Programme appraisal

The Programme Appraisal brings the investment needs for each wastewater system together into an investment needs programme for the North Kent Catchment. We look across the river basin catchment to review the investments needed, the timing of these needs and how they combine to reduce the risks to our customers and the environment.

We also look at the wider risk reduction that each option provides across all the planning objectives. Some actions, like separating rainwater from wastewater sewers, could reduce risks under several planning objectives such as storm overflows, external flooding, bathing water quality, shellfish water quality and good ecological status. The details of the method for prioritisation can be found in our Technical Summary on Programme Appraisal.

 

The investment needs in the North Kent River Basin Catchment include

• Reducing the number of spills from the 33 storm overflows which together currently spill around 300 times per annum
• Separating or attenuating excess rainwater in the sewer networks to reduce the risks of flooding and frequency of storm overflow discharges, especially in Queenborough and Sittingbourne
• Investigating the potential impact of wastewater discharges on the Sarre Penn and River Wantsum and the measures needed to achieve Good Ecological Status
• Investigating the potential impact of wastewater discharges on the Swale, Medway Estuary and Marshes and identify the requirements to secure Nutrient Neutrality
• Planning for potential significant development at Faversham, Sittingbourne and the Teynham Area of Opportunity
• Identifying the impact of storm overflow discharges on shellfish waters at Faversham and the Swale
• Assessing the condition of sewers to identify groundwater and saline intrusion in Queensborough
• Improving the resilience of our networks and treatment works to prevent pollution incidents, particularly in Sheerness and Faversham
• · Reducing the risk to groundwater by reducing leakage from our sewers in Faversham and Sittingbourne.

 

Investment Needs for the river basin catchment

We progressed three wastewater systems through the ODA stage in the first cycle of the DWMP. These three wastewater systems serve a population of around 125,000 which is approximately 91% of customers in this river basin catchment.

We extrapolated the investment needs for these three systems to the other two systems in the North Kent river basin catchment. This provides an estimate of the total investment needs required to reduce the risks in all our wastewater systems in the catchment to Band 0 (not significant). This concept of “Band Reduction” and full details of the process for extrapolation is explained in the Technical Summary on Programme Appraisal.

A graph to illustrate the extrapolation of investment needs across the whole river basin catchment is shown in figure 1.

 

 

Figure 1: North Kent: Extrapolated Investment Needs and Risk Band Reduction

The programme appraisal for North Kent identified the following:

• A total of 43 band reductions are required in 2020 across the 14 planning objectives are required for the three wastewater systems.
• By 2050, this requirement will increase to 50 band reductions due to the impact of climate change, growth and creep.
• The options identified to date would cost around £255 million for the three systems and is expected to provide 22 Band reductions in 2050 (the options do not result in a band 0 for all risks).
• North Kent has five wastewater systems which require 58 band reductions in 2020 and 66 band reductions by 2050 in order to achieve band zero across 14 Planning objectives.
• Extrapolating the investments needs for all the systems in North Kent will cost around £550 million for a 137,000 population. This illustrates the scale of investment needed to get to Band zero by 2050 for all 14 planning objectives.

These investment needs provide indicative costs that allow us to understand the level of funding required to reduce the risks. The funding has not been secured at this stage. The DWMP informs the development of our 5 yearly Business Plan which is submitted to our economic regulator, Ofwat, to agree how we should invest the money received from our customer bills.