Presenters:

John Tetteroo (GHD Ltd),

Veenay Rambisheswar (Auckland Transport),

Managing Road Stormwater Contaminants

for Auckland Transport Through Innovative

Solutions

Introduction

Auckland Transport Asset Management Contract:

• 4 Year Contract

• Condition/Performance assessment of road structures and drainage assets

• Drainage Level of Service:

– Quality (condition of catchpits)

– Responsiveness (maintenance response timeframes)

– Environmental Sustainability (regulatory compliance)

• Development of 1-, 3-, and 10-year Forward Works Programmes

Transport Assets:

• 27,500 catchpit

• 2,300 soakholes

• 521 manholes

• 1,360 culverts

• 197,000 m pipe leads

• 100+ treatment devices

• 5 watercourses

• 2,500 km kerb and channel

• 38 Stormwater catchments

• 44 Cleaning catchments

• Auckland Isthmus: 15,423 ha; 48% impervious area

• Hauraki Gulf Islands: 37,040 ha; 1% impervious area

• Isthmus: 33% area dependent on ground soakage

Auckland Central Area – Drainage Infrastructure

Auckland Transport (AT) / GHD Partnership

• Joint Initiatives: Working together to get the best outcomes for the city,

ratepayers, customers.

• Auckland Annual Plan (2012): “Auckland to be the worlds most liveable city”.

Strategic Direction 7 target – reduce the overall yield of suspended sediment to

priority marine environments from 2012 levels by 15%. The Hauraki Gulf is a

priority receiving environment.

• AT Strategic Objectives: The road drainage network to treat stormwater and

mitigate environmental effects of the transport network. To provide a level of

service of environmental sustainability, protecting the receiving environment.

• AT Key Drivers: Reduce adverse environmental effects from Auckland

Transports system.

• AT Priority Focus: Improve Transport safety and reduce the adverse impact

from transport on the surrounding environment.

Data Management and Integration

• RAMM (Road Assessment and Maintenance Management) efficiency in

capturing data accurately

• Leading edge mobile GIS unit with GPS

• Records spatial location and attribute information

• GIS integration of AMIS (Asset Management Information System) and RAMM

• Digitised mapping and record information

Stormwater Contaminant Management

GHD working with Auckland Transport / Auckland Council in the achievement of

their strategic objectives through minimising stormwater pollution to the receiving

environment.

Issues

• Cumulative impacts of pollution from urban road stormwater run-off

• Rising heavy metal contaminant levels in waterways and harbours

• Marine ecology at risk

• Recreational users of waterways, beaches, and harbours at risk

Challenges

• Lack of suitable space to treat stormwater in urban environments

• Stormwater treatment devices are difficult and expensive to maintain

• Limited budgets available to help resolve stormwater contaminant issues

• Innovation required to provide sustainable solutions

The Rubbish Dump under Sydney Harbour

Divers were able to fill two sacks of waste

in just 12 minutes

Divers have captured Sydney's

underwater scrapheap on film

Environmental group Two Hands says

rubbish covers the harbour floor

Divers have found all kinds of objects under

water

Singapore River - Pollutants

Singapore River - Pollutants

Plastics – a major source of chemical pollution

Typical Catchpit

Parameters

• Primary source of stormwater capture within the road reserve

• Auckland central has 27,500 catchpits, 92,000 total in the wider Auckland region

• Catchpits cleaned 3-5 times annually by vacuum loading truck (central area)

• Standard catchpit sump depth 450 mm (outlet pipe invert to base of catchpit)

• Catchpit location and details managed electronically in GIS database

• First point of opportunity for stormwater treatment

Catchpit Management

Standard 660x460 mm

760 mm back entry

Street 800x500 mm

2.4 m back entry

Street 800x500 mm

1.2 m back entry

Double Street 800x500 mm

2.4 m back entry

The TetraTrap Programme

Developed to increase performance of catchpits by utilising redundant space and

improve retention of gross pollutants, sediments, and heavy metals:

TetraTrap Features

• Ability to capture gross pollutants (litter), sediments, and heavy metals

• Approx. 75-175% increase in sediment capture

• Can be retrofitted to existing catchpits

• High level overflow weir

• Low maintenance, robust, removal not generally required

• Expanded metal screen

TetraTrap2 TetraTrap1 TetraTrap3 Auckland Transport

Standard Engineering Detail

TetraTrap Features

• Asset lifecycle of 25 years

• Cost effective (NZ $600 supply)

• Utilises redundant space in catchpit

The TetraTrap – Results

• 75-175% increase in sediment

removal

• Ease of cleaning (4 monthly)

• Easily retrofitted into existing catchpits

• Low cost

• Asset life of 25 years

• Low maintenance – stainless steel

• Increased effective sump depth

• Projected increase in Central Area

pollutant removal from ~4,400 t/yr.

dry wt. (current) to ~7,600 t/yr. dry

wt.

