The Cork Main Drainage Scheme was funded by the Irish Government and part financed by the European Union under the National Development Plan

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1 Contract Teams Cork City Council - Executive Authority City Manager - Joe Gavin Former City Managers - Jack Higgins, Tom Rice City Engineer - Kevin Terry Former City Engineer - Liam Fitzgerald Director of Services Environment - Denis O Mahony Law Agent - Deborah Hegarty Former Law Agent - David O Hagan Project Engineer - Denis Duggan Consultants E.G. Pettit & Co. - Consulting Engineers E.G. Pettit & Co. / Mott McDonell - Consulting Engineers Casey Communications - Communications Consultants Contractors Consort Joint Venture - Ondeo Degremont - Electrical Pump Services Ltd. - Vinci Grand Projects Ltd. - PJ Hegarty & Sons Ltd. - Northumbrian Water Projects Ltd. Ascon Ltd. Ascon Nuttal Joint Venture Ltd. Van Oord ACZ Sorenson Construction & Plant Company Ltd. Morrison Leneghan Ireland Ltd. McGinty & O Shea Ltd. Coffey Construction Ltd. Cork City Council Response Engineering Ltd. Electrical Pump Services Ltd. Jer Ryan Electrical Ltd. Sean Ahern Electrical Ltd. Bowen Water Technology Ltd.

2 The Cork Main Drainage Scheme was funded by the Irish Government and part financed by the European Union under the National Development Plan The project was co-financed by the Cohesion Fund of the European Union.

3 Cork Main Drainage Scheme Layout Under River Siphon Collector Sewers LITTLE ISLAND CITY CENTRE Main Interceptor Sewer Atlantic Pond Pumping Station BLACKROCK Lilttle Island Sewers Ballinure Header Chamber MAHON Lough Mahon Sipons Wastewater Treatment Plant DOUGLAS Ronaynes Court Pumping Station Outfall Tramore Valley Sewers ROCHESTOWN

4 Foreword from Lord Mayor It is with great pleasure that I acknowledge the successful completion of the Cork Main Drainage Scheme. This scheme represents a substantial investment in meeting the highest environmental standards and in restoring the water quality of our beloved River Lee. The project has delivered on all that it promised and will be seen in years to come as the beginning of a new era for the city. Congratulations to all concerned. Cllr. Sean Martin Lord Mayor Tá an áis chóireála séarachta tánaisteach úrscothach ag Carrigrennan anois curtha ar aon leibhéil leis na cathracha is nuaaimseartha san Eoraip. Ba mhaith liom mo bhuíochas a ghabháil leis na conraitheoirí éagsúla a chuir an tionscadail i gcrích go hiomlán agus do fhoireann innealtóireachta agus Riaracháin na Comhairle Cathrach fhéin a rinne maoirseacht ar an tionscadal dúshlánach seo. Ar deireadh, ba mhaith liom ar son an Comhairle Cathrach mo bhúiochas a gabháil do dhaonra Chorcaí a fhulaing na hoibreacha fada deacra seo. Ba mhaith liom freisin búiochas speisíalta a ghabháil le pobal gnó Chorcaí agus go speisíalta dos na cumainn ionadíochta mar Cumann Tráchtála Chorcaí,Cumann Ghnó Chorcaí agus Dúthlán Chorcaí. Cabhraigh foigne agus tacaíocht na grúpaí seo go mór le bhainistíocht na scéime. Seosamh Ó Gabháin Bainisteoir na Cathrach Is mór an chúis áthais domhsa críoch ráthúil deireadh Lár-Chóras Séarachta a adhmháil. Léiríonn an scéim seo infheistíocht substainteach trí na caighdeáin chomhshaoil is airde a bhaint amach agus trí chaighdeán an uisce inár Abhainn ionúin féin - an Laoi - a athchóiriú. Tá seachadadh déanta ag an tionscadal ar gach rud a bhí geallta aige agus feéachtar chuige ins na blinata até romhainn mar thus ré nua don chathair. Comhghairdeas do gach éinne a bhi páirteach. Seán Ó Mairtín, Árd-Mhéara Foreword from City Manager The impact of the Cork Main Drainage Scheme on the water quality in the River Lee has been nothing short of extraordinary. The River Lee can now be used to its full advantage with opportunities for boating, leisure, transport and waterfront development. The state of the art secondary treatment sewage facility at Carrigrenan has brought Cork in line with the most modern of European cities. I would like to thank the numerous contractors who delivered the project in its entirety and the City Council s own engineering and administrative staff who along with the Consulting Engineers, managed this challenging project. Finally, on behalf of Cork City Council, I would like to thank all the people of Cork who endured these long and difficult works. In particular, I would like to give special thanks to the business community and the representative bodies of Cork Chamber of Commerce, Cork Business Association and Cork City Challenge. The patience and support of these groups assisted greatly in the management of the Scheme. Joe Gavin City Manager

