in the matter and in the matter statement of ......page 3 eic of andre bresler (water intake...

EIC of Andre Bresler (Water Intake Feasibility) FINAL 21.5.2021 - 35013999 v 2.docx

IN THE MATTER of the Resource Management Act 1991

AND

IN THE MATTER of a Board of Inquiry appointed under s149J of the Resource

Management Act 1991 to determine an application for

resource consents sought by Watercare Services Limited for

its Waikato River Take and Discharge Proposal.

STATEMENT OF EVIDENCE OF ANDRÉ RYNHARD BRESLER ON BEHALF OF

WATERCARE SERVICES LIMITED

Water Intake Feasibility

1. Introduction, Qualifications and Experience

1.1 My name is André Rynhard Bresler. I am a civil engineer and hold a Bachelor

of Engineering degree from the University of Stellenbosch, South Africa, and

am a Chartered Member of Engineering New Zealand with over 25 years’

design consultancy experience, the majority in water related design.

1.2 I am currently employed with GHD Ltd as a Technical Director, having held this

role for the last approximately two years, previously having the role of Principal

Engineer for approximately three years with GHD.

1.3 Prior to my employment with GHD in 2016, I held various Principal Engineer

(water) and Water Design Engineer roles with URS (now Aecom) in New

Zealand (2009 to 2014), and with several consulting engineering companies in

South Africa (1993 to 2008).

1.4 My New Zealand based career includes working on the following projects with

river or storage lake intakes in the role of project manager, designer or design

reviewer:

(a) The Central Plains Water Irrigation Scheme Rakaia River intake and

canal (2011 – 2014);


(b) The North Otago Irrigation Scheme Waitaki River intake assessment

and pump station intake modelling (2014);

(c) The Kurow Duntroon Irrigation Scheme intake and fish screen on Lake

Waitaki and a temporary river intake on the Waitaki River (2016 –

2020);

(d) CFD modelling of a fish screen for the Te Marua emergency pump

intake on the Hutt River for Wellington Water (2019); and

(e) The Wakamoekau Community Water Storage Scheme intake on the

Waingawa River (2020 – present).

1.5 This evidence is provided in support of Watercare’s application for all necessary

consents to enable the taking of up to 150,000 cubic metres (net) of water per

day from the Waikato River for municipal supply purposes (Project).

1.6 I have been involved with the Project from 2016, assisting Watercare with the

assessment of Waikato River intake locations and concept design options.

2. Code of Conduct

2.1 My qualifications as an expert are set out above. I confirm that I have read the

Expert Witness Code of Conduct set out in the Environment Court's Practice

Note 2014. I have complied with the Code of Conduct in preparing this evidence.

Except where I state that I am relying on the evidence of another person, this

evidence is within my area of expertise. I have not omitted to consider material

facts known to me that might alter or detract from the opinions expressed in this

evidence.

3. Executive Summary

3.1 The proposed new 150 Million Litres per Day (MLD) Waikato A Water Treatment

Plant (Waikato A WTP) near Tuakau requires a new raw water intake from the

Waikato River. The new intake is designed to abstract raw water at a peak

instantaneous rate that is sufficient to achieve a peak daily treated water

capability of 175 MLD. The intake must also avoid fish entrainment and

impingement, be able to be cleaned mechanically, and must not impact the


operation of the existing WTP intake and abstraction system nor the Waikato

50 intake.

3.2 An options assessment process was undertaken to determine a preferred intake

type and location for the new intake. This assessment commenced with a long

list of 10 options that was assessed at a workshop using a fatal flaw analysis

and basic traffic light-based assessment process. Five of the ten options were

chosen for a short list for further assessment.

3.3 Following the Long List Assessment, a basic multi-criteria analysis was

undertaken on the five short listed options to determine the preferred intake

solution. This assessment also took place in a workshop environment,

assessing each option against the following:

(a) Impacts on the ecology in the Waikato River and on land during

construction and operation; and achieving high resilience against high

river flows;

(b) Impacts on Waikato River user activities during and after construction;

and visual amenity;

(c) Construction complexity; disruption to the existing WTP supply; likely

construction cost and timeframes; and potential to reduce construction

carbon;

(d) Likely operating and maintenance cost-effectiveness; likely operation

and maintenance safety; flexibility of operation with long term

bathymetric suitability of the riverbed; and

(e) Consenting requirements; perceived consentability risk; and

requirement for additional easements or designations.