Sediment Depths

Test Location Catchpit Details (GV3) Sediment Depth (m)

Percentage Increase

Testing Sites Catchpit

Type Vehicles per Day

Catchpit Depth

(m)

Sump Depth

(m)

Outlet Diameter

(mm)

Without Unit

With Unit

582 Great South Rd Standard >20,000 1.65 0.70 225 0.18 0.53 194%

10-12 Federal St Standard <5,000 1.37 0.49 225 0.24 0.35 46%

15 Federal St Standard <5,000 1.13 0.80 225 0.21 0.34 62%

30 Laurie Ave (1) Street <1,000 1.80 0.48 300 0.15 0.46 206%

30 Laurie Ave (2) Street <1,000 1.80 0.48 300 0.12 0.29 142%

30 Laurie Ave (3) Street <1,000 1.80 0.48 300 0.14 0.48 243%

19 Laurie Ave Street <1,000 1.89 0.81 300 0.10 0.30 200%

2 Golf Rd (east) Standard <1,000 1.86 0.61 225 0.28 0.68 143%

2 Golf Rd (west) Standard <1,000 1.87 0.62 225 0.08 0.33 312%

41 Middleton Rd on Ada St Street <1,000 1.85 0.98 225 0.35 0.89 154%

43 Middleton Rd on Ada St Street <1,000 1.70 0.98 225 0.37 0.72 95%

Catchpit Sediment Loading

0

0.1

0.2

0.3

0.4

0.5

0.6

582 Great South Road

10-12 Federal

Street

15 Federal Street

30 Laurie Avenue

(2008)

30 Laurie Avenue

(2009)

19 Laurie Avenue

2 Golf Road (east pit)

2 Golf Road (west pit)

Average

Sed

imen

t D

ep

th (m

)

Copper Concentration in Catchpit Sediment

0

20

40

60

80

100

120

140

160

180

15 Federal Street

Auckland Central

30 Laurie Avenue

Parnell

25 Symonds Street,

Auckland Central

49 Symonds Street,

Auckland Central

96 Symonds Street,

Auckland Central

Co

nc

en

tra

tio

n (

mg

/kg

dry

)

Zinc Concentration in Catchpit Sediment

0

200

400

600

800

1000

1200

15 Federal Street

Auckland Central

30 Laurie Avenue

Parnell

25 Symonds Street,

Auckland Central

49 Symonds Street,

Auckland Central

96 Symonds Street,

Auckland Central

Co

nc

en

tra

tio

n (

mg

/kg

dry

)

Testing Results (With and Without TetraTrap)

0.0

50.0

100.0

150.0

200.0

250.0

300.0

30 LaurieAvenueWithout

TetraTrap

30 LaurieAvenue With

TetraTrap

25-29Symonds

StreetWithout

TetraTrap

25-29Symonds

Street WithTetraTrap

49 SymondsStreet

WithoutTetraTrap

49 SymondsStreet WithTetraTrap

15 FederalStreet

WithoutTetraTrap

15 FederalStreet WithTetraTrap

Rela

tive Q

uan

tity

Sediment Particle Size Distribution

Without

TetraTrap

With

TetraTrap

Without

TetraTrap

With

TetraTrap

Without

TetraTrap

With

TetraTrap

>2.000 mm

0.063 - 2.000 mm

<0.063 mm

Note 1: Samples taken over a 4-month cleaning cycle with and without a TetraTrap

Note 2: Samples taken over a 3 year period

Sampling & Analysis

To determine pollutant loading and

particle size, samples taken prior to

TetraTrap installation and following

4 month sediment capture with unit

installed:

• Copper concentration mg/kg

dry weight (average +10%)

• Zinc concentration mg/kg

dry weight (average +12%)

• Typical sediment particle

size distribution (dry weight)

Particle

Size

(µm)

