Old Mervue Lead Distribution Contract

Case Studies

Old Mervue Lead Distribution Contract

Summary:

Replacement of Lead Distribution Watermain in the Old Mervue Area in Galway City. The purpose of the works was to eliminate the existing lead distribution pipes from the water distribution network.

Project Background:

In September 2008 over 250 households were affected by elevated levels of lead detected in the water supply at Old Mervue in Galway City.

The householders received their potable water through a network of lead pipes leading off a 4-inch and 6-inch cast iron supply pipe. The lead network was taken from this watermain at branch locations and distributed to the individual houses from their
respective rear gardens. Most of the houses were in terraced blocks of 5 or 6 and a number of these had only pedestrian access to the front door with no driveway.

It became necessary to provide a lead-free distribution watermain to each house through a new individual water services control box located either in a public space at the front of the house or from a laneway located to the rear of some properties. Galway City Council's responsibility was to provide this supply up to the property boundary. Thereafter the householder was responsible for connection into his or her own property. Currently the stopcocks are located on the lead network at the back of each house with no council access.

ShareRidge Ltd were contracted by Galway City Council to replace the lead distribution watermain at Old Mervue by means of horizontal directional drilling and insertion of varied size water service delivery pipes, including saddles, valves, water services control boxes and fire hydrants up to the boundary of each identified property.

We were also contracted by the residents committee to carry out private connections for each householder from the newly laid distribution main to the location of the stopcocks at the rear of the properties. This work was also carried out by means of horizontal directional drilling.

Work Procedures:

  1. Site Survey
    A detailed site survey was carried out at each household to identify the proposed location of the reception pit.
  2. Barrier off the site to Public
    The footpath and surrounding areas were closed off to the public and alternative measures were put in place.
  3. Location of underground services
    Trial holes and utility drawings were used to identify all locations of existing services.
  4. Excavation of Launch Pit
    Excavate Launch Pit in footpath – 1100mm breath, 600mm width and 800mm depth approx.
  5. Excavation of Reception Pit
    Excavate Reception at rear of the property in location of stopcock. - 1000mm breadth, 800 width and 1200 depth.
  6. Install Directional Drilling machine
    Drilling Machine installed into the Launch Pit and timber struts and plates placed to the sides of the excavation to secure the machine in place during works.
  7. Carry out the drilling works
    The bores varied in length from between 15m to 50m due to the different sizes of front gardens. Due to the lack of side access to the rear of the properties, it was necessary to directionally drill beneath the house foundations. To reduce any concerns to the householders ShareRidge Ltd carried out the pilot boring operation
    remotely with a Radio Detection G2 locating system. This system provided the trained operative a constant feedback with regards to the depth and inclination of the bore head throughout the operation. The average depth which the bore head passed beneath the foundations of the properties was 1200mm. This eliminated any risk of disturbance to the house foundations. The bore head was directed to the location of the reception pit.
  8. Installing the Service Pipe
    Once the pilot bore had been completed, the Sonde housing (sensor unit on the drill head) was removed and the new 20mm PE water service was connected directly to the drill rods via a swivel and then pulled back through the bore hole as the drill rods were retrieved from the Launch Pit. This eliminated the existing lead service with a direct line to the cast iron mains.
  9. Connection to the Existing Watermain
    A WSCB was installed and connected to the cast iron watermain in each Launch Pit. The house service was then connected to the WSCB.
  10. Reinstatement
    Permanent Reinstatement works were carried out after the excavations were
    backfilled.

The average time to carry out a complete bore varies depending on the distances and the ground conditions involved. Over a distance of 20m and good ground conditions a complete bore can be carried out in 1 hour and 30 mins. This includes connection to the existing main in the footpath.

ShareRidge Ltd demonstrated our vast knowledge and experience in working with profuse pipe to Galway City Council and proposed the use of this pipe to carry out this contract as opposed to HDPE SDR11 as specified in Tender Documents. Galway City
Council accepted our proposal.

Throughout the contract ShareRidge Ltd and Galway City Council representatives met with each and every householder to advise them of the work methods to be carried out and ease any concerns they had with the works.

The interaction between all parties involved made the project most enjoyable. The new distribution main and 250 private connections were fully complete in 4 months.

Due to Galway City Council's satisfaction with the works in Old Mervue our contract was extended in order to complete works in the Shantalla and Claddagh areas of the city where lead service mains were also located. The same principle of work was carried out in these area and a further 80 houses were completed before the Christmas break.

Letters and emails of comments received from Galway City Council and the residents of Old Mervue can be viewed on request.

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Images from the works
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"All works were completed by ShareRidge Ltd. to the highest standards of quality and safety in accordance with the contract. The contract was completed on time, and within budget. The reinstatement work, in particular, was completed to an excellent standard."

"ShareRidge staff on site interacted in a very professional manner with the local residents and to the satisfaction of Galway City Council."

"Galway City Council would be delighted to see ShareRidge Ltd. continue to tender for future works in Galway City."

- Extracts from a letter from Senior Engineer, Water Services Project Office, Galway City Council (full text available on request)

"I just want to take this opportunity to say a huge big thank you to the Management and Staff of ShareRidge Ltd. who were involved in the replacement of lead pipes in the Old Mervue area in Galway during 2009. From Michael McNamara to yourself to the workmen on the ground the people in Mervue have nothing but praise for you all."

"Once again thanks for everything and for a job that was and still is superbly done."

- Extracts from an email from the Chairperson of (Old) Mervue Residents Committee (full text available on request)