Drought Plan 2013 Appendix 1
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2014 Drought Plan Appendix 1 Resource Zone Characteristics & Drought Measures Drought Plan 2014anglianwater.co.uk Appendix 1 Contents Resource Zone Characteristics & Drought Measures Resource Zone Characteristcs & Drought Measures 2 Central Lincolnshire 4 Characteristics 4 Previous drought 5 Drought Measures 6 East Lincolnshire 8 Characteristics 8 Previous Droughts 9 Drought Measures 10 West Lincolnshire 13 Characteristics 13 Previous Droughts 14 Drought Measures 14 Hunstanton 16 Characteristics 16 Previous Drought 16 Drought Measures 16 Fenland 18 Characteristics 18 Previous Drought 19 Drought Measures 19 North Norfolk Coast 22 Characteristics 22 Previous Drought 23 Drought Measures 23 Norwich & The Broads 25 Characteristics 25 Previous Drought 25 Drought Measures 26 Norfolk Rural 28 Characteristics 28 Previous Drought 28 Drought Measures 29 Cheveley, Ely, Newmarket, Sudbury & West Suffolk 31 Characteristics 31 Previous Drought 32 Drought Measures 32 East Suffolk 34 Characteristics 34 Previous Drought 35 Drought Measures 35 Drought Plan 2014 Appendixanglianwater.co.uk 1 South Essex 37 Characteristics 37 Previous Drought 38 Drought Measures 38 Central Essex 40 Characteristics 40 Previous Drought 40 Drought Measures 40 Ruthamford North 42 Characteristics 42 Previous Drought 43 Drought Measures 43 Ruthamford South 45 Characteristics 45 Previous Drought 45 Drought Measures 46 Hartlepool 48 Characteristics 48 Previous Drought 48 Drought Measures 48 Drought Plan 2014 Appendix 1 anglianwater.co.uk Contents Resource Zone Characteristics & Drought Measures Resource Zone Characteristcs & Drought Measures 2 Resource Zone Characteristics & Drought Measures Resource Zone Characteristcs & Drought Measures Resource Zone Characteristcs & Drought Measures The resource zones (RZ) have been assessed in our Water resources Management Plan and a number of the zones have been divided. The revised list of RZs are presented in Table A1. For each RZ we describe the characteristics of the zone, any details from previous droughts and the drought measures that we would take in each zone. Resource Zones (RZs) Central Lincolnshire East Lincolnshire West Lincolnshire Hunstanton Fenland North Norfolk Coast Norwich & Broads Norfolk Rural Ely Newmarket Cheveley Sudbury West Suffolk East Suffolk South Essex Central Essex Ruthamford North Ruthamford South Hartlepool Drought Plan 2014 Appendixanglianwater.co.uk 1 Resource Zone Characteristics & Drought Measures Central Lincolnshire 4 Resource Zone Characteristics & Drought Measures Central Lincolnshire Central Lincolnshire Central Lincolnshire RZ Characteristics The Central Lincolnshire RZ extends south from the Humber and is based on the supply systems for Scunthorpe, Lincoln, Grantham and Sleaford. The main water resource for the zone is Lincolnshire Limestone aquifer. There are also groundwater abstractions from the Sherwood Sandstone and the Chalk. Surface water is abstracted from the River Ancholme, which is supported with water from the River Witham and the River Trent. Customers to the Drought Plan 2014 Appendixanglianwater.co.uk 1 5 south of this zone are also supplied with raw water supplies from Rutland Water. The new Hall WTW was opened in July 2014, which will treat water abstracted directly from the River Trent for supply to customers in Lincoln. The zone includes five drought vulnerable groundwater sources. Increasing nitrate levels in the Lincolnshire Limestone aquifer have been managed by developing satellite groundwater sources in the confined limestone aquifer, which have also secured source reliable outputs and hence deployable outputs under low groundwater level conditions. The Elsham WTW is reliant on augmentation of the flow of the River Ancholme by the Environment Agency’s Trent-Witham-Ancholme (TWA) transfer scheme during lower summer flows. The TWA scheme is managed by the Environment Agency under a section 20 agreement. Previous drought The Northern Chalk was most affected with the early 1990’s groundwater drought, during which the Section 20 Agreement (see East Lincolnshire RZ for more details) was fully invoked by the National Rivers Authority and use of both the TWA and Great Eau transfers was maximised. The drought of the early 1990’s affected the Lincolnshire Limestone aquifer in this zone. This was addressed by the development of satellite boreholes and additional boreholes were drilled during the 2011-12 drought to help further improve the security of supply. Groundwater levels in the Lincolnshire Limestone reached historic lows during the 2011-12 drought, but recovered remarkably quickly as a result of the extended period of rain that followed (in some instances levels in the Lincolnshire Limestone recovered by 10 metres