Shaw v The Minister Administering the Water Management Act 2000
[2013] NSWLEC 1027
•20 February 2013
Land and Environment Court
New South Wales
Medium Neutral Citation: Shaw & anor v The Minister Administering the Water Management Act 2000 & Ors [2013] NSWLEC 1027 Hearing dates: 12 February 2013 Decision date: 20 February 2013 Jurisdiction: Class 1 Before: Fakes C Decision: Appeal upheld subject to conditions
Catchwords: WATER; appeal against refusal of an application for water supply works; more than minimal harm to an adjoining property; contributory factors Legislation Cited: Land and Environment Court Act 1979
Water Management Act 2000Category: Principal judgment Parties: Arthur & Jean Shaw (Applicants)
The Minister Administering the Water Management Act 2000 (First Respondent)
Jacqueline Dean & Dave Mehrtens (Second Respondents)Representation: Applicant: Mr G O'Reilly (Solicitor)
First Respondent: Mr S Vincent (Solicitor)
Second Respondent: Ms J Dean (Litigant in person)
Solicitors
Applicant: O'Reilly & Sochacki Lawyers
First Respondent: NSW Department of Trade and Investment, Regional Infrastructure and Services
File Number(s): 10584 of 2012
Judgment
COMMISSIONER: Mr and Mrs Shaw, the applicants in these proceedings, are appealing against the Minister's determination to refuse an application for water supply works (30WA307388), being a dam, on their property at Dulguigan. The appeal to the Court is made under s 368(1)(g) of the Water Management Act 2000 (the Act).
The applicants contend that there is no basis for the Minister's refusal of the application on the grounds of causing more than minimal harm by degrading land.
The first and second respondents contend that water leaking from the dam is causing more than minimal harm to the western portion of the second respondents' property that is in close proximity to the applicants' dam.
The dam
The applicants' Statement of Facts and Contentions describes the proposal as "the construction of a dam on the site for off-river and runoff harvesting storage for environmental purposes". The application describes the purpose of the dam as 'domestic'. The dam is 50m long, on average, 3m deep, and with a calculated capacity of 4.5 megalitres.
The dam is situated on the western side of a small ridgeline on the eastern side of the applicants' 2.95 ha property. The second respondents' property is to the east of this ridgeline. The dam has been cut into the ridge with the spoil forming the southern and western embankments. The dam is fed from the north by a small watercourse. When full, the water backs up and flows generally to the south to another small dam below it and then into the cane field drainage system further to the south.
On top of the ridge is an access track to the applicants' dwelling. To the east of the track the embankment to the east is part engineered but primarily natural in its form. New trees have been planted on this embankment. There are established trees towards the base of the embankment, principally on the second respondents' land.
The dam was constructed in May 2010; the application for water supply works, pursuant to s 92 of the Act, was lodged in July 2011. Under delegation from the Minister, the Office of Water refused the application on the basis that "the application is not consistent with the principles of the Water Management Act 2000 as it will cause more than minimal harm by degrading land".
The affected land
"The more than minimal harm" and land degradation at the core of this matter is to land belonging to the second respondents in these proceedings, Ms Dean and Mr Mehrtens. The Dean/Mehrtens property is down slope and to the east and south-east of the Shaw property.
The portion of land said to be degraded is generally to the south-east of the applicants' dam and the western portion of the second respondents' land. The second respondents' position is that water leaking from the applicants' dam saturates their land, damages the pasture, makes it untrafficable, and therefore renders it unusable for their business of breeding alpacas.
The second respondents' property traverses a watercourse which captures and drains runoff from hills to the north and is diverted under the public road at the northern end of the property. Within this watercourse, and on their property, are two dams, one at the northern end adjacent to the road and the other some 40m or so to the south. The water then flows from the second dam to the cane field drains to the south of the second respondents' property. The drainage system between the road and the second dam has been upgraded with the installation of underground pipes between the two dams. The western portion of the second respondents' land slopes gently down to this watercourse.
