The North Fringe Project
Delivery of Sewer and Water Infrastructure to North Dublin
Adrian P. Conway, Chartered Engineer
Dublin City Council
20th November 2006
1. North Dublin – A Brief History of Sewer and Water Services
1.1. North Dublin Sewers
Dublin City, in common with many major cities, grew up around an existing river.
There were many reasons for this, including easy access to a port and access inland by
river. However, one very important reason was the river and its tributaries represented
easy availability of fresh water to drink, and a convenient method of disposal of
human and animal waste.
The river system was able to support both of these uses as long as the population
remained small. As Dublin grew, the use of the city rivers and streams for disposal of
waste rendered them unfit for use as sources of drinking water. It also resulted in the
rivers and streams and the adjacent streets becoming open sewers. The original sewers
of Dublin were created when many of these streams and open sewers were covered
over to reduce the nuisance, but the sewage continued to discharge directly to the
Liffey.
Further growth resulted in the increased pollution of the river and increased public
health problems. The result was the construction of the interceptor sewers north and
south of the Liffey and the transmission of the combined stormwater and sewage to
the new treatment plant at Ringsend.
Dublin’s main growth was to the south for many years. However, from early in the
twentieth century, the city started growing to the north with the developments around
Drumcondra, Glasnevin, and over to Marino and Clontarf. The sewage from these
areas was catered for by extending the north inner city sewers northwards. However,
by the middle of the century, these sewers had become completely overloaded. Dublin
Corporation devised a new sewerage scheme running from west to east discharging to
a new deep sea outfall, at the Nose of Howth. The only treatment was a screening of
the sewage prior to disposal to sea. This was the first major sewer in Dublin not to
discharge to the Liffey.
The new sewer, known as the North Dublin Drainage System (NDDS) ran from
Ashtown along the Tolka Valley to the sea north of Clontarf and along the seafront to
Howth. A low lying area on the lower reaches of the Tolka, including Fairview, and
Clontarf discharged to a pumping station at Clontarf and was pumped to the NDDS
Sewer. The new system was a partially separate system with some stormwater flows
catered for.
While this dealt with the problem admirably in the short to medium term, history
repeated itself in the continued expansion of the city northwards, particularly from the
1970s. The new areas included Finglas, Ballymun, Artane, Coolock and Raheny. The
NDDS itself became increasingly overloaded, with consequent increasingly frequent
spillages from the many storm overflows to the local rivers and streams and into
Dublin Bay. The increased load from the new town of Blanchardstown was removed
from the NDDS to the Grand Canal Tunnel scheme constructed in the 1970s.
1.2. North Dublin Watermains
In relation to water supply, one of the features of Dublin City water supply was that
all of the sources of drinking water developed from the nineteenth century were south
of the city. As North Dublin grew, the water supply network grew north with it. The
most recent extension to the North was the North City Arterial water scheme
developed in the 1980s.
However, there were areas along the outer northern suburbs such as Finglas,
Ballymun, Coolock and Raheny that could not be reached by the south city supply
neworks due to elevation and headloss. These were supplied from the Dublin County
Council source at Leixlip, which was pumped to a reservoir at an elevated location at
Ballycoolin, north of Blanchardstown, from where a trunk main system supplied the
northern areas of Dublin City as far east as Howth. Again, as in the case of the sewer
network, the continued growth put increasing demands on the capacity of this supply
system.
For a detailed description of the history of Dublin’s water supply and sewer systems I
refer you to the recent book “Our Good Health” by Michael Corcoran.
2.
“The North Fringe”
The North Fringe was a term devised to cover the area, largely undeveloped, to the
immediate north of the Dublin metropolitan area. By the late 1990s it was largely the
area between the developed area and the M50 /Airport. (See Map 1).
Map 1
From the 1980s it had become apparent that the NDDS was overloaded and that any
continued development in the catchment would inevitably result in increased
overflows and pollution. Dublin Corporation decided to put in place an embargo on
all proposed development in the NDDS Catchment area. It is worth noting that this
policy was driven by the capacity deficiency of the sewer network.
There was only limited resistance to this in the 1980s as the economy stalled. There
was increasing pressure from developers and landowners from the start of the 1990s
as the demand for housing and residential development picked up. However, with
some exceptions, the policy was kept in place.
3.
The 1994 North Dublin Drainage Scheme Report
Consultants M.C. O’Sullivan and Co. Ltd. were engaged by Dublin Corporation to
examine the North Dublin Drainage catchment area and come up with
recommendations to cover existing and future demands. The report was produced in
1994. It was produced as part of and to be compatible with the overall study of the
sewage treatment and sludge disposal issue that ultimately became known as the
Dublin Bay Project.
In relation to the North Dublin Drainage catchment, the 1994 report divided the entire
catchment of the NDDS system into a number of sub catchments and reported on
each. A hydraulic model was constructed for each sub catchment and the various
problem areas identified.
One of the key outcomes was a recognition that the NDDS trunk sewer was heavily
overloaded and the catchment area discharging to this sewer had to be significantly
reduced. The report than proposed a series of new works and network improvements.
These included upgrades for storm overflows and increasing the diameter of certain
sewers.
A major proposal of the report involved the construction of two new trunk sewers
across North Dublin to remove a significant part of the existing load from the NDDS.
The first new sewer was called the Northern Interceptor sewer running from west
Finglas to Ballymun along the existing road artery of Mellowes Road, Ballygall Road
West and onto Glasnevin avenue, discharging to a proposed pumping station at
Ballymun Road. The purpose of this sewer, as the name suggests, was to intercept the
existing sewers in the area which were flowing south to the NDDS system.
