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Here you will learn about the impacts expected from climate change by the 2050s on the utilities sector. This includes the following topics:
The information is reported at Regional and Sub-regional scales only since further information would be needed regarding each individual asset to enable reporting at the Local scale.
Description The three supply zones are virtually discrete in terms of treatment capacity, but they can all zones can all be supported from Kielder Reservoir. Kielder Reservoir was opened in 1982 and is the largest man-made lake in Europe with a capacity of almost 200 billion litres of water. This water is discharged into the North Tyne and can be supplied via a tunnel to the Rivers Wear and Tees and therefore can be used as a strategic resource to supplement the water resource network. The Kielder Supply Scheme consists of a pumping station at Riding Mill on the River Tyne which pumps into a rising main to Letch House: The Tyne Tees Tunnel Transfer System. The rising main then falls via a gravity tunnel; to Frosterley discharge into the River Wear and to Eggleston on the River Tees 34km away. The rising main and tunnel are designed to remain charged and have a capacity of 230,000m2 Airy Holm reservoir acts as a head pond correcting any imbalances between pumping and discharge rates on the tunnel and is maintained at near full capacity with ideally no spillage losses due to pumping from Riding Mill. At Riding Mill there are six pumps, though a maximum of three pumps is used at any one time and their usage is alternated. The principal objective of the transfer system is to carry water from the River Tyne to the Rivers Wear and Tees to support public and industrial water supply abstractions from the rivers and to ensure that prescribed minimum maintained flow requirements in the rivers are met. The transfer system may be used to directly support the water supply from Mosswood WTW where a connection allows water from the tunnel to be used as a substitute for water from Derwent Reservoir when resources are stretched. Water from the tunnel can also be abstracted at Waskerley airshaft and used to support Honeyhill WTW. The availability of support from Kielder has enabled the cheaper local resources available from the reservoirs within each supply zone to be used more effectively, and to be drawn down further, without the necessity to place restrictions on water use. Greater detail on the water treatment works and waste water is provided at the sub-regional level of reporting. The Government published Meeting the Energy Challenge, A White Paper on Energy in May 2007 and as the title suggests is their plan on how to meet future energy demands whilst also meeting reductions in the production of carbon dioxide to meet international agreements such as the Kyoto Protocol. The draft Climate Change Bill and sets a reduction of at least 60% in carbon dioxide through international and domestic action. The report also looks to address the other challenges such as rising fossil fuel prices and their location in increasingly unstable areas of the world, the increasing reliance of the UK on imported energy and the needed investment in the UK’s energy infrastructure. Meeting the future energy demand comes from firstly reducing energy use and greater energy efficiency in the business, domestic and transport sectors whilst also bolstering the UK’s energy supplies. The Government target is that renewables grow as a proportion of our electricity supplies to 10% by 2010, with an aspiration to double this by 2020. The government aims to do this by increased support for the development and deployment of renewable energy sources along with changes to the planning system and the removable of barriers to connecting renewable energy sources to the national grid. Due to the need for a diverse energy generation mix and the intermittent supply of many renewable energy sources fossil fuel and nuclear power will still play an important part in the Government’s energy plans. The future use of fossil fuels will need to ensure the processes are cleaner such as the use of carbon capture and storage (CCS) which could reduce the emissions from fossil fuel power stations by up to 90%. However, this technology has not been demonstrated at a commercial scale and is still being developed. Nuclear power currently accounts for 18% of the UK’s electricity generation and is a low emission supplier, with the Government stating that emissions would have been 5 to 12% higher in 2004 if it was not for nuclear power. There is great public concern with regard to nuclear power with regards to its safety, both to the public and the environment and also issues to do with decommissioning and the long-term storage of nuclear waste. Many of the current power stations, such as Hartlepool, are currently due for decommissioning (Hartlepool is due for decommissioning to be complete by 2014). The White Paper states that the Government’s preliminary view is to allow the private sector to option of investing in new nuclear power stations to replace and bolster the current power stations and the Government is issuing a consultation on this issue. British Energy are considering the construction of a new nuclear power station on the site of the existing one at Hartlepool following it’s decommissioning. Impacts The summer floods of summer 2007 that struck Gloucestershire, Yorkshire and the surrounding areas highlighted the impact that the indirect effects of flooding can have greater impact than those due directly to flooding. The Pitt Review with was launched following the floods to see what lessons could be learned from the events states:
The loss of electricity and water caused around 350,000 homes to be without water for 10 to 17 days with other homes without water for much shorter durations and this was mainly due to the impact of flood water on water treatment works. Mythe Water Treatment Works operated by Severn Trent Water in Gloustershire was shut down in advance of inundation to limit the damage due to flooding. Once flood waters receded it took up to 17 days to re-commisssion the works and to recharge the network and service reservoirs that has been drawn-down since the shutrdown. This caused up to 350,000 people to be without water as the Mythe works were one of the treatment works that could not be supported from supplies from elsewhere in the network. In addition to the water treatment works hundreds of waste water treatment works and pumping stations were also affected. In addition to water treatment works the loss of hundreds of electricity sub-stations including two major National Grid sub-stations meant over 70,000 customers lost supply for less than a day with around 9,000 customers on rota disconnections for several days. Measures were put in place by National Grid during the 2007 summer floods to ensure continuity of gas supplies to the Sheffield and Toll Barr areas, though a gas main was severed when a bridge collapsed and the areas had to be evacuated as a precaution. During the summer floods the telecommunications network was impacted as much as was originally thought partly due to the increased use of glass fibre cabling as opposed to copper cabling and that impacts were also reduced due to the resilience provided in part by the interconnected nature of the telecommunications system. These are all examples of impacts that could be expected in the North East Region with the changing climate and especially the expected increase in flooding. Flooding has been dealt with in greater detail within the flooding section of this study. The impacts associated with the finer aspects of the utilities section such as infrastructure susceptible to subsidence, dams and telecommunications are covered in the sub-regional section of this study. The major expected changes in mean annual and seasonal resource are for decreases in overall annual effective rainfall. These changes will be mediated through increased evaporation as well as significant decreases in summer rainfall though the storage available within the region may possibly offset summer reductions. The expected increases in surface water drought and thus any impact on the smaller reservoirs can be more than offset by discharges from Kielder Reservoir if required. The decrease in the severity of long-term water resources drought means that there should be limited impact on Kielder Reservoir allowing it to continue in its strategic support role, especially over the lifetime of this study. The availability of resource for use within the region could dimish with increasing calls for the creation of a national water grid. This would allow water to be delivered to the areas of the country suffering from potential water shortages, with the worst of these will be the south-east. The conclusion of an Environment Agency report into the need of a “National Water Grid” especially for supply into south-east England published in September 2006 concluded that there is no new evidence of a need for large-scale transfers of water to south east England from the north of England or from Wales. Water companies’ existing plans provide for water supply in south east England to 2025 without the need for large scale transfers. Such transfers are more expensive and environmentally damaging than the measures already in water companies’ water resources plans. In the longer term, beyond the 2020s, further water transfer may prove necessary. We are about to start work on our next water resources strategy for England and Wales. As part of this strategy the Environment Agency will review the need for further water transfers. Water companies across south east England have plans to develop new resources in the next decade. They must follow these plans so that there is no delay in the detailed investigation of the need for these proposed new schemes and reservoirs. At the same time, water companies must take all possible opportunities to manage demand. Changes in the Government’s energy policy may mean that additional climate change consideration will mean that we will see many more applications for renewable energy sources in the region. Their can be seen in the sub-regional section that there are many applications already for wind power across the region and these applications can be expected to grow in number and scale, both onshore and offshore especially with the expected changes in planning. Wind turbines for example are generally not popular with the local community and it would be interesting to see if any major objections would be voiced if a large scale wave energy scheme was proposed for the north east coastline. The continued reliance on fossil fuel and nuclear power could see the possibility for new power stations in the region (such as a new nuclear power station at Hartlepool) and the need for large quantities of cooling water would see these located on the coast or estuaries of the region. Considerations will no doubt be given to sea level rise and coastal erosion for such a development due to their critical importance. The investment in new energy sources may be needed in part to meet a possible increase in energy demand from a growing population. It is a possibility that the north east becomes an increasingly popular destination for inward migration as temperatures increase and house prices continue rise at a greater rate in the south. Reductions in energy usage will offset any growth in the population of the region.
