Eurobodalla
Indicator: Discharge to Waters
Results for this indicator are also available for [an error occurred while processing this directive]
Please note: Text or data highlighted in this colour represent an update to this indicator for the period 2008/09.
What the results tell us for Eurobodalla
Most effluent generated within Eurobodalla Shire is treated at one of five sewage treatment plants in Narooma, Batemans Bay, Moruya, Tomakin, and Tuross. Each treatment plant is licensed by the New South Wales (NSW) Department of Environment and Climate Change (DECC) to discharge treated effluent into nearby streams, estuaries and the sea.
The Sewage Treatment Plants have the following discharges and licence conditions:
- Batemans Bay treatment plant discharges via an ocean outfall off the rock shelf adjacent to Surf Beach, south of Batemans Bay township and a portion is also recycled to the Catalina Country Club. It has a maximum volume daily limit of 25,000 KL/day.
- Moruya treatment plant is discharged to Ryan's Creek, which flows into the Moruya River, and also recycles some of the discharge to the Moruya Golf Club and Moruya High School. It has a maximum volume daily limit of 14,000 KL/day.
- Narooma treatment plant discharges via a submerged ocean outfall pipe off a rock shelf at Kianga (240m east of Dalmeny Drive Bridge). It has a maximum volume daily limit of 20,000 KL/day.
- Tomakin treatment plant discharges via a submarine outfall pipe at Long Noise Point to the sea. It has a maximum volume daily limit of 14,000 KL/day.
- Tuross sewage treatment plant discharges via sand exfiltration ponds at the rear of dunes at Bingie Beach. The plant also recycles some of the treated discharge to Tuross Head Country Club. It has a maximum volume daily limit of 7,000 KL/day.
Comprehensive details for Eurobodalla Shire Council can be viewed at the National Pollutant Inventory website. This website shows that four of the five sewage treatment plants contribute 12.9% of the emissions in the Shire Council (Figure 1). This figure is primarily made up from the 21,000 Kg/year of Total Nitrogen and the 17,000 Kg/year of Total Phosphorus.
Figure 1. Eurobodalla Shire Top Sources
Source: National Pollutant Inventory
In 2005-06, the Batemans Bay sewage treatment plant went into bypass mode once, which resulted in the treatment processes being bypassed, due to storm event inflows. During the same year, the total nitrogen and total phosphorus loads discharged from the treatment plant exceed the limits in the licence on one occasion. The nutrient load limits were also exceeded in 2004-05, however this was caused by increased hydraulic load from catchment growth.
The Moruya treatment plant exceeded the 90 percentile limit for the total phosphorus on seven occasions during 2004-05, due to a defective alum dosing pump, and again in 2005-06 on two occasions.
The Narooma sewage treatment plant also went into bypass due to wet weather in 2005-06. The bypass skipped the inlet and flowed the raw sewage straight to the tertiary pond, as per the design.
The Tomakin treatment plant undertook emergency repair and maintenance works to the tertiary pond in 2005-06, which resulted in the diversion of the treated effluent from the clarifier to the outfall. The plant inflow meter also recorded an inflow of 2,200 KL which was likely to generate a discharge of greater than the maximum daily volume on 23 October 2004.
The Tuross sewage treatment plant discharged effluent without intermittent decant process and exceeded the 100 percentile concentration of the BOD, both due to a faulty decant weir gearbox, on 3-5 October and 2 November 2004 respectively.
Accidental discharges will periodically occur in a gravity sewage system. These discharges are typically caused by:
- blockages in the pipeline, caused by tree roots, debris, fat etc;
- the collapse of a pipeline;
- an under-capacity sewage network, specifically when the flows increase during wet weather; and
- the failure of mechanical or electrical assets where standby equipment either does not operate or lacks capacity to handle the sewage flows within the system.
Between 2004-05 and 2007-08 a number of accidental discharges from treatment plants were recorded in the shire. These discharges per year are shown in Table 1. While discharge volumes are known, the total mass loads of nitrogen and phosphorus are not.
| Period | Volume (mL/year) | Type | Estimated accidental discharge (L/year) | Receiving waters | Mass load (kg) | |
|---|---|---|---|---|---|---|
| Nitrogen | Phosphorus | |||||
| 2004–05 | 0.112 | Sewage | 112,000 | Pacific Ocean | Unknown | Unknown |
| 2.560 | Sewage | 2,560,000 | Waterway | Unknown | Unknown | |
| 0.005 | Sewage | 5000 | Beach | Unknown | Unknown | |
| 2005–06 | 0.130 | Sewage | 130,000 | Pacific Ocean | Unknown | Unknown |
| 0.902 | Sewage | 902,250 | Waterway | Unknown | Unknown | |
| 0.002 | Sewage | 2200 | Beach | Unknown | Unknown | |
| 2006–07 | 3.524 | Sewage | 3,524,160 | Pacific Ocean | Unknown | Unknown |
| 10.183 | Sewage | 10,183,320 | Waterway | Unknown | Unknown | |
| 2007–08 | 1,015 | Sewage | 1,015,700 | Waterway | Unknown | Unknown |
| 0.289 | Sewage | 289,500 | Beach | Unknown | Unknown | |
| 2008-09 | 0.058 | Sewage | 58,100 | Waterway | Unknown | Unknown |
Source: Eurobodalla Shire Council
Beach Closures
Over the reporting period there were a number of beach closures due to sewage surcharges:
- 2004-2005: five closures
- 2005-2006: six closures
- 2006-2007: four closures
- 2007-2008: fourteen closures
- 2008-2009: four closures
Beach closures can also result from other causes. On one occasion, a significant burst water main in George Bass Drive, near Towrang Avenue caused significant discolouration of the Ocean off Surf Beach, with resulting significant urban-based contamination. This resulted in the beach being closed.