The western portion of the second respondents' land contains one or more natural springs which vary in activity depending on rainfall events.
Background to the appeal
According to the evidence in the first respondent's bundle, and given under oath by Ms Dean on behalf of the second respondents, within a year of the construction of the applicants' dam, the second respondents raised concerns with Mr Shaw about the possibility of water leaking from his dam onto their property. At that stage, Mr Shaw denied that the dam was leaking.
In June 2011, the second respondents engaged Mr Peter Elkington, a geotechnical engineer from Soil Surveys Engineering Pty Ltd, to inspect the site and prepare a report. During that inspection, Mr Elkington viewed the dam and spoke to Mr Shaw. According to Mr Elkington's report and reiterated in court by Ms Dean, Mr Shaw stated that the dam had been leaking to the south and was recharging a smaller dam on his property. Mr Shaw also agreed that it was possible that the dam was also leaking to the east but that the inundation of the second respondents' land was likely due to water moving from the north of their land. He is also reported as expressing an opinion that dams often leak on construction and may take years to seal.
Following Mr Elkington's inspection, the second respondents contacted the Compliance Unit of the Department of Primary Industries Office of Water regarding their issues with the applicants' dam. The Compliance Unit investigated the matter.
In July 2011, the Shaws lodged the application the subject of this appeal. The application was duly advertised in the local paper. The second respondents lodged an objection on the basis of waterlogging on their property adjacent to the dam.
The application was assessed by Mr John Findlay, Assessment Officer, Office of Water. On the day of his inspection, 27 September 2011, he found water lying on the surface of the second respondents' land but the precise source of water could not be identified. Based on the evidence before him, he concluded that the dam was leaking badly. He also considered that the location of the dam [within the ridgeline] might have interrupted the natural migration of sub-surface water.
In October 2011, the second respondents provided Mr Findlay with photographs of the applicants' dam showing an apparently rapid reduction in water levels. During October/ November 2011, following a dry period, the second respondents engaged a local farmer to plough, lime, fertilise and seed their paddocks, including those on the western boundary.
Mr Findlay referred the matter to Mr Chris Rumpf, Regional Hydrogeologist, Office of Water, for further comment. Mr Rumpf, in the company of Mr Findlay, inspected the site on 6 December 2011. He noted water seeping from the toe of ridgeline on which the dam is situated with water flowing across the soil surface. In addition to his site inspection, Mr Rumpf viewed images from Google Earth and noted changes in waterlogging characteristics over a number of years - wetter or drier than average.
In an internal memo to Mr Findlay, Mr Rumpf concludes that:
It is likely that the area in question is naturally prone to water logging to some degree during wet periods.
It is unlikely that the building of the dam has resulted in the redirectioning of the local hard rock groundwater flow pushing groundwater toward the water logged area.
It is likely that the dam is leaking water into the shallow groundwater system, which could potentially be contributing to the wet soils of the subject site.
Further correspondence between the Office of Water and the applicants in January 2012 indicates that the applicants accepted that there had been water leaking from the new dam on its southern boundary but that a sealant had been applied and the dam had not been losing water for some months. Despite requests for further information on the construction of the dam, the applicants did not submit any hydrogeological or engineering reports to the Office of Water.
Based on the evidence before him, Mr Findlay recommended the application be refused on the basis that water leaking from the applicants' dam was causing damage to the second respondents' property.
In June/ July 2012, the second respondents photographed the overgrown condition of their western paddock in the vicinity of the applicants' dam, due, they say, to water seeping from the applicants' dam during the wet season from December 2011 to March 2012.
In August 2012, the applicants engaged Mr Neil Sutherland, Principal Agricultural and Environmental Scientist, Gilbert and Sutherland Pty Ltd, to review and report on the reasons for refusal of the application. Mr Sutherland carried out a number of investigations including the digging of three bore holes, soil analysis, and the chemical analysis of groundwater extracted from each hole. At the time of his inspection, the second respondents' land was trafficable.