The second proposed sewer was called the North Fringe Sewer and was designed to
run from Ballymun Road at Santry Demesne via the Santry River valley and the
Mayne River valley to Baldoyle and on to the proposed Sutton Pumping Station
which would pump both the North Fringe Sewer discharges and those of the NDDS to
the proposed new treatment plant at Ringsend via a proposed submarine pipeline. The
North Fringe sewer was designed to carry the discharges from the North Fringe
Interceptor sewer, and also to intercept further NDDS flows through a series of north
south spur sewers. Given its geographical location through what were then largely
undeveloped lands, the new sewer was also designed to cater for future flows from
planned developments along the northern edge of Dublin City and the southern areas
of Fingal.
In order to connect the flows from the Northern Interceptor sewer to the North Fringe
sewer, a pumping station was proposed at Ballymun Road and a twin rising main
from there to the head of the North Fringe sewer.
4.
The North Fringe / Northern Interceptor Sewer Project
4.1 Engagement of Consultants
As stated previously, the effective embargo on new developments within the
catchment of the NDDS was resulting in increased pressure from Dublin Corporation
and from developers on central government to act. This was happening at the same
time as upcoming deadlines set by the European Union Urban Wastewater Treatment
Directive prohibiting direct discharge of untreated sewage to the sea and the dumping
of sewage sludge at sea.
In 1998 the Department of the Environment, Heritage and Local Government
approved a brief to engage consulting engineers to design the North Fringe and
Northern Interceptor sewers.
The Department also agreed to include the construction of a new storage tank and
combined storm overflow on the NDDS trunk sewer at Clontarf to replace an existing
sub standard overflow system. This was one of the recommendations of the 1994
Report and was seen as a priority to prevent pollution of the Wad River which
discharges to Dublin Bay near the sensitive Bull Island. This element of the project is
designated as the Clontarf CSO.
Since the proposed sewers would be serving both Dublin City and Fingal, and the
North Fringe sewer route was partly within Fingal, a decision as to which local
authority should lead the project was required. Following discussions it was agreed
that Dublin Corporation would act as the lead authority and client in relation to the
proposed project.
Following a procurement competition, the successful consultants were a joint venture
of M.C. O’Sullivan and Co. Ltd and P.H. McCarthy and Partners. Dublin Corporation
formally engaged the joint venture in December 1998
4.2 Design Review Report
The brief required the consultants to review the 1994 report in the light of the
developments since 1994 and also taking into account future developments in the
catchment area of the new sewers. The resultant Design Review Report was produced
in June 1999.
The report retained the essential elements proposed in the 1994 report. The proposed
diameters were updated to cater for future demands, based on projected growth rates
and the ultimate development of the entire catchment.
However, following an analysis of future demands and the location of zoned lands, it
was realised that there was a significant catchment between the existing areas of
Finglas and Ballymun and the M50 that was not adequately served by the proposed
sewer layout as envisaged in the 1994 report.
A further change was required due to the construction of the Finglas By Pass
subsequent to the 1994 report. The new road was constructed west of Finglas village
in a cutting. This meant that the proposal to connect west Finglas to east Finglas in a
single gravity sewer was no longer possible.
The Design Review Report proposed the construction of an additional pumping
station at Mellowes Park which would take in the existing west Finglas flows and
pump them north parallel to the new Finglas Bypass (N2) to a discharge point on the
west side of the N2 just south of the M50.
From there a new proposed gravity sewer, called the Meakstown sewer, would run
through the undeveloped lands north of Finglas and Ballymun and down Ballymun
Road to the proposed Ballymun pumping station.
This resulted in the need to increase the capacity of the Ballymun Pumping station
and the twin rising main.
The additional flows from the west, together with a considerable increase in the
foreseen future flows from the North Fringe catchment, resulted in a significant
increase in the proposed diameter of the North Fringe sewer.
The diameters ranged from 525mm to 600mm in the Interceptor sewer, from 750mm
to 900mm in the case of Meakstown sewer and from 900mm to 1600mm for the
North Fringe sewer. The proposed layout is shown in Map 2
The Design Review Report was approved by the Department of the Environment,
Heritage and Local Government in November 1999.
Map 2
4.3 North Fringe / Northern Interceptor Sewer Project Overview
I refer you to the layout referred to earlier in Map 2. The 1999 Design Review Report
identified the various contracts under which the project would be constructed. A
further section of sewer on Swords Road was set up as a separate contract due to the
imminent construction of a Quality Bus Corridor at this location, and the need to have
the sewer constructed prior to this.
The various elements are set out in the following table 1
Contract No.
6-2
6-3a
6-4a
6-4c
6-3b
6-5
Contract Name
Total Length
(trunk sewer only)
Meakstown Sewer
3.5km
Northern Interceptor
6km
North Fringe Sewer
12km
Swords Rd. Sewer
620m
Mech – Elec Contract
N/a
Clontarf CSO
N/a
Table 1
Diameter Range
750mm to 900mm
525mm to 600mm
900mm to1600mm
900mm
N/a
N/a
4.4 Meakstown /Poppintree Sewer Advance Contract 6-2
During the Design Review phase in early 1999, it became apparent that a new sewer
was required to serve the undeveloped zoned lands north of Finglas. At this time also,
Dublin Corporation were starting the Ballymun Regeneration Project.