The assessment also considered the views of Waikato-Tainui regarding the

potential cultural effects of each option.

3.4 Based on the short list assessment, an intake located immediately downstream

and adjacent to the existing intake was selected as the preferred location. An

intake manifold consisting of either air or brush cleaned cylindrical screens,

similar to the existing intake, was selected as the preferred type of intake. The

preferred screen intake would be connected to a raw water pump station


situated either adjacent to the existing pump station or at the proposed new

Waikato A WTP location.

3.5 The cylindrical screens would be mounted on a concrete structure piled into the

riverbed and constructed of stainless-steel wedge wire with maximum 1.5 mm

wide slots and designed for a maximum approach velocity of 0.15 m/s at a peak

intake flow rate of 3,200 L/s.

3.6 A temporary construction platform, installed above the water level on temporary

piles, would allow heavy equipment to access and install the intake manifold. A

temporary coffer dam would be constructed on the riverbed, extending from the

riverbank into the river, to allow for the construction of the intake’s connection

to the proposed raw water pump station in the dry. The intake manifold itself

would be constructed in the wet.

3.7 Construction is expected to take around 21 months. Upon completion of

construction the temporary works would be removed and the site rehabilitated.

4. Scope of Evidence

4.1 My evidence addresses the following matters:

(a) The key performance requirements for the new proposed raw water

intake;

(b) The intake options assessment process;

(c) The preferred intake option;

(d) The design of the proposed intake; and

(e) The construction methodology for the intake.

5. Key performance requirements for the new proposed intake

5.1 As set out above, I have been involved in assisting Watercare with the design

of the proposed intake structure that will be used by Watercare to abstract up

to 150 MLD of water from the Waikato River, and convey it to treatment at the

proposed Waikato A WTP.


5.2 Key operational requirements that have informed the design of the proposed

intake structure are:

(a) Peak treatment capacity: to enable a consistent net treated water

output of up to 150 MLD, the Waikato A WTP requires a peak design

treatment capacity of up to 175 MLD;

(b) Maximum Instantaneous flow rate: to provide sufficient raw water to the

Waikato A WTP to achieve a peak treatment rate of 175 MLD, the

maximum instantaneous rate for raw water abstraction from the river

must exceed the peak treated water rate to allow for the fact that:

(i) abstraction cannot be a continuous steady rate throughout

any given day, as the intake screens and pumping system will

occasionally be offline for maintenance or due to breakages

and other unforeseen events. Approximately 15% additional

capacity is allowed for system downtime;

(ii) not all abstracted raw water is treated and supplied as part of

the net 150 MLD or peak 175 MLD output, with some returned

as process discharge water. Approximately 10% additional

capacity is allowed for process discharge water loss; and

(iii) flexibility is required to allow the new intake to supply both the

existing and new WTPs should the existing intake not be

operable at all. Approximately 35% additional capacity is

allowed for the existing intake being offline.

To account for the above, a maximum instantaneous rate of take

through the intake of 3,200 L/s is proposed.

(c) Fish impingement: the intake must provide protection against

impingement or entrainment of fish as required by the Waikato

Regional Plan which specifically states that the maximum intake

velocity through the screen apertures or slots (referred to as the

approach velocity), is not to exceed 0.30 m/s and that screen mesh

apertures/slots shall not exceed 1.5 mm width. The proposed intake

design is more stringent than required by the Regional Plan, in that the


maximum approach velocity of the proposed screen would not exceed

0.15 m/s.

(d) Cleaning: the screens need to be equipped with a mechanised

cleaning system (as opposed to relying on manual cleaning) to remove

debris and biological growth from the screen which would impede

screen performance by blocking apertures.