The statutory framework
The applicants' dam is defined as a 'water supply work' in the Dictionary accompanying the Water Management Act 2000. Section 90(2) of the Act provides that "a water supply work approval authorises its holder to construct and use a water supply work at a specified location".
Section 92 of the Act provides that any person may apply to the Minister for approval and that the application may be required to be advertised. Section 93 provides that any person may object to the application and that the Minister must inform the applicant of the objection.
Section 95(1) of the Act states that:
(1) After considering an application and all matters relevant to the application, the Minister is to determine the application:
(a) by granting the approval to which the application relates, or
(b) by refusing the application.
The Act gives the Minister a wide discretion in the determination of applications.
Section 97 provides for 'Grounds of refusal of certain applications'; relevantly in s 97(2):
(2) A water management work approval is not to be granted unless the Minister is satisfied that adequate arrangements are in force to ensure that no more than minimal harm will be done to any water source, or its dependent ecosystems, as a consequence of the construction or use of the proposed water management work.
Section 100 considers the range of conditions that may be imposed on approvals should approval be granted.
Section 368 enables appeals to be made to the Land and Environment Court. Section 39(2) of the Land and Environment Court Act 1979 states:
(2) In addition to any other functions and discretions that the Court has apart from this subsection, the Court shall, for the purposes of hearing and disposing of an appeal, have all the functions and discretions which the person or body whose decision is the subject of the appeal had in respect of the matter the subject of the appeal.
The hearing and the evidence
The hearing commenced with an inspection of the dam on the applicants' property. The parties' experts, Mr Sutherland, Mr Rumpf and Mr Elkington were present. Mr Findlay was in attendance however he did not participate in the preparation of a joint report. At the time of the view, the dam was almost at full capacity, there having been recent heavy rain. The experts determined that full capacity is a height of RL 9.5m. No waterlogging of the applicants' property was indicated.
Mr Sutherland identified the location of the bore holes: BH3 approximately mid-slope of the embankment; BH1 approximately midway between BH3 and BH2; and BH2 close to the nearest edge of the second dam on the second respondents' property.
We proceeded to the second respondents' property. As described above, the area in question is the western portion of the property at the base of the embankment that forms the eastern side of the ridgeline between the two properties. The area was largely saturated with free water observed to be running across parts of the surface. The saturated soil was some metres inside the second respondents' property below the embankment. One of the springs was clearly identified by the presence of sedges in the pasture. A shallow hole was dug to demonstrate the nature of the soil.
In court, Ms Dean appeared as a witness and affirmed the statements made in the material filed with the court, in particular, the conversations with Mr Shaw regarding the possible leaking of the dam, and the former condition of the western portion of her land.
Evidence was also given by Mr Graham Martin, a local cane farmer who has lived in and around the immediate locality for about 40 years and who was familiar with the area in question before the parties' properties were subdivided. Mr Martin owns the property to the south into which water from the parties' properties drains. In his experience, the portion of the second respondents' land in question has always been swampy after periods of heavy rainfall or prolonged wet periods.
Mr Sutherland, Mr Rumpf and Mr Elkington prepared a joint report and gave concurrent evidence. The experts agree that:
- there is a potential downward gradient between the applicants' and second respondents' properties;
- there can be coincident saturation of the second respondents' land at the same time the applicants' dam is full;
- the soils on the second respondents' land are of low permeability;
- the source of water inundation on the second respondents' land cannot be definitively determined using the salinity and alkalinity levels observed in BH1 and BH3;
- water inundation on the seconde respondents' land could originate from sources other than the applicants' dam; and
- the increased growth rates of pastures on the western boundary compared to other parts of the property observed by the second respondents in dry periods could be due to a range of factors other than water from the applicants' dam.
The principal areas of disagreement are:
- the significance of the hydrochemistry results obtained by Mr Sutherland;
- whether there is water leaking from the applicants' dam onto the second respondents' land;
- the significance of the upstream catchment as a source of inundation; and
- whether the ridgeline between the properties acts as a barrier to the movement of water from the dam.