| Northumberland | Tyne & Wear | County Durham | Tees Valley |
Description Water Supply The area in and around Berwick and Wooler is unique in the region in that it cannot be supported by Kielder Water and forms its own water resource zone: the Berwick and Wooler Supply Zone. The water in this zone is solely supplied from groundwater with the system operating in two distinct sections. Both sections use boreholes that abstract water from the fell sandstone in this region with all the boreholes located at least 5 km from the coast. The northernmost section is fed from the boreholes of:
All the raw water abstracted from these boreholes is treated at Murton Water Treatment Works (WTW) for use in the locality of Berwick. This system of boreholes currently has excess water capacity with 7 to 8 Ml/d being used of the available 15Ml/d. The water for the southern half of the Berwick and Wooler Supply Zone is sourced from Fowberry Mains and at the Fowberry WTW. This resource is currently operating near capacity, with the current abstraction license set at 2.5Ml/d (mega litres per day), with a future increase to 2.6Ml/d already agreed with the Environment Agency. During summer months water resource can be insufficient and tankering has to be undertaken. A single main running through Haggerston connects the systems but this cannot be used to move any large volumes of water between the two systems. Therefore, schemes are currently being investigated to increase the available water in the southern half of this supply zone. Surface Water Resource Within Northumberland and also the region as a whole the rivers are one of the main methods for the movement of water with river abstractions needed at various locations to either feed reservoirs, supply mains or treatment works. Water is abstracted from the Tyne at Gunnerton and Barrasford and can be used to supply Hallington and Whittle Dene Reservoir, as well as Gunnerton WTW. Whittle Dene Reservoir can also be supplied from river abstraction at Ovingham, which can be fed to Horsley or Whittle Dene WTW. Barrasford is currently being overhauled with the installation of new pumps and screens. Water is also abstracted from the Tyne at Riding Mill for the Tyne-Tees tunnel when required. Catcleugh reservoir in Redesdale feeds Hallington reservoirs by gravity which in turn connect to the Whittle Dene group of reservoirs drawing in, on the way, part of the natural flow from the upper catchment of the River Pont. Two additional reservoirs, Colt Crag and Little Swinburn contribute flows to Hallington Reservoirs. The river abstraction at Barrasford is pumped to Hallington reservoirs. The pumped abstraction at Ovingham is used to supply Horsley water treatment works or to support Whittle Dene reservoirs. The Rede pipeline from Catcleugh to Hallington is limited (by construction) to 55Mld when the reservoir is full and therefore normally operates at full capacity. Reserve storage at other reservoirs is balanced to ensure that water is not wasted through spillage, especially at Whittle Dene, whilst higher level reservoirs are still drawn down. Water treatment is provided at six works, three very small works supplying Otterburn, Redesdale and Byrness. Gunnerton supplies the area west of Hexham and the remaining treatment works at Whittle Dene and Horsley can be fed from either the Whittle Dene reservoirs or from the Tyne water abstracted at Ovingham. Whittle Dene normally treats predominantly reservoir water; Horsley predominantly treats river water. The two works jointly meet part of Tyneside and SE Northumberland demands. Redesdale is depended on Catcleugh reservoir for sole supply and theoretically the needs of this area should limit the rate of transfer to Hallington and Whittle Dene. However, in practise, the capacity of the Rede pipeline restricts the rate of drawdown such that, even in extreme drought the need of Redesdale does not act as a constraint. Transfers from Catcleugh to Hallington can therefore operate at full pipeline capacity. The Tyne-Tees Tunnel transfer system is a tunnel by which water from Kielder can be used throughout the majority of the region and allows transfers via a pumping station at Riding Mill on the River Tyne. This tunnel is covered in greater detail at the regional level of reporting due to it’s significant role and that of Kielder Water as a strategic regional resource. Dams Dams are located at all the reservoirs within Northumberland such as Kielder, Bakethin Dam, Catcleugh, Hallington and Whittle Dene. The size, age and construction of the dam structures varies and detailed assessment of each of the structures is not possible as part of this study. Waste Water Typically foul/combined (wastewater) systems will comprise a network of drainage sewers, often combining areas of separate and combined drainage, eventually discharging to a Wastewater Treatment Works. Various ancillary structures will be included through the system to assist network performance, primarily pumping stations, combined sewer overflows (CSOs), and storage tanks. Within Northumberland the concentration of the population close to the coast is not as marked as Tyne and Wear and Tees Valley though it is still relatively large in size. With Northumberland there is a greater spread of the population inland and in smaller rural communities as well as towns such as Wooler, Morpeth and Hexham. The rural nature and spread out population means that many properties in the sub-region will use a cess pit, sceptic tank or similar as a method for storing waste water for removal by tanker. These tankers then take the extracted effluent to one of the waste water treatment works which services the more densely populated areas. The treatment works for the larger urban conurbation in Northumberland such as Berwick, Amble and the urban areas in and around Blyth and Newbiggin are of a bigger scale than seen elsewhere and due to their costal location the effluent from these works is discharged through five long sea outfalls at various locations. Wastewater collection systems are spread extensively across the region, being particularly concentrated in the urban areas. They provide the drainage for foul flows, both industrial and domestic, and surface water runoff. Historically, urban sewer systems have been designed to carry the combined flows of household and industrial waste and rainwater. For the last 30 years, however, drainage systems have generally been developed to carry storm water flows separately, although combined drainage systems are still common in older areas, some dating back to Victorian times. This legacy means that the vast majority of the existing sewer network in the urban locations will comprise predominantly combined sewer systems. In the rural areas of Northumberland which dominate this sub-region it is likely that any formal surface water drainage that does exist will generally be directed into a soakaway or else directly into a local stream or river. The foul or combined sewerage network will be prevalent in the urban areas and to many of the villages and larger conurbations that surround them. For the more isolated premises and communities as mentioned earlier in this section they will generally have a cess pit, septic tank or similar serving individual or a group of properties. Combined sewer overflows (CSOs) provide an overflow release from the drainage system into local watercourses or adjacent surface water systems during times of high flows to protect local areas from flooding. There are over 1,400 CSOs within the Northumbrian Water region of which around 200 are in Northumberland. Surface water drainage networks will typically drain smaller, more localised areas than the foul/combined networks to discharge into local watercourses. Networks will not usually include the additional ancillary structures used in the foul/combined systems, such as pumping stations or storage facilities, and are generally designed to transfer and discharge the storm surface runoff as swiftly as possible. Surface water systems will not usually include treatment devices, although silt traps and sediment/oil interceptors will often be included for car parks and large roads to retain contaminants and protect the receiving watercourse from runoff pollutants. Network Pumping Stations Electricity Distribution Substations are typically located in order to feed electricity into the large towns and urban areas around the centre of the catchment. No information has been available for the remainder of the distribution system within the catchment, but it is likely to exist as lower voltage underground distribution cables. Underground cables are particularly more common in heavily urban areas. These will generally be thoroughly spread throughout the catchment to connect the surrounding urban areas to the various local substations. Electricity Demand Wind Power
Infrastructure Susceptible to Subsidence National Grid operate two gas pipelines that run in a southerly direction west of Morpeth in the lowlands of Northumberlan. The first pipeline runs towards Newcastle-upon-Tyne and surfaces to pass through a gas works just south of Saltwick. The other line runs towards Corbridge and then follows the A68 in the directions of Consett. A further gas line runs from the North West across the uplands of the Tyne Valley across Allerdale Common heading towards Teesside. There is also an ethylene pipeline that runs through Northumberland, from Teesside to Grangemouth in Scotland. Within the catchment there are also large amounts of infrastructure to distribute water and collect waste water and surface water runoff. The treatment works such of Whittle Dene, Horsley and Warkworth are located in rural areas and water is transported from these to the users. In Northumberland many isolated dwellings and small hamlets meant that there is a vast amount of pipework to reach the isolated and dispersed population. In addition to these there is also the Tyne-Tees tunnel which runs from Riding Mill on the River Tyne through to Eggleston on the River Tees. The infrastructure associated with water supply and waste water collection is dealt with in greater detail elsewhere in this section. Building foundations and underground infrastructure in addition to pipe work are threatened by subsidence and heave. Mechanisms for this are influenced by loading based consolidation and shrink/swell movement of soils as well as groundwater movement. Older assets and infrastructure are often more vulnerable, in part due to the natural ageing process but also if they are of non-standard design; they are less likely to be readily adapted. Furthermore, their initial design is less likely to have encompassed subsidence factors and there may be regulatory obstacles to any major alterations. Telecommunications Network TV and Radio Transmitters and Centres
Impacts Groundwater Increased temperatures throughout all seasons, and especially the large summer increases of over two degrees coupled with the expected 32% decrease in summer rainfall could impact heavily on the groundwater resource in this region. A reduction in rainfall will result in less infiltration and this may be worsened by increasing temperatures and the associated increase in evaporation. This reduction of precipitation into the aquifer combined with the current or indeed increased abstraction rates that may result in population increase may result in the lowering of aquifers, causing possible limits on abstraction. The boreholes located to the west of Berwick are located the closest to the coast and these are sufficiently inland so that they are not at risk from saline intrusion due to increased sea level rise. During summer months in the southern half of the Berwick and Wooler Supply Zone water resource can be insufficient and tankering has to be undertaken. A single main running through Haggerston connects the systems but this cannot be used to move any large volumes of water and this link will become increasingly strategic with the likely reductions in groundwater flows due to increased temperatures and reductions in summer rainfall. Northumbrian Water is currently schemes to increase the available water in the southern half of this supply zone with this link becoming. Surface Water Resource Sea level rise may cause the tidal limits within the rivers to extend further upstream than is currently seen (surface saline intrusion), and to negate any environmental impacts this causes the Environment Agency may require NWL to release greater compensation flows into the rivers to dilute this increased salinity, with this greater baseline release impacting on reservoir levels especially during summer when river flows will be less. This could mean an additional draw on reservoir resources impacting on impounded water levels. Dams Reservoirs and dams have potential to be influenced by climate change through several mechanisms. Changes to precipitation will alter inflows and rising temperatures will lead to increased reservoir evaporation. This may also lead to increased probability of failure and reservoir sedimentation. More than 50% of Britain’s reservoirs are over 100 years old and made of earth embankments. Under the medium-high climate change changes to precipitation and increases in wind are expected to result in the total surcharge (i.e. rise in water level above normal retention level during a storm) increasing by 5% in the 2050s. The increase could be as much as 11% in winter rainfall in higher climate change scenarios. Embankment dams, particularly those without wave walls or parapets, are thought to be more vulnerable to this loading than concrete and masonry dams. Other rainfall-induced mechanisms are principally due to saturation and erosion. Heavy rainfall is more likely to increase erosion, whilst changes to seasonal rainfall could result in increased saturation and consequently higher pore pressures within the fill and a resulting loss of strength in the fill and the embankment as a whole. This is most likely to effect grassed cohesive fill dams greater