Angelo Vasili v Liverpool City Council

Catchwords: DEVELOPMENT APPLICATION – development of rainwater gardens/detention basins in flood liable land within a regulated catchment – s 6.8 of State Environmental Planning Policy (Biodiversity and Conservation) 2021 engaged – if there is a flood, whether that results in a release of pollutants that may have an adverse impact on the water quality of the natural waterbody being the Georges River

Legislation Cited: Environmental Planning and Assessment Act (NSW), s 8.7
State Environmental Planning Policy (Biodiversity and Conservation) 2021, Ch 6, s 6.8

Category: Principal judgment

Parties: Angelo Vasili (Applicant)
Liverpool City Council (Respondent)

Representation: Counsel:
C Gough (Applicant)
J Garcia (Respondent)
Solicitors:
Storey & Gough Lawyers (Applicant)
Liverpool City Council (Respondent)

File Number(s): 2025/88521

Publication restriction: Nil

JUDGMENT

This decision was given as an extemporaneous decision. It has been revised and edited prior to publication.

1. These proceedings arise following an appeal by the applicant, Angelo Vasili pursuant to s 8.7 of the Environmental Planning and Assessment Act (NSW) (EPA Act) against Liverpool City Council’s (Council) refusal of his development application DA 353/2024 lodged on 12 August 2024 (DA).

2. The DA proposed the demolition of an existing single storey dwelling house and the construction of 74 horse stables, installation of a horse walker structure, installation of a horse treadmill, office/residence and storage spaces on Lot 21 in DP 1088639, known as 2 Shore Street, Warwick Farm NSW 2170 (Site).

3. The site is identified as flood liable land within the regulated catchment of the Georges River, located in both High and Medium Flood Risk Zones with more than 80% of the area in the High-Risk Flood Zone.

4. The Council raised several contentions advocating for a refusal of the DA on the grounds of flood impact. At the hearing the parties invited me to deal first with contention 6 and the sufficiency of the proposed stormwater drainage measures and the site’s suitability for the proposed use in accordance with Ch 6 of the State Environmental Planning Policy (Biodiversity and Conservation) 2021 (SEPP BC).

Determinative issue

5. Section 6.8 of the SEPP BC provides as follows:

6.8 Flooding

(1) In deciding whether to grant development consent to development on land in a regulated catchment, the consent authority must consider the likely impact of the development on periodic flooding that benefits wetlands and other riverine ecosystems.

(2) Development consent must not be granted to development on flood liable land in a regulated catchment unless the consent authority is satisfied the development will not—

(a) if there is a flood, result in a release of pollutants that may have an adverse impact on the water quality of a natural waterbody, or

(b) have an adverse impact on the natural recession of floodwaters into wetlands and other riverine ecosystems.

6. For the reasons that follow, I am not satisfied on the evidence before me that the development will not, if there is a flood, result in the release of pollutants that may have an adverse impact on the water quality of a natural waterbody (being the Georges River).

Stormwater management

7. The DA proposed the construction of two raingardens/detention basins for onsite water quality treatment.

8. Mr Haddad, the applicant’s engineer gave evidence in Court, consistent with the joint report (Ex 4), that the detention basins will ensure that stormwater runoffs leaving the site comply with Council’s water quality standards. Furthermore, that the proposed treatment facilities, located within the High-Risk Flood Area were designed to capture all gross pollutants and liquid contaminants from the stormwater before discharging it downstream, or into Council’s stormwater system. As he explained it, MUSIC modelling software had been used in the design of the water quality treatment works and it had been demonstrated that the stormwater and detention system satisfied the DRAINS modelling file having been verified using Council’s MUSIC link. Mr Hossain, the Council’s engineer agreed with this much of Mr Haddad’s evidence, noting that the draft conditions required the submission of a water quality modelling report and electronic copies of MUSIC model to the Council.

9. That said, Mr Hossain, did not accept, in the event of a flood that the Court could be satisfied on the evidence that the development would not result in a release of pollutants that may have an adverse impact on the water quality of the Georges River (a natural water body some 400m from the site).