There was some difference in opinion as to the definition and applicability of the terms groundwater, interface drainage and near surface infiltration. Notwithstanding this difference in opinion, it is my understanding that the experts agree that there is likely to be some interface drainage of infiltrated surface water between the two properties, largely as a consequence of the differences in levels between the two properties and the characteristics of significantly different soil types on the parties' properties.
In Mr Sutherland's opinion, despite the potential gradient between the two properties, there is no data to support the contention that water is leaking from the applicants' dam. In his view, the nature of the soil in the embankment between the two properties (non- dispersive, impermeable, heavy clay) is such that it represents a barrier to water movement. Mr Elkington and Mr Rumpf disagree on the basis that there are likely to be pathways for water movement created by root channels and other biopores as trees previously existed along the ridgeline. Mr Elkington and Mr Rumpf also contend that the dam contributes a new and permanent 'head' of water that will continue to supply/ recharge ground water/ interface drainage between the two properties.
In particular, Mr Sutherland relies heavily on the differences in salinity and alkalinity detected in the groundwater in BH3 (applicants' land) and BH1 (second respondents' land near the spring); BH3 being considerably more saline and less alkaline than BH1 (more alkaline, less saline). In his opinion, as the water in the applicants' dam is of low salinity and low alkalinity, if there was seepage from the dam through groundwater in BH3 then BH1 groundwater would not exhibit elevated alkalinity. In his view, absent any other data from the other experts, the 'hydrochemical signature' of the water in BH1 suggests the water is more likely from a source other than the dam. The other experts question both the sampling methodology and Mr Sutherland's interpretation of the results. In Mr Rumpf's opinion, the difference in water chemistry could be attributed to differences in soils and the nature of surface water, rather than ground water, that may have been collected in the shallow bore hole at BH1.
It is Mr Sutherland's opinion that the waterlogging on the second respondents' property is primarily a consequence of upstream drainage combined with the shallow, impermeable soils (with dispersive subsoil) in the area in question. Mr Sutherland supports his opinion with reference to aerial photographs taken in 1962 and 1970 (pre-subdivision) that he says demonstrate that the western portion of the second respondents' land is a naturally wet area. Mr Elkington and Mr Rumpf consider the contribution of water from upstream has less significance than that afforded by Mr Sutherland because of the relative levels of the waterlogged area, being higher, than the watercourse on the second respondents' land. In their view, there is sufficient evidence of water moving onto the second respondents' land from above the springs but below the dam and from the embankment, to support their view that water leaking from the dam has exacerbated the waterlogging on the second respondents' property.
Should a finding be made that the dam is leaking, the issue of potential remediation measures was canvassed in the joint report and discussed on site and in court. In [19] and [20] of the joint report, the experts state:
19 All of our deliberations (detailed below) would be resolved if a suitably designed, engineered and installed cut-off drain was constructed between the Applicant's dam and the Second Respondent's 'waterlogged' area. If this drain was constructed at the toe of the batter slope on the Second Respondent's property, it is likely to be less than 1.0m deep. However NS [Mr Sutherland] and CR [Mr Rumpf] have agreed that if the minimum level of 8.93m is acceptable to the Court, this would negate the need for any cut-off drain(s).
20 Whilst PE [Mr Elkington] is not in a position to be able to define the maximum water level he feels that installing a suitable cut-off drain would render the definition of that level irrelevant.
The experts maintained their positions at the hearing.
The position of RL 8.93m is based on the height of water in the dam at the time Mr Sutherland investigated the property and when the second respondents' land was trafficable.
While not discussed in the joint report, Mr Elkington's report considers that amongst other things, sealing the dam would enable the second respondents' land to return to its previous useable state.
Various methods of sealing were discussed including the use of a plastic liner, introduction of bentonite [a swelling clay] into the dam water, or incorporation and compaction of bentonite into the walls and floor of the dam [after emptying].
