Central Coast Drinking Water Source Documents for HSC Chemistry (Module 9.4: Chemical monitoring and management)

1. Introduction

This PDF document, Central Coast Drinking Water , addresses the following statement on page 61 of the NSW HSC Chemistry Syllabus:

“gather, process and present information on the features of the local town water supply in terms of - catchment area - possible sources of contamination in this catchment - chemical tests available to determine levels and types of contaminants - physical and chemical processes used to purify water - chemical additives in the water and the reasons for the presence of these additives ” (Source: NSW HSC Chemistry Syllabus, Section 9.4 Chemical Monitoring and Management).

Its purpose is to complement the excellent teaching/learning module 'Water Quality: HSC Chemistry ' produced by the Catchment Authority (see SCA at http://hsc.sca.nsw.gov.au/chemistry/introduction ).

Specifically, this document presents information for students and teachers on the Central Coast of NSW; information about the local water supply that will enable students to address the Chemistry Syllabus dot points in familiar terms and with relevant examples.

This document does not attempt to deal with the broader issues of water testing purposes and methodology prescribed in the Syllabus. These issues are already well treated in the SCA module.

Rather, the materials here are selected secondary sources that will assist Central Coast students to better understand the particular features of their Water Supply system and the regimes in place to monitor and ensure that high quality drinking water is available for all residents. These secondary sources should enable Central Coast students to complete the kind of assessment task suggested on the SCA webpage http://hsc.sca.nsw.gov.au/chemistry/drinking_water/report .

2. The structure of the current Central Coast water supply system

Gosford City and Wyong Shire Councils share a joint water supply scheme administered by the /Wyong Council’s Water Authority. This is the third largest water supply system in NSW (see Figure 1).

Figure 1: The Current Central Coast Water Supply System (Source: Gosford Wyong Councils’ Water Authority http://www.gwcwater.nsw.gov.au/index.php/our-system)

Water is drawn from four streams (Mangrove and Mooney Creeks in Gosford and and Ourimbah Creek in Wyong). The building of water storage infrastructure was begun 75 years ago, but most infrastructure in use today was completed during the past thirty years.

Currently, the system incorporates three dams, three weirs, two treatment plants, 40 reservoirs, and 1900 km of pipelines. It has a total catchment area of about 700 square kilometres. Water is drawn from Mooney Dam and weir pools on Wyong River, Mangrove Creek and Ourimbah Creek. Wyong River and Ourimbah Creek extractions are stored in Mardi Dam. During dry periods, when the Coastal Mooney and Mardi Dams cannot meet the demand for water, supply can be released from Mangrove Creek Dam to provide adequate inflows at the weirs on Mangrove Creek and Wyong River.

A key new element in WaterPlan 2050 (the long term water supply strategy for the Central Coast) is the Mardi-Mangrove Link Project. This will consist of a new 19 kilometre buried water pipeline from Mardi Dam to the existing Boomerang Creek tunnel at Mangrove Creek Dam together with supporting infrastructure. Construction of the pipeline will commence in early 2010 and will secure the region’s town water supply over the next four decades.

Before being delivered to the community, the “raw” water is treated to produce a water quality that complies with the high standards of the NHMRC/ARMCANZ Australian Drinking Water Guidelines – 2004 . The JWSS has two water treatment plants, one located at Somersby in Gosford City and the other at Mardi, in Wyong Shire. Currently, approximately 60,000 properties in the Gosford local government area are supplied with a total of about 230 million litres of town water. About 290 million litres per week are consumed within Wyong Shire.

3. The Catchments

A catchment is an area where water is collected by the natural landscape. In a catchment, rain will eventually flow to a dam, creek, river, lake or ocean, seep into the groundwater system, be used by vegetation and animals or evaporate.

Each dam, river and creek has its own catchment. Together, the combined catchment areas of the Central Coast region’s drinking water system are about 727 square kilometres (Table 1).

