Hey, does anyone know when the guidelines will be past draft stage? Does anyone know of any councils accepting MUSIC 4 modelling? thanks,Kane
New draft MUSIC Guidelines for SEQ
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I can answer the first part of that question.
The draft MUSIC Modelling Guidelines for SEQ will remain draft until all technical matters have been resolved particularly with respect to how current load-based water quality objectives should be assessed using Version 4 of the software and we have had time to determine some robust assessment and reporting advice. See the “important notice” at the front of the guideline for further information.
We anticipate that a final of the guideline will be made available no later than the end of the first quarter 2010 if not before.
Others may like to comment on which Councils are accepting MUSIC Version 4 modelling.
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Kane,
As far as I know, Ipswich Council is currently unable to accept Version 4 modelling.
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There has been some confusion regarding when MUSIC V4 modelling should be used (some of this is my fault I think). MUSIC v4 is generally a better predictive tool than v3, and should generally be used in preference to v3. An issue exists when modelling bioretention systems with saturated zones in v4 (compliance with the TN objective will become more achievable but satisfying the TP objective becomes difficult). We're working with eWater, FAWB researchers and local experts and hope to have some formal advice on how to address this issue. In the meantime, it is worth considering one of two interim approaches:
- If the saturated zone is primarily for the sustenance of vegation during dry periods, do not use a carbon source in the saturated zone in your designs and model the system without a saturated zone in the interim.
- If the receiving environment is a nitrogen limited marine environment, it would be worth exploring if the benefits of improved TN removal outweigh the shortfall in TP removal.
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Hi Alan, Paul and other draft guidelines authors,
With regards to Section 4.8...
Firstly can I commend you on including in the guidelines a requirement that the specified devices cannot be changed without demonstrating that the devices are truly equivalent. As a consultant I always struggled with a bucket being equivalent to a swimming pool just because the same flow rate passed through it, and assessment officers that didn't seem to understand.
I do, however, have concerns about some of the statements in Section 4.8. Namely:
- "pollutant reduction parameters independently verified using a method to suit conditions in SEQ" - Who determines the "method to suit conditions in SEQ?" This statement implies that ALL manufacturers will have to supply information to satisfy someone (who?) because there is insufficient data out there now. This is a patently false implication. Further, all the latest research from the US suggests that full-scale laboratory testing is more accurate than field testing (BUT should still supplement lab testing) because field testing can never be replicated.
- "performance under dry weather flows (to account for potential pollutant leaching)" - Can you please provide the references demonstrating this has been rigorously tested and confirmed, that warrants such a requirement. All the research I have seen to date is grab sampling with no correlation to flows, hydrology or hydraulic residence times. Further, is this being applied to bioretention and wetlands? - I've seen plenty of research demonstrating "potential pollutant leaching" from them too during dry weather flows.
- "Low to medium density residential development is typically characterised by low anthropogenic gross pollutant loads. Low litter loads combined with relatively high maintenance demands of GPTs generally means that wet sump GPTs are not a suitable treatment option for this land use." A properly sized and maintained GPT will cost between $1,500 and $3,000 per year to maintain. I suppose when you consider that most bioretention systems and wetlands are never maintained until their is a problem, this might seem a high demand. I'd be interested in knowing the cost to maintain an average size biorenttion system per year. The CRCCH/eWater CRC papers and ARQ suggest ~1 cubic metre of gross pollutants and sediment per hectare per year from a residential catchment. I wouldn't call that a low load. Further, I've seen what that load can do to wetlands and bioretention systems when a GPT isn't used (eg. Coomera Waters).
I agree that there should be a single process (like the NJCAT ETV program) that tests all GPTs but I think it should go further and be applied to bioretention systems and wetlands too. A common program that allows everyone to a) repeat the tests, b) present information in a similar format, and c) be able to compare apples and oranges is long overdue. I do feel though that implementing this should be via a transparent, public process. The wording of Section 4.8 of the guidelines currently reinforces my perception that the "baby is being thrown out with the bathwater" with respect to GPTs and the goal posts are being moved but no one is saying where to.
I extend, again, an open invitation to discuss this with the authors before the draft becomes final.
I'd be interested to know how practitioners feel about complying with these requirements in their Management Plans. Do you feel sufficent information exists to comply?
Darren Drapper, Humes Water Solutions.
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Darren, You've raise a number of interesting points.
1. There are a number of reasons underpinning the approach to how gross pollutant traps (GPT's) are modelled in the MUSIC Modelling Guidelines. These include that there has been inappropriate and in many cases unethical marketing of GPT's by some vendors over the past decade overstating the treatment performance of products, coupled with clear evidence of leaching of nutrients if systems are not emptied or maintained at the appropriate frequency (In an earlier post about council's not accepting GPTs in residential areas I provided some references on issue of wet-sump GPTs, and the transformation of pollutants into soluble forms if not cleaned imemdiately following rainfall events).
2. The requirement for peer reviewed research to justify performance applies equally across all stormwater treatment measures, not just GPTs. In the case of bioretention and wetland systems, that research is integrated into the treatment algorithms in the MUSIC software. It is most appropriate in my opinion that those selling proprietary products for commercial gain be required to present independent verification from a source with no conflict of interest.