Mr Elkington considers either the use of a plastic liner or the incorporation and compacting of bentonite into the walls and floor of the dam to be the preferred options. Mr Rumpf and Mr Sutherland consider that a reduction in water level and the application of bentonite to the water would be sufficient in the circumstances.
Submissions
Applicants
The applicants rely on Mr Sutherland's expert report and his assessment that there is no land degradation due to the presence of the dam, and no data to demonstrate that the dam is leaking onto the second respondents' land. Even assuming there is degraded land, there is no data to support the allegations that the dam will cause more than minimal harm. Mr O'Reilly for the applicants asserts that of the experts who inspected the site, only Mr Sutherland undertook investigations from which data were produced. Essentially, the water-logged and degraded area on the second respondents' land coincides with the historical records of it being a swamp, with the principal impact being from upstream flows and pre-existing drainage problems.
While not accepting that the inundation of the second respondents' property is caused by the applicants' dam, the applicants' position is that if the Court takes the view that conditional approval be granted, the conditions should be limited to fixing a maximum water level of RL 8.93m and application of bentonite to the water. The applicants reject the requirement for a dam liner or cut-off drain.
First respondent
Mr Vincent for the Minister contends that the delegated decision to refuse the application was the correct and preferable decision given the available evidence. While he accepts that the waterlogging on the second respondents' property could originate from sources other than the dam, he submits that the applicants' dam is contributing to the problem. He relies on the evidence of Mr Rumpf and Mr Elkington and their reported observations of water cascading through the ridgeline and the potential link between the dam and the second respondents' property afforded by the potential gradient and associated groundwater connections/interface drainage.
Mr Vincent contends that the different water quality signatures determined by Mr Sutherland cannot exclude water from the dam as contributing to the waterlogging and degradation of the second respondents' land and little weight should be placed upon them.
While Mr Vincent considers it is open for the Court to adopt the Minister's position and reject the application, he submits that conditional approval could be given requiring the fixing of a maximum water level and the treatment of the dam to limit further leakage.
Second respondents
Ms Dean remains firmly of the view that the waterlogging and degradation problems on the western portion of her property began occurring after the applicants installed their dam. She contends that prior to the construction of the dam, the property was 'park-like' and capable of supporting a small herd of breeding alpacas. Since the loss of those paddocks, the alpacas have had to be relocated to Victoria, at significant expense.
Ms Dean contends that the problem with the waterlogging is confined to the area below and beside the dam and is not seen on areas of the property lower in elevation. She maintains that the application should be refused, or if approved, require the full lining of the dam in order to provide certainty that the dam will not continue to leak.
Findings
Is there leakage from the dam and if so, is it causing more than minimal harm to the second respondents' land?
It is common ground that the waterlogged conditions on the western portion of the second respondents' land are due in part to the presence of natural springs, its position in the catchment, and shallow and naturally poorly drained soils. While Mr Vincent objected to Mr Martin's evidence on the basis of it being lay opinion, it does support the historical evidence of the aerial photographs, particularly the 1962 image, that the western portion of the second respondents' property is a naturally wetter area. The evidence of the aquatic vegetation that has regrown since the 2011 re-seeding of the paddocks, and noted on the site view, supports this opinion.
It is clear from the evidence that the extent and duration of the saturated conditions of the western portion of the second respondents' land vary with seasonal rainfall. It is also clear from the photographic evidence provided by the second respondents that the area in question has been dry enough to enable it to be cultivated and re-seeded since the construction of the dam. The experts' reports indicate that they encountered different moisture conditions on the second respondents' property, however, it appears as though only Mr Sutherland observed the site to be trafficable and not saturated.
It is highly likely that the activity of the springs is related to recharge from the broader catchment. However, the evidence, including as seen on the day of the hearing, is that the saturated conditions arise above the level of the obvious spring and towards the base of the embankment below the dam. While this may be partly due to the variable activity and location of springs, I agree with Mr Rumpf and Mr Elkington that it is entirely feasible that water captured by the dam is contributing to the natural movement of groundwater that would be expected as a consequence of the gradient between the properties.
