Hereford sewer challenge

DrainsAid, has successfully completed a major sewer rehabilitation project in Hereford for the Dwr Cymru Welsh Water (DCWW) Capital Delivery Alliance. The DCWW Delivery Partner overseeing the project was Morgan Sindall working with Arup. The contract period was 10 weeks and value of £500,000.00.

Higher than expected dry weather flows (DWF) indicated that groundwater was infiltrating a section of sewer and causing operational issues for the downstream sewage treatment works. A CCTV survey confirmed the prognosis and it was decided to reline almost 900m of sewer and refurbish several manholes. The sewer in question was 850mm the lining of this diameter pipe would be considered as a large bore pipe, an area that DrainsAid specialises in with both hot cure and UV Lining systems.

The DrainsAid team surveyed the sewer and subsequent CCTV footage, the site investigations produced a refined rehabilitation design proposal, for both the large bore lining of the sewer and rehabilitation of a number of manhole chambers. The solution made full use of DrainsAid’s experience and expertise in both CIPP (Cured in Place Pipe) and the innovative M-Coating technique’s utilised for the Manhole rehabilitation.

DrainsAid also utilised cutting edge technology in the installation of large bore UV Lining system on this scheme, this method involves winching the protected Liner through the host pipe, inflating to the desired pressure and curing the light sensitive liner with a robotic light train that traverses the length of the liner at a controlled rate and number of passes until the curing process is complete.

In addition to large bore lining this site also had number of manhole chambers that were completely rehabilitated using the M-Coating process.

M-Coating is a proprietary manhole rehabilitation process developed by Hermes-Technologie, which greatly reduces the time on site in comparison with traditional techniques and provides a permanent solution to water ingress to the vertical walls of the chambers.

The many benefits of this operation are the minimal man entry into a confined space and the conservative application that is controlled by a computer programme ensuring appropriate coverage without waste.

By all key business metrics the project was a success. The completed scheme was fit for purpose and exceeded client expectations; feedback from DCWW and its partners was positive, the scheme was delivered safely and there were no reportable injuries or lost-time accidents.