The Chalfonts and Amersham
2 - Overview
There are concerns that conclusions are reached based on hydrological surveys having been carried out yet there is no evidence that any such surveys have taken place. Monitoring of water flow and pollution is listed as a mitigation measure before any necessary remedial action. This is not mitigation as the damage would have been done and not avoided. It must be remembered that this could have a dramatic effect on the public water supply as well as the River Misbourne and Shardeloes Lake.
Chalfont St Peter vent shaft
2.2.7 describes the arrangements for emergency access and egress to and from the tunnel at the Chalfont St Peter vent shaft. Similar facilities are discussed at the other vent shafts along the route. However no mention is made anywhere in the Environmental Statement about the cost to the emergency services of providing and maintaining the equipment and training needed for such specialised rescue services. These costs and needs should be assessed for the entire HS2 project and included in the cost estimates.
Chalfont St Giles vent shaft satellite compound
2.3.34 states that there will be permanent widening of Bottom House Farm Lane whereas 2.3.38 says the Lane will be closed temporarily and local access maintained by a temporary traffic route if needed (our italics). 2.3.37 however states that no road realignment is required in the Lane. These statements are confusing and seemingly contradictory. When would the need for a temporary traffic route be decided ? This is vital for the residents of Bottom House Farm Lane as well as the business users and must be included in the ES.
2.3.39 concerns the installation of four new utilities in the area of the Chalfont St Giles vent shaft compound. No mention is made of the need to strengthen the existing bridge over the River Misbourne in Bottom House Farm Lane. In view of the increased amount of traffic and heavy vehicles that will be using this lane during the construction has such a measure been considered?
Operation of proposed scheme
2.4.7 says that during the night-time period (midnight to 5am) maintenance staff will regularly access the tunnels via the vent shafts to carry out inspections and maintenance. The work will include grinding and milling of rails and, periodically, "heavy" maintenance. This will inevitably generate noise - sometimes loud and consistent - and an element of light pollution which has the potential to seriously disturb residents living within the immediate area. There is no mention of measures proposed to combat this pollution. No mention is made of whether or not the vent shafts will be illuminated permanently.
2.5.4 points out that concerns at the Community Forums included that of noise from the vent shafts and the preference for their design to be sensitive to local settings. The ES makes
no effort to address these concerns. It makes no mention of whether or not headhouses could be sited partially or completely below ground.
2.5.4 also refers to the concerns at the Community Forums over vibration impacts during tunnelling and when the service is operational with particular reference to Amersham Hospital, the equine centre, and the Chalfont St Peter Epilepsy Centre. The ES makes no effort to address these specific concerns.
2.5.4 refers to concerns at the Community Forums over traffic impacts from construction, given existing traffic congestion levels and road realignments and the fact there these could deter visitors and affect the local economy. These concerns remain. The ES makes light of these concerns and makes no effort to address them satisfactorily.
2.5.4 notes concerns at the Community Forums that the Metropolitan Line and Chiltern Rail lines would be affected during construction of the route, and road realignments could cut off access routes between Chesham and surrounding villages. No reassurances to meet these concerns are included in the ES and these concerns remain. These issues serve to confirm the views of many people in the area that the Community Forums were a sham, designed to allow local people to express their views and concerns but with no real intention of paying heed to these view or taking action to address them.
3 - Agriculture, forestry and soils – permanent effects
3.4.20 says that following the construction period there will be a permanent loss of six hectares of Best and Most Versatile (BMV) land, which is assessed as an impact of high magnitude. This is unacceptable in an area where BMV quality land is already at a premium.
3.4.21 concludes that the amount of forestry lost in this CFA area is "not significant" because "the proportion of forest cover as a land use in the study area is greater than the average national land use forest cover". This is a subjective view, to be expected from the proponents of the development. It fails to take into account that the area is AONB and, as such, should be given special consideration and protection as laid down in the National Parks and Access to the Countryside Act. The loss of any forestry from such an area is not insignificant. Indeed, it is highly significant.