I agree with the experts that there is a strong contrast in the soil types between the two properties. While I agree that the soil profile results for the dermasol forming the embankment on the applicants' property indicate a subsoil structure that is stable and of relatively low permeability, I agree with Mr Rumpf and Mr Elkington that it does not preclude the presence of biopores or other natural pathways that enable water movement through the soil. I also agree that the hydrosol on the affected portion of the second respondents' property is shallow, of very low permeability and demonstrates the characteristics of frequent saturation [the gleyed/ grey soil observed on the site view]. In this regard, these soils are naturally prone to waterlogging when the amount of water received exceeds their ability to remove it.
While I appreciate that Mr Sutherland was the only expert who undertook quantitative investigations of the soil and water, I am not satisfied that the extent of the investigations, that is the limited number of bore holes and the number of water samples tested, prove his clients' position. In particular, the water from bore hole BH1 near the spring on the second respondents' property may have been surface or ground water and its chemistry may have been influenced by pasture treatments (including the late 2011 application of lime). Therefore I concur with Mr Rumpf and Mr Elkington, and with Mr Vincent's submissions, that little weight can be afforded to the 'hydrochemical signatures' of the bore holes.
I also note the evidence sworn by Ms Dean that Mr Shaw admitted that the dam was leaking to the south and that it may be leaking elsewhere.
However, notwithstanding the recent wet conditions and the naturally occurring spring/springs, I am satisfied on the evidence before me that is open for me to find that there is water leaking from the dam and that it is contributing to the waterlogged conditions on the western portion of the second respondents' land. In putting the second respondents' case at its highest, I am also satisfied that the water from the dam causes more than minimal harm as it exacerbates the natural predisposition to waterlogging of that portion of the land.
What orders should be made?
While water from the dam is likely to contribute to the inundation of the second respondents' land, I am not satisfied that the extent of degradation requires the refusal of the application. The fact that the dam was constructed without approval is not relevant to my determination.
On the basis of the discussion of reasonable measures to minimise the negative impacts of the dam on the second respondents' land, I am satisfied that the measures agreed by Mr Sutherland and Mr Rumpf are appropriate in the circumstances. That is, the capping of the maximum water level to RL 8.93m and the addition of bentonite to the water. The reduction of the water level will require construction of a spillway to the east and away from the second respondents' land.
Mr Elkington pressed the option of a cut-off drain, however, this would require a water management work approval under the Act. Mr Sutherland and Mr Rumpf are satisfied that if these works are carried out, a cut-off drain will not be required and I find no reason to disagree with their opinion.
While Ms Dean contends that nothing less than fully lining the dam would provide the certainty she seeks, I consider the cost of doing so would be prohibitive and unnecessary on the advice of at least two of the experts. While Mr Elkington questions the long-term success of adding bentonite to the water and prefers the draining of the dam and subsequent incorporation and compaction of bentonite into the clay shell of the dam, the evidence before the Court does not support the more extensive and expensive treatment.
Orders
Therefore, on the evidence before me, the Orders of the Court are:
(1) The appeal is upheld.
(2) Water Supply Works approval (30WA307388) is granted subject to the following conditions, definitions and schedule of works.
(3) The applicants are to carry out the following works on Lot 17 DP 866759 being 56 Hoop Pine Road, Dulguigan NSW (the land):
(a) By 5 April 2013, carry out the works specified in Schedule A and the definitions in Annexure A;
(b) By 26 April 2013, at the applicants' cost, obtain and provide to Mr John Findlay, Senior Licensing Officer, NSW Office of Water, an engineer's report by an engineer on the National Professional Engineers' Register (the Engineer) certifying that the pipe spillway:
(i) has been constructed in accordance with Schedule A;
(ii) provides for the free passage of water from the dam;
(iii) will be effective in maintaining the water level in the dam at a level not higher than RL 8.93 metres; and
(iv) has been constructed in accordance with standard engineering best practice.