In the context of the increasing demand for housing, it also became clear that this new
sewer was needed urgently to serve a parcel of housing land at Meakstown which
represented an opportunity to have new housing provided at an early date.
It was therefore decided to have the proposed Meakstown Sewer constructed as an
advance contract for the following reasons:
• The need to coordinate with the construction programme of Ballymun
Regeneration Ltd. in particular the proposed reconstruction of Ballymun Road
• The need for an early solution to the lack of sewage services for the
Meakstown Housing Area
• The need to serve the substantial amount of commercial development planned
for the area at the N2 / M50 Interchange
In order to allow the commissioning of the Meakstown sewer in advance of the North
Fringe Sewer, it was necessary to establish that there was some spare capacity in the
existing sewer system on Ballymun Road. Based on the 1994 Report the consultants
established that the existing system could take up to 40 litres per second of additional
flow which would allow the construction and occupation of up to 1,000 houses
pending the full completion of the North Fringe Sewer.
This proposal was accepted by the DEHLG and tenders were invited in October 1999.
The contract was awarded to Pat Mulcair Civil Engineering in May 2000.
The sewer ran from a point on the west side of the N2 just south of the M50 in a south
easterly direction and included a section along existing industrial estate roads off St.
Margaret’s Road and Jamestown Road. One section under these roads was
constructed by pipejacking due to the extreme depth and the likely disruption of open
cut.
The pipe ran across Poppintree Park and into Ballymun via Sillogue Road. It was
decided that the sewer should follow the alignment of the future road network as
planned by Ballymun Regeneration Ltd. Part of this new road alignment was still
occupied by one of the “spine” apartment blocks which was due for demolition in the
future. It was decided to pipejack a section of the sewer underneath this apartment
block thus ensuring the sewer would be aligned with the future road network.
A further section of the pipe was located within Ballymun Road, in particular within
the new “Main Street” which was about to be constructed. Following discussions with
Ballymun Regeneration Ltd. it was agreed that this section would be constructed as
part of the Main Street Contract by Ballymun Regeneration contractor Careys
Construction Ltd. This agreement also included a section of the twin 450mm rising
main from Ballymun Pumping Station. The remainder of the rising main was
constructed under Contract 6-2
Construction commenced in June 2000 and was completed in June 2001.
The Meakstown Sewer route is shown in conjunction with the North Fringe/ Northern
Interceptor Sewer in Map 3 below.
Map 3
4.5 Northern Interceptor Sewer – Contract 6-3a
The Northern Interceptor Sewer consisted of four distinct elements (See Map 3)
• The construction of a pumping station and intake pipeline at Mellowes Park to
collect the discharges from the North West Finglas catchment
• The construction of 1.4km of 300mm rising main from the Mellowes Park
Pumping Station to a discharge manhole at the head of the Meakstown sewer.
• The construction of 2.4km of gravity sewer from Finglas to Ballymun
• The Construction of a Pumping Station at Ballymun Road
The contract also included some local sewer upgrades as recommended in the 1994
Report.
The location of the proposed pumping station at Mellowes Park had to be changed to
cater for Dublin Corporation plans to construct a Swimming Pool and Leisure Centre
at the location. A suitable alternative was found at a nearby location occupied by a
playground. A new playground was constructed by a specialist contractor in advance
of the pumping station construction.
The main Interceptor sewer run was located along the existing roads of Ballygall
Road West and Glasnevin Avenue. Due to the volumes of traffic on these roads and
the amount of frontal development, the design envisaged the use of pipe jacking. The
tender drawings gave the diameter as 1050mm in order to allow manual pipe jacking,
although the hydraulic requirements were for a lower diameter.
The tender documents also provided two alternative routes to the proposed Pumping
Station at the Ballymun Road end, one via the Ballymun Road / Glasnevin Avenue
junction and the alternative via residential roads at Willow Park, together with a
section through private gardens.
The tenders were invited in May 2000 and the contract was awarded to Pierse
Contracting Ltd. in March 2001, based on the alternative route.
The contractor proposed the use of a tunnel boring machine as an alternative to
pipejacking. This was accepted and allowed the construction of a 600mm sewer in
accordance with the hydraulic design. The use of the TBM proved very successful in
terms of the alignment of the sewer and in terms of the reduced disruption to local
residents and traffic.
Construction commenced in May 2001 and was completed in October 2003.
Map 4
4.6 North Fringe Sewer – Contract 6-4a
The North Fringe Sewer consisted of the following distinct elements (see Fig Map 4)
•
•
•
•
9km of gravity sewer from 900mm to 1050mm
3km of 1600mm pressure sewer
4.7km of Branch sewers
5,000 cubic metre storage tank and CSO
The contract also included some local sewer and CSO upgrades as recommended in
the 1994 Report
The sewer was generally located in areas that had not yet been developed, and was
constructed by open cut. A number of sections were pipe jacked, including a crossing
of the M1 Motorway, the Belfast Railway and the DART at Sutton.
The final 3km of the sewer was designed as a pressure sewer. This was to allow for
surcharge conditions in the event that there was a failure, overload or shutdown of the
Sutton Pumping Station to which the North Fringe Sewer discharges. Under those
circumstances the pressure section would surcharge and eventually overflow to a new
5,000 cubic metre off line storage tank at the head of the pressure section. If this
storage tank in turn filled, it could spill to the adjacent Mayne River through an
overflow. The tank was fitted with an automatic cleaning system using tipping
buckets.