in less than 2 weeks). Despite the vulnerability of these groundwater sources to drought, we do not envisage any problems in maintaining deployable outputs from groundwater sources during a drought. Under current demands there is both average and peak headroom capacity in this zone. The raw water transfer from Rutland Water to the zone was constructed in response to the 1976 drought. In 1976, the TWA transfer licence from the River Trent was found to be the limiting factor for our direct intake from the River Ancholme. This period has been used to define the reliable yield of the source. Whilst the RZ as a whole has a surplus of potable water available, the proposed development of non-potable supplies to meet increasing industrial demand has driven the extension of our Elsham WTW. Minor investment is also being delivered to maintain the security of supplies through local enhancement to the trunk main and local distribution systems to facilitate increased internal transfers within the RZ. 6 Resource Zone Characteristics & Drought Measures Central Lincolnshire Drought Measures We would look to optimise conjunctive use of groundwater and surface water sources in the RZ. Anglian Water would look to increase Elsham sourceworks output to the daily licensed quantity, which would require continued support through the TWA scheme. Additional resources from this scheme would only be available under a Drought Order to change the Environment Agency abstraction licence from the River Trent. The option exists to re-commission the intake on the River Witham and install the required treatment, however, the low flows experienced during drought conditions would not make this a particularly reliable option. We will routinely monitor our drought vulnerable boreholes to identify the onset of potential drought conditions. On a local scale replacement / satellite boreholes would be developed if required to sustain source reliable outputs and hence deployable outputs from the Limestone aquifer sourceworks. Intra-Zonal transfers would be used to balance supplies with demands using existing or new trunk mains. Drought Plan 2014 Appendixanglianwater.co.uk 1 Resource Zone Characteristics & Drought Measures East Lincolnshire 8 Resource Zone Characteristics & Drought Measures East Lincolnshire East Lincolnshire East Lincolnshire Resource Zone Characteristics The East Lincolnshire RZ extends from the Humber to the Wash and is based on the supply systems for Grimsby, Louth, Skegness, Boston, Bourne, Spalding and Stamford. In the northern part of this zone, the main water resources are abstractions from the Chalk and Spilsby Sandstone. A Section 20 Water Resource Management Agreement with the Environment Agency serves to protect and limit the use of the Northern Lincolnshire Chalk aquifer during periods of naturally low groundwater levels, which can result in low spring flows from the Lincolnshire Wolds and saline intrusion along the south bank of the Humber Drought Plan 2014 Appendixanglianwater.co.uk 1 9 Estuary. The Section 20 Agreement restricts abstraction from the Chalk during drought to protect groundwater quality. This restriction limits the average deployable outputs of 13 of our groundwater sources and is accounted for in our water resource management planning process. We are currently investigating the potential impact of a number of our Northern Lincolnshire Chalk groundwater sources on low flow rivers and streams, as part of the AMP5 National Environment Programme. A downward trend in groundwater levels in the confined Spilsby Sandstone over the last decade has led to a voluntary reduction of the previously increased licensed abstraction quantities from the aquifer, with an increase of surface water being transferred south. This has been supported by investment into reinforcement of trunk mains. We abstract from the Louth Canal to fill Covenham reservoir. We also have the option to operate the Great Eau transfer scheme to provide a significant increase to the contributory catchment and augment the yield of Covenham reservoir during drought periods. The Great Eau scheme is managed with the Environment Agency under a section 20 agreement. In the southern part of this zone we abstract groundwater from the Southern Lincolnshire Limestone aquifer. Abstraction boreholes are all located in the confined aquifer beneath the Fens, which receives recharge through the narrow band of outcrop that runs north south through Stamford and Sleaford. The zone has historically exported water to Peterborough, however as demand has grown this has ceased and water is now imported from Rutland Water. Borehole yields in the confined aquifer are prolific and abstractions are only limited by the need to restrict drawdown in the aquifer to maintain confined discharges from natural springs known locally