10. Therefore, based on Mr Hossain’s evidence, the Council submitted that s 6.8(2) of the SEPP BC precluded the grant of development consent.

Considerations and Findings – s 6.8 of State Environmental Planning Policy (Biodiversity and Conservation) 2021

11. As the transcript records**,** Mr Hossain gave evidence in Court that flooding events occur in the Georges River in the Liverpool Local Government Area (LGA) even when there has been little rainfall in the Liverpool LGA because:

“…the Georges River is [a] very huge catchment, starting from Epping to Botany Bay and 960 square kilometres, and most of the catchment area is upstream. So, in practice you may not see much rain in your pool, but suddenly you can see flood” (T42:44-47)

12. When that flooding event occurs, Mr Hossain said that the proposed onsite stormwater detention tanks will overflow and release untreated pollutants that may have an adverse impact on the water quality of the Georges River, some 400m from the site.

13. Mr Hossain’s explanation of his concerns about the accumulation of untreated pollutants in the detention basins is recorded in the following transcript of this evidence to the Court:

WITNESS HOSSAIN: In relation to this rain garden, Commissioner, I don't have any issue with the design aspect that my friend mentioned. It is a six month that is the design criteria. But when we look at the amount of pollutants that is entering to the rain gardens

COMMISSIONER: Where do I find those?

WITNESS HOSSAIN: These are the MUSIC model, this is [the] document. It shows that total suspended solids, the pre development was 12 kilogram per year, and after this development it is 273, which is approximately 2000% increase. Total phosphorus is 3000% increase. Total nitrogen 4000% increase. So by doing this treatment facilities, you are actually holding those pollutants into the system, you know, and this is only for five year. And it accumulate, say for that's why the maintenance requirement is every five years. You remove the and wash, clean the filter, because it will clog.

COMMISSIONER: Yes.

WITNESS HOSSAIN: Because of these pollutants loads. You know.

COMMISSIONER: Yes. So this 2000% increase on those two examples you've given, under the system as designed by the engineer, is cleaned and is disposed of if there is no flood; it works to

WITNESS HOSSAIN: Yeah. It is the ideal situation, so it is normal rain, trickle, trickled rain, you know.

COMMISSIONER: I understand.

WITNESS HOSSAIN: So it is the first flush, you know, when immediately it start rain, it will clean the surface, go into the rain garden and hold this, all the pollutants, you know.

COMMISSIONER: Yes.

WITNESS HOSSAIN: And it will accumulate over every year, you know.

COMMISSIONER: Yes. So in five years you clean out the filters, yes.

WITNESS HOSSAIN: Five years. So when there is a major flood, like, this will be under water and everything will washed away. Because it is open and end up in the next natural river is Georges River.

COMMISSIONER: Right. I'm sorry to ask these questions but I.

GOUGH: No, no, no.

COMMISSIONER: Even if we've had the little rain, which has cleaned it all, put it into the filter and the filter's doing its job I'm calling the retention tank the filter because of build up over time of remnant pollutants or treated material, you say it'll be flushed up--

WITNESS HOSSAIN: Yes.

COMMISSIONER: --in any event. Even if the system's working perfectly to in its own way deal with it?

WITNESS HOSSAIN: Yes.

COMMISSIONER: I'll come to you, and I appreciate you don't agree, but I just need to understand that's the council's position.

WITNESS HOSSAIN: Yes.

COMMISSIONER: The council, in dealing with this SEPP on other occasions, does it form a particular interpretation that you've applied?

WITNESS HOSSAIN: In my experience, I haven't dealt with any development in this sort of flood zone, and that this issue never came [up]…”

(T43:34-T45:2)

14. The proximity of the site to the Georges River can be understood from the photo taken from the Statement of Facts and Contentions reproduced below.

15. Based on Mr Hossain’s evidence, the Council submitted that the Court could not be satisfied as required by s 6.8(2)(a) of the SEPP BC and is therefore unable to grant development consent to the DA.

16. Mr Haddad was given an opportunity to respond.

WITNESS HADDAD: My position, Commissioner, is that that the concentration that I spoke about, and those pollutants that may cause impact on the receiving body, which is the Georges River, we've already treated those in a minor storm event that preceded that peak that I was stalking about, and there's no issue at all. Like, the concentration that could potentially harm bodies that water bodies is already being dealt with.