A significant section of the pressure sewer was located along the beach at Baldoyle.
Tenders were invited in March 2000 and the contract was awarded to Pierse
Contracting Ltd. in November 2000.
The contract was awarded on the basis of an alternative tender which proposed the use
of GRP pipes for the 1600mm pressure section rather than the specified ductile iron.
This alternative provided a significant saving to the client.
As can be seen from the layout, there were a number of branch sewers included in the
contract. The function of the major branch sewers was to intercept flows from the
NDDS system and divert these flows north into the North Fringe Sewer. The most
significant branch sewers were on Malahide Road and Grange Road. Due to the need
to minimise disruption to traffic, most of the Malahide Road Branch was constructed
by tunnel. A significant section of rock was encountered in this section, necessitating
the use of a special rock boring machine.
Construction commenced in January 2001 and was completed in September 2003.
4.7 Clontarf CSO – Contract 6-5
This contract incorporated a 750 cubic metre off line storage tank and overflow to the
Wad River which was to be constructed alongside the North Dublin Drainage Scheme
Trunk sewer at Clontarf Golf Club near Donnycarney. This was to replace an existing
sub standard overflow system.
Tenders were invited in November 2001. The contract was awarded to Wills Brothers
in September 2002. Construction commenced in September 2002 and was completed
in April 2004.
4.8 Contract 6-3b Mechanical Electrical Contract
This contract included the electrical and mechanical requirements of the Mellowes
Park and Ballymun Road Pumping Stations, together with those of Grange Tank. It
also included the telemetry / flow monitoring requirements along the route of the
sewer, including the need to measure sewage flows at each point where the sewer
crosses the boundary between Dublin and Fingal.
Tenders were invited in November 2000 and the contract was awarded to Response
Engineering Ltd in November 2001.
5.
Dublin City North Fringe Water Supply Scheme - 1999 McCarthy Acer
Strategy Report
Once the approval to appoint consultants for the North Fringe / Northern Interceptor
sewer was received, it became apparent that the long standing embargo on new
developments in the area would no longer apply. Based on the Dublin Corporation
and Fingal development plans then in force, it was estimated that an additional water
demand of 36.5 ML per day would arise in the North Fringe area. This, together with
an anticipated reduction in water transfer to Dublin City from Fingal would lead to
inadequate levels of service and for much of the North City lead to system failure.
Dublin Corporation had previously appointed McCarthy Acer to carry out an
examination of the situation and to bring forward proposals.
The consultants used a calibrated model of the Dublin City water network and
estimated the projected demand in the year 2010, based on the Development Plans.
The Report, issued in June 1999, recommended a combination of additional storage
and new trunk mains, including new storage at Ballymun, a new watermain from
Cappagh to Ballymun, a new watermain from Fairview to Kilbarrack Road and
various upgrades of existing mains
6.
The North Fringe Water Supply Scheme
6.1 Engagement of Consultants
In June 2000 Dublin Corporation advertised seeking submissions from Consultants.
Following a selection procedure and Departmental approval McCarthy Hyder
Consultants were appointed in January 2001 to proceed to final design stage, based on
an update and Design Review of the 1999 report.
6.2 Design Review Report
The Design Review incorporated out a review of the 1999 Report taking into account
the impact of new and proposed developments up to the year 2021. It also took into
consideration such current reports as the Bacon Reports on the Housing Market and
the Stategic Planning Guidelines. The Report dealt with the demand, storage and
distribution of water to the North Fringe area.
A network model was created extending from the Cookstown and Stillorgan
reservoirs to the Ballycoolin / Jordanstown Reservoirs.
The report, completed in July 2001, found that the additional daily demand at full
catchment development in year 2021 would be 149ML, being 119ML of additional
demand in Fingal and 30ML in Dublin.
In order to cater for this demand, the Report recommended a new network of trunk
mains and new storage at Sillogue (see Map 5)
The new mains were in two main sections:
• From Cappagh to Baldoyle (approx 16.5km) – the North Fringe Watermain
• From Fairview to Baldoyle (approx 10.4km)– the Coastal Arterial Watermain
The storage at Sillogue would be a 40ML ground level reservoir and a 5ML Tower.
The Design Review Report was approved by the Department in November 2001,
subject to a revised calculation of the storage at Sillogue. This revision resulted in a
reduction in the size of the ground level reservoir to 30ML.
Map 5
6.3 North Fringe Water Supply Project Overview
Based on the Design Review Report the Project was divided into the following
contracts
Contract No.
3 (watermain)
7 (watermain)
5 (watermain)
6 (Storage)
Location
Length (km)
Diameter Range
Cappagh to Ballymun 9
800mm
Ballymun to Baldoyle 13.3
600mm to 450mm
Fairview to Baldoyle 10.4
600mm to 450mm
Sillogue
N/a
N/a
Table 2
Sillogue storage was further divided into Contract 6a for the Civil Works and
Contract 6b for the Mechanical / Electrical Works.
6.4 Contract 3 – Cappagh to Ballymun
This section of 800mm watermain starts with a connection at Cappagh to the existing
trunk main carrying water from Ballycoolin. The new main is routed parallel to and
north of the M50, crosses the M50 and then runs parallel to the M50 to cross the
North Road and run beside the Meakstown sewer until Jamestown Road where it
turns north and then heads east to terminate on Ballymun Road. It includes a twin
800mm main to and from the Sillogue Storage site, including a twin crossing of the
M50. The Contract also includes a north south branch, also 800mm diameter, which
runs along Ballymun Road and connects to the northernmost section of the Dublin
City Cookstown supply at Mobhi Road. This connection is very significant in that, for
the first time, it allows the bulk transfer of water from the Cookstown supply to the
Ballycoolin supply and vice versa.