than 50 years old as they often lack modern drainage features. Deep-seated instability is the greatest risk to complete structural failure of a dam or reservoir and there is no evidence that this will increase with rainfall, and although shallow slips are not uncommon, increased rainfall will make these more likely though safety is not expected to be compromised. Other mechanisms such as subsidence or a landslip into the reservoir are also sensitive to changes in climate, although evidence from dams in countries with different climate regimes suggests that they are robust to the expected changes. Sediment delivery to reservoirs is a function of the amount of sediment available to rivers (generated often by soil erosion) and variation in river flows over time. More intense rainfall and more frequent storms are likely to increase sediment transport rates (providing that the sediment gets to a river channel) and increased high flows are likely to lead to increased transport of sediment to the reservoir. Even where average rainfall decreases, an increasing frequency of intense rainfall may generate more sediment. Evidently, this has potential implications for reservoir management and water resource supply (should increased sedimentation require dredging). However, notable changes in sedimentation have not yet been observed. There is a general consensus that the main climate threat to dams and reservoirs is in relation to increased extreme surcharge. The latest DEFRA guidance in PPS25 gives increases in peak rainfall intensity or planning purposes that when backed by the increase in winter rainfall predicted by UKCIP02 suggests that increased surcharge is a distinct possibility. However, there is currently little evidence to suggest that there will be a general problem for dams and reservoirs. However, embankment dams with low freeboard are at greatest risk. Increased evaporation due to higher temperatures is expected to result in reduced performance of dams and reservoirs. The impact of this will decrease with latitude. Increased sedimentation is a possible mechanism, although this is evidently uncertain and has not been observed in recent studies. Sub-surface infrastructure Higher temperatures and longer summers will lead to drier soils causing shrinkage of the soil. This could lead to increased subsidence of buildings and infrastructure. In 2003, the insurance industry reported claims of £400m and expect the annual average to be £600m by 2050. The rate of rise in groundwater levels could be changed by increased winter rainfall although the impacts of this change are uncertain as the average annual rainfall will decrease. However, potentially more significant is the impact of commercial and industrial water abstraction on groundwater level. Lowering groundwater levels have been reversed at locations that have seen a decline in industrial abstraction leading to a rapid rise in water levels, threatening tunnels and building foundations. Overall, this could lead to higher moisture differentials: shrinkage at the surface and saturation at depth placing stress on sub-surface infrastructure. Water Treatment Rises in sea levels may mean the inland migration of the tidal extent passed current river abstraction points requiring decisions to be made regarding the future of the works, e.g. structures to prevent the inland migration of tidal water or movement of the intake or the works itself. Surface saline intrusion may be a problem for certain works close to the coast, namely Warkworth in Northumberland. Increases in temperature will mean that arable farming becomes viable in the Northumbrian Region and measures such as activated carbon filters may need to be installed at treatment works, if not already in place, to deal with the levels of pesticides in raw water that has to be treated at the works. The temperature is projected to increase throughout all seasons especially during the summer months with 90th and 95th percentile temperatures increasing by three degrees. However, no major problems are expected with the processes within the treatment works as impacts were not experienced during the extended heatwave of July 2006. Surface Water and Waste Water Collection For surface water and local drainage, summer flooding will generally be more problematic than larger volume winter storms due to systems being less expansive and designed to pass flows quickly. Summer rainfall events are typically shorter but higher intensity storms, e.g. thunderstorms, which will quickly saturate or bypass the permeable areas leading to fast runoff flows and overwhelming local drainage systems. Surface water systems have been developed more recently, since the 1960’s, and these have therefore been designed under better, more informed planning guidance. Therefore typically the surface water systems do not currently have the same level of capacity problems exhibited by the foul/combined networks. Despite this however, with the frequency and magnitude of high intensity storms expected to increase surface runoff from these storms may overload and bypass the formal drainage systems which are designed to standards that do not consider climate change. Urban surface water drainage systems are currently designed to accommodate flows from a 1 in 30 year return period storm, although older systems are often overwhelmed by rainfall events much more frequently than this. Blockages within the system can exacerbate problems and commonly drainage grids can become obstructed by debris and leaves during intense events. In addition to impacts due to increased rainfall, future runoff volumes will increase due to an increased contributing area. New development ‘creep’ is known to be an ongoing problem for surface water drainage systems. It is becoming increasingly common for residents to build extensions and conservatories and look to pave over garden areas with hard-standing. Typically to keep areas well drained drainage grids are connected into the property’s surface water drain. It is also not uncommon for illegal misconnections into the foul sewer to be made which will obviously further exacerbate the problems in these systems. For new developments this issue has been found to increase impermeable areas connected into the local drainage by up to 20% in the first ten years. A recent report across the UK by the Royal Horticultural Society concluded that the North East region had the highest incidence of ‘creep’ with 43% of properties having paved over their front yard areas. For foul only sewerage systems it is unlikely that increases in rainfall will cause major problems as they the increases in flows from individual households should not vary much, and in fact they may reduce with a move to better water management including more water efficient lavatories and household appliances. However, sewerage systems may be at risk to insufficient capacity due to the increase in housing stock. The government is committed to increasing the number of homes in the UK including the north east to meet demand and currently developers commonly assume that the local drainage network will have capacity to accept these additional flows. This may not be a major problem for foul systems and may be a greater problem for surface water networks. Increase in winter rainfall will result in an increase in the height of the water table in many locations and this may impact on the flows that reach the water treatment works due to infiltration into the joints and any possible cracks or damage in the sewerage system. Waste Water Treatment Winter rainfall increases will cause more water to reach the treatment works through the surface water network especially in the urban areas where combined sewerage networks are prevalent. Waste water treatment works may be undersized for this increase in flows and water quality may be affected as a result. The increased seasonality of rainfall with less summer rainfall and more winter rainfall will result will result in problems during both seasons. Increases in temperature will have effects on the treatment processes currently used in the treatment works. Problems experienced during the July 2006 heatwave give an insight into future problems. Biological filters were found to have problems with the drying of the filter medium causing reduced quality of the treated effluent. Alternatively, activated sludge treatment was found to be more effective, although changes had to be made to accommodate the associated increase in activity due to the higher temperatures. Whilst the increase in mean temperatures is unlikely to cause serious issues, there is increased risk associated with dry, hot spells. Sea Outfalls
Network Pumping Stations Continued cyclic coastal flooding will cause corrosion. The infiltration of coastal flooding water into drainage sewers during flood events and the subsequent pumping of saline water will lead to corrosion of the pumps and mechanical equipment causing rusting or seizure and requiring increased maintenance. Also, as with fluvial flooding, flooding will produce increased flows through the system requiring the increased usage of pumps resulting in increased maintenance. For all pump stations and especially those inland where increases in rainfall are expected to be greatest, increased winter rainfall will result in increased flows within the sewer network through the direct runoff entering the system through highways and roof drainage, and infiltration into the pipe network due to higher ground saturation. The increased flows may result in pumps being undersized to pass the higher expected winter flows resulting in more frequent spills from emergency overflows (EOs) and maintenance being required on a more regular basis through increased use and therefore greater, more rapid wear. Electricity Distribution Wind speeds are projected to decrease slightly in County Durham; however, as mentioned previously in this report wind is notoriously hard to make climate projections for. So impacts to the electivity network associated with wind can be expected to reduce on average. Increases in rainfall are unlikely to affect the transmission lines; however any resulting flooding may potentially affect the network if fast flowing water were to undermine a tower structure. Flooding of the sub stations or booster stations may also be a problem if the flooded areas were to increase. In general, in terms of the transmission lines, flooding and rainfall are unlikely to have a negative impact on the system. Flooding has been dealt with in greater detail in the flooding section of the report. All seasons cab expect an increase in temperature and this increase includes severe high temperatures during summer. Transmission cables will be susceptible to sagging with extreme high temperatures. During hot temperatures cables are de-rated to maintain sag limits. Lines will usually be assigned two ratings, for summer and winter periods. With higher average temperatures the overhead conductors will remain loaded to its normal rating for a longer period and the conductor temperature, and hence sag, is likely to increase. Overhead lines are constructed to ensure that the degree of allowable sag does not become a safety hazard. As discussed, increasing temperatures will reduce the transmission capacity of the lines. With increasing energy demand for cooling purposes during extreme hot periods, with the increases in both average and extreme temperatures this is likely to mean a greater load on the UK grid network as a whole, which could lead to dips or breaks in the supply during extreme hot periods. The increased extreme temperatures will also have an adverse effect on the sag of transmission lines. The rating of existing lines is most likely to be affected by prolonged There are obviously further issues with respect to energy generation aspects concerning new government targets for reductions of carbon emissions in relation to reducing further climate change effects. It is not within scope of this study to consider how The slight increase in winter wetness and predicted soil moisture content is likely to cause an increase in the number of cable breakages due to ground movements; this should be minimal so long as the correct laying of the cable has been carried out. With the increased soil moisture, there is a likely increase in the risk of instability of substations, although this should be limited, dependant on the particular ground conditions, which will be site specific. Detailed site investigations should be carried out to review conditions and susceptibility. The increase in soil moisture is not likely to lead to a wide reduction in cable lifespan due to the soil thermal resistivity because of the limited increase predicted. Flooding has been dealt with in greater detail within the flooding section. Electricity Demand Further demand will be placed on the electricity with an increase in population in the area and through the current boom in the housing market to meet demand. These new houses and especially their location could impact on the network, especially in areas where energy supply is running close to capacity. Wind Farms Infrastructure Susceptible to Subsidence Telecommunications Network In the upland areas, a slight increase is expected in mean winter wind speeds. While this increase in average wind speeds is likely to cause no additional damage an increase in extreme wind speeds may lead to the failure of structures, particularly vulnerable structures are those located on the crest of hills and those which are already heavily laden with communication equipment. It is often found that the older structures in this category, which are designed to older design codes, are approaching, or are at, their structural capacity. An increase in load of this nature may be sufficient to cause the structure to collapse. A recent failure of this nature occurred at a Northern Constabulary site, Maaruig in the Western Isles of Scotland where the design wind speed was exceeded. TV and Radio Transmitters and Centres