COMMISSIONER: And you don't think there's any remnant complained of by the council within the system?

WITNESS HADDAD: Not at all. So by retention basins the filter at the bottom, yes, it could be a five year maintenance schedule, it could be a two year depending on the circumstance, but also the actual surface of it, where the sedimentation will build up, that is actually cleaned every sixth month. And because it has vegetation in it and that vegetation is neutral and to remove all vegetation as well, designed to tolerate water and to absorb nutrients, that is also maintenance by the landscaping. Yeah, obviously, on any site, not necessarily this one but any site.

COMMISSIONER: So if it's the day before the six month clean, you say what's the reason of having a clean then?

WITNESS HADDAD: You see the position of silt, like because water carries silt with it.

(T45:16-39)

17. After explaining how his stormwater system worked – in particular how it treated the onsite stormwater pollutants after a rainfall and before discharge into the catchment or the Council’s drainage system, Mr Haddad accepted that in major flood events the system would not cope and that the water would flow out of the detention tanks but that it would have been treated.

18. In his expert assessment there would be no release of pollutants that may have an adverse impact on the water quality of the Georges River.

19. In forming that view, Mr Haddad did not accept that the Georges River would flood without it raining on the site and therefore the contaminants would have been washed into the detention system and treated before theses tanks overflowed. He also expressed the view that the residue in the tanks removed each 12 months when cleaned (not 5 years) was essentially silt and not untreated pollutants.

WITNESS HADDAD: So the pollutants that were talked about, and the concentration of those pollutants that we are required to treat from pre versus post, they are only the concentration of pollutants that are in the very, very frequent storm. So we're talking anything below the one in one year event. Right. So we're not talking about the 20%, 5%, 2%, 1%. There is no requirement under the Water Sensitive Design Guide or any guidelines that are available that refer to NorBE that you have to deal or you have to treat concentration, or lower the concentration of pollutants between pre versus post to anything above that, that threshold, which we consider the 50% of the one in one year ARI; which is the 100% AEP. So these both basins that are on our stormwater plans, they have been designed to deal with that. As Mr Haddad explained to the Court : “The way that MUSIC software works is, you're actually putting in the actual software, at least at, I think, a minimum of ten years you have to put in of actual recorded rainfalls. So it's based on real rainfalls that have been recorded, it's not designed storm events like the 5%, the 20%.

COMMISSIONER: Yes.

WITNESS HADDAD: You generate those the MUSIC, obviously you put in the treatment notes and you generate a report like this one that you see on our drawings. So those frequent events that happen, water comes on the side, and we're talking about a trickle of water, right, so we're not talking about major storm events. Water, the rainfall drops on the side, becomes runoff, ends up in those rain gardens. They get treated through infiltration through the media. They end up in the aggregate line that is underlying the base of the bioretention basin, and they go out into the stormwater system in the roads basically. That's what happens in this case. Now, when the larger storms occur and rain increases on the site, all this rainfall completely bypasses this system because this system is not designed to deal with larger storm events. The reasoning behind all of this, Commissioner is that the larger concentration of pollutants happen in the frequent event. That's when the site has been dry for, let's just say, a month, for example, and you get that rainfall, and that rainfall generates a lot of concentration. Because, firstly, the rainfall is tiny, so the amount of water is small, and because the site has been dry, so it has accumulated those pollutants with time.

COMMISSIONER: Where are they; in the tank?

WITNESS HADDAD: No, they are on the roof, the roof, when the roof drainage of the roof runoff happens, ends up in the gutters, and that goes into the rainwater tanks.

GOUGH: On the hard surfaces.

WITNESS HADDAD: And also on the hard surfaces.

COMMISSIONER: They haven't been collected yet, they're just all over the site, these pollutants?