The Shire Council has also included a precautionary category in its sewage surcharge (sewage flows) reporting format. The new category ‘threatening major’ includes any surcharge that, although not obvious, may have entered a waterway or caused a health threat. Major cleaning of the site occurs immediately, but the consequence of any environmental influence is confirmed in the laboratory, with samples of the receiving waters being analysed and reported within 24 hours.
The analysis either confirms the incident as a ‘major’ or ‘minor’ incident, to allow correct reporting procedures to follow. As a precautionary measure the Health Officer immediately closes the beach. Once determined, major incident sites have the ‘sign-posted’ measure maintained for public awareness, while further recovery operations and sampling takes place. Minor incident have the ‘sign posting’ removed following receipt of the official result. This temporary period, between closing the beach with immediate ‘signage’ at the time of the incident and finding that contamination had not taken place, remains as a ‘beach closure’ in the reporting, but not as a major surcharge event on Shire Council’s records.
On ten occasions, in 2007-08, following the results of the initial bacterial testing, it was discovered that the sewage did not contaminate the waterway and the incident was downgraded from a ‘Threatening Major Incident’ to a ‘Minor Incident’.
On five occasions, in 2007-08, sewer discharged during dry weather periods as a result of tree root infestation, which is becoming a significant influencing contributor, after eight successive periods of drought or near drought conditions. Shire Council operates a significant ‘root cleaning’ program, with extended periods of sewer jet flushing, to cut tree roots from the pipe work. It is noticed that pipe work is becoming more vulnerable to tree root infestation, as significant deep ground drying takes place with current long-term dry weather events. This results in ground shrinkage with subsequent re-swelling once rainfall takes place. Ground movements at this depth cause undue stress on pipe work and maintenance access points, which then causes asset cracking, opening the possibility for hairline sized tree roots to penetrate and swell to gorge on the water and nutrients from the system.
On one occasion, in 2008-09, sewer discharged as a result of a sediment pond at a construction site discharging stormwater to the sewer reticulation system during a storm event. Investigation revealed that an old sewer connection at the site had not been effectively sealed resulting in the uncontrolled stormwater discharge to sewer causing the sewer system to surcharge to the ocean adjacent to a boat ramp. A Penalty Infringement Notice was issued to the offending construction company.
Eurobodalla Shire continues to experience accidental sewer surcharges to the environment. Major infrastructure improvements are underway which are aimed at reducing the pressures within the system which are leading to overloads and increased risk of spill in some areas. For instance the diversion mains which will see a redirection of sewage from the Surf Beach to the Tomakin Treatment plant are expected to come into operation in 2010-11 and will significantly reduce the pressures within the system.
While these major works are underway Eurobodalla Shire has continued to focus efforts on improvements to ability of the system to cope with surcharges. In recent years the construction of detention structures have meant that when a spill occurs, the impact on the environment and public health is reduced. Improved targeted maintenance programs and more recently the introduction of ongoing pre-emptive rather than breakdown maintenance should also provide improved performance.
In 2003, Shire Council adopted a Liquid Trade Waste Policy and commenced implementation of Liquid Trade waste charges from 2003-04 to minimise discharge of pollutants to the environment via the sewer system.
All businesses connected to the sewer were assessed to determine their trade waste discharges and assigned discharge factors in accordance with DIPNR and IPART guidelines. Those factors are based on the volume and type of trade waste discharged into the sewer. At 30/6/08 there were 437 businesses subject to the liquid trade waste charge.
The trade waste charges were phased in over a three year period from 2003-04 with charges per kilolitre moving from 80c to $1.00 to $1.20 during that time. A much higher charge of $11 per kilolitre applies to discharge from non compliant users. Initial inspections undertaken in 2003-04 assisted identification of business types and appropriate discharge factors. Subsequent inspections to assess compliance are conducted regularly. There is only one customer classified as non compliant and Shire Council continues to work with this customer to improve the environmental performance to elevate the status to full compliance.