Table 1: Gosford-Wyong Councils’ Water Supply System (Source: Gosford Wyong Councils’ Water Authority http://www.gwcwater.nsw.gov.au/images/PDF/joint_water_supply_061103.pdf )

Catchment Year Catchment Maximum built area (km 2) capacity (ML) Mooney Mooney Dam 1961 39 4,600 Mardi Dam 1962 4 7,400 Lower Wyong River Weir 1968 355 300 Lower Mangrove Creek Weir 1975 140 300 Ourimbah Creek Weir 1978 88 100 Mangrove Creek Dam 1978-82 101 190,000 Totals 727 202, 700

Managing and protecting our catchments is a key process for ensuring good water quality. Gosford and Wyong Councils have catchment policies which identify specific activities which can be carried out within each catchment area (see Figure 2).

Water supply extractions from weirs on the lower sections of Wyong River and Ourimbah Creek have no impact on the upper sections of the waterways but may reduce flushing in the lower saltwater sections during extended periods of low rainfall. In times of water shortage, water is released from Mangrove Dam into Wyong Creek to allow extractions to continue and to allow for environmental flows down stream. Possible impacts from this on Wyong Creek, such as unnaturally cool flows and introduction of new species of aquatic organisms, are monitored by the Water Supply Authority. The weirs also have the potential to block fish from swimming up and down stream, possibly affecting breeding. So, appropriate fish ladders have been put in place by the Water Supply Authority to overcome this.

Figure 2: The Central Coast water supply catchments (Source: WaterPlan2050 ( http://www.gwcwater.nsw.gov.au/index.php/waterplan-2050 ) showing the planned Mardi-Mangrove Link (http://www.gwcwater.nsw.gov.au/index.php/mardi-mangrove-link )

4. Possible Sources of Water Contamination

Potential contamination of water supplies depends on the nature of the catchment areas from which the raw water is gathered. As examples of the kinds of contamination possible within the Central Coast catchment areas we consider the Mangrove Creek Dam, Lower Wyong River Weir, and Mardi Dam catchments.

Mangrove Creek Dam

Mangrove Creek Dam is the Central Coast’s major storage dam. It is located on Mangrove Creek and is the main storage that supplies the Coast during times of low rainfall. When there is insufficient storage in Mooney Mooney and Mardi Dams, or insufficient flows in Mangrove Creek, water is released from Mangrove Creek Dam.

Water is drawn from the dam by a 50 metre high intake tower which transfers it under the dam wall and releases it into Mangrove Creek to supply Gosford City. Another, smaller intake tower draws water from the dam and pumps it through the Boomerang Creek Tunnel and into Wyong River to supply Wyong Shire.

The catchment area of Mangrove Creek Dam is sandstone eucalypt bushland and is bounded by George Downes Drive to the east to the north and the Great North Road to the west. The land use in the catchment area as it was at the time of the dam’s construction is summarised in Table 2 and Figure 3.

Table 2: Summary of land use in upper Mangrove Creek catchment as described in 1975 prior to the construction of the Mangrove Creek Dam ( Source: Where would you have put the dam? http://www.blueplanet.nsw.edu.au/SiteFiles/blueplanetnsweduau/Water%20History%20Case%20 Study.pdf ).

Freehold or Leasehold McPherson Vacant Zones of impact for Stage 1 (hectares) State Forest Unreserved of the Mangrove Creek dam Agriculture Forest (hectares) Crown Land (hectares) Stored waters 140 690 340 0 Within 0.8 km of stored waters 0 370 3310 0 Within 0.8 km to 3.2 km of waters 90 720 3210 740 Remainder of Catchment area 120 50 100 160

(“Land Use Planning for the Catchment of the Proposed Mangrove Creek Dam” ‘Report on Investigations for Water Supply to the Gosford-Wyong Region’, Report No 2, Sept 1975, Department of Public Works N.S.W (page 11))

Figure 3: Original land use within the Mangrove Creek Dam catchment area. (Source: “Environmental Impact of the Proposed Dam“, Volume 2, “Mangrove Creek Dam – Environmental Impact Statement” 1977, Gosford-Wyong Water Supply, NSW Department of Public Works.)

The Mangrove Creek Dam catchment is in excellent condition.

