deviate north-east to Abbey Mills. The main tunnel length would be about less than the River Thames Route and save about £900 million. Route and sites selection A long list of 373 potential sites was created using a desktop survey of the land on either side of the 34 most polluting CSOs (as identified in the Thames Tideway Strategic Report). These sites were then further evaluated against more detailed planning, engineering, environmental, property and community considerations resulting in a shortlist of sites. The three tunnel routes, as well as the shortlist of sites, were then put out for consultation between September 2010 and January 2011. In total 2,389 feedback forms (both online and hard copy), 480 pieces of correspondence and five petitions were received. In response to the comments received, changes and improvements to some of the sites, including the potential use of alternative sites and alternative technical solutions, were considered. Based on this a round of interim engagement took place from March to August 2011. Residents around 11 specific sites were sent letters explaining that these sites were being considered as alternative sites, and invited to attend drop-in sessions to pose questions and gain a better understanding of the project. In total ten two-day sessions and one community liaison meeting were held. These were attended by over 800 people. In all 168 comment cards and 147 pieces of site specific correspondence were received and considered. Based on this first round of consultation and interim engagement it was recommended that, for the project to be as cost-effective as possible and cause the least disruption, while still meeting the requirements of the UWWTD, the preferred scheme for the Thames Tideway Tunnel would need to involve: the Abbey Mills route a main tunnel long with an internal diameter of ; direct interception of 21 CSOs; indirect interception of a further 12, and a local solution for the remaining CSO; selection of five out of 52 possible access shafts to be built including three to be combined with CSO interception; and selection of seventeen out of 71 CSO alternate positionings from the final shortlist. The new preferred route and sites were then sent out for a second round of public consultation and feedback. Phase 2 and targeted consultation The second phase of consultation was carried out between November 2011 and February 2012 when local authorities, land owners, local businesses and communities were consulted