1. Waterway Investment prioritisation
The Merri Creek Catchment Pilot Study

2. The question…
“Can we deliver better value to the community by integrating our water management programs and services?”
Hypothesis: By integrating water agencies and local councils’ waterway investments, greater value can be provided to the community in terms of (1) improved waterway health and (2) provision of amenity
Approach: Undertaking a wholistic waterway investment review exercise of existing and planned waterway health and amenity programs within a selected pilot catchment.

3. Inflow & Infiltration

4. Emergency Relief structure

5. Historical approach
Grey Infrastructure
Large sewer duplications

6. Current Planned investment – 5 years
Yarra Valley Water
Melbourne Water
Sewer main duplications
TOTAL EXPENDITURE ~ $19M
Revegetation
Community grants
Weed management
Stabilisation
Desilting
TOTAL EXPENDITURE ~ $5M
Councils
Parkland and stream management programs
Education programs – Stormwater and site management practices
Stormwater runoff programs / local WSUD assets
Local Stormwater harvesting and reuse projects
TOTAL EXPENDITURE ~ $1M
Only place more than one slide per page if you are making comparisons between them. Remember to reference the author.
For tips on using graphs in your presentations see:

7. Community Expectations
Only place more than one slide per page if you are making comparisons between them. Remember to reference the author.
For tips on using graphs in your presentations see:

8. Understanding the Impact
Three key waterway attributes were assessed:
Public Health
Environment
Amenity/Aesthetics

9. PUBLIC HEALTH What do we know about the Merri Creek?
Too much background E.coli for primary contact
Too much E. coli during wet weather for secondary contact
Wastewater overflows in wet weather are very infrequent (less than 1 per year)
Large dilution during wet weather leads to sewer spills due to hydraulic capacity having minimal impact
Urban storm water contributes 99% of all pollutant loads

10. PUBLIC HEALTH Key Conclusions?
Primary or secondary contact in Merri Creek is not practically achievable regardless of wastewater infrastructure upgrades
Wastewater overflows are very low risk for contact recreation in Yarra River and Port Phillip Bay
Complete elimination of wastewater overflows would result in no measurable benefits for practically achievable public health outcomes or mitigation of risk to the Yarra River and Port Phillip Bay
Identification and rectification of illegal sewer to storm water connections is best public health risk mitigation measure for Yarra River and Port Phillip Bay
There are other barriers to achieving secondary or primary contact standards in the Merri Creek – e.g. turbidity, toxicants, hydraulics, etc.

11. Aesthetics & Amenity
Melbourne Water and Council’s contribute to vegetation management / enhancement
Key risks to aesthetics and amenity include:
Gross pollutants from Stormwater discharge (high frequency)
Gross pollutants from wastewater overflows (low frequency)
Odours in the Merri Creek haven’t been a key issue in the past and are considered low risk
Turbidity / water murkiness is a key issue and vast majority of sediment loads come from stormwater

12. Environment Current Status:
Urban sections of Merri Creek are highly degraded and typical for an urban stream
Sediments contaminated with heavy metals and pesticides which represent the main threats to plant & animal life
Mixture of point source and diffuse pollution
Primary Areas of Focus?
Stormwater pollutant load reductions
Source control measures
Riparian vegetation enhancement.

13. Planned expenditure vs outcome
Description
Investment
Outcome
Benefit
Sewer Hydraulic Upgrades to meet current SEPP 1 in 5yr wet weather containment standard
~$19M
(80%)
Public Health (YR &PPB only)
Very Low
Capital program for vegetation management (ecological enhancement and some amenity)
~$1.5M
(6.5%)
Aquatic Life, Riparian vegetation, Aesthetics
High
Maintenance programs (vegetation and litter/debris/sediment removal)
~$1.8M
(7.5%)
Stormwater Runoff / WSUD / harvesting and reuse projects/capacity and education programs
~$1.4M
(6%)
Aquatic Life, Aesthetics
High (local)
TOTAL
~ $25M

14. Alternative approaches
Stormwater:
Strategic stormwater to sewer diversion
Additional gross pollutant traps
Raingardens
Community group grants
Riparian Vegetation
Sewer:
ERS screening
Sewer illegal connection identification and rectification
Inflow and infiltration rectification

15. Next steps
Currently monitoring to establish baseline and determine target areas:
Litter surveys
Drain surveys
Water quality monitoring
Working towards regulatory approval (EPA) for revised approach
Further community consultation

16. Questions