5.3 The proposed intake must also:

(a) Allow continued operation of the existing raw water intake and pump

station, both during construction of the new intake and during operation

of the completed new intake, except for very short durations (defined

in terms of hours rather than days). Shutdown of the existing Waikato

WTP must be avoided during construction; and

(b) Not affect the operation of the Waikato 50 floating intake infrastructure

and rising main that is being installed just upstream of the existing river

intake manifold.

6. The intake options assessment process

6.1 The existing Waikato WTP near Tuakau is supplied with raw water from an

existing intake on the bed of the Waikato River, and an existing pump station

located on the Waikato River’s true right bank, adjacent to the intake.

6.2 An intake options assessment was carried out to determine both the location of

a new intake as well as the type of intake. The location for a new intake is

required to be on the same bank of the Waikato River as the existing Waikato

WTP (the true right bank), and within a reasonable proximity to the proposed

location for the new Waikato A WTP to prevent excess pumping requirements.

6.3 A key requirement for the new intake structure is that it is located in an area of

the river that has long term bed stability, to prevent sedimentation or burial of

the intake screen, and sufficient water depth to allow for natural fluctuation of

the river water level without affecting hydraulic performance or creating an

underwater hazard to river users.


6.4 As well as the in-river considerations outlined in paragraph 6.3 above, an initial

desktop assessment of potential intake site locations considered factors such

as:

(a) The location for a pump station to pump the water to the WTP;

(b) The likely rising main alignment;

(c) Access routes for services to the intake and pump station locations;

and

(d) Proximity to sensitive environmental and cultural areas.

6.5 A desktop assessment of potential intake types was also undertaken. This

assessment considered three general types of intake, namely:

(a) A submerged fine screen intake manifold anchored to the riverbed,

similar to the existing intake;

(b) A floating fine screen intake using a barge anchored to the riverbank

(likely to be similar in design to, but significantly larger than, the

Waikato 50 intake); and

(c) A course screen (trash rack) intake with tunnel to a travelling vertical

fine screen at the pump station, including a fish return mechanism.

6.6 Several of the options considered (Options 1 to 4) included different methods of

utilising the existing intake infrastructure, resulting in various layouts at the

same location as the existing intake. Additionally, some screen intake types

were not suited to some intake locations, whereas other locations could

accommodate several intake types.

6.7 A list of potential options was developed for discussion in a Long List Options

Workshop (Workshop 1). This workshop was attended by Watercare staff,

planning and technical specialists. In this workshop, the long list was first

evaluated for potential fatal flaws. For the purposes of the options assessment,

a fatal flaw was defined as one of the following scenarios:

(a) The river bathymetry is assessed as unsuitable for a river intake

structure (riverbed stability and water depth);


(b) Significant risk and downtime to the existing intake and pump station

that cannot be sufficiently managed during construction;

(c) Sufficient resilience of the new intake against high river flows, riverbank

erosion, intake sedimentation, land instability and seismic events

cannot be achieved;

(d) Significant cultural impact (where known – see paragraph 6.13 below);

and

(e) Ecological impact.

6.8 Options that were not deemed fatally flawed then formed the refined long-list

and were assessed in further detail by considering various criteria such as

environmental, cultural, construction, operation and maintenance.

6.9 Ten intake options were presented and considered at the Long List Workshop,

consisting of various permutations of three intake types in five different

locations. Figure 1 below shows the location of these ten options.


Figure 1. Long list options overview layout


6.10 Of the ten options, five were deemed fatally flawed. The five fatally flawed

options are summarised in the following table, together with a brief description

of the primary reason for the fatal flaw assessment:

Fatally Flawed Options Primary Reason Option 1 – Existing intake with combined supply

Would severely impact the existing intake and WTP supply and operations

Option 2a - Additional separated intake with extended pump station

Would severely impact the existing intake and WTP supply and operations

Option 5a – Downstream intake at the beach

Unfavourable bathymetric conditions (too shallow)

Option 5c – Downstream intake adjacent to SNA*


Option 6 – Upstream intake


* Significant Natural Area

6.11 Five of the ten options were considered further in more detail in Workshop 1.

These are summarised in the following table:

Options Assessed Further Option 2b – Additional separated intake with separated pump station Option 3 – Additional separated intake with coarse screen Option 4 – Floating intake Option 5b – Downstream intake near the bluff above the beach Option 7 – Tunnel and pump station located at Waikato A WTP