5 Introduction The Cork Main Drainage Scheme was funded by the Irish Government and part financed by the European Union under the National Development Plan The Project was co-financed by the Cohesion Fund of the European Union. The Wastewater Treatment Plant currently can facilitate a population equivalent of 413,000. It has been designed in a modular format to allow for easy expansion to cater for future demands. The Cork Main Drainage Scheme was one of the largest environmental projects ever undertaken in the history of the state. The problem was daunting. To provide a commercial city with a new sewer network, pumping stations, deep water siphons and a modern day Wastewater Treatment Plant within a short time frame was a complex and difficult project. Denis Duggan, Project Engineer. The Lee is a majestic river; rising in Gougane Barra in west Cork, flowing through valleys and plains before entering Cork City where it separates into two channels, that divide the north and south of the city. The River Lee, Lough Mahon and the Estuary are arguably Cork s finest natural assets. They have shaped the development of the city both physically and commercially. Since earliest times they have also acted as the only system for the disposal of the City s wastewater. In the late 18th Century many of the waterways in the city were walled in and arched over, forming the familiar thoroughfares of South Mall, Grand Parade and St. Patrick s Street. Beneath these new streets however nothing changed, foul wastewater continued to flow into the River Lee and to the Estuary, without treatment of any sort. The European Union Wastewater Treatment Directive of 1991 demanded that adequate treatment processes be put in place, and all discharges of untreated effluent be collected and brought to a new Treatment Plant. Work started in 1998 and at that stage 59 million litres of raw sewage was discharging into the river daily. By 2004 all wastewater had been removed from the river.

6 City Centre works A Far Reaching Scheme Considerable works had been carried out in the 60 s and 70 s laying interceptor sewers along the north and south quays. This work merely transferred the discharge points to Kennedy Quay and Horgan s Quay, near the eastern tip of the island. To comply with the EU Wastewater Directive, a huge pipe work and pumping system would have to be constructed to bring the wastewater from these points to the new Treatment Plant to be constructed at Little Island. A complete new drainage system would also have to be laid under the streets of the City Centre Island. The Cork Main Drainage Scheme comprised of 22 separate contracts, each falling into one of four areas City Centre Drainage Link Pipes and pumping stations from City to Treatment Plant A collection system for the Lower Glanmire Road and Tivoli areas Treatment Plant and Little Island Sewers City Centre Drainage New sewers had to be laid in every street on the Central Island of the city. A network of over 38,000 metres of pipe were used around Cork and the city suburbs, ranging in size from 200 mm diameter to 3,000 mm diameter. When necessary a variety of tunnelling techniques were employed, particularly in narrow streets, near structurally sensitive buildings or where traffic flow was an issue. Archaeology Work within the old city walls required full archaeological excavations and was more suited to a direct labour approach than by contract. The City Council s own staff completed this work. Never before have Archaeologists been able to examine the buried evidence at such a depth. The Cork Main Drainage dig has in effect been a window on the past - a window that will only ever open once. Typical works at the junction of Oliver Plunkett Street and Grand Parade Maurice Hurley, City Archaeologist. Traffic Management Team Meeting

