimumallowances for topsoil and impervious 

liner (where required) 




and adequate 

Delivery docket of liner material submitted 

and adequate 


Geotechnical engineer certification / sign off 

of key bunds 





Inlet and outlet pipes and headwalls 

correctly set out and at correct level 

(upstream and downstream ends) 


Overflow pit is correct size and crest is 

at correct level 


Maintenance pipe and valve installed 

at correct location and level 

Maintenance access installed to basin 

Rock protection provided at correct locations and 

rock size consistent with design (applicable to 

sediment basin, only) 


Comments 


Print Name: 

Date: 



Form B – Sediment and Erosion Control 

Purpose: 

To ensure sediment and erosion control measures are correctly installed to protect either downstream 

treatment systems (in the case of sedimentation basins) or minimise clean-out post construction (in the case 

of an ornamental pond). 

Checklist: 

Items 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Continuous silt fences installed around all 

elements of basin / pond 




High flow bypass channel protective measures in place 

(that is, turf installed and where required reinforced turf) 

Basin profile stabilised through sterile grasses, while 

terrestrial planting established around the basin perimeter 

SEDIMENT BASIN, ONLY 

Ensure overflow from sediment basin disconnected from 

any downstream treatment devices (such as wetlands) 

POND, ONLY 

Ensure inlet to pond is isolated from any upstream 

sediment control measures 

Hold Point - Sign off is required from superintendent and basin/pond designer before proceeding 

Comments 


Print Name: 

Date: 



Form C – Topsoil and Finished Levels 

Purpose: 

To ensure the topsoil is installed to the correct depth and finished levels of wetland are correct and meet the 

design. 

Checklist: 

Item 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 

Sedimentation basin desilted prior to plant establishment 

Topsoil meets the requirements of AS4419 and laboratory 

tests provided 

Topsoil has been screened and is free of large debris 

Topsoil applied to base (minimum 300 mm depth) 

Final topsoil levels are consistent with design levels 

Surface is smooth and free of local depressions and debris 

Hold Point - Sign off is required from superintendent and basin/pond designer before proceeding 

Comments 


Print Name: 

Date: 




Purpose: 


Checklist: 

Item 

Checked 

Satisfactory 

Action/s 

(if required) 

Actions 

addressed 

(initial) 



wetland designer/ecologist and marked up on 

as-constructed drawings 





batters and bunds above the normal water level 


As constructed drawings marked up with final plant 

species and densities 


Comments 


Print Name: 

Date: 



Appendix B – Regular Maintenance 

Checklists 



B.1 Bioretention Basins 

Item 

Performance 

Target 

Schedule 


Investigation 

(circle relevant category) 

Immediate 

Action 

Required 

Comment 

Action Processed 

1 GPT / trash rack/s 

GPT clear of 

litter 

GPT 10 percent 

full 

greater than 30 

percent full 

2 Inlet structures 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

3 Overflow pits 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

4 Underdrains 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

5 Sediment Forebay 

Sediment 

absent 

Sediment 

accumulation 

appears 

excessive 

Sediment 



depth 

6 Erosion Erosion absent 

Erosion 

damage visible, 

but function 

not impaired 


Damage 

impairing 

function of 

device 

Location (mark on attached 

map of bioretention basin) 

7 

Sediment 

accumulation 

(bioretention basin) 

Sediment 

absent 

Sediment 

accumulation 

appears 

excessive 

in sediment 

forebay. 

Fine sediment 

accumulation 

apparent on 

bioretention 

media surface. 

Sediment 


half the forebay 

depth 

Coarse 

sediment or 

large volumes 

of sediment 

accumulation 

apparent on the 

bioretention 

media surface 





Item 

Performance 

Target 

Schedule 


Investigation 


Immediate 

Action 

Required 

Comment 


8 

Compaction of filter 

media surface 

No compaction 

evident 

Localised 

compaction 

or subsidence 

evident. 