6.12 A traffic light-based assessment of risks/impact/implications (minor, medium

and significant) of five unweighted criteria was conducted on the remaining five

options at Workshop 1, these criteria being:

(a) Environmental – minimal negative impact on the ecology in the

Waikato River and impact on the vegetation on land;

(b) Statutory – meets permitted and/or discretionary consenting

requirements with minimal cost implication and perceived consenting

risk;

(c) Construction Cost; represents the lowest estimated construction cost

– based on a qualitative assessment only;

(d) Operation, Maintenance and Asset Management – represents the

lowest likely operational and maintenance cost (ongoing), highest likely

operation and maintenance safety and resilience; and


(e) Constructability – provides a solution that is perceived to be the least

complex, safest to construct and minimises risk to the existing WTP

supply.

6.13 Cultural aspects were not assessed at Workshop 1 as representatives of

Waikato-Tainui were not present.

6.14 Three of the five options considered in more detail at Workshop 1 (i.e., not

deemed fatally flawed) were found suitable for inclusion on a short list for further

discussion and consideration at a second workshop, namely the Short List

Workshop (Workshop 2). These being Options 2b, 4 and 7.

6.15 Workshop 2 was attended by Watercare staff, planning and technical

specialists, as well as representatives from Waikato-Tainui. At the outset of

Workshop 2, it was agreed that one of the non-shortlisted options from

Workshop 1 (Option 5b) would be included in the shortlist assessment for further

consideration, resulting in four options being assessed at Workshop 2. The four

options considered at Workshop 2 were:

Workshop 2 Options Considered Option 2b – Additional separated intake with separated pump station Option 4 – Floating intake Option 5b – Downstream intake near the bluff above the beach Option 7 – Long tunnel and pump station located at Waikato A WTP

6.16 The following scoring system was used to assess the identified criteria:

Score Definition

5 Strongly meets the criteria in all respects 4 Meets the criteria in most respects 3 Only partially meets the criteria 2 Does not meet the criteria 1 Fails to meet and is contrary to the criteria

6.17 The five unweighted criteria scored at Workshop 2 were:

(a) Environmental – minimal negative impact on the ecology in the

Waikato River and on land during construction and operation; and high

resilience to river flows;


(b) Community – perceived minimal negative impact on Waikato River

user activity during and after construction; and visual amenity;

(c) Constructability – provides a solution that is the least complex to

construct in the most suitable geology; with the least disruption to the

existing WTP supply; at the lowest cost; within required timeframes;

and has the highest potential to reduce construction carbon;

(d) Operation, Maintenance and Asset Management – represents the

lowest likely operational and maintenance cost; highest likely operation

and maintenance safety; highest flexibility of operation with long term

bathymetric suitability of the riverbed; and

(e) Statutory Compliance – meets permitted and/or discretionary

consenting requirements with minimal cost implication and perceived

consentability risk, and does not require additional easements or

designations.

6.18 Cultural aspects were not scored at Workshop 2, instead Waikato-Tainui

provided the following feedback:

(a) The existing intake site has particular significance to Waikato-Tainui

because it is adjacent to a culturally significant wahi tapu site;

(b) The floating intake is strongly not preferred due to its likely above river

size and effects/disruption to the river;

(c) In general, the proliferation of structures on the riverbed is a concern

for Waikato-Tainui. The preference is to have the footprint minimised

on the riverbed. One combined intake structure is preferred but they

acknowledge the risks and challenges that this option would present;

(d) On the landward side, it is also preferred to minimise modification of

the existing site; and

(e) Two pump stations next to each other is better than two located at

separate sites.

6.19 The two highest scoring of the four options considered at Workshop 2 were

Option 2b and Option 7. The options scored as follows against the criteria

mentioned in 6.17 above:


Criteria Option 2b Option 4 Option 5b Option 7

Environmental 18 16 17 22

Community 9 5 8 9

Constructability 19 17 18 18

O & M 14 14 12 13

Statutory

Compliance

13 11 11 13

Total 73 63 66 75

6.20 Taking the Waikato-Tainui comments and the scoring into account, Options 2b

and 7 were confirmed as the preferred options. Although there is not a single

preferred option, Options 2b and 7 are in the same location on the river, using

the same abstraction method, but with a different on-land pump station and

rising main location, alignment and design. Further discussion on the preferred

options and reasons for this selection is presented in section 6.21 following.