• The land comprises extensive undeveloped, uninhabited land which helps to maintain a pristine catchment area. • The site has a rock foundation. Areas with a sandy base are not suitable for dam construction. • The naturally V-shaped valley is the ideal storage with a small surface area compared to volume – which means evaporation at the site is low. • The dam site is located relatively close to all other water catchments – which minimises the costs associated with transfer pipelines and pumping stations.

One other catchment within the Central Coast supply with similar forested landscape Mangrove Creek Dam is the Dam catchment (39 km 2).

Lower Wyong River Weir

Wyong River Weir has a catchment (355 km 2) three times the size of that of Mangrove Creek Dam (Figure 4). The weir’s catchment consists of significant areas of agricultural land in contrast to the mainly forest land of the storage dam. Agricultural enterprises include cattle grazing, small scale horticulture and orchard enterprises, and turf production. Other features within the Wyong River catchment include the F3 highway and feeder roads, and the small rural villages of Dooralong, Jilliby and Yarramalong. The business park, airport and new suburbs in the Warnervale area are in the Porters Creek catchment which joins Wyong River below the Weir and so have no influence upon the water supply except during severe drought when water from the Porters Creek wetland has been pumped into the weir. Porters Creek wetland is a natural filter reducing the level of industrial contaminants entering Wyong River below the weir.

Land use Area % of (ha) total area State Forest 25077 54.60 Conservation Bushland 11842 25.77

Pasture 7349 15.99

Orchards 498 1.08

Powerline 449 0.98 Easements Water Supply 202 0.44 Turf 191 0.42 Farms Small Lot 82 0.17 Subdivisions Market Gardens 69 0.15 Intensive Animal 62 0.13 Husbandry Nurseries 46 0.10

Poultry 33 0.07

Villages 27 0.06 Community Facilities Roads 9 0.01

Quarries 6 0.01

Hydroponics 5 0.01

Figure 4: Land use in the Wyong River catchment west of the F3 freeway. Although this data was collected a decade ago land use has not changed significantly since that time. (Source: Wyong Valleys Study Planning Report, Wyong Shire Council, 1998).

The catchments for Lower Mangrove Creek Weir (140 km 2) and Ourimbah Creek Weir (88 km 2) resemble the Lower Wyong River Weir catchment in their mix of minor agricultural pursuits and low density settlement. Mardi Dam

Water from Lower Wyong River Weir is pumped to Mardi Dam, then to Mardi Treatment Plant, before being distributed for drinking. In dry times, water can be released from Mangrove Creek Dam through Boomerang Tunnel to the Wyong River and then for drinking water. Mardi Dam itself has a very small catchment of 4 km 2 of mainly Eucalypt bushland.

Potential Contaminants

Potential contaminants of drinking water are of four main types: inorganic nutrients (e.g. ions that contain phosphorus or nitrogen, often arising from agricultural land); organics and biologicals (e.g. manure and algae); potential toxins arising from industry, mining and agriculture (e.g. paints, herbicides and heavy metals like cadmium and lead); pathogenic organisms (e.g. coliform bacteria and Cryptosporidium ).

Runoff from undisturbed forest will carry twigs, leaves, ash, a small amount of organic topsoil, and very low levels of native animal manure depending on the intensity of the precipitation producing the runoff. These materials will be low in phosphorus and relatively low in nitrogen.

By contrast, runoff from agricultural land will have a range of extra components depending on the particular enterprise. From freshly cleared and cultivated farming land, runoff will usually contain soil materials especially after heavy rainfall events; clay and silt particles will be suspended in the runoff leading to high turbidity readings . From established horticultural crop land, runoff may be enriched by nutrients (e.g. phosphorus, nitrogen and potassium) derived from fertilisers and may contain pesticide and herbicide residues. Manure, carcases, and eroded soil materials from livestock country can be additional sources of nutrients and turbidity. Strict environmental controls are placed on dairy, pig and poultry industries to prevent manure reaching waterways.

New residential areas, industries, and transport infrastructure (highways and railways) have the potential to produce a lot of eroded soil materials during land clearing and construction. Once established, these areas can be sources of garbage, detergents, oils, greases, heavy metals and faecal coliform bacteria, arising if stormwater and sewage outflows are poorly managed.

