Davies & Anor v Ku-ring-gai Council
[2007] NSWLEC 65
•9 February 2007
Land and Environment Court
of New South Wales
CITATION: Davies & Anor v Ku-ring-gai Council [2007] NSWLEC 65 PARTIES: APPLICANT
RESPONDENT
Mr Mark Thomas Davies & Mrs Catherine Maree Davies
Ku-ring-gai Municipal CouncilFILE NUMBER(S): 20905 of 2006 CORAM: Hussey C KEY ISSUES: Appeal :- Section 180 Order: Rectifying stormwater on - site management scheme LEGISLATION CITED: Local Government Act 1993 DATES OF HEARING: 09/02/2007 EX TEMPORE JUDGMENT DATE: 9 February 2007 LEGAL REPRESENTATIVES: APPLICANT
Mr S. Kondilios, solicitor
of MaddocksRESPONDENT
Ms D. Holm, solicitor
Mr R. Graham, solicitor
Ms C. Bracks, solicitor
of Abbott Tout
Agent for Mr & Mrs Burns
JUDGMENT:
THE LAND AND
ENVIRONMENT COURT
OF NEW SOUTH WALES
Hussey C
20905 of 2006 Mr Mark Thomas Davies & Mrs Catherine Maree Davies v Ku-ring-gai Municipal Council9 February 2007
This decision was given extemporaneously. It has been revised and edited prior to publication.
Background.
JUDGMENT
1 This appeal arises out of the issue by Council of an Order pursuant to item 12 to the table of s124 of the Local Government Act 1993, served on the applicant on 4 September 2006. The order applies to the subject property, which is known as 34 Bushlands Avenue, Gordon.
2 The Order concerns the control and discharge of stormwater on and from the subject property, pursuant to works required in development consent No 1776/01, which involved building alterations and additions to the existing dwelling.
3 The order states:
- This order requires you to install stormwater drainage measures within the rear yard of 34 Bushlands Avenue, Gordon to comply with the design requirements of Development Control Plan No. 47 -Water Management to the satisfaction of Councils Team Letter, Engineering Assessment Unit to overcome existing drainage and/or flooding problems caused to 25 Browns Road, Gordon within SIXTY (60) days of the date of this order.
4 Consequently the threshold issue concerns the rate of stormwater runoff through the pool area into the neighbouring downstream property at 25 Brown Road.
The site.
5 This property is described as Lot B in DP 320384. It has a frontage of 18.29 m, a depth of 55.68 m and total area of 1018.39 sq m. The land slopes from the street frontage towards the rear boundary.
6 There is a part 1/2 storey dwelling erected at the front of the property with an in-ground swimming pool along the rear boundary.
Statutory Controls.
7 The land is zoned Residential 2(a) under the Ku-ring-gai Planning Scheme Ordinance.
- facilitate the consistent and timely merit-based assessment of development proposals;
- provide certainty for the long-term viability of water management measures employed in Ku-ring-gai;
- facilitate attractive, sustainable and affordable development that relates well to the built and natural environments and that suits a range of needs;
- ensure the long-term viability of natural watercourses, ecosystems and habitats in Ku-ring-gai and beyond; and
- enhance liveability of Ku-ring-gai.
- Development Control Plan No 47 - Water Management is applicable to this matter. The purpose of this plan is to:
8 Section 1.5 allows variations to the controls as follows:
- A development control plans contains requirements for development against which a proposal will be assessed when submitted to Council. Variations to the controls may be acceptable, providing the applicant is able to demonstrate compliance with the objectives of the Plan.
- Council encourages innovative water management techniques where they are demonstrated to fulfil the DCP's objectives. Where the developer proposes an alternative method to that required by this DCP, Council will consider the proposal on its merits.
9 The on-site stormwater management provisions are contained within chapter 6 and state the following objectives:
- 2. Development that does not increase the impact of rainfall in events.
4. Development that does not increase service and sub-service runoff to neighbouring properties.
6. Stormwater management design that demonstrates a consideration for the existing capacity of public drainage system.
8. Development that does not adversely affect integrity of natural waterways, groundwater and ecosystems.
10. Stormwater management that is integrated with the overall site design and reflects the analysis of the site.
12. Stormwater management that is designed, constructed and maintained in accordance with best engineering practices.
14. Stormwater management measures that are functional and effective for the duration of their existence.
15. Efficient use of stormw ater.
The Evidence.