Description Water Supply The Northern and Central Supply Zones are covered in greater detail in the Northumberland and County Durham Reporting sections due to these supply zone being predominantly within these sub-regions. Water is abstracted from the Tyne at Gunnerton and Barrasford and can be used to supply Hallington and Whittle Dene Reservoir, as well as Gunnerton WTW. Whittle Dene Reservoir can also be supplied from river abstraction at Ovingham, which can be fed to Horsley or Whittle Dene WTW. Barrasford is currently being overhauled with the installation of new pumps and screens. Water is also abstracted from the Tyne at Riding Mill for the Tyne-Tees tunnel when required. The water demands of Newcastle and Gateshead are met by the treatment works at Whittle Dene and Horsley can be fed from either the Whittle Dene reservoirs or from the Tyne water abstracted at Ovingham. Whittle Dene normally treats predominantly reservoir water; Horsley predominantly treats river water. The two works jointly meet part of Tyneside and SE Northumberland demands. The Wear Valley water treatment works uses water exclusively from Burnhope Reservoir which lies at the head of the River Wear in County Durham and supplies the Durham area as well as parts of Sunderland through a system of service reservoirs and booster stations. Water is also abstracted at Lumley on the River Wear to supply Sunderland from the west and can also supplement the area supplied from the Wear Valley water treatment works. Releases from the Tyne-Tees Tunnel ensure that river abstractions can be met at all times. The predominantly urban areas of Horden, Easington, Seaham and parts of Sunderland are supplied from the Wearside Ground Water Stations of:
These are all shaft boreholes, some were previously mine shafts and are some 5m in diameter and 300m deep. These sites are all located relatively close to the coast. The Tyne-Tees Tunnel transfer system is a tunnel by which water from Kielder can be used throughout the majority of the region and allows transfers via a pumping station at Riding Mill on the River Tyne. This tunnel is covered in greater detail at the regional level of reporting due to it’s significant role and that of Kielder Water as a strategic regional resource. As the water is supplied from Northumbrian Water’s reservoirs located in the uplands of Northumberland and County Durham, Tyne and Wear does not contain any dam structures. Waste Water Typically foul/combined (wastewater) systems will comprise a network of drainage sewers, often combining areas of separate and combined drainage, eventually discharging to a Wastewater Treatment Works. Various ancillary structures will be included through the system to assist network performance, primarily pumping stations, combined sewer overflows (CSOs), and storage tanks. Tyne and Wear as a sub-region is located on the coast and is primarily urban with some of the regions largest conurbations of Newcastle, Gateshead and Sunderland and as a result a major proportion of the regions population situated within it. Due to the dense nature of the population this sub-regions waste water treatment is handled from two large treatment works at Howdon in Newcastle and Hendon in Sunderland. The treated effluent from both these works is then discharged through long outfalls into the sea at Hendon and into the estuarial reaches of the Tyne at Howdon. As this area is predominantly urban the wastewater collection sewerage system is generally a combined system. They provide the drainage for foul flows, both industrial and domestic, and surface water runoff. Historically, urban sewer systems have been designed to carry the combined flows of household and industrial waste and rainwater. For the last 30 years, however, drainage systems have generally been developed to carry storm water flows separately, although combined drainage systems are still common in older areas, some dating back to Victorian times. This legacy means that the vast majority of the existing sewer network in the urban locations will comprise predominantly combined sewer systems. CSOs provide an overflow release from the drainage system into local watercourses or adjacent surface water systems during times of high flows to protect local areas from flooding. There are over 1,400 CSOs within the Northumbrian Water region of which around 450 are in Tyne and Wear. Surface water drainage networks will typically drain smaller, more localised areas than the foul/combined networks to discharge into local watercourses. Networks will not usually include the additional ancillary structures used in the foul/combined systems, such as pumping stations or storage facilities, and are generally designed to transfer and discharge the storm surface runoff as swiftly as possible. Surface water systems will not usually include treatment devices, although silt traps and sediment/oil interceptors will often be included for car parks and large roads to retain contaminants and protect the receiving watercourse from runoff pollutants. Network Pumping Stations Electricity Distribution A further towered electricity cable that is owned by National Grid runs around the west of the main urban area of Newcastle-upon-Tyne between Kingston Park and Newcastle International Airport. The cable crosses the River Tyne west of Denton Burn and runs in a southerly direction past the west of Blaydon and through Rowlands Gill. The voltage carried by each of these lines is not known. There are further, shorter lengths of transmission lines and pylons that have been identified from the map search, but it is not known exactly how these connect into the main grid network, possibly indicating the extension of sub-surface transmission cables in some areas. Substations are typically located in order to feed electricity into the large towns and urban areas that dominate this sub-region. No information has been available for the remainder of the distribution system, but it is likely to exist as lower voltage underground distribution cables. Underground cables are particularly more common in heavily urban areas. These will generally be thoroughly spread throughout the catchment to connect the surrounding urban areas to the various local substations. Electricity Demand Wind Farms Infrastructure Susceptible to Subsidence Due to large developed areas dominating Tyne and Wear there is extensive energy and water infrastructure in the catchment, largely located in the middle and lower reaches. Knowledge of two highly important gas pipes exists; a large gas feeder pipe that enters the catchment in the south west from Teesside and also an ethylene pipeline that runs from Teesside to Grangemouth, Scotland. Within the catchment there are also large amounts of infrastructure to distribute water and collect waste water and surface water runoff. Water supply in brought into the region from outside the sub-regional and therefore due to the dense population there are extensive lengths of water supply and sewerage infrastructure. In addition to these there is also the Tyne-Tees tunnel which runs from Riding Mill on the River Tyne through to Eggleston on the River Tees. The infrastructure associated with water supply and waste water collection is dealt with in greater detail elsewhere in this section. Building foundations and underground infrastructure in addition to pipe work are threatened by subsidence and heave. Mechanisms for this are influenced by loading based consolidation and shrink/swell movement of soils as well as groundwater movement. Older assets and infrastructure are often more vulnerable, in part due to the natural ageing process but also if they are of non-standard design; they are less likely to be readily adapted. Furthermore, their initial design is less likely to have encompassed subsidence factors and there may be regulatory obstacles to any major alterations. Telecommunications Network TV and Radio Transmitters and Centres
Impacts Groundwater The Fulwell GWS is reasonably close to the coast and as no current problems exist and using the recent sea level rise estimates from DEFRA this station is unlikely to be at risk from saline intrusion or coastal flooding. However, the assessment of the risk of saline intrusion is not well known and a more robust assessment is not possible without further assessment due to the complex issues that influence it. Surface Water Resource and Dams Sub-surface infrastructure Higher temperatures and longer summers will lead to drier soils causing shrinkage of the soil. This could lead to increased subsidence of buildings and infrastructure. In 2003, the insurance industry reported claims of £400m and expect the annual average to be £600m by 2050. The rate of rise in groundwater levels could be changed by increased winter rainfall although the impacts of this change are uncertain as the average annual rainfall will decrease. However, potentially more significant is the impact of commercial and industrial water abstraction on groundwater level. Lowering groundwater levels have been reversed at locations that have seen a decline in industrial abstraction leading to a rapid rise in water levels, threatening tunnels and building foundations. Overall, this could lead to higher moisture differentials: shrinkage at the surface and saturation at depth placing stress on sub-surface infrastructure. Water Treatment Rises in sea levels may mean the inland migration of the tidal extent passed current river abstraction points requiring decisions to be made regarding the future of the works, e.g. structures to prevent the inland migration of tidal water or movement of the intake or the works itself. Water is not abstracted within Tyne and Wear though there is an abstraction at Lumley on the River Wear that supplies areas of Sunderland which is located upstream of the tidal limit which is currently at Labmbton Bridge downstream of Chester-le-Street. Using the expected rises in sea level by the 2050s of around 200mm given by the latest Defra guidance, surface saline intrusion will not be a threat to this works. The temperature is projected to increase throughout all seasons especially during the summer months with 90th and 95th percentile temperatures increasing by three degrees. However, no major problems are expected with the processes within the treatment works as impacts were not experienced during the extended heatwave of July 2006. Surface Water and Waste Water Collection For surface water and local drainage, summer flooding will generally be more problematic than larger volume winter storms due to systems being less expansive and designed to pass flows quickly. Summer rainfall events are typically shorter but higher intensity storms, e.g. thunderstorms, which will quickly saturate or bypass the permeable areas leading to fast runoff flows and overwhelming local drainage systems. Surface water systems have been developed more recently, since the 1960’s, and these have therefore been designed under better, more informed planning guidance. Therefore typically the surface water systems do not currently have the same level of capacity problems exhibited by the foul/combined networks. Despite this however, with the frequency and magnitude of high intensity storms expected to increase surface runoff from these storms may overload and bypass the formal drainage systems which are designed to standards that do not consider climate change. Urban surface water drainage systems are currently designed to accommodate flows from a 1 in 30 year return period storm, although older systems are often overwhelmed by rainfall events much more frequently than this. Blockages within the system can exacerbate problems and commonly drainage grids can become obstructed by debris and leaves during intense events. In addition to impacts due to increased rainfall, future runoff volumes will increase due to an increased contributing area. New development ‘creep’ is known to be an ongoing problem for surface water drainage systems. It is becoming increasingly common for residents to build extensions and conservatories and look to pave over garden areas with hard-standing. Typically to keep areas well drained drainage grids are connected into the property’s surface water drain. It is also not uncommon for illegal misconnections into the foul sewer to be made which will obviously further exacerbate the problems in these systems. For new developments this issue has been found to increase impermeable areas connected into the local drainage by up to 20% in the first ten years. A recent report across the UK by the Royal Horticultural Society concluded that the North East region had the highest incidence of ‘creep’ with 43% of properties having paved over their front yard areas. For foul only sewerage systems it is unlikely that increases in rainfall will cause major problems as they the increases in flows from individual households should not vary much, and in fact they may reduce with a move to better water management including more water efficient lavatories and household appliances. However, sewerage systems may be at risk to insufficient capacity due to the increase in housing stock. The government is committed to increasing the number of homes in the UK including the north east to meet demand and currently developers commonly assume that the local drainage network will have capacity to accept these additional flows. This may not be a major problem for foul systems and may be a greater problem for surface water networks. Increase in winter rainfall will result in an increase in the height of the water table in many locations and this may impact on the flows that reach the water treatment works due to infiltration into the joints and any possible cracks or damage in the sewerage system. Waste Water Treatment Winter rainfall increases will cause more water to reach the treatment works through the surface water network especially in the urban areas where combined sewerage networks are prevalent. Waste water treatment works may be undersized for this increase in flows and water quality may be affected as a result. The increased seasonality of rainfall with less summer rainfall and more winter rainfall will result will result in problems during both seasons. Increases in temperature will have effects on the treatment processes currently used in the treatment works. Problems experienced during the July 2006 heatwave give an insight into future problems. Biological filters were found to have problems with the drying of the filter medium causing reduced quality of the treated effluent. Alternatively, activated sludge treatment was found to be more effective, although changes had to be made to accommodate the associated increase in activity due to the higher temperatures. Whilst the increase in mean temperatures is unlikely to cause serious issues, there is increased risk associated with dry, hot spells. Flooding has been dealt with in much greater detail within the flooding section but in addition the potential risk to Hendon WWTW is best identified here. Hendon is at risk due to its location directly on the coast, protected by a rubble breakwater and is currently identified within the EA Flood Zone 2. Increases in sea levels will mean that these sea defences will be at an increased risk of overtopping as not only will the freeboard of the defence reduce due to sea level rise but due to the increased depth of water at the toe of the defence will result in waves of greater magnitude impacting upon the structure, causing increased overtopping of the defence and an increased likelihood of damage. This increased overtopping, as mentioned earlier, may impact on the treatment processes of the works. Sea Outfalls
