This from Graham Setterfield 09/02/2020
I attach some notes I have prepared since our meeting regarding areas that I think are important in considering future housing growth in Faversham and the development of a neighbourhood plan. As yet, these are not refined and there may be some items which can be eliminated as not being with the purview of an NP. I am happy for you to share the notes, and welcome any and every comment. I am sure some of them can be challenged, as I do not pretend to have up to date information on some topics. I have tried to avoid jargon or endless abbreviations – which might make the notes over-simplified to the more technically minded.
Neighbourhood Plan Issues relating to the water environment.
1 Wastewater treatment
- The only wastewater treatment facility is Faversham Wastewater Treatment Works beside Faversham Creek
- This works discharges treated effluent into The Creek.
- The works previously treated effluent from Shepherd Neame brewery before the brewery built the treatment facility in North Lane, this has created spare capacity at the works. The extent of this spare capacity should be investigated. The current treatment standards include a biological oxygen demand figure (BOD) and a suspended solids figure (SS). How well the works has been performing is not known.
- During heavy rainfall events, the works has storm storage facilities. Once the storm has abated, then effluent stored is treated before discharge. In the event that more rain falls than can be stored then Combined Storm Overflows come into use to prevent flooding of property. The current number, performance and frequency of use of these overflows should also be investigated.
- Future housing development and population growth will put a load onto the works. At the lower end of the numbers of new houses being built, it may be that the works can theoretically cope, at the higher end it seems unlikely.
- Future housing should be designed with separated foul water and storm water systems, designed to mitigate the increase of hard landscape/rooves etc causing greater run off in the event of heavy rainfall. The use of SUDS is of interest (Sustainable Urban Drainage Systems).
- In a report prepared by JBA for Swale BC as part of the Surface Water Management Plan, JBA do not mention Faversham WWTW as being a works of concern.
- Southern Water has recently produced a new 5 year capital plan which has been approved by Ofwat and the Environment Agency. Is Faversham WWTW included?
- Climate change will create more events where heavy rainfall especially in summer, overloads the hydraulic capacity of the works.
- An increase in housing also means an increase in sludge production. Will this mean more tanker movements to and from the works?
Suggested actions needed
- Contact to be made with Southern Water regarding past and present performance of Faversham WWTW, future plans, CSO performance and conditions imposed upon new build homes for separate sewers and sludge production.
- Contact to be made with the Environment Agency re performance of Faversham WWTW and future standards for the works.
- Speak to Swale BC re planning and separate systems for rain and foul water
2 Sewerage and flooding
- There are three ways that flooding occurs, fluvial, pluvial and from the sea. Faversham is not affected by fluvial flooding.
- Records of pluvial flooding do not seem to tie up with residents own recollections
- The sewerage system serving Faversham is thought to be already overloaded.
- Where flooding occurs due to highway drains failing, this is often apocryphally blamed on the sewerage system.
- Climate change will make the present situation worse due to the predicted increase in rainfall intensity.
- One of the reports for Swale BC does not include any of Faversham in the worst category (risk level 4) for sewer network capacity. (Southern Water has models of Faversham’s sewer system.)
- Southern Water is required to maintain a Sewer Incident Report Form register, which should show all incidents of internal and external flooding due to sewer system failures.
- All future housing will increase the pressure on the present sewer network and increase the risk of flooding.
- Tanker movements into the town are excessive and need to be managed better. Perhaps this is an opportunity for SW to improve the present situation.
Suggested actions needed
- Contact Southern Water re their records of sewer flooding and compare these with others.
- Work with SW to identify where their records seem incorrect
- Identify bottlenecks in the system
- Speak to Swale BC and possibly KCC re their records of highway flooding
3 Water resources and supply
- South East Water is our water supplier. When a property is granted planning permission and is built, they are required to connect it to the public water supply system. They are not a formal consultee on new planning applications. It is assumed the water will be available.
- They are required to have a 25 years water resources plan, the growth data for which is supplied by the various planning authorities.
- The Environment Agency grants licences for water resource abstraction, whether from underground sources or from river abstraction. They work in conjunction, but not always in agreement with SEW.
- In cases of over-abstraction due to excessive licences having been granted in the past, it is the Environment Agency who are charged with remediating the problem.
- Lowering of the per capita consumption (PCC) is one of the keys to future water resource requirements. This in itself is a topic of some complexity as it depends upon peoples habits, the domestic appliances in use, grey water systems, leakage from house taps etc, garden watering, and the density of occupation of new homes to name but a few. That doesn’t specifically include retrofitting more efficient systems into older property.
- Climate change will have an impact upon water availability; intense summer rainfall doesn’t help recharging aquifers. Hotter summers cause problems both for supplies for the companies and for distribution of water within the town’s infrastructure.
- We should be pressing the Environment Agency for them to enforce a reduction in the licenced quantities taken from the chalk sources at Ospringe and the Belmont scheme. This is the only way that flows might be restored to the Westbrook Stream. This may well run counter to the plans of the water companies given the increase in homes.
- I suspect that the Cooksditch was a more of a drain than a spring fed chalk stream.
- The water distribution system within the town may not be fit for purpose with all the houses now being added to the system.
Suggested actions needed
- Contact South East Water and discuss their assumptions about growth in Faversham and where the supplies are coming from and their distribution system within the town particularly when under stress due to hotter summers
- Contact the Environment Agency re growth in demand through housing and their plans to improve flows in the Westbrook Stream and the impact of climate change on water resources
- Faversham is at risk from tidal flooding and is protected by sea defences along the length of the Creek and the Swale.
- The Environment Agency is responsible for maintaining these defences, which are all earth bund type walls, usually with concrete slabs facing the seaward side where wave action is anticipated. With climate change the level of protection will reduce due to changing weather patterns, rising sea levels and the gradual sinking of the south east of England. (This was estimated at 3mm per year relative to the rest of the UK in the 1980’s. The current figure is unknown)
- The areas around the Creek and Abbey Farm are most vulnerable to flooding especially from a combination of weather and tidal events, that include low pressure over the North Sea, north easterly winds and spring tides. (as occurred in 1953 and 1978)
- The risks are measured by Annual Exceedance Probability (AEP) in reports.
- If tidal flooding occurs at the same time as heavy rain then more severe flooding will occur within the town. Climate change scenarios may well indicate this to be more rather than less likely.
- Faversham is at risk from surface water flooding due to heavy rainfall and is identified as having a higher density of surface water flooding than other areas within Swale.
- This is an area of particular concern to residents of several areas of the town, especially Cyprus Road and Whitstable Road.
Suggested actions needed
- A dialogue with the Environment Agency regarding the risks associated with tidal flooding, the current standard of protection afforded by the sea walls, future plans for sea defences and the impacts of climate change should be initiated.
- Swale BC should have definitive records of surface water flooding, whatever the cause, whereas Southern Water are only required to keep records of sewer flooding. Both should be approached to determine current known problems and their records compared with those of residents.
- Reference to improvements in spring flow in the Westbrook Stream are covered in section 3.
- Further work on this requires discussion amongst our working group.