A feature of this section was that, in the time period between completion of the tender
documents and award of contract, a substantial amount of development had either
commenced construction or been awarded planning permission. The result of this was
the need to significantly alter the route of the watermain to avoid digging up newly
constructed housing estates or affecting sites with full planning permission, resulting
in major delays and claims for compensation. These late changes did result is
additional contract costs, but the overall effects on the project delivery were
minimised.
Tenders were invited in December 2002 and the contract was awarded to Coffey
Construction Ltd. in November 2003.
Construction commenced in December 2003 and was completed in June 2005.
6.5 Contract 7 Swords Road to Baldoyle
The section of watermain from Ballymun Road to Swords Road had been constructed
previously as part of the Santry Demesne Development and was not included in
Contract 7.
This contract ran through a number of industrial estates before crossing the M1 and
turning north to then run east north of and parallel to the N32. From the Malahide
Road the watermain runs parallel to the North Fringe Sewer, crossing the Belfast
Railway, before turning south, crossing the DART line at Bayside station and out onto
the coast road.
In the case of this watermain, it was largely constructed just before the developers
arrived. However, in one area just west of the Belfast Railway, the development was
well underway. It was agreed that the developers contractor would construct this
section of the watermain to avoid conflict between contractors and their respective
programmes.
Tenders were invited in August 2003 and the contract was awarded to Ward and
Burke in April 2004
Construction commenced in June 2004 and was completed in December 2005.
6.6 Contract 5 Coastal Arterial Watermain
This contract has been delayed due to a number of issues including a requirement to
incorporate proposed coastal flood protection works into the contract. It is now at
final design stage and it is anticipated that construction will take place in 2008. The
Contract will consist of 10.4 km of watermain of diameter 600mm and 450mm
connecting the existing high pressure supply at Fairview to the end of the North
Fringe Watermain at Baldoyle, thus creating a ring main around north Dublin. The
completion of this contract is a key element in maximising the benefits of the North
Fringe Water Supply Scheme.
6.7 Sillogue Storage Contract 6a (Civil) and 6b (Mechanical / Electrical)
The site, on the northern boundary of the M50 was selected due to its location close to
the tower’s Water Supply Area, but in an area free from development. The site was
also in the ownership of Fingal County Council.
The Consultants engaged architects Michael Collins and Associates to carry out an
architectural design of the tower and the overall complex. A number of options were
drawn up.
Due to the fact that the height of the tower was approximately the same as the width
at the top, the double curvature shape was deemed by the design team, together with
planners from Fingal County Council in whose area it is situated, to present the best
aesthetic solution. Given the high profile location beside the M50 and beside the
airport it was felt that an aesthetically pleasing design was essential.
The design of the roof of the tower was altered to a flatter profile to cater for the
requirement of the Irish Aviation Authority not to exceed a given level, due to the
proximity of Dublin Airport. (See Fig 1)
Fig 1
The tower consists of a shaft with access staircase supporting a bowl holding 5ML of
water. The shaft’s external diameter ranges from 16.8m at the base to its most slender
at 8m, widening upwards towards the maximum bowl width of 38m at the top.
The tower is constructed using a proprietary formwork system supplied by Austrian
firm Rund-Stahl-Bau. This system is designed and constructed off site and the inside
and outside shutters operate independently, the external shutters being supported off
the structure itself. (See Fig 2)
Fig 2
The ground level reservoir is 92m long and 66m wide and consists of two 15ML
cells.The reservoir will be largely buried. The cells incorporate HDPE curtain walls to
ensure that adequate flow is maintained throughout the water body.
There is also a pumping station, which houses the three pumps and associated
Mechanical and Electrical installations required to lift the water to the tower.
The contract also incorporates an earthen overflow attenuation lagoon and completion
of the 800mm inflow and outflow watermains constructed up to the site boundary
under Contract 3.
Due to the location and scale of this contract, it was decided to carry out an
Environmental Impact Assessment under Section 175 of the Planning and
Development Act 2000.
Tenders were invited for Contract 6a in April 2004 and the contract was awarded to
John Cradock Ltd. in May 2005.
Tenders were invited for Contract 6b in July 2004 and the contract was awarded to
Earth Tech Ireland Ltd in August 2005.
Both Contracts are still underway at the time of writing (November 2006). The
anticipated completion date for the civil works is January 2007 and for the
Mechanical Electrical Works is April 2007.
7.
Review of North Fringe Project 1999 to 2006
In this section of the paper I propose to review the project by setting out a number of
issues that arose, particularly those issues that are likely to arise in similar projects in
the future.
I have grouped these issues under two headings – Strengths and Weaknesses.
I also indicate where, with the benefit of hindsight, some improvements could be
made in dealing with similar project issues in the future.
7.1 Strengths
•
The North Fringe Project Office
Shortly after the engagement of the consulting engineers for the sewer in 1998/99, it
became apparent that the scale and urgency of the project needed a new approach if
the project were to be delivered on time. Dublin Corporation Engineering Department
decided to establish a dedicated Project Team to project manage and deliver the
project. Initially the team consisted of two engineers, who were joined by an
Administrative Assistant.
