Construction work for water projects

Tender description

Stillorgan reservoir is a modular storage facility for treated drinking water, built in two stages between 1862 and 1885. The site has a total plan area of approximately 16 hectares and is subdivided into 3 discrete water storage reservoirs, the gray, upper and lower reservoirs. The lower and upper reservoirs were constructed first, as part of the vartry water supply scheme. The gray reservoir was built in 1885 following a period of severe water shortage in Dublin City. The reservoirs originally contained water from the vartry supply scheme alone; however, following construction of the Liffey Supply Scheme at Ballymore Eustace in the 1940s, a 24” main was laid between Saggart Reservoir and Stillorgan Reservoir to link the 2 supplies. An additional 1 000 mm diameter trunk main linking the supplies was constructed on a phased basis during the 1990s. Stillorgan Reservoir is a modular storage facility for treated drinking water, built in 2 stages between 1862 and 1885. The site has a total plan area of approximately 16 hectares and is subdivided into three discrete water storage reservoirs, the gray, upper and lower reservoirs. The lower and upper reservoirs were constructed first, as part of the vartry water supply scheme. The gray reservoir was built in 1885 following a period of severe water shortage in Dublin City. The reservoirs originally contained water from the vartry supply scheme alone; however, following construction of the Liffey supply scheme at Ballymore Eustace in the 1940s, a 24” main was laid between Saggart Reservoir and Stillorgan Reservoir to link the 2 supplies. An additional 1 000 mm diameter trunk main linking the supplies was constructed on a phased basis during the 1990s. The planned works are necessary to ensure compliance with EU Directives, Irish National Standards and Regulations relating to treated water for human consumption. It is intended that the works will be implemented under a design and build contract. The contract primarily consists of the following: Design-build: — Draindown of Gray reservoir, — 160 ML covered storage in Gray reservoir, consisting of 3 cells and internal baffle walls, — manifold building (ca. 2,900 m2 area) for rationalisation of incoming pipework, — replacement of incoming pipework (ca. 3 km length varying diameter 600 mm – 1 200 mm) including tunnelling works (ca. 25 m length, 1,5 m diameter) under the Green Luas line, — new site entrance off St. Raphaela’s Road, — On-Site-Electrolytic-Chlorination (OSEC) plant for secondary disinfection dosing at Stillorgan, — following commissioning of new storage and disinfection dosing, decommissioning upper and lower reservoirs, — internal road network, — site drainage, — site services, — site landscaping.