(excluding inflation) to average annual wastewater bills from around 2019. However, these figures were subsequently revised downwards. In August 2015, the impact was expected to be around £20 to £25 per year by the mid-2020s. Disruption Some people who live alongside proposed sites were concerned about the noise, disruption and potential loss of public space resulting from construction. To address this Thames Water put together a Code of Construction Practice to outline site-specific and project-wide requirements and measures to minimise the impacts of the construction and ensure that best practice standards and requirements across all sites and contracts. The Code also covered transport (both road and river transport), noise and vibration mitigation, air quality and water resources, land quality, waste management and resource use, ecology and conservation and historic environment. In the report that concluded its inspection of these documents, the Planning Inspectorate found that Thames Water had "underestimated of impacts on those that have been identified as having a significant effect and underestimated the number of receptors experiencing a significant effect" (12.97) and concluded "We do not consider that [Thames Water's] proposals meet the first aim of the NPS test to avoid significant adverse impacts on health and quality of life from noise" (12.357). The need for a tunnel Some people prefer an option that Thames Water's studies show would be up to three times more expensive. This is a sustainable urban drainage system (SUDS) under Central London streets and open spaces with small pumping stations in places of low gradient. They outline the added benefits of building green infrastructure, particularly uncovering streams and rivers in some places in inner London Boroughs where they were culverted in the past. Their most progressive arguments are for replacing paved, impermeable surfaces in London with permeable options and implementing green roofs, swales and water butts to promote the infiltration of rain-water, preventing it from reaching the combined sewer system, thus reducing peak flows and limiting the number of CSO overflows. Some of these advocates denounce Thames Water's 2011 five theoretical case studies of the solution (finding the threefold cost), citing householders' assistance such as emptying water butts, gardening more, and not using land for parking, and say this could be the cheapest option. Green infrastructure would have further benefits for London in addition to addressing the rainwater overflow problem, such as: Increased resilience to drought and floods, Reduction in urban air pollution,