Table 3 gives some idea of the potential nutrient outflow (N and P) from different land uses in Wyong Shire (but not necessarily located in the drinking water catchment areas).

Table 3: Typical nutrient pollution from different land uses in the Shire. (Source : Walkerden G. and Gilmour A. 1996, and Catchment AEAM Project Final Report, Wyong Shire Council, Wyong.)

Land Use Phosphorus export rate (kg/Ha/yr) Nitrogen export rate (kg/Ha/yr) Disturbed land 20.0 60.0 Mining 10.0 30.0 Septic residential 7.0 20.0 Intensive agriculture 5.0 10.0 Industry/commerce 3.0 8.0 Turf farms / golf 8.0 8.0 Sewered residential 1.5 7.5 Ash dams 1.5 7.5 Rural residential 0.6 4.0 Extensive agriculture 0.3 3.0 Forestry 0.4 1.5 Bushland 0.1 1.0 Wetlands 0.0 0.0

5. Water Treatment

Mardi Water Treatment Plant

Process Flow Chart

MARDI DAM

Flocculation Alum & Poly Chlorine Chamber

Sludge Backwash Filters Lagoons Water

Fluoride Outlet Structure Chlorine Hydrated Lime Ca (OH) 2

Clear Water Carbon Tank Dioxide

Distribution

• Water is pumped from dam to Treatment plant. Chlorine is added to oxidise dissolved materials. Alum and Poly-electrolyte are added to flocculate and coagulate suspended matter.

• The water is filtered through a mixed bed filter (anthracite, sand & gravel). Clean water passes to Outlet Structure. Chlorine is added for disinfection. Fluoride is added.

• Water passes towards “Clear Water Tank”. Lime is added for pH correction and corrosion protection. Carbon dioxide is added to neutralise excess lime and control pH whilst maintaining alkalinity for corrosion protection. Water then proceeds to distribution.

• Filters are periodically backwashed. This water and collected solids go to the Sludge Lagoons. Solids settle, and clarified water is recycled back to the Dam.

Mangrove Creek Dam and Mardi Dam water is treated as follows

1. Chlorine is added to oxidise unwanted dissolved materials and make the water more receptive to flocculating chemicals.

2. Liquid alum (Aluminium Sulphate) and Polyelectrolyte (Polyacrylamide) are added and mixed to flocculate and coagulate the suspended particles.

3. The water containing the flocculated particles is then:- a. For Gosford Water Treatment Plant - settled in a sedimentation channel where the bulk of the flocculated particles fall to the bottom. The clearer top layer is then filtered through a bed of gravel, sand and anthracite. b. For Wyong Water Treatment Plant, filtered directly through gravel, sand and anthracite.

4. After filtration, the water is further chlorinated to disinfect it. It is then:- a. For Gosford , fluoridated for prevention of teeth decay, and adjusted for pH using soda ash to minimise corrosion in the system.

b. For Wyong , fluoridated for prevention of teeth decay, and pH corrected using lime and carbon dioxide for corrosion protection.

5. Water is then distributed to a series of roofed reservoirs before further distribution to consumers.

Reduction of risk of infection is achieved firstly by filtration where much of the bacteria are held back and all larger parasites such as Giardia and Cryptosporidium . Secondly, after filtration, the chlorination kills any bacteria which may still survive. These two processes are the main contributors to reducing the risk of infection. Roofing of storage reservoirs assists in providing a safe storage of treated water so that no re-contamination will occur by exposing the water to birds and atmospheric fallout.

Water quality is enhanced by chlorination, coagulation, flocculation and filtration; causing nuisance dissolved materials such as iron and manganese to be minimised and at the same time dirt and organic materials to be removed, enhancing colour and clarity. The pH correction minimises corrosion in the system: such corrosion could otherwise lead to the dirty appearance of water, to the staining of household fittings, baths and sinks, and to the spoiling of laundry processes resulting in the spotting of washed clothes.

