Rising Main Isolation & Access Design

Rising Main Isolation & Access Design

Principal Designer CDM

An integral part of WGM Engineering is our Technical and Design department. Offering comprehensive support to all areas of the wider business by produce designs which are safe, efficient and also comply with strict British/European standards and also client specifications. Our Technical and Design team have gained an inclusive knowledge of the construction industry, which aids in developing solutions to ensure that we exceed our clients’ expectations.

WGM’s Technical & Design team (T&D) were commissioned by Veolia Water Services to carry out the role of Principal Designer, in conjunction by WGM Civils, named as Principal Contractor.  The scope of works was to design and install suitable isolation and access facilities, on a 1200mm diameter, GRP, pumped rising main to allow for specialist engineering teams to carry out internal joint repairs.  Given the scope of works, it was crucial that a Principal Designer was appointed to manage the design phase, ensuring the construction phase could be undertaken with due consideration for Health, Safety & Welfare of all associated parties.

Design Phase

We conducted several site survey visits and reviewed various record drawings to determine the optimum position for installing a 1200mm Dia isolation gate valve.  Given the nature of a GRP main, it was critical that the isolation valve was installed in an independently supported fashion to ensure no loads were transferred to the relatively lightweight rising main.  A suitable RC cradle structure was designed to support the valve and in such a manner that it could be constructed around the live rising main, therefore minimising the shutdown period.  A suitable Temporary Works Design was also provided to ensure this could be carried out safely and efficiently.  Similar Designs were also provided for the access point, which comprised a 1200mm dia “T” piece being inserted into one of the deepest parts of the main with a blank flange acting as the access point for future interventions where necessary.

Construction Phase

All designs were coordinated and completed by WGM and ultimately accepted by the Client, prior to works commencing.  The support structure for the isolation valve was constructed in advance of the shutdown as was the temporary support to permit installation of the access “T”, all in line with the Temporary Works Designs.  Upon confirmation from the Client that the main was shut down, construction teams at both sites cut out suitable sections of the GRP main to allow for the installation of the respective isolation and access components.  Thereafter, access was provided for the joint repair works, which was duly completed safely and on time.  The main was subsequently brought back on-line with both the isolation valve operating successfully and the access point being suitably sealed with a blank flange to allow pressurisation of the main.  All works were carried out safely with no accidents or issues, with final “As-Built”, details being handed back to the client as part of the Health & Safety File at completion.

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