Localised 

ponding longer 

than 24 hours 

after storm 

event 

Water remains 

ponding longer 

than 24 hours 

after storm 

event 



9 Weeds 

No weeds 

present 

Weeds present 

Noxious or 

environmental 

weeds present, 

or weed cover 

more than 25 

percent 



Identify weed species 

10 Plant condition 

Healthy 

vegetation 

Poorly growing 

or visibly 

stressed 


plants 



Identify species requiring 

replacement 

11 Litter (organic) No litter visible Litter visible 

Litter thickly 

covers filter 

media surface 

or detracting 

from visual 

amenity 



Note type of litter removed 

12 

Litter 


No litter visible 

Litter visible 

Litter blocking 

structures or 






13 Oil spills / inflows No visible oil 


limited visible 

oil 

Extensive or 


layer of oil 

visible 



B.2 Constructed Wetlands 

Item 

Performance 

Target 

Schedule 


Investigation 


Immediate 

Action 

Required 

Comments 


1 GPT / trash rack 

GPT clear of 

litter 


full 

GPT / trash 

rack for than 30 

percent full 

2 Inlet pipe 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

3 

Pipes connecting 

macrophyte cells 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

4 Outlet pit 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 


Erosion 


but structure 

functional 


Damage 

impairing 

function of 

device 

Location 

(mark on attached map of 

wetland) 

6 Sediment build-up 

Sediment 

absent 

Sediment 

accumulation 

appears 

excessive 

Sediment 



depth 

Location 


wetland) 

7 

Aquatic weeds 

(submerged, 


No weeds 

present 

Weeds present 

Noxious or 

environmental 

weeds present 

Location 


wetland) 




Item 

Performance 

Target 

Schedule 


Investigation 


Immediate 

Action 

Required 

Comments 


8 

Terrestrial weeds 

(e.g. within the batter 

slopes) 

No weeds 

present 

Weeds present 

Noxious or 

environmental 

weeds present 


map of wetland) 


9 Algal blooms 

No algae 

apparent 

Algae visible 

Algal growth 

prominent or 

extensive 

10 

Plant condition 

(aquatic macrophytes) 

Healthy 

vegetation 


or visibly 

stressed 


plants 

Note species which require 

replanting 

11 


(terrestrial) 

Healthy 

vegetation 


or visibly 

stressed 


plants 


replanting 



structures or 






13 Litter (anthropogenic) No litter visible Litter visible 


structures or 








B.3 Sedimentation Basin 

Item 

Performance 

Target 

Schedule 


Investigation 


Immediate 

Action 

Required 

Comment 


1 GPT / trash rack/s 

GPT clear of 

litter 


full 

greater than 30 

percent full 

2 Inlet structures 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

3 Overflow pits 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

4 Sediment Forebay 

Sediment 

absent 

Sediment 

accumulation 

appears 

excessive 

Sediment 



depth 


Erosion 


but function 

not impaired 


Damage 

impairing 

function of 

device 

Location 


sedimentation basin) 

6 

Sediment 

accumulation 

Sediment 


less than half 

the basin depth 

Sediment 


half basin depth 

Sediment 

accumulation 

greater than 


depth 

Note timing since last desilting 

operation 



Item 

Performance 

Target 

Schedule 


Investigation 


Immediate 

Action 

Required 

Comment 


7 Weeds 

No weeds 

present 

Weeds present 

Noxious or 

environmental 

weeds present, 

or weed cover 

more than 25 

percent 

Location 




8 Plant condition 

Healthy 

vegetation 


or visibly 

stressed 


plants 

Location 



Identify species requiring 

replacement 


Litter thickly 

covers filter 

media surface 

or detracting 

from visual 

amenity 

Location 




10 

Litter 


No litter visible 

Litter visible 


structures or 



Location 




11 Oil spills / inflows No visible oil 


limited visible 

oil 

Extensive or 


layer of oil 

visible 



B.4 Ponds 

Item 

Performance 

Target 

Schedule 


Investigation 


Immediate Action 

Required 

Comments 


1 Inlet pipe 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 

2 Outlet pipe 

Clear and 

undamaged 

Partially 

Blocked 

Observed 

damage 


Severe damage 


Erosion 


but structure 

functional 


Damage 

impairing 

function of 

device 

Location (mark on attached map 

of pond) 

4 Sediment build-up 

Sediment 

absent 

Sediment 

accumulation 

appears 

excessive 

Sediment 



depth 


of pond) 

5 

Aquatic weeds 

( s u b m e r g e d , 


No weeds 

present 

Weeds present 

Noxious or 

environmental 

weeds present 


of pond) 


6 

Terrestrial weeds 

(e.g. within the batter 

slopes) 

No weeds 

present 

Weeds present 

Noxious or 

environmental 

weeds present 


of pond) 