6.21 Options 2b and 7 were preferred over the other shortlisted options for the

following reasons:

(a) The intake would be located in the ideal location from a bathymetric

perspective. A deep and stable scour channel in the riverbed would

provide sufficient depth for the intake structure and screens. Refer to

Dr Keller’s evidence;

(b) From a geotechnical and seismic resilience perspective, the current

raw water pump station and intake tunnel are likely to be the best

position for the new intake tunnel and pump station, compared to the

other locations considered;

(c) The potential effects on river ecology during operation are well known

based on data available for the existing intake;

(d) Reduced impacts on terrestrial ecology compared to constructing at a

new greenfield site, as the existing access road and some of the

existing infrastructure can be shared;

(e) Locating the intake below the water surface and adjacent to the

existing intake reduces the potential effects on recreational activities,

visual amenity, and natural environment, and is preferable to Waikato-

Tainui compared to a floating intake;


(f) The operation and maintenance would be the same as, or similar to,

the existing intake and therefore, provide certainty and familiarity to

Watercare;

(g) The intake structure on the riverbed is an expansion of the existing

intake site, and the resultant pump station will be adjacent to the

existing or at the new WTP. It does not therefore result in the

proliferation of structures on the riverbed or riverbank by requiring the

development of a new site in a different location, which is a concern to

Waikato-Tainui; and

(h) Proposed construction activities and temporary works and the location

of the structure itself is outside a 20 m buffer from the wahi tapu site on

the riverbank.

7. The preferred intake option

7.1 The preferred intake option is located at the existing intake site. It consists of a

new in-river fine screened intake manifold, immediately downstream of the

existing intake manifold, approximately 10 m to 13 m from the riverbank and

installed underwater on a concrete structure piled into the riverbed.

7.2 Should Option 2b be adopted, a pipeline from the intake manifold would be

installed in an approximately 85 m long, 2,550 mm diameter tunnel to a new

pump station, adjacent to but separated from the existing pump station.

7.3 Should Option 7 be adopted, a pipeline from the intake manifold would be

installed in an approximately 450 m long, 2,550 mm diameter tunnel to a new

pump station in the Waikato A WTP site.

7.4 The top of the screens would be approximately 2.3 m below the low river water

level (set at 0.61 mRL as per Watercare as-built drawing number 2003230.449),

and the bottom of the screens approximately 2 m above the riverbed level

(based on the last bathymetric survey undertaken in 2017), although this latter

dimension can vary significantly, being approximately 0.8 m below the proposed

screen level in a 1964 survey.

7.5 The new intake structure would be located directly downstream of, and in line

with the existing intake structure. As such it would benefit from the protection


afforded by the existing structure and its debris deflector. However, depending

on the type of screen cleaning system used, the screens could be mounted

either vertically (the same as the existing screens), or horizontally, in which case

further design refinement may require an additional debris deflector.

7.6 The bathymetric information indicates an area of low bed levels directly

downstream of the existing intake, providing a lower risk of screen

sedimentation due to bed level increase than at the existing intake manifold, as

discussed in Dr Keller’s evidence.

7.7 The intake screens would be mounted to a 1,200 mm diameter manifold pipe

using a slotted flange arrangement, which would facilitate removal for servicing

if required. The manifold structure is supported by concrete piles in the riverbed.

A new 1,200 mm diameter pipeline would convey water from the manifold to a

new pump station wet well.

7.8 The existing 600 mm process discharge water pipeline would be retained, and

extended from the existing intake manifold to the new intake manifold such that

it discharges downstream of both intakes. Provision is made for an additional

600 mm process discharge pipeline, adjacent to the existing one, with capacity

to service the Waikato A WTP.