Network Pumping Stations Continued cyclic coastal flooding will cause corrosion. The infiltration of coastal flooding water into drainage sewers during flood events and the subsequent pumping of saline water will lead to corrosion of the pumps and mechanical equipment causing rusting or seizure and requiring increased maintenance. Also, as with fluvial flooding, flooding will produce increased flows through the system requiring the increased usage of pumps resulting in increased maintenance. For all pump stations and especially those inland where increases in rainfall are expected to be greatest, increased winter rainfall will result in increased flows within the sewer network through the direct runoff entering the system through highways and roof drainage, and infiltration into the pipe network due to higher ground saturation. The increased flows may result in pumps being undersized to pass the higher expected winter flows resulting in more frequent spills from emergency overflows (EOs) and maintenance being required on a more regular basis through increased use and therefore greater, more rapid wear. Electricity Distribution Wind speeds are projected to decrease slightly in County Durham; however, as mentioned previously in this report wind is notoriously hard to make climate projections for. So impacts to the electivity network associated with wind can be expected to reduce on average. Increases in rainfall are unlikely to affect the transmission lines; however any resulting flooding may potentially affect the network if fast flowing water were to undermine a tower structure. Flooding of the sub stations or booster stations may also be a problem if the flooded areas were to increase. In general, in terms of the transmission lines, flooding and rainfall are unlikely to have a negative impact on the system. Flooding has been dealt with in greater detail in the flooding section of the report. All seasons cab expect an increase in temperature and this increase includes severe high temperatures during summer. Transmission cables will be susceptible to sagging with extreme high temperatures. During hot temperatures cables are de-rated to maintain sag limits. Lines will usually be assigned two ratings, for summer and winter periods. With higher average temperatures the overhead conductors will remain loaded to its normal rating for a longer period and the conductor temperature, and hence sag, is likely to increase. Overhead lines are constructed to ensure that the degree of allowable sag does not become a safety hazard. As discussed, increasing temperatures will reduce the transmission capacity of the lines. With increasing energy demand for cooling purposes during extreme hot periods, with the increases in both average and extreme temperatures this is likely to mean a greater load on the UK grid network as a whole, which could lead to dips or breaks in the supply during extreme hot periods. The increased extreme temperatures will also have an adverse effect on the sag of transmission lines. The rating of existing lines is most likely to be affected by prolonged There are obviously further issues with respect to energy generation aspects concerning new government targets for reductions of carbon emissions in relation to reducing further climate change effects. It is not within scope of this study to consider how The slight increase in winter wetness and predicted soil moisture content is likely to cause an increase in the number of cable breakages due to ground movements; this should be minimal so long as the correct laying of the cable has been carried out. With the increased soil moisture, there is a likely increase in the risk of instability of substations, although this should be limited, dependant on the particular ground conditions, which will be site specific. Detailed site investigations should be carried out to review conditions and susceptibility. The increase in soil moisture is not likely to lead to a wide reduction in cable lifespan due to the soil thermal resistivity because of the limited increase predicted. Flooding has been dealt with in greater detail within the flooding section. Electricity Demand Further demand will be placed on the electricity with an increase in population in the area and through the current boom in the housing market to meet demand. These new houses and especially their location could impact on the network, especially in areas where energy supply is running close to capacity. Wind Farms Infrastructure Susceptible to Subsidence Telecommunications Network In the upland areas, a slight increase is expected in mean winter wind speeds. While this increase in average wind speeds is likely to cause no additional damage an increase in extreme wind speeds may lead to the failure of structures, particularly vulnerable structures are those located on the crest of hills and those which are already heavily laden with communication equipment. It is often found that the older structures in this category, which are designed to older design codes, are approaching, or are at, their structural capacity. An increase in load of this nature may be sufficient to cause the structure to collapse. A recent failure of this nature occurred at a Northern Constabulary site, Maaruig in the Western Isles of Scotland where the design wind speed was exceeded. TV and Radio Transmitters and Centres
Description Water Supply The Tyne-Tees Tunnel transfer system is a tunnel by which water from Kielder can be used throughout the majority of the region and allows transfers via a pumping station at Riding Mill on the River Tyne. This tunnel is covered in greater detail at the regional level of reporting due to it’s significant role and that of Kielder Water as a strategic regional resource In the Central Supply Zone the key resources are the two main reservoirs of Derwent and Burnhope and the three smaller reservoirs of Smiddy Shaw, Hisehope and Waskerley. Derwent reservoir supplies the Mosswood Treatment Works. A direct cross connection for the Tyne-Tees Tunnel means that while Derwent Reservoir itself cannot be supplied with water the supply to the Mosswood WTW allows better use of the Derwent resource. The availability of support from Kielder has enabled the cheaper local sources to be used more effectively, and to be drawn down further, without the necessity to place restrictions on water use. Water from Waskerley, Hisehope and Smiddy Shaw (the Waskerley Group) can be transferred under gravity to Honeyhill WTW which supplies a large area of North Durham, Chester-le-Street and as far as Winlaton and Crook. Honey Hill WTW also supplies the large rural area close to the works including the towns of Stanley and Consett. The needs of Honeyhill WTW cannot be fully met by these reservoirs and support is available from Burnhope Reservoir. Water can be transferred under gravity to Waskerley, Smiddy Shaw or directly to Honeyhill from Burnhope. Water can also be extracted from Waskerley airshaft on the Tyne-Tees tunnel into Waskerley Reservoir. Water from Tunstall Reservoir is used to sustain the flow in the River Wear and support the minimum maintained flow at Chester-le-Street. This allows better use of Burnhope and the Waskerley Group without the need to resort to the use of water from the Tyne-Tees Tunnel. To ensure that sufficient water remains in the River Wear after abstractions, a prescribed minimum maintained flow is set at Chester-le-Street gauging station of 2.0 cumecs and this is monitored by both Northumbrian Water and the Environment Agency. The Wear Valley WTW uses water exclusively from Burnhope Reservoir which lies at the head of the River Wear and supplies the Durham area as well as parts of Sunderland through a system of service reservoirs and booster stations. Water from Burnhope can be used to supply Wear Valley treatment works and the raw water pipeleine to the Waskerley, Hisehope and Smiddy Shaw group of reservoirs. Wear Valley WTW and the compensation water can only be provided from Burnhope. Therefore, sufficient resources must be retained at all times to provide for these two demands. Water is also abstracted from Lumley on the River Wear to supply Sunderland from the west and can also supplement the area supplied from the Wear Valley WTW. Releases from the Tyne-Tees tunnel at Frosterley ensure that river abstractions can be met at all times. Cow Green is the principal river regulating reservoir on the River Tees, and is used to support abstractions from the lower Tees. River regulation demand can normally be met from Cow Green releases but are augmented when necessary by regulation from Lune/Balder reservoirs or the Kielder transfer system. Water released from Cow Green is extracted further down the Tees for use in the Broken Scat WTW which then supplies Darlington, Stockton and Middlesbrough as well as the surrounding areas. Raw water is also abstracted at Broken Scar and transferred untreated to industrial customers in Teesside. The use of raw water by industrial customers in Teesside has been in decline in past years and Northumbrian Water expect this to continue until 2015 when they expect the usage to stabilise. River needs in the upper Tees are met by the compensation flow and the requirement to reserve water such that at least one third of the regulation releases at a given time come from Cow Green, as specified in the Tees Valley and Cleveland Water Act 1967. Cow Green also has a flood control role during winter months with levels being drawn down to provide flood storage. The Lune and Balder reservoirs consist of Selset and Grassholme on the River Lune and Balderhead, Blackton, Hury Subsiduray and Hury on the River Balder used conjunctively with an interconnecting tunnel. The Lune and Balder reservoirs support the demand by direct supply through the Lartington Treatment Works which then supplies the local towns such as Barnard Castle. Water may be available for regulation releases in support of the River Tees when the reservoirs are in the surplus zone. Waste Water Typically foul/combined (wastewater) systems will comprise a network of drainage sewers, often combining areas of separate and combined drainage, eventually discharging to a Wastewater Treatment Works. Various ancillary structures will be included through the system to assist network performance, primarily pumping stations, combined sewer overflows (CSOs), and storage tanks. Within County Durham the concentration of the population close to the coast is not as marked as Tyne and Wear and Tees Valley though it is still relatively large in size. Within County Durham there is a greater spread of the population inland and in smaller rural communities as well as the city of Durham and the towns of Chester-le-Street, Bishop Auckland, Consett, Spennymoor, Barnard Castle and Peterlee. Wastewater collection systems are spread extensively across the region, being particularly concentrated in the urban areas. They provide the drainage for foul flows, both industrial and domestic, and surface water runoff. Historically, urban sewer systems have been designed to carry the combined flows of household and industrial waste and rainwater. For the last 30 years, however, drainage systems have generally been developed to carry storm water flows separately, although combined drainage systems are still common in older areas, some dating back to Victorian times. This legacy means that the vast majority of the existing sewer network in the urban locations will comprise predominantly combined sewer systems. Newer towns or towns that have largely expanded over recent times may feature separate foul and surface water sewerage systems. The west of the sub-region is largely rural and the sparse population means that many properties in the sub-region will use a cess pit, sceptic tank or similar as a method for storing waste water for removal by tanker. These tankers then take the extracted effluent to one of the waste water treatment works which services the more densely populated areas. The treatment works for the larger urban conurbation in County Durham such as Durham and Newton Aycliffe are treated before being discharges into nearby watercourses. The coastal works located at Seaham and Hordon that treat the effluent from the areas in and around Seaham and Peterlee respectively discharge the effluent through long sea outfalls. In the rural areas of County Durham it is likely that any formal surface