Bega Valley
Indicator: Discharge to Waters
Results for this indicator are also available for [an error occurred while processing this directive]
What the results tell us for Bega Valley
Effluent generated in the urban areas of Bega Valley Shire is treated at one of ten sewage treatment plants in Bega, Merimbula-Pambula, Bermagui, Tathra, Tura Beach, Eden, Wolumla, Cobargo, Candelo and Kalaru. Effluent generated in rural areas of Bega Valley Shire is treated in on-site systems. Various systems including transpiration beds, septic tanks and composting toilets are used in rural areas across the shire.
Annual total mass loads of nitrogen and phosphorus vary between treatment plants and between years during the reporting period. There were no consistent trends in changes to nitrogen and phosphorus loads over the period in treated effluent from the treatment plants.
The New South Wales (NSW) Department of Environment and Climate Change (DECC) regulates most sewage treatment systems owned by state and local government. In the Bega Valley, DECC has issued a number of licenses relating to discharge to waters from treatment plants:
- the Bega Sewage Treatment Plant is licensed to discharge via pipe from the third oxidation pond leading to Rixon’s effluent lagoon. The plant is licensed to discharge the overflow from Rixon’s effluent lagoon to Bega River at a maximum daily rate of 2,500 KL/day.
- the Bermagui Sewage Treatment Plant is licensed to discharge from the effluent pit to the ocean outfall at the rock platform on the southern end of Beares Beach, with a maximum daily volume of 1,200 KL/day. The treatment plant is also licensed to discharge from the effluent pit to Bermagui Country Club Golf Course to the effluent storage dam.
- the Eden Sewage Treatment Plant and Associated Network is licensed to discharge to the ocean outfall on the northern headland of Yallumgo Cove at Eden. The plant is also licensed to discharge from the balance pond to Eden Golf Course. The plant has a maximum daily volume of 2,000 KL/day.
- the Merimbula Sewage Treatment Works is licensed to discharge the ocean outfall at Merimbula Beach and to the golf course pump shed on Pambula Golf Course. The maximum daily volume for this plant is 3,000 KL/day.
- the Tathra Sewage Treatment Plant is licensed to discharge to an utilisation area from the chlorine contact tank, with a maximum daily volume of 200 KL/day.
- Tura Beach Sewage Treatment Plant and Associated Network is licensed to discharge from final detention pond to exfiltration trenches located in sand dunes adjacent to the golf course. The plant is also licensed to discharge from the final detention pond to the Tura Beach Country Club’s irrigation system. A maximum daily volume of 500 KL/day applies.
DECC issues non-compliance reports where a treatment plant exceeds its operating licence. For example, in 2004-2005, the Bega plant exceeded the maximum daily volume on three occasions with infiltration following a large storm, and a valve opened that was operated manually by a dairy. The maximum daily volume was also exceeded once in 2005-06 for concentration limits of total suspended solids and Biochemical Oxygen Demand. No other non-compliance reports were available for the rest of the reporting period.
The Tathra plant had one non-compliance report in 2004-05, where it did not measure the daily volume discharging from the plant on 5 occasions, due to construction work on the sewage treatment plant, a faulty meter, and the meter being hit by lightening.
The Tura Beach plant exceeded the volume limit on 364 occasions during 2004-05. The non-compliance notices states plant upgraded as a part of the Bega Valley Sewage Program, however the volume limit was 271 occasions in 2005-06. No non-compliance reports were available for 2006-07 and 2007-08.
The Bermagui, Merimbula and Eden plants had no non-compliance reports available for the entire reporting period.
During the reporting period Council also completed the Bega Valley Sewerage Program (see Bega Valley Snapshot). This program completed the construction of new sewerage treatment plants at Wolumla, Cobargo, Candelo and Kalaru as well as upgrades to the Merimbula, Tura Beach, and Tathra Plants, reconstruction of the Bega Plant and the provision of sewerage to Fairhaven, Beauty Point and Wallaga Lake Heights. The Wolumla, Cobargo, Kalaru and Candelo plants are regulated by the DECC though not licensed. All four plants have effluent reuse schemes as well as approved discharges to the environment. Data regarding discharges to waters from the four new plants will be available for reporting in the next state of environment report.