A third engineer was added in 2002 when the new water scheme was added to the
project portfolio.
The fact that there was a full time team dedicated solely to the project had a major
impact on the success of the project. Project Management techniques were introduced,
some of which are covered later in this section. The fact that the client had a team
working exclusively on the project ensured that all of the various planning, statutory,
wayleave and other issues were dealt with in a timely manner and that these issues did
not delay the project. The Project Office was, in effect, the “one stop shop” and driver
for the project and assisted significantly in decision making, communication flow and
anticipating and avoiding problems.
•
Health and Safety
Compliance with all of the requirements of the Safety, Health and Welfare at Work
Act 2005 and the previous Act, together with those of the Safety, Health and Welfare
at Work (Construction) Regulations 2001 and 2006 is an important aspect to all
projects. The use of a Project Office assists greatly in ensuring standardised
procedures in carrying out the client’s legal duties under this legislation. These
procedures include the selection and appointment of Project Supervisors under the
Regulations. The 2005 Act also puts additional onus on the client’s to take Health,
Safety and Welfare issues into account in selecting a contractor. This latter issue is
one that needs a considerable amount of attention in relation to current procurement
practice and contract award criteria.
•
Wayleaves
Early Consultation
The consultants for the sewer project employed an engineer to go out to the properties
on the sewer alignment and seek to meet with the various property owners or
occupiers. This was done with particular reference to lands that were then
undeveloped. This process was informal and was carried out prior to any official
property title searches. In most cases, it was possible to ascertain who the owner was
through informal contacts. In those cases meetings were arranged and an outline of
the project provided. Names and contact details of the principles on both sides were
exchanged. The initial views of the landowner on the proposed works, together with
any particular requirements of the landowner were recorded. This process greatly
assisted the design teams in aligning the pipelines and incorporating, where possible,
the requirements of the landowners into the contract documents.
Wayleave Procedure
The wayleaves for both the sewer and the watermain were served under the Public
Health Act of 1878 (as amended).
As part of the Project Management approach, a set of standardised procedures and
templates were set up at the start of the sewer project. These were improved
subsequently for the watermain project.
It was decided to send a letter from the Project Manager to each affected party, the
letter to accompany the wayleave notice. This allowed the Local Authority set out
some details of the project in relation to programme, disruption and reinstatement. It
also provided the affected party with easily accessible named people whom they could
contact, and reduced the somewhat impersonal legalistic tone of a wayleave notice.
One key aspect was establishing a unique reference for each wayleave, based on the
OS Map reference. This allowed easier tracking of the wayleave through the various
processes, often over many years. One of the strengths of the 1878 Act was that it
allowed immediate entry onto the lands once the wayleave was properly served. If the
landowner refused access there was immediate recourse to the District Court where a
Court Order could be obtained, which was enforceable in law. This process had to be
invoked in one instance in the sewer project.
This will no longer be possible on the enactment of the Water Services Bill which,
while repealing the provisions of the earlier legislation, does not incorporate any
provisions for serving of wayleave.
Future wayleaves will be served under the Planning and Development Act of 2000.
This process may prove more difficult to manage in that, if a landowner objects,
reference must be made to an Bord Pleanala, even where objections often only
become apparent when construction is underway. Assuming a positive outcome, a
Court Order may still be required to enforce entry. It will be interesting to see how
these procedures develop.
•
Planning and Statutory Procedures
One of the key tasks of the client’s Project Team was to identify which legal, planning
and statutory processes would apply to the project at the earliest date possible. Apart
from wayleaves, which is covered above the following were some of the key
processes identified:
Part 8 Procedures under the Local Government (Planning and Development)
Regulations 2000 – Formerly Part X Procedures under the 1994 Regulations
Part 10 (EIS) Procedures under the Local Government (Planning and
Development) Regulations 2000 – Formerly Part IX Procedures under the
1994 Regulations
Foreshore Licence under the Foreshore Act 1933 – (now under Part XV of the
Planning and Development Act 2000)
Crossings of National Roads and Motorways – Statutory Approval
Crossings of Railways –Statutory Approval
Roadworks / Road Openings – Statutory Approvals
Discharge Licences
The early identification of these processes and their timely implementation prevented
any significant delays to the various contracts. In the case of crossings of railways, it
was important to include the requirements of Irish Rail in the tender documents. This
involved early engagement with Irish Rail engineers in order to agree the engineering
conditions.
In the case of proposed roadworks, it was important to agree the outline traffic
management and reinstatement requirements with the relevant roads authority at an
early date for incorporation into the tender documents.
• Public Consultation
Significant sections of the sewer and watermain were routed through residential and
commercial areas. Prior to the commencement of construction, contact was made
with all representative groups in an area. If there were no official representative
groups, contact was made by mail drop. An initial meeting was held in each area and
a Liaison Group established. This group would have representatives of all residential,
commercial and other local interest groups.
Regular meetings of the Liaison Group were held locally in the evenings attended by
members of the Project Team, together with members of the Resident Engineer team
and a representative of the contractor. It was our experience that this process resolved
most major difficulties with local groups and often prevented problems arising. The
fact that the meetings were held regularly up to the end of the construction meant that
there was confidence that any undertakings would be complied with.
• Project Management Tools
The following are some of the Project Management tools used during the projects.
Some, such as change control and earned value management, were introduced during
the water project.
Risk Analysis – this was a particularly useful technique which involved the
use of workshops attended by stakeholders such as the ultimate users of the
new infrastructure – maintenance crews, telemetry teams, plant managers etc.