water drainage that does exist will generally be directed into a soakaway or else directly into a local stream or river. The foul or combined sewerage network will be prevalent in the urban areas and to many of the villages and larger conurbations that surround them. For the more isolated premises and communities as mentioned earlier in this section they will generally have a cess pit, septic tank or similar serving individual or a group of properties. Combines Sewer overflows (CSOs) provide an overflow release from the drainage system into local watercourses or adjacent surface water systems during times of high flows to protect local areas from flooding. There are over 1,400 CSOs within the Northumbrian Water region of which around 200 are in Northumberland. Surface water drainage networks will typically drain smaller, more localised areas than the foul/combined networks to discharge into local watercourses. Networks will not usually include the additional ancillary structures used in the foul/combined systems, such as pumping stations or storage facilities, and are generally designed to transfer and discharge the storm surface runoff as swiftly as possible. Surface water systems will not usually include treatment devices, although silt traps and sediment/oil interceptors will often be included for car parks and large roads to retain contaminants and protect the receiving watercourse from runoff pollutants. Network Pumping Stations Electricity Distribution The majority of substations are located around Durham, Spennymoor and Bishop Auckland, with key sub-stations identified near Spennymoor and south of Hetton-le-Hole. These are typically located in order to feed electricity into the large towns and urban areas around the centre of the catchment. There is a further identified substation at Eastgate, towards the upper end of the Wear Valley, presumably situated to feed the villages and remote properties in the upper areas of the catchment. No information has been available for the remainder of the distribution system within the catchment, but it is likely to exist as lower voltage underground distribution cables. Underground cables are particularly more common in heavily urban areas. These will generally be thoroughly spread throughout the catchment to connect the surrounding urban areas to the various local substations. Electricity Demand Wind Farms Infrastructure Susceptible to Subsidence Due to large developed areas such as Durham, Consett, Easington and Bishop Auckland there is extensive energy and water infrastructure in the catchment, largely located in the middle and lower reaches. Knowledge of two highly important gas pipes exists; a large gas feeder pipe that enters the catchment in the south west from Teesside and also an ethylene pipeline that runs from Teesside to Grangemouth, Scotland. Within the catchment there are also large amounts of infrastructure to distribute water and collect waste water and surface water runoff. The treatment works such of Mosswood, Honey Hill and Wear Valley are located in the uplands of County Durham and water is transported from these to the larger urban areas of Durham and Sunderland. In addition to these there is also the Tyne-Tees tunnel which runs from Riding Mill on the River Tyne through to Eggleston on the River Tees. The infrastructure associated with water supply and waste water collection is dealt with in greater detail elsewhere in this section. Building foundations and underground infrastructure in addition to pipe work are threatened by subsidence and heave. Mechanisms for this are influenced by loading based consolidation and shrink/swell movement of soils as well as groundwater movement. Older assets and infrastructure are often more vulnerable, in part due to the natural ageing process but also if they are of non-standard design; they are less likely to be readily adapted. Furthermore, their initial design is less likely to have encompassed subsidence factors and there may be regulatory obstacles to any major alterations. Telecommunications Network TV and Radio Transmitters and Centres
Impacts Groundwater Surface Water Resource Sea level rise may cause the tidal limits within the rivers to extend further upstream than is currently seen (surface saline intrusion), and to negate any environmental impacts this causes the Environment Agency may require NWL to release greater compensation flows into the rivers to dilute this increased salinity, with this greater baseline release impacting on reservoir levels especially during summer when river flows will be less. This could mean an additional draw on reservoir resources impacting on impounded water levels. Rises in sea levels may mean the inland migration of the tidal extent passed current river abstraction points requiring decisions to be made regarding the future of the works, e.g. structures to prevent the inland migration of tidal water or movement of the intake or the works itself. Water is not abstracted within Tyne and Wear though there is an abstraction at Lumley on the River Wear that supplies areas of Sunderland which is located upstream of the tidal limit which is currently at Labmbton Bridge downstream of Chester-le-Street. Using the expected rises in sea level by the 2050s of around 200mm given by the latest Defra guidance, surface saline intrusion will not be a threat to this works. Dams Reservoirs and dams have potential to be influenced by climate change through several mechanisms. Changes to precipitation will alter inflows and rising temperatures will lead to increased reservoir evaporation. This may also lead to increased probability of failure and reservoir sedimentation. More than 50% of Britain’s reservoirs are over 100 years old and made of earth embankments. Under the medium-high climate change changes to precipitation and increases in wind are expected to result in the total surcharge (i.e. rise in water level above normal retention level during a storm) increasing by 5% in the 2050s. The increase could be as much as 11% in winter rainfall in higher climate change scenarios. Embankment dams, particularly those without wave walls or parapets, are thought to be more vulnerable to this loading than concrete and masonry dams. Other rainfall-induced mechanisms are principally due to saturation and erosion. Heavy rainfall is more likely to increase erosion, whilst changes to seasonal rainfall could result in increased saturation and consequently higher pore pressures within the fill and a resulting loss of strength in the fill and the embankment as a whole. This is most likely to effect grassed cohesive fill dams greater than 50 years old as they often lack modern drainage features. Deep-seated instability is the greatest risk to complete structural failure of a dam or reservoir and there is no evidence that this will increase with rainfall, and although shallow slips are not uncommon, increased rainfall will make these more likely though safety is not expected to be compromised. Other mechanisms such as subsidence or a landslip into the reservoir are also sensitive to changes in climate, although evidence from dams in countries with different climate regimes suggests that they are robust to the expected changes. Sediment delivery to reservoirs is a function of the amount of sediment available to rivers (generated often by soil erosion) and variation in river flows over time. More intense rainfall and more frequent storms are likely to increase sediment transport rates (providing that the sediment gets to a river channel) and increased high flows are likely to lead to increased transport of sediment to the reservoir. Even where average rainfall decreases, an increasing frequency of intense rainfall may generate more sediment. Evidently, this has potential implications for reservoir management and water resource supply (should increased sedimentation require dredging). However, notable changes in sedimentation have not yet been observed. There is a general consensus that the main climate threat to dams and reservoirs is in relation to increased extreme surcharge. The latest DEFRA guidance in PPS25 gives increases in peak rainfall intensity or planning purposes that when backed by the increase in winter rainfall predicted by UKCIP02 suggests that increased surcharge is a distinct possibility. However, there is currently little evidence to suggest that there will be a general problem for dams and reservoirs. However, embankment dams with low freeboard are at greatest risk. Increased evaporation due to higher temperatures is expected to result in reduced performance of dams and reservoirs. The impact of this will decrease with latitude. Increased sedimentation is a possible mechanism, although this is evidently uncertain and has not been observed in recent studies. Sub-surface infrastructure Higher temperatures and longer summers will lead to drier soils causing shrinkage of the soil. This could lead to increased subsidence of buildings and infrastructure. In 2003, the insurance industry reported claims of £400m and expect the annual average to be £600m by 2050. The rate of rise in groundwater levels could be changed by increased winter rainfall although the impacts of this change are uncertain as the average annual rainfall will decrease. However, potentially more significant is the impact of commercial and industrial water abstraction on groundwater level. Lowering groundwater levels have been reversed at locations that have seen a decline in industrial abstraction leading to a rapid rise in water levels, threatening tunnels and building foundations. Overall, this could lead to higher moisture differentials: shrinkage at the surface and saturation at depth placing stress on sub-surface infrastructure. Water Treatment Rises in sea levels may mean the inland migration of the tidal extent passed current river abstraction points requiring decisions to be made regarding the future of the works, e.g. structures to prevent the inland migration of tidal water or movement of the intake or the works itself. Water is not abstracted within Tyne and Wear though there is an abstraction at Lumley on the River Wear that supplies areas of Sunderland which is located upstream of the tidal limit which is currently at Labmbton Bridge downstream of Chester-le-Street. Using the expected rises in sea level by the 2050s of around 200mm given by the latest Defra guidance, surface saline intrusion will not be a threat to this works. Increases in temperature will mean that arable farming becomes viable in the Northumbrian Region and measures such as activated carbon filters may need to be installed at treatment works, if not already in place, to deal with the levels of pesticides in raw water that has to be treated at the works. The temperature is projected to increase throughout all seasons especially during the summer months with 90th and 95th percentile temperatures increasing by three degrees. However, no major problems are expected with the processes within the treatment works as impacts were not experienced during the extended heatwave of July 2006. Surface Water and Waste Water Collection For surface water and local drainage, summer flooding will generally be more problematic than larger volume winter storms due to systems being less expansive and designed to pass flows quickly. Summer rainfall events are typically shorter but higher intensity storms, e.g. thunderstorms, which will quickly saturate or bypass the permeable areas leading to fast runoff flows and overwhelming local drainage systems. Surface water systems have been developed more recently, since the 1960’s, and these have therefore been designed under better, more informed planning guidance. Therefore typically the surface water systems do not currently have the same level of capacity problems exhibited by the foul/combined networks. Despite this however, with the frequency and magnitude of high intensity storms expected to increase surface runoff from these storms may overload and bypass the formal drainage systems which are designed to standards that do not consider climate change. Urban surface water drainage systems are currently designed to accommodate flows from a 1 in 30 year return period storm, although older systems are often overwhelmed by rainfall events much more frequently than this. Blockages within the system can exacerbate problems and commonly drainage grids can become obstructed by debris and leaves during intense events. In addition to impacts due to increased rainfall, future runoff volumes will increase due to an increased contributing area. New development ‘creep’ is known to be an ongoing problem for surface water drainage systems. It is becoming increasingly common for residents to build extensions and conservatories and look to pave over garden areas with hard-standing. Typically to keep areas well drained drainage grids are connected into the property’s surface water drain. It is also not uncommon for illegal misconnections into the foul sewer to be made which will obviously further exacerbate the problems in these systems. For new developments this issue has been found to increase impermeable areas connected into the local drainage by up to 20% in the first ten years. A recent report across the UK by the Royal Horticultural Society concluded that the North East region had the highest incidence of ‘creep’ with 43% of properties having paved over their front yard areas. For foul only sewerage systems it is unlikely that increases in rainfall will cause major problems as they the increases in flows from individual households should not vary much, and in fact they may reduce with a move to better water management including more water efficient lavatories and household appliances. However, sewerage systems may be at risk to insufficient capacity due to the increase in housing stock. The government is committed to increasing the number of homes in the UK including the north east to meet demand and currently developers commonly assume that the local drainage network will have capacity to accept these additional flows. This may not be a major problem for foul systems and may be a greater problem for surface water networks. Increase in winter rainfall will result in an increase in the height of the water table in many locations and this may impact on the flows that reach the water treatment works due to infiltration into the joints and any possible cracks or damage in the sewerage system. Waste Water Treatment Winter rainfall increases will cause more water to reach the treatment works through the surface water network especially in the urban areas where combined sewerage networks are prevalent. Waste water treatment works may be undersized for this increase in flows and water quality may be affected as a result. The increased seasonality of rainfall with less summer rainfall and more winter rainfall will result will result in problems during both seasons. Increases in temperature will have effects on the treatment processes currently used in the treatment works. Problems experienced during the July 2006 heatwave give an insight into future problems. Biological filters were found to have problems with the drying of the filter medium causing reduced quality of the treated effluent. Alternatively, activated sludge treatment was found to be more effective, although changes had to be made to accommodate the associated increase in activity due to the higher temperatures. Whilst the increase in mean temperatures is unlikely to cause serious issues, there is increased risk associated with dry, hot spells. Sea Outfalls