3.4.23 states that Ashwells Farm and Upper Bottom House Farm will lose a fifth of its land and suffer the demolition of its manége respectively. This is described as a "moderate" permanent adverse effect. Again this is a subjective assessment by a proponent of a proposed development. To the businesses concerned, the impact is far more severe than "moderate".
5 - Community
5.4.1 describes measures proposed to mitigate community effects during the construction period. It states that where "reasonably practicable" there will be maintenance of Public Rights of Way, for instance, or that where "practicable" there will be an avoidance of large goods vehicles operating adjacent to schools. Who will decide whether or not these measures are practicable? The use of such terms is completely meaningless and offers no
reassurance to local residents and parents. Firmer measures must be imposed before Parliament considers the Second Reading.
5.4.9 says the disruption due to nearby construction and increased traffic will have a "minor adverse effect" for "users" of the Chalfont Valley Equestrian Centre (disregarding the "major adverse effect" on the business because of the loss of its horse-exercising area, see below). This assessment fails to take into account the effect on the horses using the stables at the centre. The owner confirms that horses are susceptible to noise and disturbance. No recommendations are made to protect the business from the effects of noise and disturbance.
5.4.11 admits that the loss of the manége (exercise area for horses) will threaten the future viability of the Chalfont Valley Equestrian Centre, and further admits (5.4.13) that alternative centres nearby are not directly comparable. No attempt has been made to accommodate the manége within the Proposed Scheme.
6 - Cultural heritage
CFA 8 has a particularly high number of important heritage assets that will be affected by HS2 to varying degrees. Their presence in the area, and the magnificence of their setting, are important aspects in generating visitors and income to the area. Their existence contributed to the designation of AONB status to the area.
6.3.3 and 6.3.4 lists the following heritage assets within the ZTV (zones of theoretical visibility)
- Four grade I listed building of high value
- Twelve Grade II* listed buildings of high value
- 239 grade II buildings of moderate value of moderate value
- Five conservation areas of moderate value and one of high value
- One grade II registered park and garden of moderate value
- 21 areas of ancient woodland of high value
According to 6.3.19 The Domesday Book contains entries for Amersham, Chalfont St Giles and Chalfont St Peter and 6.3.20 tells of evidence for medieval (AD 1066 to AD 1540) settlement is most likely to be found in proximity to the historic cores of the three settlements of Amersham (a medieval planned town), Chalfont St Giles and Chalfont St Peter.
6.3.21 mentions that medieval manorial sites have been identified at Shardeloes (CHA067) and The Vache (CHA025). Farmsteads with potential medieval origins have also been recognised at Ashwell’s Farm (CHA017), Gellibrands (CHA007), Bowstridge Farm (CHA011), Coldharbour Farm (CHA0044), Woodrow Farm (CHA052) and probably at Lower Bottom Farm (CHA031). Some of these may also represent former manorial sites.
The Chalfonts and Amersham area is rich with assets of historical significance. The construction of HS2 and its eventual permanent placement will have an impact on these supposedly protected properties and treasured area which the ES does little to quantify. In Volume 1, (9.1) HS2 asserts that its approach to mitigation in priority order is to Avoid; Reduce; Abate; Repair and Compensate. Without full assessments on these areas, it is not possible to assess how the impact could be reduced, abated, repaired or compensated. Thus, the only practical solution is to avoid the area altogether.
7 - Ecology
2.1.5 Figure 8 fails to show Shardeloes Lake.
7.2.3 states that: It was not possible to access all of the land areas where general habitat surveys (Phase 1 habitat survey) were proposed. Locations with the potential to support key ecological receptors where access could not be gained for survey include the River Misbourne upstream of Shardeloes Lake.
7.3.5 states that: Four Local Wildlife Sites (LWS) and a single Biological Notification Site (BNS) are relevant to the assessment in this area including : Shardeloes Lake LWS (15.4ha) – is designated for standing open water and wetland birds. Between 2003 and 2011, the site supported a diverse assemblage of wintering birds, including gadwall, green sandpiper, shoveler, snipe, teal, whooper swan and wigeon.
