WCC wastewater network issues, actions and way
forward plan
Prepared by R Jayaratne – 30 August 2016
1. Key Objectives
Long Term Vision/4th Order
Objective Area
Objective Targets
Outcome Stormwater and wastewater
How the wastewater network
General management processes and
systems support healthy people
interacts with the stormwater
design, construction and performance
and ecosystems
network and the consequent
issues those are relevant across all areas
impacts on the city’s aquatic
of the network over the catchment.
receiving environments.
Focuses on reducing the incidence and
impact of wastewater from overflows
within the city’s reticulated network.
Coastal water and sediment
Water quality and its
Using the relevant guidelines provides
quality supports healthy people
management
consistency in identification of ecosystems
and ecosystems
and monitoring regimes appropriate to
the receiving environment.
Networks meet current and
Understand catchment wide
Safe and reliable conveyance of
desired levels of service
wastewater network
wastewater
performances - capacity, and
constructed overflow
performances, contamination
locations (hot spot areas,
cross-connections/miss-
connections etc)
2. Wastewater Network Issue Definition
Issue
Causes / Description
Existing networks do not meet current and desired levels of service caused by:
Aging infrastructure
pipe age, condition and/or capacity
low level of historical investment in asset maintenance and renewal
low historical focus on amenity considerations of networks
Existing stormwater
asset management weakly aligned with newly identified values, issues, growth,
and wastewater
development, amenity and ecological needs and external risks such as climate
networks are not
change and associated effects
future-proofed
Wastewater
exfiltration from wastewater network
Interactions with
o age/state of repair
o
stormwater systems
loss of capacity due to growth
design overflows from wastewater network
infiltration and inflow into wastewater network:
o age/state of repair
o illegal cross-connections and faulty private drains
o gully traps too low/in secondary flow paths
possible poor construction standards of new wastewater and stormwater
reticulation
Figure 1: Growth areas for Lambton Harbour catchment
NOTE: Similar map available for Moa Point wastewater catchment
Figure 2 a: Wastewater network issues Lambton Harbour catchment
NOTE: Maps to be prepared for Moa Point wastewater catchment
Figure 2 b: Inflow and infiltration status for Moa Point wastewater catchment
Figure 3: Localised issues priorities – wastewater impacts Lambton Harbour
catchment
NOTE: Maps will be prepared for Moa Point wastewater catchment by March 2018
3. Actions and Timing – wastewater network
Table 1: Overview of catchment-wide
actions identified in Lambton Harbour Catchment ICMP (NOTE: Detail actions are identified for each
issue marked in the maps, refer to the draft Lambton Harbor ICMP)
ID Number and Name
Description
Timeframe
-
8)
mr
m
e
r
203
t
)
m
u
(2018
e
t
–
di
e
mr
hort S (2018
M
et 2021)
ongL (2021
C-1
Investigation and Analysis
Pipe capacity (performance) analysis and condition assessment for wastewater and stormwater
network in order to set a target (detail actions are listed for each issue areas)
C-2
Hydraulic network
Completion of model calibration/verification
modelling
C-3
Performance analysis
Detail network performance analysis and refining issues (preliminary capacity issues are
identified based on other analysis)
C-4
Preliminary option
Solution identification – (previously identified actions are implemented and progressing )
s
assessment
tion
C-5
Solution workshops
Refining solutions / costing – MCA analysis
Ac
C-6
Inspect gully traps
Investigate whether stormwater discharges into gully traps in high priority areas
alr C-7
Illegal cross connection data Investigate illegal connections and faulty private drains in high priority areas
e
n
C-8
Public awareness
Conduct baseline survey to identify the current level of public awareness and set benchmarks
Ge
and targets (Table B14-Item 1, 2 and 3)
C-9
Education and Training
Re-align existing education plan to include Stage 2 ICMP findings (including business premises
and other localised sources of contamination)
C-10
Intra and Inter agency Co-
Working with other internal and external parties to make sure priorities are aligned with city
ordination
wide planning concepts. (Table B-10, item 4)
C-11
Strategies Co-ordination
Linking in with other strategies such as the Central City Framework, Growth Study, Town Belt
and Biodiversity.
C-12
Existing work Plan updates
Updating all relevant planning programmes
4. Tentative Action Schedule: March – November 2016
(Identified in the Lambton Harbour ICMP)
Item
Responsible*
Comments
1
Completion of hydraulic model
Hywel
90% is completed for
Lambton Harbour catchment.
Other models are progressing
2
Performance assessment
Hywel / Rajika
To refine the catchment
issues identified
3
Preliminary solution assessment
Hywel / Rajika lead -
Brain storming of ideas –
discussions with
assessing big picture and
Steve/Ryan/Iqbal/??? aligned with other on-going
WW work programmes
4
Option workshops
Hywel / Rajika /
Initial workshops with the
Steve/Ryan/Iqbal/??? Development, Ops and
Delivery teams
5
Cost estimation and MCA analysis
Rajika lead with the
Discussions with WCC / WWL
help of Delivery team
and ND & D staff
6
Implementation
ND & D
Include to the LTP
NOTE: * identified while developing ICMP actions in May 2016. Subject to change, will discuss
with Wastewater Chief Advisor ND & D.
