Case Study

Essex & Suffolk Water – Chigwell Site

Chigwell Water Treatment Works
Aquatic Engineering
Chigwell, Essex

The Bullring is a holding reservoir for raw water it is approximately 90m diameter and 5m deep, its holds 31ML/d approximately. The Bullring had not been cleaned since 2014 and we knew it had a vast number of mussels built up in the and around the Bullring. We had a few companies come in and quote for the job, but Aquatic Engineering seemed the most professional. We had sat down with Glyn and his team and discussed a plan of action. All Risk assessments and method statements were delivered in plenty of time for them to be checked over and agreed.

Aquatic Engineering arrived on time every day and always in the correct PPE, they are very professional in the way they approach their work, Health and safety was always a top priority. If there were any problems, they would stop work immediately and discuss a solution of how they would safely proceed. All work was completed in the agreed time frame, and a debrief was held at the end to look at any learning points.

Aquatic Engineering cleaned up any mess at the end of each day and left the site as they originally found it, Clean and tidy. For a small company they work to a very high standard and I would recommend them to any Utility Company that had a complex or challenging project to undertake.

Martin Mansworth
Water Supply Team Manager
Chigwell Water Treatment Works

Aquatic Engineering have a long-standing working relationship with NWL. It started back when we were heavily involved in the dredging of a new offtake pipe channel at Abberton Reservoir, prior to its enlargement in 2010, a full case study is available for this complex project. Below AE dredging a channel for Carillion.

Later we became involved in several projects at Chigwell WWTW, most notably the maintenance and cleaning of the ‘Bull Ring’ reservoir below:

The Bull Ring is a difficult to access asset, it is the main collection reservoir for water piped in from Thames Water. As with most systems in the Thames Valley, the non-native invasives, zebra & quagga mussels are an ongoing issue.

Aquatic Engineering were commissioned to provide a safe methodology and then carry out the works in 2021.

Works need to be well planned and undertaken as quickly as possible so that water supplies could be restored to the works asap. The reservoir has sheer sides, both at ground level and internally, with absolutely no access.

The scale of the problem below – accumulated dead mussel shells after work commenced!
Our compact plant was lifted into the Bullring by a 50-tonne mobile crane
Our 23 tonne Kobelco 15m Longreach fitted with a clamshell bucket loaded contracted hauliers. Once in situ, the longreach kept tracking and subsequent remedial works to a minimum.