The Chiltern tunnel will pass under the River Misbourne in two places, one at Chalfont St Giles and one upstream of Shardeloes Lake where field surveys recorded a natural channel with marshy margins and wet woodland. Owing to its size, geomorphological characteristics and the rarity and distinctive assemblages of chalk stream species, the River Misbourne is of regional value.
These statements contain contradictions. 7.2.3 states that it was not possible to access all of the land areas including upstream of Shardeloes Lake yet 7.3.5 states that: … upstream of Shardeloes Lake where field surveys recorded a natural channel with marshy margins and wet woodland. There is no evidence surveys have been undertaken yet 7.3.5 suggests they have. Which is correct?
7.3.20 Table 8: Records brown trout present but there is no mention of rainbow trout. The River Misbourne is one of only three rivers where they breed in the wild and so has national value. As the tunnel passes 20 metres below Shardeloes Lake, there is a danger that it would not survive as it sits on a low porous and permeable formation and disturbance of the structure as a groundwater pathway would impact on the lakes existence.
Figure 2 on page 8 fails to show Shardeloes Lake.
7.4.6 states that: There is the potential for ground settlement and loss of flow from the river to the chalk aquifer due to possible fractures in the chalk, however, the risk of this is low and no likely significant water effects have been identified. Therefore any indirect impacts on ecology are unlikely.
In the absence of hydrological surveys this is an unjustified assumption. The River Misbourne is one of the few precious Chalk Streams in the Chilterns. These are an internationally scarce and protected habitat and it’s loss would have a massive ecological impact.
8 - Land Quality
8.4.4 states that contaminated soils will be treated as necessary to remove or rendered inactive "wherever reasonably practicable" . This means that wherever it is not deemed to be "reasonably practicable" contaminated soils will be left exposed and accessible. This is not acceptable.
9 - Landscape and visual assessment
The Misbourne Upper South Landscape Character Area (LCA) and the Penn South LCA (9.3.6 and 9.3.7) are both within the Chilterns AONB and, as the ES acknowledges, are highly
sensitive to change. The conclusions (9.4.17 and 9.4.19) that the proposals constitute a "moderate adverse effect" is highly subjective and greatly disputed.
Natural England, the government's advisor on the natural environment, describes Areas of Outstanding Natural Beauty as areas of "high scenic quality (with) statutory protection…to conserve and enhance the natural beauty of its landscape."
Natural England's website further declares :"AONBs are designated solely (our italics) for their landscape qualities, for the purpose of conserving and enhancing their natural beauty, which includes landform and geology, plants and animals, landscape features and the rich history of human settlement over the centuries,
"They are designated under the provisions of the 1949 National Parks and Access to the Countryside Act, in order to secure their permanent (our italics) protection against development that would damage their special qualities, thus conserving a number of the finest landscapes in England for the nation's benefit."
The construction of a tunnel through these areas is, of course, a considerable mitigation. However, the permanent intrusions into these landscapes do not conserve or enhance their natural beauty. Indeed they are ugly scars that will considerably detract from the natural beauty. They include:
- A vent shaft headhouse and auto-transfomer station at Chalfont St Giles.
- A vent shaft headhouse at Bottom House Farm Lane
- A vent shaft headhouse at Amersham and
- A vent shaft a auto-transfomer station at Little Missenden in CFA 9, but clearly visible from CFA 8.
These headhouses and shafts will have associated access roads, security fencing and lighting, all of which will intrude on the landscape scene.
During construction, large cranes will be visible and the "increase in construction plant and associated traffic levels will reduce tranquility within the LCA" (9.4.18).
9.4.16 notes that "cranes and temporary stockpiles on adjacent fields will introduce prominent new features within the rural landscape" and adds "the addition of prominent new features associated with construction works will bring about a noticeable change in landscape character…"
9.5.2 lists the avoidance and mitigation measures proposed over the 60 years from the year of completion. It talks of screening and fresh planting; of new earthworks and of integrating land drainage areas into the landscape, even though balancing ponds are not a natural feature of the Chilterns landscape. 9.5.1 covers landscaped perimeters to the vent shafts.
These sort of landscape measures are run of the mill, the "bog-standard" sort of landscaping you would expect to find in any urban or semi-urban development.