8. The design of the proposed intake

8.1 The proposed new intake, under either Option 2b or Option 7, would be

equipped with three or four cylindrical fish screens, depending on final design

refinement and the type of automated screen cleaning system adopted.

8.2 The cleaning system currently used on the existing intake is an airburst system

that uses compressed air released inside the screens to dislodge debris and

algal growth from the screen. Watercare operations staff have reported that this

system is less effective during low river level periods when algal growth

accelerates and the airburst system fails to dislodge all the algae, resulting in

some residual screen blockage (and therefore reduced intake capacity) after

cleaning. Divers are used to manually brush the screens from time to time. At

low intake flows, the frequency of this manual brushing is once every four to six


months and at high intake flows, the frequency could be up to once every three

weeks.

8.3 There are two feasible alternative cleaning systems that should prevent the

current cleaning issues experienced from time to time, namely:

(a) An airburst system similar to that in use at the existing intake, possibly

with a revised, more effective in-screen design. Four static screens are

required for the intake to achieve the screen design requirements.

Airburst cleaning of the intake is expected to occur up to eight times

per day. Refer to the screen installation Figure 2 below (note that the

debris deflector shown may not be required); or

Figure 2. Airburst screen intake option

(b) A rotating brushed screen system that uses fixed internally and

externally mounted brushes to mechanically remove debris and algal

growth while the screen rotates. A minimum of three rotating screens

are required for the intake as there are less constraints on the size of

the mesh area per screen and the orientation of the screens compared

with an airburst system. The screen rotation speed, duration and

direction can be set to suit requirements. Refer to the Figure 3 below

(note that the debris deflector shown may not be required).


Figure 3. Brushed screen intake option

8.4 The airburst system utilises a compressed air accumulator on shore to

discharge high volumes of air to each screen individually, likely via 150 mm

diameter pipelines (one pipeline per screen).

8.5 Water abstraction continues unimpeded during the airburst sparging process

and the pumps are never turned off. The screens would be checked by divers

and manually brush cleaned (if required), as currently takes place on the

existing screens.

8.6 The rotating brushed screens are rotated using electric motors. This would

require the installation of electrical cables to the two motors in each screen.

8.7 Divers would check the screens periodically and are able to access underwater

hatches in the screen units should a motor require maintenance or replacement.

This would negate the requirement for screen removal and retrieval if work was

needed on the motors.

8.8 The intake screens, irrespective of the type of cleaning system used, would

consist of a cylindrical stainless steel wedge wire mesh with 1.5 mm wide slots

(or openings). The new intake (i.e. all operating screens) would be designed to

convey a combined peak instantaneous design flow of 3.2 m3/s (or 3,200 L/s),

while ensuring that a maximum screen approach velocity of 0.15 m/s is not

exceeded. Approach velocity being defined as the velocity of the water within

the screen slots (or openings). Refer to the Figure 4 below.


Figure 4. Brushed intake screen

8.9 All screen sizing calculations include a blockage allowance of 10% of the screen

mesh area.

8.10 The proposed mesh described above is similar to the existing intake screen

design, and should the airburst cleaning option be preferred, the intake would

consist of four identical screens, mounted vertically, in a near duplication of the

existing intake screen manifold setup.

8.11 Each airburst screen would be around 1,520 mm in diameter, 4,550 mm long,

and the complete four-screen manifold is expected to be around 20 m in length.

8.12 The four-screen setup would allow three of the screens to operate at 85% of the

maximum flow rate (should one screen be taken out of commission), whilst still

complying with the maximum allowable approach velocity of 0.15 m/s.

8.13 Should a rotating brushed screen cleaning system be preferred, at least three

cylindrical screens would be required to meet the design requirements, although

four smaller screens could also be considered. These screens could be

mounted horizontally or vertically.

8.14 Each brushed screen would be around 1,520 mm in diameter, 6,300 mm long,

and a complete three-screen manifold is expected to be around 20 m in length.


8.15 The three-screen setup would allow two of the screens to operate at 88% of the

maximum flow rate (should one screen be taken out of commission), whilst still

complying with the maximum allowable approach velocity of 0.15 m/s.