(c) By 26 April 2013, at the applicants' cost, obtain and provide to Mr John Findlay, Senior Licensing Officer, NSW Office of Water, certified and verifiable evidence that the dam has been treated with bentonite in accordance with Schedule A in Annexure A;
(d) On an ongoing basis, ensure that the pipe spillway remains unimpeded and unblocked; and
(e) On an ongoing basis, ensure that the pipe spillway and surrounding area is vegetated by the sowing of grass (including stabilising the vegetated area with matting in order to establish groundcover vegetation).
(4) The Court notes the agreement of 'no order as to costs'.
(5) The exhibits are returned.
_________________________
J Fakes
Commissioner of the Court
ANNEXURE A
Definitions
The Dam means the dam on the Land constructed in or around May 2010 and marked with an asterisk (*) on the map on Attachment A.
Pipe Spillway means concrete pipes of not less than 600mm (equivalent) in diameter, set vertically in a concrete footing within the storage area of the dam with the top of the pipe(s) set at RL 8.93 metres, connected with a concrete pipe of not less than 450mm in diameter set horizontally into the vertical pipe the height of which is set at the bed level of the Unnamed Watercourse at the bottom of the horizontal pipe.
Sill Level means the top of the vertical pipe(s) (referred to in the definition of 'Pipe Spillway' above) installed in the storage area of the dam which is set at RL 8.93 metres.
Cut-off Collar means a device manufactured of concrete or plastic fixed around the horizontal pipe (referred to in the definition of 'Pipe Spillway' above), placed at every 3 metres along the horizontal pipe so as to prevent water from seeping from the dam along the outer surface of the horizontal pipe.
Energy Dissipater means a device of either rock or concrete installed at the bottom/ discharge end of the horizontal pipe so as to reduce the kinetic energy of water passing through the pipe spillway.
Storage Area means the area within the dam wall where water will be stored.
Schedule A
The Applicants must carry out the following works on and adjacent to the dam:
Installation of a Pipe Spillway
a) Prior to installation of the pipe spillway, deploy appropriate erosion and sediment control measures consistent with current best management practice.
b) Maintain the erosion and sediment control measures referred to above in working condition for the duration of the installation of the pipe spillway and until the site has been stabilised.
c) Excavate and remove material from the dam and adjacent to the dam in the area marked with the letter 'a' on the map on Attachment A, and install a pipe spillway.
d) The sill level of the pipe spillway shall be set at 1.07 metres (at RL 8.93 metres***) below the level of the benchmark established on the south-western corner of the footbridge near the dam (as marked with the letter 'b' on the map on Attachment A).
e) The pipe spillway must be fitted with cut-off collars at 3 metre intervals along the horizontal pipe so as to prevent leakage of water from the dam.
f) An energy dissipater must be installed at the outlet end of the horizontal pipe so as to prevent erosion of the Unnamed Watercourse.
g) At the completion of the pipe spillway installation, stabilise all areas disturbed as a result of the works by sowing with a pasture grass mix.
h) Apply a suitable fertiliser to all areas sown with pasture grass mix as specified above to ensure the timely establishment of vegetation.
i) Remove all the material extracted from in and around the dam as a result of the installation of the pipe spillway and lawfully dispose of it.
j) The installation of the pipe spillway must be constructed and maintained in such a manner that will ensure its safety and as well, preclude the possibility of damage being occasioned by it, or resulting from it, to any public or private interest.
k) Ensure that during installation, operation and maintenance of the pipe spillway, any activity that results in soil or vegetation disturbance is to be performed so as to prevent soil erosion and the entry of sediments into any river, lake watercourse, wetland or groundwater system.
Sealing the dam
l) Apply bentonite which is suitable for the sealing of farm dams within the storage area of the dam.
*** Level datum for all AHD levels is based on Mr Neil Sutherland's survey and contained in Mr Sutherland's report dated 11 October 2012.
Ordered by the Court
20.2.13
Decision last updated: 20 February 2013
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