Council maintains a database of all unlicensed discharges from the sewerage reticulation system across the Shire. In most cases it is though very difficult to distinguish from the database if the discharge has effected waters. Unlicensed discharges and overflows to streets largely in the urban areas of Bega Valley did occur in the reporting period and undoubtedly some of these did impact waters. All discharges are investigated by Council Engineering and Environmental staff and events where there is a likely impact on the environment are also separately reported to DECC. Council reports that over the last two years of the reporting period, there were a decreasing number of unlicensed accidental discharges, as well as the volumes discharged. This is clearly demonstrated in Table 1.
| Year | Licensed/ unlicensed |
Type | Estimated volume discharged illegally (L/year) | Estimated volume discharged accidentally (L/year) | Receiving waters | Mass load of nitrogen (kg) | Mass load of phosphorus (kg) |
|---|---|---|---|---|---|---|---|
| 2004/05 | Unlicensed | Sewerage | Nil | 93,726 | Street | 7 | 1.2 |
| 2005/06 | Unlicensed | Sewerage | Nil | 555,286 | Street | 84 | 14.4 |
| 2006/07 | Unlicensed | Sewerage | Nil | 300,862 | Street | 25 | 3.9 |
| 2007/08 | Unlicensed | Sewerage | Nil | 59,801 | Street | 3.5 | 0.6 |
Source: Bega Valley Shire Council
The Shire Council has committed funds towards further investigation of sewer overflows across all six of Councils sewerage systems, in Bega, Tathra, Bermagui, Merimbula, Eden and Tura Beach. The investigations were based on three years of sewer choke records. The investigation resulted in a risk based approach to inspections of assets within catchments of high and significant risk overflows. As a result of these investigations, the Shire Council has planned maintenance schedules for all pipelines, manholes, pump stations and the sewerage treatment plants, including planned renewals of the assets. The Shire Council anticipates that the downwards trend in the number and volume of sewage discharges will continue into the future.
In addition the study caused enhancements to incident information management systems and provided for augmentation works to increase the capacity of the system to convey wet weather flows. All likelihood classifications for overflows and sewer chokes as well as impact classifications used in the investigation and report were based on DECC’s Risk Matrix system.
This Risk Management system is based on pipeline and manhole inspection programs, pipeline cleaning and repair, manhole cleaning and repair, sewer pump station planned maintenance, and pipeline and non pipeline asset renewals. In addition a CCTV investigation has been undertaken and future CCTV is planned as a part of the asset inspection program.
Unlicensed 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.
The Shire Council has developed in conjunction with DECC a protocol that specifies the roles and responsibilities for the Shire Council’s staff in responding to any such unlicensed discharges. The Shire Council responds to all incidents in line with the protocol and actions to protect public and environmental health are assessed as necessary. All accidental discharges are reported to DECC.
Comprehensive details for Bega Valley Shire can be viewed at the National Pollutant Inventory website.
Trade Waste
Bega Valley Shire Council issues trade waste approvals for all new developments that generate trade waste. However, the Shire Council currently has approximately 300 commercial and industrial premises that discharge trade waste to the Shire Council’s sewerage system without a trade waste approval.
Current levels of resourcing of this aspect of the Shire Council’s sewage management system is insufficient to retrospectively assess these premises, quantify and classify the discharge, and ensure better regulatory outcomes. Council could place a higher priority on the regulation of existing trade waste discharges.
About the data
Information was supplied by Bega Valley Shire Council. Additional information was obtained from the DECC’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 3 October 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.
DEWHA - see Department of the Environment, Water, Heritage and the Arts