10 The drainage issue was assessed by Ms K Hawken, councils team leader/engineering assessment unit. The applicant’s drainage proposal was presented by Mr G Keighran, consulting engineer.
11 An objection was lodged on behalf of Mr & Mrs Burns, neighbours from 25 Browns Road. Their concern is about concentrated stormwater flows from the pool area in the subject property entering their property and causing nuisance and damage.
12 The initial concern was that the building alterations involved an increase in the impervious area of the site, with hard surfaces covering approximately 60% and no satisfactory means of stormwater control being provided, considering the fall of the land towards the rear boundary. Apparently the applicant was unable to negotiate a downstream drainage easement to enable the discharge of the stormwater.
13 However, the applicant subsequently provided a drainage system (Keighran Geotechnics Report 02208/GK/1), involving the roof and driveway areas of the house being piped height into small pits and discharged into the lawn area at the rear of the dwelling. Ms Hawken acknowledged that this was acceptable for the major part of the site.
14 However, she was dissatisfied with the stormwater dispersal arrangements for the smaller, pool area of the south-western corner of property because of the permeability of the subsurface material. Also, the DCP does not generally favour this form of stormwater dispersal.
15 The applicant’s proposed drainage dispersal system for this area, involved:
- a masonry perimeter retention wall approximately 400 mm high around part of the swimming pool and atop the existing rear boundary retaining wall,
- an infiltration landscaping area between the pool coping and rear retaining wall,
- a further collection drain and infiltration area along the northern edge of the pool terrace.
16 In accordance with the provisions of DCP 17, Ms Hawken considered a more appropriate solution would be to connect the pool skimmer box to the sewer, so that excess stormwater flows were disposed of via the sewer.
17 Mr Keighran opposed this alternative due to the difficulty in excavation required for connection to the existing junction in the sewer main.
18 The engineers conferred and agreed on a number of the design factors and matters to be incorporated in the stormwater management from the site as follows:
- litter and sediment controls should be installed upstream of any on-site stormwater management measures for runoff from the driveway and roof,
- a suitable design storm would be the 5 minute duration, 50 year Average Recurrence Interval event,
- that a proportion of infiltration storage should be provided below the ground in a trench or equivalent.
19 The main point of disagreement between the engineers concerned the portion of stormwater to be contained in below ground storage.
Conclusions.
20 Having considered the evidence and my observations on the site inspection, I accept Mr Keighrans evidence that there are some practical difficulties in connecting the pool skimmer box to the sewer junction, considering its location and relative level. Also, I have some concerns with this alternative that in some storms events it is likely that the sewer will be overloaded, resulting in some discharges into natural watercourses. This would be contrary to the water management controls, which proposes that development is not adversely affect integrity of natural waterways, groundwater and ecosystems.
21 Instead, it seems to me that taking into account the topography of the land and location of the swimming pool, which has involved the placement of some fill material, this then should enable satisfactory infiltration of the relatively small area of stormwater runoff from the pool area. The integration of the two infiltration areas with the perimeter retention wall should effectively reduce overland stormwater flows, so as to minimise nuisance runoff onto the adjoining property, to a satisfactory level.
22 I therefore consider that Mr Keighrans modified, on-site stormwater management scheme reasonably satisfies the relevant objectives of DCP 47 and merits variation as allowed in section 1.5. For these reasons, the Court makes the following modified orders.
This Order requires you to:
Court Orders.
1. The appeal pursuant to s.180 of the Local Government Act 1993 is upheld.
2. The Order issued by the Respondent to the Applicants, dated 1 September 2006, pursuant to s. 124 (Item No. 12) of the Local Government Act 1993, in respect of the stormwater system installed at the rear of the dwelling house at 34 Bushlands Avenue, Gordon, is modified pursuant to s. 180(4)(b) of the Local Government Act 1993 as follows:
1. Install a dispersal trench system of 30 m in trench length, or an equivalent area of below-ground crate-type system (such as “Atlantis” or “Versi-tank”). The dispersal trench system is to have an effective volume of 8.4 cubic metres and hold the runoff from a 5 minute duration in a 50 year Average Recurrence Interval storm event prior to infiltration commencing;
2. Install a ground drainage system consistent with Annexure “A” to these orders.
3. Install litter and sediment control to treat runoff from the driveway and roof.
4. Orders 1, 2, and 3 shall be complied with to the reasonable satisfaction of the council, and a works as executed plan shall be provided by the Applicant to the Council, within 90 days of the date of these orders.
___________________
- R Hussey
Commissioner of the Court
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