To Release or Not to Release?
The Australian climate presents substantial challenges to water and wastewater industry operators. Our weather events can be quite extreme, especially in Queensland, where 87% of the state was drought-declared just weeks before Cyclone Debbie made landfall.
Shrewd operators know that keeping an eye on the weather forecast is vitally important, especially if their treatment plant relies on irrigation for release of treated effluent to the environment. Balancing storage pond volumes during extreme wet weather can be tricky. It all comes down to a balance of how much water enters storage (ponds, dams, or tanks), and how much can be released. Licence conditions will stipulate that irrigation cannot occur if there’s a risk of surface runoff, which is invariably the case with a decent drop of rain. The conditions will also restrict operators from releasing treated effluent or sewage outside of their irrigation area (unless some other licensed off-site disposal option is available).
So, what’s the best way to build a contingency plan to deal with an extreme wet weather event?
The calm before the storm
The sooner a storm is anticipated, the sooner it can be prepared for.
- Storage volumes should be reduced to a minimum by irrigating the maximum allowable volume (assuming the weather is still fine).
- Ensure to keep in accordance with all licence conditions, including for water quality and surface ponding. In some cases, a vacuum truck might be the best option for taking effluent off-site if access permits.
- Any irrigation management plans should be referenced, and a suitable plan if not already documented can be made for the specific event.
- If there’s a chance that an incidental release might occur, it goes without saying that your management staff should be notified.
- Furthermore, a temporary emissions licence (TEL) can be sought from the Department of Environment and Heritage Protection (DEHP). The TEL can provide an allowance to irrigate during extreme wet weather events (possibly to an alternate release point), which can be crucial to saving plant infrastructure such as earthen dams and ponds from reaching capacity and potentially over topping.
- Pumps and valves should be checked and determined to be problem-free before rainfall lands. This would also include spare pumps as these may need to be deployed to control an unauthorised release as well as being prudent backup.
The wet weather event
During the wet weather event, there’s usually a short timeframe to make key decisions on how to prevent or minimise environmental harm. This is the general environmental duty of any operator, and they must keep this in mind. Proper planning before the storm can assist in decision-making to avoid or minimise harm.
To avoid or minimise environmental harm and unauthorised releases of effluent, proactive decision-making should consider:
- The safety of on-site personnel and downstream neighbours as well as livestock;
- Risk of pond failure if overflowing occurs (i.e. releasing the full pond volume; typically, the licence will require a minimum freeboard to prevent pond instability);
- Where the effluent could ultimately end up (e.g. unused land on site, neighbouring lot, creek system).
If there’s no time to prepare for the event, these factors will have to be considered on the fly.
Keeping the storage volume from overtopping might be the main priority to both prevent failure and prevent an uncontrolled release (with the volume released being an estimate only). A potential solution could be to deploy pumps and lay-flat hose from the dam and release water away from sensitive receptors, such as creeks or wetlands, if possible. This is especially important if the water quality released is poor. The pump-out volume might be sufficient to prevent any overtopping and therefore limit the area affected by an unexpected release (plus the released flow can be calculated more easily).
It’s necessary to record as much detail as possible about the event to permit post-event evaluation and assessment, and this should include not only what has happened, but what could have happened.
- Details to record should include rain gauge and flow meter readings and observations.
- You can never take too many photographs in these instances, for which a camera with a waterproof housing is a great idea.
- Carrying out on-site testing and taking water quality samples of the release and the necessary environment (creek/stormwater/lake, upstream and downstream of the release) during the storm is crucial, to get an idea of the water being released.
- Water quality samples should be taken upstream and downstream of the release point and at the release point itself, in the natural stream (creek, lake, or river, if applicable), and surface runoff from the release point.
The EP Act (Section 320) provides for strict timelines for reporting, which, in some circumstances allow 72 hours for notification. However, as a general rule the DEHP state that they must be notified of any environmental harm (or potential environmental harm) at the time of the event and within 24 hours of the event taking place. Navigating legislative requirements and meeting preferred departmental timelines can be very confusing. Based on your site and your command structure, your time to report may vary, and could range 24 to 72 hours. That makes this a great area to seek expert advice on (before you find yourself in this situation!).
After the event
Before any detailed assessment of the event begins, ensure that DEHP has been notified of unauthorised releases.
A detailed assessment is then necessary to evaluate the impact of the event and any unauthorised releases. Raw sewage and rainfall flows should be quantified or estimated, in addition to the volume of water released. This information can be calculated based on flow meter figures, pump durations and flow rates, and this will aid you in determining the dilution of the sewage released. Water quality results from samples taken during the event will also shed light on the impact of the release.
It is also necessary to discuss the actions taken on site (and actions that could have been taken on site) to minimise environmental harm. Remedial actions might be recommended from the detailed assessment to prevent an unauthorised release from occurring again in the future.
Ultimately, it is up to DEHP to determine whether or not a warning or penalty is warranted. This decision is likely to be based on the efforts made to minimise environmental harm leading up to and during the event, and the degree of environmental harm caused (material or serious environmental harm). Penalties can also apply if the event is not notified to the Department in the required timeframe stipulated in your licensing conditions, but it is best to inform them within 24 hours.
Plant upgrades, remedial works or changes to management plans can still be explored before a decision by the Department is made – and demonstrates a proactive attitude to preventing environmental harm.
Penalties upwards of $10,000 have been known to be issued just for failing to notify. The Environmental Protection Act provides for fines of up to $63,075 for employers that do not notify DEHP in time (500 penalty units – the value of one penalty unit, at the time of publication of this article, is $126.15). For employees that must notify their employer, the maximum penalty is $12,615.
Penalties for the unauthorised release may include a formal warning and a fine, often in the range of $10,000-$12,000. However, the maximum penalty (for wilfully contravening a condition of the authority) under the EP Act is 6,250 penalty units. With each penalty unit currently equivalent to $126.15, that makes the maximum penalty $788,427. 50. Alternatively, the penalty could be up to 5 years imprisonment.
Why should you go through all of this effort?
The potential consequences highlight the importance of a having contingency plans in place before something happens. Fixing potential issues before they become confirmed problems means spending your dollars improving your business – not paying fines.