Network Pumping Stations Electricity Distribution Wind speeds are projected to decrease slightly in County Durham; however, as mentioned previously in this report wind is notoriously hard to make climate projections for. So impacts to the electivity network associated with wind can be expected to reduce on average. Increases in rainfall are unlikely to affect the transmission lines; however any resulting flooding may potentially affect the network if fast flowing water were to undermine a tower structure. Flooding of the sub stations or booster stations may also be a problem if the flooded areas were to increase. In general, in terms of the transmission lines, flooding and rainfall are unlikely to have a negative impact on the system. Flooding has been dealt with in greater detail in the flooding section of the report. All seasons cab expect an increase in temperature and this increase includes severe high temperatures during summer. Transmission cables will be susceptible to sagging with extreme high temperatures. During hot temperatures cables are de-rated to maintain sag limits. Lines will usually be assigned two ratings, for summer and winter periods. With higher average temperatures the overhead conductors will remain loaded to its normal rating for a longer period and the conductor temperature, and hence sag, is likely to increase. Overhead lines are constructed to ensure that the degree of allowable sag does not become a safety hazard. As discussed, increasing temperatures will reduce the transmission capacity of the lines. With increasing energy demand for cooling purposes during extreme hot periods, with the increases in both average and extreme temperatures this is likely to mean a greater load on the UK grid network as a whole, which could lead to dips or breaks in the supply during extreme hot periods. The increased extreme temperatures will also have an adverse effect on the sag of transmission lines. The rating of existing lines is most likely to be affected by prolonged periods of hotter temperatures. There are obviously further issues with respect to energy generation aspects concerning new government targets for reductions of carbon emissions in relation to reducing further climate change effects. It is not within scope of this study to consider how The slight increase in winter wetness and predicted soil moisture content is likely to cause an increase in the number of cable breakages due to ground movements; this should be minimal so long as the correct laying of the cable has been carried out. With the increased soil moisture, there is a likely increase in the risk of instability of substations, although this should be limited, dependant on the particular ground conditions, which will be site specific. Detailed site investigations should be carried out to review conditions and susceptibility. The increase in soil moisture is not likely to lead to a wide reduction in cable lifespan due to the soil thermal resistivity because of the limited increase predicted. Flooding has been dealt with in greater detail within the flooding section. Electricity Demand Further demand will be placed on the electricity with an increase in population in the area and through the current boom in the housing market to meet demand. These new houses and especially their location could impact on the network, especially in areas where energy supply is running close to capacity. Wind Farms Infrastructure Susceptible to Subsidence Telecommunications Network In the upland areas, a slight increase is expected in mean winter wind speeds. While this increase in average wind speeds is likely to cause no additional damage an increase in extreme wind speeds may lead to the failure of structures, particularly vulnerable structures are those located on the crest of hills and those which are already heavily laden with communication equipment. It is often found that the older structures in this category, which are designed to older design codes, are approaching, or are at, their structural capacity. An increase in load of this nature may be sufficient to cause the structure to collapse. A recent failure of this nature occurred at a Northern Constabulary site, Maaruig in the Western Isles of Scotland where the design wind speed was exceeded. TV and Radio Transmitters and Centres
Description Water Supply Cow Green is the principal river regulating reservoir on the River Tees, and is used to support abstractions from the lower Tees. River regulation demand can normally be met from Cow Green releases but are augmented when necessary by regulation from Lune/Balder reservoirs or the Kielder transfer system. Water released from Cow Green is extracted further down the Tees for use in the Broken Scat WTW which then supplies Darlington, Stockton and Middlesbrough as well as the surrounding areas. Raw water is also abstracted at Broken Scar and transferred untreated to industrial customers in Teesside. The use of raw water by industrial customers in Teesside has been in decline in past years and Northumbrian Water expect this to continue until 2015 when they expect the usage to stabilise. River needs in the upper Tees are met by the compensation flow and the requirement to reserve water such that at least one third of the regulation releases at a given time come from Cow Green, as specified in the Tees Valley and Cleveland Water Act 1967. Cow Green also has a flood control role during winter months with levels being drawn down to provide flood storage. The Lune and Balder reservoirs consist of Selset and Grassholme on the River Lune and Balderhead, Blackton, Hury Subsiduray and Hury on the River Balder used conjunctively with an interconnecting tunnel. Water may be available for regulation releases in support of the River Tees when the reservoirs are in the surplus zone. There is currently apparatus in place that upon completion of the finishing works (such as inlet head works) would allow water to be transferred from the Tees into Yorkshire with a current abstraction rate of 150Ml/d, even though the pipeline has a capacity of 300Ml/d. This would mean that Kielder water could be supplied into North Yorkshire. Hartlepool Water supplies water to around 90,000 people with around 35Ml supplied to both households and business customers every day. All the drinking water comes from 18 boreholes sunk into the limestone aquifer. The water is blended at three treatment works prior to supply and it distributed via six service reservoirs and through approximately 545km of water mains. Dams Waste Water Typically foul/combined (wastewater) systems will comprise a network of drainage sewers, often combining areas of separate and combined drainage, eventually discharging to a Wastewater Treatment Works. Various ancillary structures will be included through the system to assist network performance, primarily pumping stations, combined sewer overflows (CSOs), and storage tanks. Tees Valley as a sub-region is located on the coast and is primarily urban with the large conurbations of Stockton, Darlington, Hartlepool and Middlesbrough and as a result a major proportion of the regions population situated within it. Due to the dense nature of the population this sub-regions waste water treatment is handled by a variety of different scale waste water treatment works the biggest of which are located near Darlington and at Marske and Bran Sands. Bran Sands is a recently built waste water treatment and sludge treatment centre located on the Tees estuary. Domestic waster and a significant proportion of industrial effluents are treated at the works. Sludge treated at the site is treated along with sludge from throughout the region which is delivered to the Regional Sludge Treatment Centre (RSTC) via ship. About half of all the sewage sludge produced in the North-east is treated at Bran Sands, approximately 1.5M tonnes. The sludge is dried and turned into pellets which can be used for fertiliser. The pellets from Bran Sands are used by Lafarge to fuel some of its cement kilns as a substitute for coal. The treated effluent from both Bran Sands and Marske works as well as the from Graythorp south of Hartlepool is discharged through long outfalls into the sea and estuarial reaches of the River Tees. As this area is predominantly urban the wastewater collection sewerage system is generally a combined system. They provide the drainage for foul flows, both industrial and domestic, and surface water runoff. Historically, urban sewer systems have been designed to carry the combined flows of household and industrial waste and rainwater. For the last 30 years, however, drainage systems have generally been developed to carry storm water flows separately, although combined drainage systems are still common in older areas, some dating back to Victorian times. This legacy means that the vast majority of the existing sewer network in the urban locations will comprise predominantly combined sewer systems. Combined sewer overflows (CSOs) provide an overflow release from the drainage system into local watercourses or adjacent surface water systems during times of high flows to protect local areas from flooding. There are over 1,400 CSOs within the Northumbrian Water region of which around 450 are in Tyne and Wear. Surface water drainage networks will typically drain smaller, more localised areas than the foul/combined networks to discharge into local watercourses. Networks will not usually include the additional ancillary structures used in the foul/combined systems, such as pumping stations or storage facilities, and are generally designed to transfer and discharge the storm surface runoff as swiftly as possible. Surface water systems will not usually include treatment devices, although silt traps and sediment/oil interceptors will often be included for car parks and large roads to retain contaminants and protect the receiving watercourse from runoff pollutants. Network Pumping Stations Electricity Distribution The majority of substations are located around Durham, Spennymoor and Bishop Auckland, with key sub-stations identified near Spennymoor and south of Hetton-le-Hole. These are typically located in order to feed electricity into the large towns and urban areas around the centre of the catchment. There is a further identified substation at Eastgate, towards the upper end of the Wear Valley, presumably situated to feed the villages and remote properties in the upper areas of the catchment. No information has been available for the remainder of the distribution system within the catchment, but it is likely to exist as lower voltage underground distribution cables. Underground cables are particularly more common in heavily urban areas. These will generally be thoroughly spread throughout the catchment to connect the surrounding urban areas to the various local substations. Electricity Demand Hartlepool Nuclear Power Station Wind Farms Infrastructure Susceptible to Subsidence There are essentially four gas mains operated by National Grid in the Tees Valley sub-region. The first runs through the district to the east of Darlington and heads towards Bishop Auckland. The second National Gris gas line runs further east than the last in a similar north/south direction, entering the sub-region east of Durham Tees Valley Airport and heads north to towards Sedgefield. The third line enters at a similar location as the last and runs alongside it before skirting Stockon’s northern boundary and into the north bank of the Tees estuary. The final gas line operated by National Gris starts from the north bank of the Tees estuary and runs north west passed Sedgefield. There is also an ethylene pipeline that runs through Northumberland, from Teesside to Grangemouth in Scotland. Within Tees Valley there are also large amounts of infrastructure to distribute water and collect waste water and surface water runoff. Broken Scar treatment waorks are located in the sub-region and is the main source of treated water supply in the sub-reghion as well as pumping raw water to the heavy industries of Teesside. This means that there is extensive pipework to not only distribute this water to the domestic and business users but also the large quantities required by heavy industry; this is in addition to sewerage networsk that collect waste water. Building foundations and underground infrastructure in addition to pipe work are threatened by subsidence and heave. Mechanisms for this are influenced by loading based consolidation and shrink/swell movement of soils as well as groundwater movement. Older assets and infrastructure are often more vulnerable, in part due to the natural ageing process but also if they are of non-standard design; they are less likely to be readily adapted. Furthermore, their initial design is less likely to have encompassed subsidence factors and there may be regulatory obstacles to any major alterations. Telecommunications Network TV and Radio Transmitters and Centres
