Post on 29-Jul-2018
transcript
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
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 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
2012 ITU Triathlon World Champions Grand Final
Auckland Transport / Auckland Council Partnership
Swim Course
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