Sewage Management
Volumes of treated effluent including mass loads of nitrogen and phosphorus discharged over the reporting period are shown in Table 2 for the Narooma, Batemans Bay, Moruya, Tomakin and Tuross Head Sewage Treatment Plants.
Annual total mass loads of nitrogen and phosphorus varied between treatment plants and between years over the reporting period. There were no consistent trends in changes to nitrogen and phosphorus loads over the reporting period from any of the treatment plants (Table 2).
| Licensed/ unlicensed |
Volume (ML/year) | Type | Estimated volume discharged in excess of license limit (L/year) | Estimated volume discharged accidentally (L/year) | Receiving waters | Mass load of nitrogen (kg) | Mass load of phosphorus (kg) |
|---|---|---|---|---|---|---|---|
| 2004–05 | |||||||
| Licensed | 648 | Effluent – Narooma STP | Nil | Nil | Pacific Ocean | 2032 | 5357.5 |
| Licensed | 1573 | Effluent – Batemans Bay STP | Nil | Nil | Pacific Ocean | 18457.5 | 13704.7 |
| Licensed | 260 | Effluent – Moruya STP | Nil | Nil | Ryan’s Creek & Moruya Golf Club | 744.2 | 470.7 |
| Licensed | 326 | Effluent – Tomakin STP | Nil | Nil | Pacific Ocean | 1508 | 3116 |
| Licensed | 224 | Effluent – Tuross Head STP | Nil | Nil | Sand Dune | 2843.6 | 2076.2 |
| 2005–06 | |||||||
| Licensed | 503 | Effluent – Narooma STP | Nil | Nil | Pacific Ocean | 1758 | 4913 |
| Licensed | 1527 | Effluent – Batemans Bay STP | Nil | Nil | Pacific Ocean | 18381 | 15002 |
| Licensed | 190 | Effluent – Moruya STP | Nil | Nil | Ryan’s Creek & Moruya Golf Club | 898 | 189 |
| Licensed | 301 | Effluent – Tomakin STP | Nil | Nil | Pacific Ocean | 1984 | 2946 |
| Licensed | 171 | Effluent – Tuross Head STP | Nil | Nil | Sand Dune | 2364 | 1775 |
| 2006–07 | |||||||
| Licensed | 623 | Effluent – Narooma STP | Nil | Nil | Pacific Ocean | 3236 | 4687 |
| Licensed | 1584 | Effluent – Batemans Bay STP | Nil | Nil | Pacific Ocean | 22352 | 12824 |
| Licensed | 172 | Effluent – Moruya STP | Nil | Nil | Ryan’s Creek & Moruya Golf Club | 1379 | 94 |
| Licensed | 341 | Effluent – Tomakin STP | Nil | Nil | Pacific Ocean | 1280 | 2425 |
| Licensed | 201 | Effluent – Tuross Head STP | Nil | Nil | Sand Dune | 2395 | 2304 |
| 2007–08 | |||||||
| Licensed | 563 | Effluent – Narooma STP | Nil | Nil | Pacific Ocean | 1712 | 4986 |
| Licensed | 1542 | Effluent – Batemans Bay STP | Nil | Nil | Pacific Ocean | 14578 | 12037 |
| Licensed | 180 | Effluent – Moruya STP | Nil | Nil | Ryan’s Creek & Moruya Golf Club | 1759 | 93 |
| Licensed | 355 | Effluent – Tomakin STP | Nil | Nil | Pacific Ocean | 996 | 2438 |
| Licensed | 228 | Effluent – Tuross Head STP | Nil | Nil | Sand Dune | 1806 | 2341 |
| 2008–09 | |||||||
| Licensed | 501 | Effluent – Narooma STP | Nil | Nil | Pacific Ocean | 1224 | 4102 |
| Licensed | 1518 | Effluent – Batemans Bay STP | Nil | Nil | Pacific Ocean | 11842 | 11019 |
| Licensed | 245 | Effluent – Moruya STP | Nil | Nil | Ryan’s Creek & Moruya Golf Course | 1485 | 78 |
| Licensed | 386 | Effluent – Tomakin STP | Nil | Nil | Pacific Ocean | 823 | 2701 |
| Licensed | 214 | Effluent – Tuross Head STP | Nil | Nil | Sand Dune | 1319 | 1873 |
Source: Eurobodalla Shire Council
About the data
Information was supplied by Eurobodalla Shire Council. Additional information was obtained from the NSW Department of Environment and Climate Change’s public register of protection licences.
References
DECC – see Department of Environment and Climate Change
Department of Environment and Climate Change NSW (2008), Public Register for Licences, Applications or Notices, Environment Protect Licence, Section 55 Protection of the Environment Operations Act, viewed at http://www.environment.nsw.gov.au/prpoeoapp/searchregister.aspx on 24 September 2008.
Department of the Environment, Water, Heritage and the Arts (2008) National Pollutant Inventory, Commonwealth of Australia, viewed at http://www.npi.gov.au on 25 September 2008.