3. It is well established that bioretention systems can and do leach certain pollutants under certain conditions. The processes and factors contributing to this are well documented (read for example the FAWB Adoption Guidelines) and are addressed in current best practice designs and specifications to minimize the risk of leaching. You'll also be aware that MUSIC Version 4 reflects much of this research by including more detailed parameters for bioretention systems to better predict the leaching potential of various designs, and to ensure that this is taken into account when estimating overall load reductions.
4. You raise concerns about a lack of appropriate field monitoring of bioretention systems. The Water by Design program has been actively communicating some of the local monitoring activities on bioretention systems. In particular, I think you would be interested in the monitoring that has been occurring at Coomera Waters by DERM, GCCC and QUT, which is monitoring of storm events and considers the hydraulic and hydrologic issues that you are concerned are being neglected. Its also worth reading upn on BCC's monitoring work.
5. I’m not clear what point you are making in relation to maintenance for wetland and bioretention systems. It is important to note that all stormwater management measures require regular maintenance including GPT’s, and that this should be considered in the selection and design of any treatment measure. The principal difference between GPTs and bioretention/wetland systems is that well designed bioretention/wetland systems have the ability to self maintain (eg plants preserving porosity in filter media, drawing oxygen into soils to reduce anoxic conditions etc.). You may be aware that the Water by Design program has a major body of work underway looking at the issue of maintenance and supporting the establishment of appropriate maintenance budgets and regimes.
6. Caution is needed when comparing strategies to deal with construction phase sediment loads and sediment loads from established urban catchments. In most cases there are better approaches to managing the high sediment loads during the construction phase of urban development than installing permanent GPTs. From inspecting the site you'll be aware that the coarse sediment that has accumulated in some of the bioretention systems at Coomera Waters is from house construction runoff. In those subcatchments where house construction is complete you'll have noted that the load of litter and coarse sediment load has reduced significantly. These catchments and treatment systems provide an excellent illustration of why GPTs are not necessary in many residential catchments. This point also highlights the importance of integrating erosion and sediment control activities with the delivery of WSUD assets, as advocated in the Construction and Establishment Guidelines.
7. I think most in the industry see value in a standardised testing regime for stormwater treatment measures. Historically, the small scale of the Australian stormwater industry, lack of regularory drivers for stormwater treatment and threats of litigation by some vendors all help explain the absence of an independent testing regime. Different testing regimes preference different technologies, so a challenge is identifying appropriate testing regimes, getting endorsement of these from some of the particularly litigous vendors, and of course funding the scheme. The NJCAT testing regime you mention only addresses sediment removal efficiency and does not address nutrient removal. You'll also be aware that the NJCAT certifications also come with conditions attached including the required cleanout frequency for the systems in order to maintain effectiveness.
Regards,
Alan
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Hi Alan,
I hear what you are saying. The key point for me is consultation. We would like the opportunity to be involved, across the table, in a review process whereby our concerns can be outlined and addressed. We have a library of information that has never been considered. We hope to have this opportunity before the document becomes final. I agree with you about “inappropriate and unethical marketing of GPTs”, but this would and should be tested by the ACCC under the Trade Practices Act. Valid complaints should be made to the ACCC.
The transformation of nutrient forms into nitrates and nitrogen gas happens in every measure. That’s why all measures should always be part of a treatment train. Geoff Hunter’s paper, concludes that GPTs are a vital part of the treatment train to protect and maintain the integrity of downstream natural systems but that they need to be maintained. I am in full agreement with that too.
I fully support the provision of independent test data. We want to commission the research & to provide the information. We can’t find an Australian, approved protocol, or organisation that wants to do the work. We want to invest our money wisely in research that will be accepted. A transparent, fair, replicable and rigorous protocol should be able to be followed by any reputable testing authority, and prove the performance of the product. The requirement to provide verification to suit a specific locality’s conditions seems inequitable unless it is applied to everything – wetlands and bioretention included.
Self-maintenance of bioretention is, in my opinion, a false sense of security. This is a tertiary treatment device for stormwater. An experienced wastewater engineer wouldn’t expect to install a BNR plant (tertiary treatment) at a WWTP without grit separation (primary treatment), Aerated Activated Sludge systems (secondary treatment), settling tanks and a maintenance budget. Assuming that zero maintenance is required until the lifespan of bioretention is reached, the full replacement cost still needs to be amortised and budgeted for every year. If Moreton Regional Council alone have approximately $1 billion of WSUD assets, that’s a budget of $40 million/yr for the next 20 years to cover the replacement costs in today’s dollars.
Monitoring Coomera Waters (developed ~10 years) should conclude that the litter & sediment loads are smaller now. The loads do reduce after construction activities cease. It is more important, in my view, what a mature catchment (>10 years) produces. The data from the maintenance contractors on devices in developed catchments established for more than 10 years suggests more like 1 m<sup>3</sup>/ha/yr of sediment and litter.
Humes®wants to be a party at the table for the revision of the guidelines, especially for GPTs, as we believe we have a wealth of experience we can contribute. We look forward to an opportunity to have some constructive input, and welcome your contact.
Kind regards,
Darren Drapper
National Water Solutions Manager
Humes
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