Neither in tone nor wording does the ES take into consideration the unique and historic factors that make the Chilterns AONB so distinctive.
The responsibility of Government in its approach to ANOBs is quite clear in the legislation. It must ensure that permanent protection is in place to against development that damages its special qualities. If it really is necessary to deface the Chilterns with this project, a detailed and specific plan - agreed with the AONB authorities and interested parties - should be in place before any construction begins.
10 - Socio-Economic
There is growing concern about the impact construction of the Proposed Scheme will have on the local economy and its ability to recover once the prolonged construction phase is complete. It must be borne in mind that, when eventually in service, HS2 will be of no benefit to the local community as the nearest accessible station will be the London terminus at Euston. Most people travelling to Birmingham now do so by road but there are already two excellent rail links via the West Coast Main Line via Watford Junction and the Chiltern Main Line via High Wycombe.
There is also concern that the present level of service on these lines would not be sustainable and that some services would be lost. In any case the number of platforms at Euston will be reduced from 18 to 13 meaning that existing services will have to be reduced significantly regardless of whether or not excising levels of service are sustainable.
The communities of Chalfont St. Peter, Chalfont St. Giles, Little Chalfont and Amersham, both the old market town and the newer town of Amersham on the Hill, are well served by local shops and businesses. Traders also rely on custom from further afield and there can be no doubt that the A413, the main route through the area, will suffer from increased congestion. The result of this could well be that people will avoid the area altogether and take their business elsewhere to an area not blighted by HS2. The concern is that this will have an effect on the longer term viability of these businesses to the detriment of the local community.
The likelihood of congestion is also of concern to residents using Amersham Hospital which is in close proximity to the Amersham vent shaft as well as other medical facilities both locally and at Wycombe and Stoke Mandeville hospitals.
The Chilterns Crematorium covers a large part of South Buckinghamshire and is close to the Amersham vent shaft construction compound. It would be affected by traffic travelling to and from the numerous compounds using the A413. The congestion and possible delays would be particularly distressing to mourners at at time of stress.
The Amersham bypass will be badly affected but for most journeys through the area is difficult to avoid. The area has a wide range of diverse small to medium sized manufacturing businesses with specialist, highly skilled staff. It is also home to GE Healthcare which is one of the largest employers in the area.
There are many schools in the area and because of the choices within the educational system, many children travel some distance to their school of choice. A large proportion of this traffic uses the badly affected A413.
11 - Sound, noise and vibration
11.3.12 states that vibration from Tunnel Boring Machines present no risk of any building damage. In other parts of the Society's response we refer to the uncertainties of tunnelling
through a chalk aquifer and of the great age of some of the buildings likely to be impacted by HS2, particularly in Chalfont St Giles. For understandable reasons a number of property
owners did not permit HS2 engineers to take baseline sound level monitoring at their premises (11.3.5). In view of these limitations, how certain can HS2 be that vibrations will not present any risk and what further measures can to taken to reassure a sceptical public? There is 16m of rubble chalk below Chalfont St Giles leaving only 4m of solid chalk above the top of the tunnel. Rubble chalk has a high risk of settlement and an alternative alignment should be considered.
12 - Traffic and transport
The main impact on the communities during construction of the Proposed Scheme within this area will come from the increased levels of traffic it will put onto local roads.
The Chalfont St Peter vent shaft compound
This will be accessed via Chesham Lane, Denham Lane and Joiners Lane on to the A413 then the A40 and M40. These are minor local roads and according to Tables 7-24/25 (Volume 5 Appendix Transport and Traffic Assessment) had levels of traffic ranging from 72 to 275 vehicles during the AM peak with just one HGV travelling southbound along Chesham Lane/Denham Lane. Figures for the evening peak along the same roads are between 120 and 409 vehicles with just two HGVs westbound on Joiners Lane and just one eastbound and northbound along Chesham Lane/Denham Lane. Construction traffic will add up to 100 cars/LGVs to these figures. For northbound traffic on Chesham Lane/Denham Lane this represents an increase in the region of 75% during the busy period of construction. There will also be between 10 and 20 HGV two way trips during this period. As only one HGV was recorded during the peak period, we can assume that this number of vehicles constitutes a huge increase in traffic and will have a major adverse impact on these roads and the effect will be very significant.