7 One of the many old City culverts dating from 19th Century at Daunt Square Maintaining traffic flow and access to premises was a priority of the works To keep journey time between City Centre works to a minimum CMD engineers requested a novel and speedy form of transport In April 1999 the first of many excavations began on St. Patrick s Street. Over the next four years every city centre street was excavated and a new sealed foul sewer system was laid and connected into each property. The old culverts were repaired and are still in use to convey rainwater to the river. Over 11,000 metres of culvert were constructed in the city centre and in Blackpool. The Cork Main Drainage Scheme received great public support and in particular the partnership approach of Cork Chamber of Commerce, the Cork Business Association and Cork City Challenge, was central to the project s success. In consultation with the business community, the work was carried out on a gradual and phased basis in order to maintain business and minimise the inevitable disruption. Good Traffic Management was vital to enable works to proceed. An Garda Siochána, Bus Éireann, Cork City Council Traffic Office, Public Utility representatives, the Contractors, Consulting Engineers, Communications Consultants and the Project Management Team met weekly in order to plan ahead. Innovative solutions were sometimes necessary to provide sufficient space for the works to be carried out, while maintaining traffic flows and access to premises. In addition to work on the Central Island, two further contracts provided an improved drainage system for the Boreenmanna Road/ Blackrock area, and a new river culvert was constructed in Blackpool to relieve a long-standing flooding problem. A one hit on the street approach was adopted and new ducting for public utilities, the ESB and Bord Gais were laid at the same time. A new water main system was also laid in the City Centre replacing the old leaking system.

8 Link Pipes Under River Siphon A siphon under the river, linking Horgan s Quay to Kennedy Quay was constructed using specialist-engineering methods. Three shafts 10 metres in diameter and up to 30 metres deep were sunk on Horgan s Quay, the Custom House Quay and Kennedy Quay. A 2-metre diameter pipe was then tunnelled under the riverbed connecting the three shafts and forming a siphon, to allow wastewater from the northern quays pass under the river to Kennedy Quay. To carry the wastewater from Kennedy Quay to the Waste Water Treatment Plant, a distance of 9.5 kms required a major trunk sewer, a main pumping station for the City, rising mains and an underwater pipe work system crossing Lough Mahon. The work divided into four separate sections. Kennedy Quay to Atlantic Pond The main 3.5 metre diameter Trunk sewer from Kennedy Quay to Atlantic Pond was tunnelled over its entire length of 2.7 kilometres. During construction a light rail system operated 24 hours a day within the pipe taking crews and material up to the cutting head of the tunnelling machine and removing excavated spoil. The sewer was constructed in segments immediately behind the face of the tunnelling machine. The machine broke through at Kennedy Quay, 8 months after commencing at Atlantic Pond. Atlantic Pond Pumping Station 10 pumping stations were built in and around the city centre, the largest at a site east of Atlantic Pond. The main pumping station moves the wastewater on towards the Treatment Plant at Carrigrenan. It extends to a depth of 18 metres below ground. Constructed within a 33-metre diameter sheet pile wall, the station pumps forward a maximum flow of 2.45 m 3 /sec. Excess rainwater is pumped to the river in times of heavy and prolonged rainfall. Atlantic Pond Pumping Station mid-construction The Tunnel Boring Machine cutting head is lowered into the ground at the site east of Atlantic Pond Inside the tunnel crews worked 24 hrs a day 7 days a week to complete interceptor sewer No.1