6. Chemical tests for levels of different types of contaminants

A typical analysis of treated water within the distribution network of Wyong Shire is shown in Table 4.

Table 4: Typical physical and chemical analysis of Wyong Shire treated water 2008 and its relationship to the 2004 NH&MRC Guidelines. (Source: Wyong Shire Council) 2004 NH&MRC Guidelines Parameter Units WSC Health Aesthetic A: Physical Characteristics pH 7.9 N/A+ 6.5 – 8.5 Hardness mg/L as CaCO 3 60.6 N/A 200 Total Dissolved Solids mg/L 168 N/A 500 Conductivity uS/cm 280 True Colour Hazen Units 1.4 N/A 15 Turbidity NTU 0.28 N/A+ 5 Alkalinity mg/L as CaCO 3 34 N/A B: Inorganic Chemical Characteristics Acrylamide mg/L ND 0.0002 Aluminium mg/L 0.071 N/A+ 0.2 Ammonium mg/L * N/A+ 0.5 Antimony mg/L ND 0.003 Arsenic mg/L <0.001 0.007 Asbestos mg/L * N/A+ Barium mg/L 0.047 0.7 Beryllium mg/L * N/A+ Boron mg/L .06 4 Cadmium mg/L ND 0.002 Calcium mg/L 15.6 N/A Chloride mg/L 68 N/A 250 Chromium mg/L ND 0.05 Copper mg/L 0.102 2 1.0 Cyanide mg/L ND 0.08 Fluoride mg/L 0.95 1.5 Hydrogen Sulphide mg/L * N/A+ 0.05 Iodide mg/L 0.050 0.1 Iron mg/L 0.072 N/A+ 0.3 Lead mg/L 0.002 0.01 Magnesium mg/L 5.2 N/A Manganese mg/L 0.007 0.5 0.1 Mercury mg/L ND 0.001 Molybdenum mg/L ND 0.05 Nickel mg/L ND 0.02 Nitrate as NO3 mg/L 0.965 50 Nitrite as NO2 mg/L ND 3 Selenium mg/L ND 0.01 Silver mg/L ND 0.1 Sodium mg/L 35.3 N/A 180 Sulphate mg/L 15.2 500 250 Tin mg/L * N/A Zinc mg/L 0.038 N/A+ 3 * Not routinely tested by NSW Health based on potential for presence in source waters or less than detectable quantity. N/A No health based guideline value considered necessary by NH&MRC N/A+ Insufficient data to set a guideline based on health considerations. C: Disinfection By-Products and Disinfection Agents Chlorine mg/L <0.2 5 0.6 Carbon Tetrachloride mg/L ND 0.003 Trihalomethanes mg/L 0.093 0.250 No other disinfection agents or by-products have been determined or detected. D: Organic Compounds Not tested by NSW Health. Sources for compounds listed in Guidelines unlikely to occur in catchment E: Pesticides No pesticides detected at any time in OC, OP, CPA, Triazine/Phenylurea and Glyphosate groups F: Micro-organisms 1. Routine E. coli 416 samples p/a returned a 99.3% compliance rate. 6 samples/week for 100,000 persons plus 1 sample/month per additional 10,000 persons; 98% of WSC Guideline scheduled samples should be free of thermotolerant coliforms ( E. coli ) .Action should be taken if any presence detected. Number of organisms is irrelevant. 2. Non-routine Giardia and Cryptosporidium No organisms detected to date. Tested monthly since July, 1998 No guideline values. If detected, advice to be sought from relevant health authority.

On the Central Coast, potable water (i.e. water supplied for drinking purposes) is very safe for human consumption. Levels of all inorganic substances are well below the 2004 NH&MRC Guidelines health risk thresholds (see Table 4). Samples from the Wyong Shire distribution system in 2008 were completely free of Giardia and Cryptosporidium micro-organisms in regular monthly samplings. Based on analysis of 416 water samples over a one year period, tests for Escherichia coli bacteria returned a 99.3% compliance rate.

In summary, as far as human health is concerned, drinking water on the Central Coast is of very high quality. The aesthetic quality of Central Coast potable water is also very high but with some variation across seasons and localities within the network.