Chalfont St Giles Vent shaft compound
This will be accessed via Bottom House Farm Lane then on to the A413, A40 and M40 to the west and A413, A355, A40 and M40 from the east. Bottom House Farm Lane is a single track winding rural road used mainly by residents, commercial traffic associated with Upper Bottom House Farm and users of the riding stables. A maximum of two vehicles are shown Tables 7-24/25 (Volume 5 Appendix Transport and Traffic Assessment) during both AM and PM peak periods. During the busy period of construction up to 100 cars will use this route each morning and evening. There will also be up to 40 HGV two way trips (80 vehicle movements). As previously stated, it is not clear exactly what measures will be taken to accommodate this massive increase in traffic and to maintain access for residents and for existing traffic. This is a very serious shortcoming as far as the ES is concerned and causes serious concern.
Traffic from the east entering Bottom House Farm Lane and traffic travelling west leaving Bottom House Lane will all have to turn right across the busy A413. This increases the possibility of accidents especially during the peak periods.
No mention is made of the possible need to strengthen the bridge over the River Misbourne in order to support heavy construction traffic.
If Bottom House Farm Lane is widened and straightened permanently, there is likelihood that it would then become an alternative route for drivers seeking to avoid congestion on the
A413. This would change the traffic flows dramatically as well as having an impact on an otherwise tranquil setting. There is a potential for a permanent adverse effect that could be significant.
Amersham Vent shaft compound
This will be accessed via Whielden Lane then on to the A413, A355 A40 and M40. There will be up to 100 cars/LGVs entering and leaving the site each morning and evening and up to 100 HGV two way trips (200 movements) each day. All traffic (including HGVs) leaving the site will have to turn right across the very busy A404 which will lead to increased congestion and accident potential. There will be a temptation for drivers to seek an alternative route past Amersham Hospital and narrow local roads before joining the A413/A355 at the bottom of Gore Hill.
There will also be approximately 420 cars/LGVs per day (two way) and 100 HGVs per day (two way) from the adjoining CFAs 9/10 using the A413 and then the A355. In total, as a worst case scenario, there could be up to 520 extra cars/LGZs using the very busy and frequently congested A413 Amersham Bypass/A355 every morning and evening and up to 200 HGV two way trips each day during the busy period of construction. It goes without saying that this would have a massive impact on traffic flows along these roads causing delays and frustration for other users. These roads are also extensively used by local school traffic, including many buses and coaches. This extends the busy traffic periods considerably.
There would be serious implications for ambulances travelling to both to Stoke Mandeville Hospital which provides A&E facilities for the whole of South Buckinghamshire. Also affected would be the Chilterns Crematorium whose access is a short distance from where traffic would be emerging from Whielden Lane.
The ES makes takes no account of the implications of the increased traffic on the impact further afield. The A355, which is the access route listed for many of the compounds in CFAs 8/9/10, joins the A40 in Beaconsfield at a mini-roundabout which suffers from frequent congestion. At certain times during construction, there could be up to 720 cars/LGVs using this route every morning and evening along with 260 HGVs (two way trips) at other times. Two further roundabouts would have to be negotiated by this traffic before reaching the M40.
It can be assumed that the very high level of extra traffic on this route in conjunction with the regular congestion on the M25 and M40 would lead to many drivers seeking alternative routes. The most obvious of these is via the A404 from the M25 to Little Chalfont and on to the A413 at Amersham or via Cokes Lane/Nightingales Lane to the A413 in Chalfont St Giles. This would lead to extra congestion through the village which would have an impact on all users of this road but especially commuters and those using the local schools.
Along the A404, between Junction 18 of the M25 and its junction with the A413 in Amersham, there are four schools and one college (two of these with a thousand pupils) whose only access is via the A404 and another four nearby schools for whom it is the main access. This means that traffic from these schools, combined with the many other schools in the area, leads to a build-up of traffic towards the evening peak which starts at 15.00 and not 17.00 as the report suggests. The morning peak starts around 7.00 and includes this school traffic and so the impact would be even more acute at these times.