Item 

Performance 

Target 

Schedule 


Investigation 


Immediate Action 

Required 

Comments 


7 Algal blooms 

No algae 

apparent 

Algae visible 

Algal growth 

prominent or 

extensive 

8 


(aquatic macrophytes) 

Healthy 

vegetation 


or visibly 

stressed 


plants 


replanting 

9 

Plant 

(terrestrial) 

condition 

Healthy 

vegetation 


or visibly 

stressed 


plants 


replanting 



structures or 



Location (mark on 

attached map of pond) 


11 Litter (anthropogenic) No litter visible Litter visible 


structures or 



Location (mark on 

attached map of pond) 


NOTE: A check for trash racks / nets has not been included, as the pond should not be designed as a water quality treatment 

system, but rather to provide storage capacity of attenuation of peak flows to downstream waterways. 



Appendix C | Asset handover sheets 

Asset HANDOVER Checklist* 

Asset I.D. 

Asset Location: 

Construction by: 

Time since planting established and maintenance required: 

TREATMENT Y N 

System appears to be working as designed visually? 

No obvious signs of under-performance? 

MAINTENANCE Y N 

Maintenance plans and indicative maintenance costs provided for each asset? 

Vegetation establishment period completed (2 years)? 

Inspection and maintenance undertaken as per maintenance plan? 

Inspection and maintenance forms provided? 

Asset inspected for defects and/or maintenance issues at time of asset transfer Y N 

Sediment accumulation at inflow points? 

Litter within basin? 

Erosion at inlet or other key structures? 

Traffic damage present? 

Evidence of dumping (e.g. building waste)? 

Vegetation condition satisfactory (density, weeds etc)? 

Watering of vegetation required? 

Replanting required? 

Mowing/slashing required? 

Clogging of drainage points (sediment or debris)? 

Evidence of ponding? 

Damage/vandalism to structures present? 

Surface clogging visible? 

Drainage system inspected? 

COMMENTS/ACTIONS REQUIRED FOR ASSET TRANSFER 

ASSET INFORMATION Y N 

Design Assessment Checklist provided? 

As constructed plans provided? 

Copies of all required permits (both construction and operational) submitted? 

Proprietary information provided (if applicable)? 

Digital files (e.g. drawings, survey, models) provided? 

Asset listed on asset register or database? 

* Asset handover checklists are generic and can be used for all WSUD elements discussed in this booklet 



Appendix D | References 

Collins (2006), Destination SQID Waster 

Stormwater Industry Association 

available online at :- 

www.wsud.org/downloads/2006_SIA_Papers/Anthony%20Collins%20%20-%20Hornsby%20Council.pdf 

Facility for Advancing Water Biofiltration (FAWB) (2008), Workshop 

Advancing the Design of Biofiltration 


http://www.monash.edu.au/fawb/products/fawb-advancing-rain-gardens-workshop-booklet.pdf 

Facility for Advancing Water Biofiltration (FAWB) (2008) 

Guidelines for Soil Filter Media in Bioretention Systems 


http://www.monash.edu.au/fawb/products/obtain.html 

Water by Design (2009) 

Chapter 4 – Constructed Wetlands 

South East Queensland Healthy Waterways Partnership 


Chapter 3 – Bioretention Systems 



Construction and Establishment Guidelines 

Swales, Bioretention Systems and Wetlands 


WBM Oceanics Australia and Ecological Engineering (2004) 

Maintenance Guidelines for Stormwater Treatment Measures 

Hornsby Shire Council (HSC) (2001) 

Catchment Remediation Capital Works Program Annual report 2000-2001 

Water Catchments Team HSC 

Lloyd, S.D., Wong, T.H.F and Chesterfield, C.J. (2002) 


A Stormwater Management Perspective 

Cooperative Research Centre for Catchment Hydrology 

Facility for Advancing Water Biofiltration (FAWB) (2008) 

Workshop: Advancing Raingarden Design Filter Media and Landscaping 


http://www.wsud.org/downloads/Seminars%20&%20Events/fawb-workshop-vegetation-and-landscaping.pdf 

Wong, T.H.F (editor in chief) (2006), Australian Runoff Quality, Engineers Australia 



Notes 




Level 2, 330 Church Street 

Parramatta NSW 2150 

PO Box 237 Parramatta NSW 2124 

DX 28448 Parramatta 

Telephone 61 2 9841 8600 

Facsimile 61 2 9841 8688 

Printed May 2009 on recycled paper.

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