As with all water supplies, potable water on the Central Coast contains small amounts of naturally occurring minerals such as calcium, magnesium, iron and manganese. Without these substances the water would taste bland. The Central Coast water is considered soft because the concentration of calcium and magnesium is relatively low. This is because the geology of the catchments is dominated by sandstone and other sedimentary rocks.

After filtration at the Somersby and Mardi treatment plants, low levels of chlorine are added to protect the water as it travels to our homes.

The water is also fluoridated, in line with the policy of the NSW Department of Health. Water fluoridation ensures improved dental health for the entire community, regardless of a person's age, income, level of education, or ability to get dental care. A constant supply of low level fluoride can reduce the amount of cavities in children's baby teeth by as much as 60 per cent and in adults' teeth by nearly 35 per cent. At the Somersby water treatment plant, in Gosford Shire, hydrofluosilicic acid is added with precision to the water supply in liquid form through dosing pumps at a rate of 1.0 ppm. Hydrofluosilicic acid is a colourless, tasteless and odourless liquid. The dosed water is then continually monitored to ensure fluoride levels remain within the optimal concentration range. At the Mardi water treatment plant, in Wyong Shire, fluoridation is carried out by feeding sodium silicofluoride into a slurry tank and then metering it into the flow to the Clear water Tank.

The quality of water supplied to customers is regularly tested by Gosford and Wyong councils and by independent, National Association of Testing Authorities (NATA) registered, laboratories to ensure this water complies with the Australian Drinking Water Guidelines (ADWG). Tests are regularly conducted on aesthetic and health criteria to ensure the water meets the ADWG and is safe for human consumption. Most water quality concerns reported by customers are related to appearance, taste and odour and are not a health issue.

Appearance

Although town drinking water supplies are generally colourless, from time to time the water's colour can change. Sometimes, it can take on a yellow or reddish/brown to almost black tint, while other times it can appear milky white or blue. This is known as discoloured water.

Incidents of discoloured water are more common during summer and periods of high demand, in low-lying areas, suburbs at the furthest end of the water supply system, dead-ends and in areas that normally experience low velocities.

Until recently, the incidence of discoloured water in Gosford was increasing. This was, in part, due to the severe and ongoing drought which restricted Gosford Council's normal mains cleaning programs that remove accumulated materials from the water supply system.

In December 2007, Gosford Council launched an integrated program called Water Quality 2010 (see below) to minimise discoloured water events and the effects they have on the community.

Taste and Odour

The taste and odour of water can vary from tap to tap and can be impacted by naturally occurring minerals, Council treatment processes and internal plumbing. Personal likes and dislikes also influence the perception of taste and odour.

Some of the common taste and odour complaints are listed below.

Chlorine

Councils add chlorine to the water supply at the water treatment plants to remove harmful bacteria and protect water quality. A small residual of chlorine is generally present in drinking water once it reaches your tap and from time to time you may notice a slight chlorine taste or smell. Council carefully controls and monitors this process to ensure the residual poses no risk to health.

The consumer can eliminate the taste and smell of chlorine of drinking water by placing it in a covered jug in the refrigerator. It is recommended that this water be consumed within 24 hours. Domestic water filters or jug filters are also useful.

Musty, mouldy or earthy

Musty tastes and odours in drinking water can be caused by organic growth within water pipes.

Mould and bacteria can breed in internal plumbing when certain jointing compounds are used for domestic fittings or appliances, or when cold water pipes pass closely to hot water pipes that are not insulated.

Water pipes in areas of the supply system with low flow rates can also create an environment for organic growth.

Rust and metal

Drinking water with a rusty or metallic taste generally contains excessive iron, manganese and other metals. When these materials are present in high levels, a change in the colour of the water is also apparent.

Treatment processes remove naturally occurring iron and manganese from the water supply. However, as the water moves through the system to your tap, it may pick up material from corroding pipes not lined with cement. This may change the taste of your drinking water.

A rusty or metallic taste can also occur if the internal pipes of a household are corroded. When house plumbing is corroded, water may appear clear at first, but then turn rusty or black in a few minutes.