Early involvement of the client teams from the drainage and water
departments of both Dublin City and Fingal was crucial in ensuring that the
contract documents incorporated their requirements.
Standardised Procedures, filing system, forms, letters etc.
Change Control involving a formal initiation and approval process.
Monthly Project Review Meetings – these were attended by the consultant, the
project team and the client’s representatives – that is the drainage or water
engineer from the respective authorities.
Cost Management – Funding – Liaison with Funding Agencies
• Earned Value Management – use of Work Breakdown Structures
7.2 Weaknesses
•
Contract Tender Process
The following table illustrates the time period – referred to as the Tender Period taken from the date of the invitation for tender to the award of contract for the various
contracts referred to in this paper
Project
Sewer
Water
Contract
6-2 Meakstown
6-3a Northern Interceptor
6-4a North Fringe
6-5 Clontarf CSO
6-3b M&E
3 (Cappagh to Ballymun)
7 (Ballymun to Baldoyle)
6a Sillogue (Civil)
6b Sillogue (M&E)
Average
Table 3
Tender Period (months)
7
10
8
10
12
11
8
13
13
10
Given the fact that the contract documents ask the tenderer to hold their tenders for 90
days, the above periods are obviously a source of concern. The major reasons for the
delay in awarding the contracts are grouped into three areas
The Tender Assessment Process – this tends to be slow – often due to the slow
responses from tenderers to requests for further information and clarifications.
It is suggested that strict deadlines be given with all such requests and
enforced.
The Tender Approval Process – this approval process is shared between the
Local Authority and the funding Department. Significant delays can occur
here, particularly in those cases where the recommended tender is not the
lowest. It is suggested that for large and / or complex contracts a two stage or
restricted procedure may be preferable and, ultimately, quicker.
Insurances and Bonds – There are repeated delays in this process. Contractors
often forward bonds with a wording other than that in the tender documents. It
is also common to receive insurances that are out of date, or have exclusions
that are wholly inappropriate – for example excluding working at depths
below (say) three metres where the sewer in the contract is clearly deeper than
that. These delays are particularly frustrating and it is a matter for the
contractors as a group to deal with these issues.
While the tender periods outlined above are often typical, there is no good reason, in
my view, why a contract should not be awarded within six months of the tender
invitation.
I do not consider that the 90 day period in the contract documents is achievable and I
would suggest that this be amended to 180 days. This would prevent a significant
amount of paperwork in repeatedly extending the tender validity and, in a period of
relatively low inflation, should not present a major difficulty.
•
Site Investigations
There are two separate issues here
The adequacy of the Site Investigation :– In the case of pipelines, Site
Investigation is often seen as mainly concerned with identifying
underground services etc. This is often carried out to allow the
designer finalise the vertical alignment of the pipeline.
However, the site investigation should have regard to ground
conditions by having an adequate frequency of excavations to a depth
at least 0.5m below the bottom of the trench, based on the final invert
level. If a pipeline has to be lowered to avoid a service, the designer
should ensure the ground conditions are known at that depth..
Locations of large manholes or chambers should get particular
attention.
Delays in receiving the Site Investigation Report: – there is often an
undue delay between completion of the fieldwork and the receipt by
the design team of the report. Following discussions with consulting
engineers the Project Office has recommended that a significant
proportion of the payment be measured against the delivery of the
report to encourage a faster delivery. This is possible within existing
contract conditions, and has already been introduced in a recent
contract.
•
Testing of Watermains
Despite the fact that contracts will ask for sections of watermain to be tested as they
are constructed, there appears to be a tendency among some contractors to delay
pressure testing until large lengths of main are completed. This leads to obvious risks
of delays in locating any leaks should the test fail. Consideration should be given to
measuring the works and certifying payment in such a way that only partial payments
are made for untested lengths of watermain.
•
Commissioning
Despite the extensive use of workshops involving the client’s operational staff, it has
been the experience of the Project Team that the commissioning of the new
infrastructure takes longer than anticipated. The problems can lie in a number of
areas:
The designer should investigate and include within the contract all of
the works required to commission the pipeline. These works may
include connections, construction of new manholes on existing sewers,
closing off and sealing redundant sections of sewer or watermain,
laying short sections of new main to connect to the local network,
attendances on Local Authority staff etc.
“Off line” issues can arise such as the need for pressure reducing
valves to protect existing water networks when a new higher pressure
system comes into service.
In the case of sewers, an “offline” issue is the fact that the interception
of existing flows by a new system can reduce in large diameter sewers
within the existing network no longer operating at self cleansing
velocity due to a sudden reduction in their flow volumes. This may
require the relining of a section of the old sewer with a smaller invert
channel.
The client needs to recognise the need for training and familiarising the
staff with the new infrastructure. This applies to new pumping stations
or storage facilities in particular due to their complexity, but also needs
attention for new pipe networks.
As Constructed Drawings and Operation Manuals should be available
to the client before handover.
•
Buildability
All designs should be tested for buildability and practicality in the context of the
actual site. This test should include for future access and maintenance.
Examples include:
The construction of deep sewers up to six meters deep in a busy road. It may
be preferable or even essential to use tunnelling techniques, given local
constraints and traffic requirements. The designer should take into account the
cost of the disruption arising from the open cut option, together with the real
cost of reinstatement and possibly the need to extend the area of reinstatement
due to damage to the road infrastructure.
