ADS Europe BV (ADS) submitted this change proposal on 3 September 2021 to the Independent Sewerage Adoption Panel (the Panel), with the Panel publishing the proposal on its website on the same day. ADS has requested that a change be made to the Design and Construction Guidance (DCG) set out in Appendix C to the sewerage sector guidance, which is used by developers when planning, designing and constructing foul and surface water drainage systems (including pumping stations and rising mains) intended for adoption under an agreement made in accordance with Section 104 of the Water Industry Act 1991. The modification proposed is adding new sub-clauses for plastic corrugated wall arch structures for below stormwater attenuation and storage applications. The Panel recommended approving the change proposal. Ofwat has approved this change proposal using the wording recommended by the Panel with a minor grammatical adjustment. This is Ofwat's final decision.