There is also a low bridge in the village where HGVs regularly get stuck causing widespread
congestion. Presumably some of the HGV construction traffic would exceed the height limit and could have the same problem. Little Chalfont was not included in the traffic assessment when quite clearly it should have been.
The imposition of such a vast amount of additional construction traffic outlined above, in some cases over several years will place an unaceptable load on the local road network. In our view:
- It will mean increased congestion on the major and local roads over a wide area and also affect the M25 and the M40 motorways.
- It will lead to longer journeys for emergency vehicles, public transport and school transport as well as private cars.
- It will lead to greater risks, particularly involving vehicles travelling to Heathrow to catch flights, and it will increase air pollution in the immediate area.
- It will mean increased delays for business traffic and those travelling to work, bringing incalculable costs to those affected
In addition, the assumption (12.4.5) that HS2 workers starting work at 08.00 and leaving at 18.00 and therefor "arriving before the morning peak hour and leaving after the evening peak hour" is woefully inaccurate. The morning peak period in this part of South Bucks runs from 07.30 until well after 09.00 and the evening peak starts to build up from 15.00 and last until 18.30 as any local motorist will confirm.
13 - Water resources and flood risk assessment
The key environment feature at risk in this section of the proposed route is the River Misbourne, which is noted in the Environmental Statement (CF8; 7.3.12) as being “of regional value”. This chalk stream has historically shown an interrupted flow pattern as a result of the underlying complex geology and abstraction at public water sources.
Logic would normally suggest that tunnels are not constructed under valleys, which are normally selected as surface transport corridors (e.g. Bulbourne valley - A41, West Coast Mainline & Grand Union Canal). In order to alleviate the visual impact of HS2 it is proposed to enclose it in a tunnel under the Misbourne valley which, by compassion with the Bulbourne corridor example, is a totally illogical concept.
A major problem in this sector of the HS2 route is the initial crossing point through the Misbourne valley immediately to the north of Chalfont St. Giles, below Pheasant Hill. At this location the tunnel will pass below the area most adversely affected by the original route of the (pre-glacial) proto-Thames river. As a consequence of pre-glacial river action, the chalk in
this area is extremely weathered with clay filled pipes and swallow holes deeply eroded into the chalk surface.
The chalk is clearly described in an existing nearby (Grid reference TQ001911) borehole log as “firm brownish white putty chalk with some gravel size pieces of moderately weak white chalk…(weathered Upper Chalk)” to a depth of 16 metres below surface. Given that the depth of the tunnel crown in this area is within 22 metres of the surface then less than 6 metres of normal chalk exists above the tunnel in several places. The potential for ground surface collapse at such locations is recorded in the Environmental Statement (Appendix WR-002-008, section 4.2.10) where it states that “Some voids may be present in the vicinity of Chalfont St Giles within disaggregated weathered Chalk, which can have a thickness of up to 16m as indicated by Morigi et al. (2005), but it is not possible to predict their presence without detailed ground investigations.”
The placement of the Chiltern tunnel beneath the Misbourne valley at this location is highly contentious and needs to be seriously reconsidered. Detailed ground investigation in this area must be carried out before any construction work is considered.
It is clearly recorded in the Environmental Statement (Appendix WR-002-008, Table 7) that “Tunnel construction under the River Misbourne will result in settlement with a low risk of increased vertical permeability in base of River Misbourne potentially causing increased loss in flow.” Given the natural variability in the flow of the River Misbourne it seems inevitable that any “increased loss in flow” will result in the disappearance of the river from ground level. It is also asserted here that the assessment of a “low risk of increased vertical permeability” is a gross underestimate, if not disingenuous, given the known disaggregation of the chalk immediately below surface in the part of the river valley.
