Western Treatment Plant inputs and discharges

Raw sewage monitoring

(All data in mg/L unless otherwise indicated)

	2006 / 2007
Parameter (Unit)	Median	90th percentile	Maximum
Flow (Ml/day)	431	482	729
BOD5	430	590	760
Total Suspended Solids	360	490	1400
Ammonia as N	43	50	53
Total Nitrogen	65	77	110
Total Phosphorous as P	12	14	17
pH (pH units)	7.4	7.9	8.2
Colour (Pt/Co units)	100	120	140
Anionic Surfactants as MBAS	4.2	7	8.3
Silicate	13	14	15
Electrical Conductivity (µS/cm)	2000	2200	2400
Total Dissolved Solids	970	1,100	1,700
Cadmium	0.0003	0.00069	0.0013
Chromium	0.028	0.052	0.11
Copper	0.11	0.15	0.2
Lead	0.008	0.013	0.018
Mercury	0.0001	0.0003	0.0008
Nickel	0.021	0.04	0.084
Zinc	0.17	0.3	1.5
Benzene	0.0005	0.0019	0.004
Toluene	0.0015	0.0049	0.011
Total Phenols	0.68	0.93	1.3
Total PAH's	0.0048	0.007	0.008

Licence compliance

The following tables show the plant's compliance performance. Plant wide limits for all discharge parameters in the licence are based on a flow weighted average calculated using the formula:

discharge parameters in the licence are based on a flow weighted average calculated using the formula

Conditions of the EPA Victoria discharge licence outline the performance limits for effluent discharged to Port Phillip Bay via the four discharge points at the Western Treatment Plant.
The licence states that compliance with all licence parameter limits are to be calculated on a flow-weighted basis.

There is a plant wide limit of 700 million litres a day averaged over the year. The Western Treatment Plant complied with licence waste discharge limits for all parameters.

Annual and average daily discharges for 2006/07

Outlet	Total Flow (ML)	Average Daily Flow (ML)
15 East	55,344	152
145 West	23,158	63
Lake Borrie	11,255	31
Murtcaim Main Drain	546	1
Total	90,303	247

Annual discharge to Port Phillip Bay

The treatment plant's performance against the EPA licence limits for 2006/07 shown below shows that the Western Treatment Plant complied with the effluent discharge limits for all parameters. The results for 2006/07 are shown below:

(All data in mg/L unless otherwise indicated)

Parameter	Median		75th Percentile		90th Percentile		Maximum
Parameter	Limit	Result	Limit	Result	Limit	Result	Limit	Result
CBOD5	10	2.8			20	5.8		15
Suspended Solids	30	25			60	41		82
Ammonia as N	10	2.9				16	30	18
Total Phosphorous		10			15	12		14
Colour Pt/Co units	200	58			400	61		62
Anionic Surfactants					0.8	0.33	1	0.52
Cadmium			0.0011	0.00025		0.00027	0.005	0.00051
Chromium			0.04	0.0075		0.01	0.1	0.013
Copper			0.028	0.0093		0.0099	0.1	0.015
Lead			0.015	0.0044		0.0053	0.06	0.013
Mercury			0.0004	0.00012		0.00014	0.001	0.00016
Nickel			0.029	0.021		0.023	0.06	0.023
Zinc			0.06	0.035		0.054	0.2	0.081
Benzene			0.005	0.0005		0.0005	0.01	0.0005
Toluene			0.005	0.0005		0.0005	0.01	0.0005
Phenols (total)			0.04	0.007		0.0087	0.08	0.013
Total PAH's			0.0004	0.000086		0.000086	0.0008	0.000091

Annual nitrogen load to Port Phillip Bay

The nitrogen output from the Western Treatment Plant was 1560 tonnes per annum for 2006/07. The annual loads for the last three years are shown in the following table, which demonstrates that Melbourne Water has complied with the maximum target of 3100 tonnes per annum.

Annual nitrogen load from Western Treatment Plant

Financial Year	2006 / 2007	2005 / 2006	2004 / 2005	3 year rolling average	EIP Target
Total N Load (tonnes/annum)	1560	1969	2713	2081	3100

Dioxins and furans

Melbourne Water monitors polychlorinated dibenzo dioxins and furans (PCDD/F), as toxic equivalents of 2,3,7,8 tetrochloro-dibenzo-p-dioxin. Sampling of PCDD/F is carried out at the 15 East Outlet in the month of January, 145 West outlet in April, Lake Borrie outlet in July and Murtcaim Outlet in October each year. The raw sewage is sampled for PCDD/F each time an outlet is sampled (i.e. 4 times a year).

The toxic equivalent (TEQ) is calculated for each sample using the World Health Organisation's toxic equivalency factors (WHO98-TEQ) method and is represented in the following table. Results for preceding years are also presented for comparison.

PCDD/F as World Health Organisation Total Toxic Equivalents of 2,3,7,8 TCDD for 2004/05
(All results in pg/L)

SITE	WHO98-TEQ - Excluding LOD Values			WHO98-TEQ - Including Half LOD Values
SITE	2006/07	2005/06	2004/05	2006/07	2005/06	2004/05
Lake Borrie (July)	1.9	1	16	3.6	5.3	16
Murtcaim (October)	0.12	0.59	0.08	3.1	4.3	2.0
15E (January)	0.075	0.007	0.13	1.4	2.7	7.0
145W (April)	0.17	0.38	0.62	1.9	2.4	3.6
Raw Sewage (July)	2.8	1.4	1.8	5.1	5	3.6
Raw Sewage (October)	12	4.2	1.5	21	8.6	4.1
Raw Sewage (January)	13	2.5	2.4	20	6.4	7.3
Raw Sewage (April)	0.55	24	15	5.5	24	19

Whilst the best techniques available in Australia are used for the testing of dioxins and furans, many of the results are less than the level of detection and the detection limits achieved in the analytical procedures vary, even for a single sample site. Hence it is difficult to make any substantive interpretation of trends in the results.

Bacteriological monitoring

Melbourne Water conducts bacteriological monitoring by collecting a sample of seawater in 60 centimetre depth of water off-shore from Beach Road and 160 South Road every seven days and analysed to determine the concentration of E. coli in the sample. These two points are public access points to Port Phillip Bay within the Western Treatment Plant and outside the designated mixing zones for E.coli.

The State Environment Protection Policy (Waters of Victoria) schedule F6 for the Werribee segment requires the 42 day geometric mean E.coli values to be less than 1000 orgs/100ml. Melbourne Water has calculated the 42 day Geometric mean and 42 day 80th percentile for the E.coli at the two sites.

E.coli - 42-Day Geometric Means and 80th Percentiles

(All results orgs/100 ml)

	Geometric Mean		80th Percentile
42 Day Period Ends	160 South Rd	Beach Rd	160 South Rd	Beach Rd
1/8/2006	0.66	1.1	2	6
12/9/2006	1.2	3.9	2	12
24/10/2006	0.83	1.1	0	3
05/12/2006	2.3	4.4	22	30
16/01/2007	7.2	1.2	12	10
27/02/2007	12	8.7	22	18
10/04/2007	5	1.3	10	3
22/05/2007	3.1	5.5	10	44

The above results indicate that the two sites within the Werribee segment achieve the State Environment Protection Policy (Waters of Victoria), Schedule F6, Werribee Segment, bacteriological organisms quality objective of <1000 E-coli organisms / 100ml.

Sustainability Report 2006/07