8.16 Once water has passed through the screen mesh it is conveyed via a pipe

manifold into a 1,200 mm diameter steel pipeline to the riverbank, at which point

it would connect either to a sealed tunnel to the Option 2b pump station adjacent

to the existing pump station, or to a sealed tunnel to the Option 7 pump station

located at the proposed Waikato A WTP site.

9. The construction methodology for the intake

9.1 The high-level construction methodology described below is based on using

trenchless methods for constructing the tunnel between the raw water pump

station and the intake. Depending on the final alignment and detailed

geotechnical investigations, the trenchless methodology could utilise a tunnel

boring machine (TBM), drill & blast or a road header.

9.2 A temporary access track and platform would be constructed on temporary steel

piles driven into the riverbank and bed. The surface area of the track and

platform sections installed above/over the river is expected to be in the order of

300 m2.

9.3 An approximately 240 m2 piled cofferdam would be installed around the in-river

works area to allow draining of the area by pumping the water inside into the

river. These temporary works would be large enough to allow a dry exit point for

the tunneling works and to remove the TBM or other equipment after drilling

from the pump station site towards the river.

9.4 The proposed cofferdam would be approximately 21 m long and extend

approximately 10 m from the riverbank in a section of the Waikato River that is

approximately 130 m wide, equating to an approximate 8% reduction in width.

9.5 It is envisaged that the construction works would involve the following:


(a) Excavate the tunneling launch pit in the same location as the pump

station wet well;

(b) Complete the tunnel construction and raw water pipeline installation

and dispose of excavated material to approved landfill or as fill on site;

(c) Complete a trenchless conduit for airburst or control cable duct,

depending on the screen cleaning option installed. Alternatively, these

services could be installed in the common tunnel that also houses the

raw water pipeline;

(d) Drive support piles for the intake manifold and intake pipe supports,

both inside and outside the cofferdam area (i.e., dry and in-river works);

(e) Construct the intake support structure anchor boxes (formwork),

including steel reinforcing, on the piles and install the intake manifold

pipework on the support structure, up to the cofferdam by submerging

the intake assembly (including screens);

(f) The intake assembly including the anchor boxes are submerged and

the anchor boxes are filled with concrete underwater using a tremie

pipe;

(g) Flood the cofferdam, remove the cofferdam piles, and connect the

submerged inlet pipework to the supply pipeline underwater using

divers;

(h) Extend the existing and install the new process discharge pipelines to

the new intake structure underwater using divers; and

(i) Remove the temporary access track and platform and piles and

reinstate the riverbank.

9.6 The completed intake installation (intake manifold, support structure and

connection pipeline to the riverbank) is expected to comprise a footprint area of

approximately 200 m2.

9.7 The construction period for works in the Waikato River has been estimated at

up to approximately 21 months, broken down as follows:

(a) Installation of temporary works (access platform and track, cofferdam)

– 3 months;

(b) Permanent works, including construction of new tunnel – 15 months;

and

(c) Removal of temporary works – 3 months.


9.8 The indicative intake layout, including the temporary construction platform,

coffer dam and permanent structures (indicated in magenta) is shown on Figure

5. While Figure 5 shows intake Option 2b, the layout is similar for the two intake

options being considered (an intake linked to a pump station adjacent to the

existing pump station [Option 2b] or an intake linked to a pump station adjacent

to the proposed Waikato A WTP [Option 7]) in terms of in-river works. The

proposed coffer dam would be located around the proposed intake pipe works,

between the intake screen and the riverbank as indicated by the wavy light blue

line in Figure 5. The final intake layout would be as shown in Figure 5 but without

the coffer dam and temporary construction platform (shown in blue).


Figure 5. Option 2b indicative intake layout


9.9 The existing intake and pump station would need to be operational throughout

the construction of the new intake infrastructure to maintain the supply of water

to Auckland, except possibly for short periods during the connection and

installation of the electricity supply, and if applicable, during any cross-

connection installations. As indicated in Figure 5, both the existing intake and

the Waikato 50 intake lie outside the proposed work area, meaning that both

could remain operational during construction.

André Rynhard Bresler

21 May 2021

in the matter and in the matter statement of ......page 3 eic of andre bresler (water intake...

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