Impacts Groundwater Surface Water Resource and Dams Tees Valley will see more water available for potable use as the reduction in the Industrial use of raw water in Teesside continues. Northumbrian water expect this reduction to continues and this will allow to offset any demand increase over the coming years, due for instance to new housing developments. Sub-surface infrastructure Higher temperatures and longer summers will lead to drier soils causing shrinkage of the soil. This could lead to increased subsidence of buildings and infrastructure. In 2003, the insurance industry reported claims of £400m and expect the annual average to be £600m by 2050. The rate of rise in groundwater levels could be changed by increased winter rainfall although the impacts of this change are uncertain as the average annual rainfall will decrease. However, potentially more significant is the impact of commercial and industrial water abstraction on groundwater level. Lowering groundwater levels have been reversed at locations that have seen a decline in industrial abstraction leading to a rapid rise in water levels, threatening tunnels and building foundations. Overall, this could lead to higher moisture differentials: shrinkage at the surface and saturation at depth placing stress on sub-surface infrastructure. Potable Water Treatment Rises in sea levels may mean the inland migration of the tidal extent passed current river abstraction points requiring decisions to be made regarding the future of the works, e.g. structures to prevent the inland migration of tidal water or movement of the intake or the works itself. Water is at Broken Scar which is the main treatment works for the Hartlepool, Stockton and Middlesbrough areas. Using the expected rises in sea level by the 2050s of around 200mm given by the latest Defra guidance, surface saline intrusion will not be a threat to this works as the tidal limit is set by the Tees Barrage which prevents movement further up the river. The temperature is projected to increase throughout all seasons especially during the summer months with 90th and 95th percentile temperatures increasing by three degrees. However, no major problems are expected with the processes within the treatment works as impacts were not experienced during the extended heatwave of July 2006. Surface Water and Waste Water Collection For surface water and local drainage, summer flooding will generally be more problematic than larger volume winter storms due to systems being less expansive and designed to pass flows quickly. Summer rainfall events are typically shorter but higher intensity storms, e.g. thunderstorms, which will quickly saturate or bypass the permeable areas leading to fast runoff flows and overwhelming local drainage systems. Surface water systems have been developed more recently, since the 1960’s, and these have therefore been designed under better, more informed planning guidance. Therefore typically the surface water systems do not currently have the same level of capacity problems exhibited by the foul/combined networks. Despite this however, with the frequency and magnitude of high intensity storms expected to increase surface runoff from these storms may overload and bypass the formal drainage systems which are designed to standards that do not consider climate change. Urban surface water drainage systems are currently designed to accommodate flows from a 1 in 30 year return period storm, although older systems are often overwhelmed by rainfall events much more frequently than this. Blockages within the system can exacerbate problems and commonly drainage grids can become obstructed by debris and leaves during intense events. In addition to impacts due to increased rainfall, future runoff volumes will increase due to an increased contributing area. New development ‘creep’ is known to be an ongoing problem for surface water drainage systems. It is becoming increasingly common for residents to build extensions and conservatories and look to pave over garden areas with hard-standing. Typically to keep areas well drained drainage grids are connected into the property’s surface water drain. It is also not uncommon for illegal misconnections into the foul sewer to be made which will obviously further exacerbate the problems in these systems. For new developments this issue has been found to increase impermeable areas connected into the local drainage by up to 20% in the first ten years. A recent report across the UK by the Royal Horticultural Society concluded that the North East region had the highest incidence of ‘creep’ with 43% of properties having paved over their front yard areas. For foul only sewerage systems it is unlikely that increases in rainfall will cause major problems as they the increases in flows from individual households should not vary much, and in fact they may reduce with a move to better water management including more water efficient lavatories and household appliances. However, sewerage systems may be at risk to insufficient capacity due to the increase in housing stock. The government is committed to increasing the number of homes in the UK including the north east to meet demand and currently developers commonly assume that the local drainage network will have capacity to accept these additional flows. This may not be a major problem for foul systems and may be a greater problem for surface water networks. Increase in winter rainfall will result in an increase in the height of the water table in many locations and this may impact on the flows that reach the water treatment works due to infiltration into the joints and any possible cracks or damage in the sewerage system. Waste Water Treatment Winter rainfall increases will cause more water to reach the treatment works through the surface water network especially in the urban areas where combined sewerage networks are prevalent. Waste water treatment works may be undersized for this increase in flows and water quality may be affected as a result. The increased seasonality of rainfall with less summer rainfall and more winter rainfall will result will result in problems during both seasons. Increases in temperature will have effects on the treatment processes currently used in the treatment works. Problems experienced during the July 2006 heatwave give an insight into future problems. Biological filters were found to have problems with the drying of the filter medium causing reduced quality of the treated effluent. Alternatively, activated sludge treatment was found to be more effective, although changes had to be made to accommodate the associated increase in activity due to the higher temperatures. Whilst the increase in mean temperatures is unlikely to cause serious issues, there is increased risk associated with dry, hot spells. Flooding has been dealt with in much greater detail within the flooding section but in addition the potential risk to Barn Sands WTW and RSTC is best identified here. Bran Sands is not currently identified as being at risk to tidal flooding and is outside the current Environment Agency flood zones, however, sea level rise of just over 200mm by the 250s and possible increases in surge events may mean that the works face the increasing risk of tidal flooding. Sea Outfalls
Network Pumping Stations Continued cyclic coastal flooding will cause corrosion. The infiltration of coastal flooding water into drainage sewers during flood events and the subsequent pumping of saline water will lead to corrosion of the pumps and mechanical equipment causing rusting or seizure and requiring increased maintenance. Also, as with fluvial flooding, flooding will produce increased flows through the system requiring the increased usage of pumps resulting in increased maintenance. For all pump stations and especially those inland where increases in rainfall are expected to be greatest, increased winter rainfall will result in increased flows within the sewer network through the direct runoff entering the system through highways and roof drainage, and infiltration into the pipe network due to higher ground saturation. The increased flows may result in pumps being undersized to pass the higher expected winter flows resulting in more frequent spills from emergency overflows (EOs) and maintenance being required on a more regular basis through increased use and therefore greater, more rapid wear. Electricity Distribution Wind speeds are projected to decrease slightly in Tees Valley; however, as mentioned previously in this report wind is notoriously hard to make climate projections for. So impacts to the electivity network associated with wind can be expected to reduce on average. Increases in rainfall are unlikely to affect the transmission lines; however any resulting flooding may potentially affect the network if fast flowing water were to undermine a tower structure. Flooding of the sub stations or booster stations may also be a problem if the flooded areas were to increase. In general, in terms of the transmission lines, flooding and rainfall are unlikely to have a negative impact on the system. Flooding has been dealt with in greater detail in the flooding section of the report. All seasons cab expect an increase in temperature and this increase includes severe high temperatures during summer. Transmission cables will be susceptible to sagging with extreme high temperatures. During hot temperatures cables are de-rated to maintain sag limits. Lines will usually be assigned two ratings, for summer and winter periods. With higher average temperatures the overhead conductors will remain loaded to its normal rating for a longer period and the conductor temperature, and hence sag, is likely to increase. Overhead lines are constructed to ensure that the degree of allowable sag does not become a safety hazard. As discussed, increasing temperatures will reduce the transmission capacity of the lines. With increasing energy demand for cooling purposes during extreme hot periods, with the increases in both average and extreme temperatures this is likely to mean a greater load on the UK grid network as a whole, which could lead to dips or breaks in the supply during extreme hot periods. The increased extreme temperatures will also have an adverse effect on the sag of transmission lines. The rating of existing lines is most likely to be affected by prolonged periods of hotter temperatures. There are obviously further issues with respect to energy generation aspects concerning new government targets for reductions of carbon emissions in relation to reducing further climate change effects. The slight increase in winter wetness and predicted soil moisture content is likely to cause an increase in the number of cable breakages due to ground movements; this should be minimal so long as the correct laying of the cable has been carried out. With the increased soil moisture, there is a likely increase in the risk of instability of substations, although this should be limited, dependant on the particular ground conditions, which will be site specific. Detailed site investigations should be carried out to review conditions and susceptibility. The increase in soil moisture is not likely to lead to a wide reduction in cable lifespan due to the soil thermal resistivity because of the limited increase predicted. Flooding has been dealt with in greater detail within the flooding section. Electricity Demand Further demand will be placed on the electricity with an increase in population in the area and through the current boom in the housing market to meet demand. These new houses and especially their location could impact on the network, especially in areas where energy supply is running close to capacity. Hartlepool Nuclear Power Station Flooding has been dealt with in much greater detail within the flooding section but in addition the potential risk to the power station will be outlined here. Hendon is at risk due to its location directly on the coast, protected by a rubble breakwater and is currently identified within the Environment Agency's Flood Zone 2. Increases in sea levels will mean that these sea defences will be at an increased risk of overtopping as not only will the freeboard of the defence reduce due to sea level rise but due to the increased depth of water at the toe of the defence will result in waves of greater magnitude impacting upon the structure, causing increased overtopping of the defence and an increased likelihood of damage. This increased overtopping, as mentioned earlier, may impact on the treatment processes of the works. Overtopping at the power station may not be an issue to its location within the Tees estuary. Wind Farms Infrastructure Susceptible to Subsidence Telecommunications Network In the upland areas, a slight increase is expected in mean winter wind speeds. While this increase in average wind speeds is likely to cause no additional damage an increase in extreme wind speeds may lead to the failure of structures, particularly vulnerable structures are those located on the crest of hills and those which are already heavily laden with communication equipment. It is often found that the older structures in this category, which are designed to older design codes, are approaching, or are at, their structural capacity. An increase in load of this nature may be sufficient to cause the structure to collapse. A recent failure of this nature occurred at a Northern Constabulary site, Maaruig in the Western Isles of Scotland where the design wind speed was exceeded. TV and Radio Transmitters and Centres
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