WITNESS HADDAD: Pretty much. They're all over the site, yes. And their concentration varies from roof areas to ground areas which obviously have higher concentration to vegetated areas which have less concentration. So when this happens, and water, that concentration ends up in the bioretention basin, it gets trickled, it gets treated, and then it goes out, water goes out, supposedly a clean water. I say supposedly because, you know, not a lot of testing has happened over time, or it doesn't happen a lot onsite but this is what we know. So this is what happens. So when you get those larger storms, let's just say the 5% because that's the one that is critical, everyone is talking about at the moment. A 5% storm happens on the site. The runoff that is generated from that rainfall goes straight out to the street system. It does not get treated, because it can't physically and we're not required to treat those pollutants. So that happens and water runs off and goes straight out into the drainage system. That drainage system ends up, eventually, in the river. Right?

COMMISSIONER: Yes. Untreated.

WITNESS HADDAD: Untreated because, firstly, we've already treated the bigger concentration of flow in the minor storm event. So what happens in a storm event, Commissioner? You get a little bit of rainfall, rainfall, rainfall, then you get the peak after a certain period of time. So you had a few hours or a day worth of rain, you've collected all that water, you've collected the concentration, the high concentration of pollutants that comes with it. We've treated all of that, and then the big storm happens. So that big storm happens, firstly, the pollutants concentration is very low. The volume of water is quite large, we can't deal with it. It escape and goes straight out to the receiving system. That's what happens in a five year event. Now that five year event that happens on the site is not the same sorry, I should say 5% AEP, Commissioner that 5% AEP that happens on the site is not the 5% AEP sorry, it's the same 5% AEP that floods but they have two different times to peak. So water that drops on the site runs off really quickly because it's such a small catchment. The Georges River, for it to peak at 5% AEP, it will take hours and hours. So those, firstly, we've treated the pollutants in the low flows, yes, the storm event.

COMMISSIONER: Yes.

WITNESS HADDAD: The big storm has happened. It has carried with it whatever generates on our side, which we are not meant to, required to treat, and then that peak event that happens from the Georges River and flattens and goes onto the site happens again.

COMMISSIONER: You say it's already been cleaned out by the time that happens.

WITNESS HADDAD: Correct, and that is where this is why, in my mind, this is not an issue.

COMMISSIONER: I appreciate what you're saying. All this SEPP is concerned about is in the flooding event. So I appreciate the history of what's happened on the site with the little storms and the treatment, because it could handle it, and it's trained to handle it, and built to handle it. When the flooding happens, assuming the flooding happens, the little storms haven't happened, the flooding comes across onto the site, as one big storm. That never happens?

WITNESS HADDAD: No. It does not

(T40:9-T42:15)

20. The applicant invited me to accept Mr Haddad’s evidence to the Court.

21. Accepting that the threshold is low, being “may impact…”, I am not satisfied on the evidence before me that if the development consent is granted that there is not the possibility of the release of pollutants that may have an adverse impact on the water quality of a natural waterbody in the event of a flood.

22. In forming that view I accept Mr Hossain’s evidence over that of Mr Haddad.

23. I accept that the proposed development will increase the concentration of pollutants on this site within the regulated catchment. I also accept that the system will fail in a major flood, and pollutants will be released that may have an adverse impact on the water quality of the natural waterbody.

24. I also accept the evidence that flooding upstream has previously occurred with little rain on the site, and as Mr Hossain’s explained the release of pollutants from the development in that circumstance may have an adverse impact on the water quality of the natural waterbody contrary to the provisions of the SEPP BC.

25. It is also to be noted that Mr Hossain gave evidence that in all his years as a Council stormwater engineer he had not previously dealt with an application for the construction of rainwater/basins within a High-Risk Flood Zone: T44:47-T45:2.

Orders

26. Therefore, I find that I am precluded from granting development consent to this development application and the appeal is dismissed.

27. The Court orders that:

28. The appeal is dismissed.

29. Development consent for development application DA-353/2024 for the demolition of the existing single storey dwelling house and shed, erection of new 74 x Horse Stables, installation of a Horse Walker structure, installation of a horse treadmill, office/residence, and storage space at Lot 21, DP 1088639, 2 Shore Street, Warwick Farm NSW 2170 is determined by way of refusal.

30. All exhibits are returned except for Ex A.

S Dixon

Senior Commissioner of the Court

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Amendments

26 November 2025

Formatting amendments