Without

TetraTrap

Installed

With TetraTrap

Installed

< 63 3% 8.9%

63-250

41%

13.5%

58.8% 250-500 13.2%

500-2000 32.1%

> 2000 56% 32.3%

TetraTrap High Level Overflow in Operation TetraTrap Screen blinding prior to cleaning

TetraTrap Easily Retrofitted on Side or Front Face of Catchpit

“Auckland to be the worlds most liveable city”

TetraTrap Showing Blinding on the Front Face Retaining Gross Pollutants

and Sediments (not visible) – 3 Months into Cleaning Cycle

TetraTrap in Catchpit Following Catchpit Cleaning

Auckland Transport Stormwater Treatment Strategy Plan (2011 – ongoing)

Strategy – Going Forward

Prioritisation of TetraTrap Locations

2012 ITU Triathlon World Champions Grand Final

Auckland Transport / Auckland Council Partnership

Swim Course

Shortland Street Catchment TetraTrap Installation

Waterfront TetraTrap Installation

Benefits

• 145 catchpits working harder for Transport

• Current Capture Volume: 33 m³ wet / annually

• Projected Capture Volume: 60 m³ wet / annually (TetraTrap install)

(Gross pollutants extra)

• 1500 catchpits in CBD - $1.8 Million to implement TetraTraps over 8 months

Total projected capture volume estimated at 620 m³ wet / annually

Additional projected capture volume estimated at 280 m³ wet / annually

Additional Benefits of Tetra Trap Programme

• Reduces call-out costs / Flood Risk – Catchpits with half syphon outlets

regularly block up. Each Contactor call out costs were costing $1,000.Recent 1 in

20 year storm event (July 2012) in Auckland CBD – major flooding caused due to

blockage of catchpits and leads. Damage costs to properties.

• Reduces frequency of combined sewer overflows – Main Trunk Sewers

restrict flows from combined pipes though reduced 150 dia pipes causing

overflows. Rubbish from road-runoff blocks the 150 dia pipes causing more

frequent overflows.

• Immediate Implementation – It will take cities many years (20, 30, 50 years?) to

implement city-wide stormwater treatment using other approaches. This

approach can be used immediately in suitable cities with immediate

environmental benefits.

• Implementation is scalable – can be prioritised over a number of years.

Social, Economic, Sustainable Benefits

• Improved stormwater quality in receiving environment – allow recreational

use of beaches by the community; protects the marine environment

• Easily maintained, removal generally not required, cleaned when catchpits

are cleaned (4-monthly basis); low annual lifecycle cost

• Manufactured locally, no moving parts, easily retrofitted to existing catchpits,

25 year lifecycle, 100% recyclable material (stainless steel)

• Promotes a cleaner harbour – significantly reduced pollutant discharge from

roads – assists in protecting aquatic species in our harbours, and streams

• No additional space required for installation

• Catchpit working harder for council

Working Towards Best Practice

• Linking to an Asset Management Plans and Programme

• Maximise value from transport stormwater assets

• Detailed understanding of the condition/performance of assets (by data

capture)

• An integrated approach to managing stormwater contaminants

• Maximising the value of catchpit assets in road contaminant management …

cost effective solution to treat at source

• Meet Auckland Transport’s key priority – a sustainable network

encapsulating social, cultural, economic, and environmental aspects

Finalist – New Zealand Engineering Excellence Awards – Nov 2012,

“Excellence in Environmental Practice”

Where to Now?

• Auckland City-wide Study and prioritisation

• Ties in with Auckland’s vision for our Waterfront

• Promote Auckland as a sustainable city and most liveable city in the world

• Present and promote to other cities in NZ and internationally

• Modify the TetraTrap and programme to suit drainage systems for other

cities

Promoting the Programme to other cities

TetraTrap Programme incorporating a city-wide integrated study working

collaboratively with local council teams to identify any gaps whilst building

capacity of local teams, transferring NZ best practice local government

processes;

• Drainage system data collection

• Flood Study information;

• Asset Management processes and procedures;

• Assessment of stormwater management policies, guidelines and levels of

services;

• Review of operations and maintenance regimes for road carriageway

sweeping and cleaning of catchpits.

Copenhagen Harbour Bath…Auckland Viaduct!!!!

“Auckland to be the worlds most liveable city”

Finalist: 2012 Worlds most liveable city

Thank you