9 Rising Mains Twin 1100mm pipes were laid along the old Passage railway walk from Atlantic Pond to the Ballinure Header Chamber. The County Council s Tramore Valley sewer discharging at Ronayne s Court in Rochestown, was brought into the new system by laying twin 700 mm pipes across the Douglas Estuary. In all 39,000 metres of rising mains were laid, sizes ranging from 200 mm to 1200 mm diameter. Ballinure Header Chamber and the Lough Mahon Crossing Ballinure Header Chamber is a critical element of the scheme. This building contains a large tank into which sewage is pumped. After screening, the sewage discharges by gravity through twin pressure pipes laid across Lough Mahon. The level of the water in the Ballinure tank is set to ensure discharge through the pressure siphon to Carrigrenan without further pumping, thereby saving considerable annual operating costs. Lough Mahon Crossing Working closely with the Port of Cork twin siphon pipes were laid a distance of 4 km under the shipping lanes across Lough Mahon. 18,450 metres of pipe were towed from Norway to Cork in lengths of up to 400 metres. The long pipe lengths meant fewer joints and less disruption to shipping. Concrete collars manufactured in Verolme Dockyard, were fitted to each pipe length to provide protection. A channel was dredged in the riverbed and the pipes were floated into position and sunk into the prepared bed. The riverbed was then restored to its original level. Dredging was a feature of all marine engineering works The twin siphon pipes being towed past Roches Point

10 The Wastewater Treatment Plant The Plant has been designed to accommodate flows from Cork City, Tramore Valley, Glounthaune, Glanmire and Little Island areas. The plant accommodates existing flows and has been designed on a modular basis to allow expansion as necessary over the next 20 years. The plant which is highly automated offers primary and secondary treatment and has been producing treated water to a very high standard since January The secondary treatment is achieved by means of an activated sludge system which is carried out in Sequence Batch Reactors. Sludge, the by-product of the treatment process, is pasteurised, dried and turned into a granular material. Each day around 8 tonnes of granules rich in nitrogen and phosphorous are produced which are re-used in agriculture as a fertiliser and soil conditioner. An amenity area of 17 hectares has been provided surrounding the plant, togther with a two and a half-mile public coastal walkway. Existing preserved wetland areas for wildlife have been extended and enhanced and a major programme of landscaping and tree planting has been carried out. A play area for small children is also being provided at the request of the local Community Association. Main monitoring centre at Carrigrennan Plant Design Data Population equivalent 413,000 B.O.D load (kgs/day) 25,000 Hydraulic Flow (m3 /day) 59,500 Biogas Holder Biogas, a by-product of sludge digestion, is re-used to generate heat for the drying process.

11 The celebrations for the launch of Cork as European Capital of Culture 2005 centered on the rejuvenated River Lee

12 Cork Main Drainage A History of the Cork Main Drainage Scheme Cork Corporation commission a preliminary report from E.G. Pettit & Co., Consulting Engineers s-1980 s - Northern and southern interceptor sewers laid as far as Horgan s Quay and Kennedy Quay EU wastewater directive insists that all sewage discharges must be treated before being allowed to discharge into the River E.G. Pettit & Company produce a report recommending a scheme largely as is now completed Cork City Council approve the Main Drainage report Planning permission granted by An Bord Pleanála following an appeal and public oral hearing A public enquiry is held by order of the Minister for the Environment under the Public Health Act Ministerial approval for the Scheme is received Work commences on some of the major contracts City Centre works begin Work commences on Atlantic Pond Pumping Station and the under river siphon between Kennedy Quay and Horgan s Quay and other contracts. - The Contract for the design build and operation of the Wastewater Treatment Plant is awarded Work begins on the Main Trunk Sewer from Kennedy Quay to Atlantic Pond. Earth works begin at the Wastewater Treatment Plant site Construction begins on the Wastewater Treatment Plant and the Ballinure Header Chamber. - Atlantic Pond Pumping Station is successfully completed. - Archaeologists working on Washington Street discover the first evidence of a Viking settlement in Cork a major discovery The Wastewater Treatment Plant is completed and begins a phase of testing, taking wastewater from the city centre The last contract, The Little Island Sewerage Scheme, is completed The Main Drainage Scheme is officially opened in June Water quality improvement in the River Lee and Estuary is already apparent. Lord Mayor, Cllr. Tom O Driscoll and City Manager, Joe Gavin at contract signing Engineers discuss commencement of tunnelling In 2000 work commenced on the Atlantic Pond Pumping Station