Lowering watermains to avoid services whereas it may be more practical to
lay the new pipe over the service and locally relax the minimum cover
requirement.
•
Project Close Out
Part of the life cycle of all projects is the Close Out or completion phase. While some
of the issues within this phase are included under “Commissioning” above, there
should be a formal Project Close Out Report separate from the normal Final Account
Report. This should include all of the details normally included in a Final Account,
together with as constructed details, operating manuals etc. The Report should also
review the Project in terms of it’s strengths and weaknesses and produce
recommendations as to how future project management can be improved, based on
the experience gained.
A further associated problem is the delay often experienced in getting a Final Account
agreed. The Engineer should be mindful of the stated minimum amount for interim
certificates, as there is more likelihood of getting a Final Account agreed if there is a
financial incentive for the contractor. While it is preferable to agree the Final
Account, if there is undue delay in reaching agreement, the Engineer must make a
decision on the final certified amount, even if this results in the dispute resolution
procedures being invoked.
8.
Impact of the Project
I thought it would be worthwhile having a look at the impact the delivery of this
infrastructure has had on the North Fringe and the Greater Dublin areas.
8.1 Dublin Bay Project
The North Fringe / Northern Interceptor Sewer Project formed an integral part of the
overall Dublin Bay Project.
Including the sewer upgrades, the Clontarf CSO and the interception of major
volumes of flow from the North Dublin Drainage system, the project resulted in a
significant reduction in the volume and frequency of spillages from storm overflows
to the stormwater and river systems of North Dublin, thus assisting in the
improvement of water quality in Dublin Bay.
8.2 Water Supply Network Integration
When all of the elements of the North Fringe Water Supply, together with the North
City Arterial Watermain are completed, there will be a far more integrated arterial
network. While this will bring immediate benefits in allowing the transfer of bulk
water throughout the system , it may prove even more important in the future in
allowing the distribution of water from new water sources.
8.3 Housing and Commercial Development
Since the first part of the Sewer project was commenced in 2000, there has been an
explosion of housing and commercial development along the route of the new
infrastructure. The Meakstown housing area, the first to be serviced by the project, is
now well advanced with 1,350 residential units completed and 800 under
construction.
In the “North Fringe” development area over 2,100 residential units have been
completed. Planning Permission has been given to commercial and retail
developments of over 20,000 square metres, some of which are either completed or
under construction.
8.3 Ballymun Regeneration
Since 2000, approximately 1,800 new homes have been constructed by Ballymun
Regeneration Ltd. A major new Main Street has also been constructed. The North
Fringe Project Office has worked closely with the Regeneration team in ensuring that
the new infrastructure was completed in accordance with the overall plan for the area.
The new sewer and water network, together with the Sillogue Water tower will
greatly assist the regeneration of this area of Dublin.
9.
Future Directions in Water and Drainage for Dublin
Nothing stands still in the development of infrastructure, particularly at a time of such
intense growth in the Greater Dublin Region.
Since the commencement of the North Fringe Project, the Local Authorities, lead by
Dublin City Council, have engaged consultants to examine the drainage strategy into
the future. The result was a Report on the Greater Dublin Drainage Strategy which
was issued in 2005 and which will form the basis of new sewers, sewer upgrades and
sewage treatment to cater for continuing and growing needs of the Region up to 2031.
This report forms the blue print for the future drainage needs of the Greater Dublin
Area, and sets out a programme for the delivery of the proposed infrastructure linked
to a timeframe for development of the catchment.
In relation to water supply, the focus in the Greater Dublin Region is now on clean
water production and storage. To this end additional plant capacity is under
construction in Ballymore Eustace and, shortly, in Leixlip. Additional storage
capacity is under construction at Ballycoolin.
New water sources for the Dublin Region are being examined. A new study of
strategic storage requirements has been completed.
It is critically important that the rate of development in the region does not outpace
the provision of these new drainage and water projects. In the area of drainage, in
particular, if development keeps going at the present rate without the corresponding
new drainage infrastructure the pollution of watercourses and estuaries will increase
dramatically in direct conflict with the aspirations of the Water Framework
Development and the Eastern River Basin District Management Plan.
Dublin City Council, in partnership with other Local Authorities in the Region and the
Department of the Environment, Heritage and Local Government will be
endeavouring to ensure that this does not occur.
I am confident that the experience gained in delivering the North Fringe Water and
Sewer Projects will assist greatly in this regard.
END
Acknowledgements:
I wish to acknowledge the contributions made to this project by my colleagues in
Dublin City Council and Fingal County Council and by the Water Services Section of
the Department of the Environment, Heritage and Local Government.
In particular I wish to acknowledge the contribution of the following team members past and present - of the North Fringe Project Team since 1999:
Corrina Elder, Yvonne Patterson, Ronan O’Rourke, John Paul McKenna, Leah
McKenna, Rosemary McNulty and Paul Baggeridge.
I also wish to acknowledge the help and support of Matt Twomey, Assistant City
Manager and of Tom Leahy, Deputy City Engineer and Project Director.
Finally I want to thank Geoff Burns, I.T. Technician, without whom the production of
this paper and the accompanying presentation would have been impossible.
References:
“Our Good Health – a History of Dublin’s Water and Drainage” by Michael
Corcoran, Published by Dublin City Council, 2005
North Dublin Drainage Catchment Study, 1994 -M.C. O’Sullivan for Dublin
Corporation
North Fringe Water Supply Strategy Report, 1999, McCarthy Acer for Dublin
Corporation