Browne have successfully delivered the Affinity Water Mains Renewal project on Butterfly Lane over one month ahead of schedule. The project, to replace 1km of failing 18” cast iron trunk mains at Butterfly Lane, Elstree, not only delivered a time-cost saving for our client, but a huge carbon saving too!
The trunk main stretches eastward from Butterfly Lane to the railway at Borehamwood. The route has a number of challenges, including crossing the Tykeswater river, two culverts and 18m high voltage electricity cable ducts.
Prior to breaking ground, we identified the risk of isolating the 18” main, which would leave only one trunk main feeding 13,000 customers. Initial designs would have employed off-line open cut technique (trenching and laying) for almost the whole length of the project, with a small section of directional drilling. Although this design would have no direct effect on the existing 18” main during most of the works, this option would have resulted in high project costs and high embedded carbon, resulting from the greater need for excavation and backfilling.
Through collaboration with Affinity Water, we explored alternative options. Following additional hydraulic modelling and several discussions around risk, our team landed on a more cost-effective, environmentally conscious solution. The new solution used slip-lining to replace the existing main, whereby the new main is slipped into the old main, without the need for invasive excavation or backfilling.
The project was completed an impressive 38 days ahead of schedule and reduced carbon emissions by 23%, compared to the original proposal, as we reduced the need for excavation and backfilling. Delivering this project with a lower embedded carbon value demonstrates how Browne takes every opportunity to find a more cost-effective, environmentally conscious solution to not only meet our clients’ needs but help reach their sustainability goals. In doing so, we’re committed to working with Affinity Water to reach their longer-term targets of achieving Net-Zero emissions by 2030, in line with the industry’s wider sustainability goals.
The successful completion of the Mains Renewal at Butterfly Lane was only possible by the hard work, support, and collaboration with Affinity Water and other stakeholders, including Network Operations, Asset Planning and the Hydraulic Modelling team, to name a few.