The total length of the Chiltern Tunnel is below groundwater level (Appendix WR-002-008, Figure 3). It is recorded (Appendix WR-002-008, Table 7) that groundwater abstraction from licensed water sources within 1 km of the tunnel route totals in excess of 68.25 million cubic metres of water per year, equivalent to over 61.5 thousand cubic metres per day. It has been calculated that the residents of the Misbourne valley above Gerrards Cross need approximately 30,000m3 per day of water to satisfy current requirements. Between them Thames Water and Affinity Water are licensed to abstract a maximum of 14,000m3 per day. So already half of the basic water needs of the area have to be derived from outside the Misbourne catchment area. Any damage to the Misbourne aquifer during and after tunnelling will impact directly and immediately onto the regional water supply, which is already under resourced.
The tunnel route passes less than 30 metres below Shardeloes Lake (Appendix WR-002-008, Figure 3). It is difficult to envisage the lake surviving under these circumstances. The lake sits on the New Pit chalk Formation which is relatively clay rich and therefore of low porosity and permeability; however this chalk formation is known regionally to be crossed by numerous sub-vertical and sub-horizontal joints and fractures, meaning that it will still act as a ground water pathway. Disturbance of such structure both during and after tunnel construction must impact on the lakes existence.
13.4.39 states that: When the River Misbourne has water in it (it is frequently dry) the river water is not always in hydraulic connectivity with groundwater in the underlying chalk.
The river is in hydraulic connectivity with the groundwater in the underlying chalk and has flowed continuously for 20 years in the vitsl middle reaches between Little Missenden and Amersham.
13.3.24 states that vertical groundwater flow is generally restricted by a layer of weathered Chalk at the surface of the Chalk and some thin layers of finer material in the superficial deposits. However, the lower permeability layers are not consistent across the valley either in thickness or presence. Therefore in places the Chalk aquifer is vulnerable to contamination from the gravels and lakes due to the potential hydraulic continuity that is present.
Shardeloes Lake, which is upstream of Amersham, is likely to depend on inflows from further upstream during dry periods rather than groundwater contributions through the base of the lake. Information available indicates that groundwater levels will often be at or above the base of Shardeloes Lake, particularly following periods of rainfall and high groundwater levels. The recorded water levels in the area also suggest groundwater levels are rising in response to a reduction in licensed groundwater abstraction. This is expected to have changed the surface water–groundwater interaction in recent years. This is a further example of where HS2 Ltd have identified deficiencies in their understanding and then failed to set out a method to improve or resolve said issues.
13.4.16 refers to monitoring river flow where viable to monitor prompt decision making in relation to further mitigation following reduction in river flow however this mitigation is likely to be useless as it would be too late to prevent the loss of habitat, especially if the lake dries out.
13.4.21 refers to proposed monitoring to determine the potential impact on Public Water Supplies and to define mitigation and further mitigation. This statement is meaningless as once damage has been done, there would be no mitigation available to restore the loss of surface water and its inhabitants
13.4.32 states that: if fissures connect the working area of the Proposed Scheme directly to high value receptors such as PWS (even where these are in the neighbouring CFA7), the impact of even low levels of turbidity could cause the closure of a source due to the high quality required to be met for potable use.
The use of the indefinite term if is not acceptable in connection with a potential major impact leading to a significant effect.
13.4.38 states that: where the tunnels pass under the River Misbourne there could be the potential for ground settlement to occur during or soon after construction. Ground settlement could locally increase vertical permeability by activating fractures in the bed of the river.
This presents a real risk which we believe will persist.
13.4.41 states that: ….. overall there will be a relatively small stretch of the total river length where there is a low risk that settlement could affect ground conditions and therefore surface water in the River Misbourne.
We believe that the risks to the Misbourne are understated and that any level of risk is unacceptable.
13.4.49 states that: in respect of PWS, HS2 Ltd will agree a management strategy with the Environment Agency in consultation with Affinity Water that will cover timing of any physical mitigation, the scale and nature of monitoring and the thresholds at which actions are invoked (in terms of both quality and flow), the nature of other intervention measures and the responsibilities for ensuring agreed actions occur.
At this late stage it is unacceptable that a management strategy has still to be agreed.
13.4.52 states that: until a management strategy is agreed with the Environment Agency in consultation with Affinity Water, as described above, there is the potential for a likely significant temporary residual effect on the Affinity Water groundwater abstractions.What more can be said?