Rotten egg smell

Rotten egg gas - hydrogen sulfide - is typically caused by decay of organic matter or chemical reactions in your plumbing, or by bacteria which change naturally occurring sulfates into hydrogen sulfide. These bacteria can be present in the water supply system, groundwater or hot water systems.

If the smell only comes from your hot water tap, there may have a problem with your hot water system. However, if the smell is strong from both hot and cold water taps when they are first turned on and diminishes after the water has run, the bacteria are probably in the water supply system. In the Wyong Shire, there is no problem of hydrogen sulfide in the town water supply

Fluoride

The taste and smell of drinking water does not change as a result of water fluoridation because the type of fluoride used to fluoridate the water supply has no taste or smell.

Household Water Quality

The quality of water delivered to your home can be affected by the nature of pipes inside your property. This is particularly so if you have corroding galvanised pipes.

While Gosford and Wyong Councils accept responsibility for the maintenance, repair and renewal of the water supply system up to the water meter on a property, it is the responsibility of homeowners to maintain the plumbing and draining on their own properties. This includes all fittings, pipes and rainwater tanks.

It is highly recommends that a licensed plumber carry out any plumbing work required within your property. The plumber should also provide the owner with a Certificate of Compliance once the work is completed, particularly for work valued at over $500.

Gosford City’s ‘Water Quality 2010’ to reduce the Incidence of Discoloured Water

Water Quality 2010 is a multi-million dollar drinking water quality management program. Launched in 2007, the main aim of the program is to reduce the incidence of discoloured water throughout the Gosford City area. In September 2008, the Federal Government announced a $4.5 million funding commitment in support of the capital works component of the program.

Capital works include improvements at the Somersby water filtration plant, upgrades to reservoirs, and refurbishment of pipelines, and as well as upgrades to the facilities for monitoring and analysing water quality.

Improvements to the Water Filtration Plant at Somersby include:

• Construction of a lime and carbon dioxide dosing system to stabilise the treated water; buffering it against pH changes in the system and minimising the corrosion of cement- lined pipes. • Construction of a potassium permanganate dosing system to facilitate manganese removal from the water, thereby minimising the amount of discoloured water-causing material entering the water supply system. • Construction of a pre-chlorination system to provide an additional barrier assisting in the removal of manganese from the water. • Installation of a facility to remove wastewater containing high iron and manganese levels from the treatment process.

Improvements to the Reservoirs include: • Replacement of corroded ladders. • Refurbishment of roofing and bird-proofing. • Replacement of roof hatches where gaps in roofing are present. • Installation of devices to encourage mixing within the reservoir.

Improvements to Pipelines include: • Installation of pipe-work and valves to facilitate cleaning of large trunk mains between Somersby and North Gosford, and between Kariong and Woy Woy. • Replacement of unlined valves and hydrants in the Peninsula.

Other possible improvements may include removal of dead ends in water mains and creation of supply zones in areas where complex networks of pipes exist so as to improve water velocities through the pipes.

Upgrades to Monitoring facilities include: • Flow-meters installed in key locations throughout the system. • Installation of new in-line monitoring equipment to provide information on water quality at key locations in the system and act as early warning systems for water quality issues. • New portable monitoring equipment to allow water quality investigations at specific properties. • New laboratory analysis equipment. • New field sampling equipment.

7. References for Further Study

1. A comprehensive list of websites for this topic within the HSC Year 12 Chemistry syllabus is available from Curriculum Information (http://www.blueplanet.nsw.edu.au/templates/blue_content.aspx?edit=false&pageID=558 )

2. Specific Water Information on the BluePlanet website of direct relevance to this topic include:

Water Infrastructure on the Central Coast (http://www.blueplanet.nsw.edu.au/templates/blue_content.aspx?edit=false&pageID=447 )

Types of Water (http://www.blueplanet.nsw.edu.au/templates/blue_content.aspx?edit=false&pageID=516 )

Water Usage (http://www.blueplanet.nsw.edu.au/templates/blue_content.aspx?edit=false&pageID=518 )