Land West of 75 Town Furze Objection
The developer seeks to build two four-bedroom houses directly above the South Fen Unit of the Lye Valley SSSI (purple) as below:
The Development Site
How To Object
21/02639/FUL | Erection of 2 x 4 bed dwellinghouses (Use Class C3). Provision of amenity space, car parking and bin stores. Associated landscaping, boundary treatments and ancillary works. | Land West Of 75 Town Furze Oxford OX3 7EW
REVISED DEADLINE IS DECEMBER 3th 2021
Friends of Lye Valley
Please Join Friends Of Lye Valley (FOLV) to help save this precious place:
Lye Valley SSSI – An Introduction
The Lye Valley and the associated SSSI (North and South Fen units) survival are dependent on rainwater infiltrating into the ground, becoming calcareous via flowing in aquifers and emerging at a springline ABOVE the sloping fens.
Groundwater will be lost via rainwater redirection to stormwater drains, evaporation from hard surfaces or blockage of underground flows via foundations.
Thames Water stormwater drains running along the Lye Valley also scour the Brook causing water to flow under the fen. The brook does not supply water directly to the fen, but helps to maintain hydrostatic pressure and slow groundwater loss.
The fen is on life support and any further ground water loss is unacceptable.
NO LOSS AT ALL of ground water in the ground water or surface water catchments can be acceptable. Every new development is only an incremental loss but cumulatively new hard surface and/or attachments to Thames Water drainage has led to approximately 60% loss of natural ground water to the Lye SSSI due to redirection of flows from infiltration into the ground to Thames Water drainage.
Important areas outside the SSSI are also worthy of protection. (Warneford Meadow, Lye Valley LNR and the Boundary Brook Wildlife Corridor and restorable former fen areas)
- The North and South Fens are the only surviving patches of a once extant fen under high risk of any negative change
- This development is at the focal point of the South Fen groundwater catchment the smallest and most sensitive fen in the Lye Valley. This will have an adverse effect on ALL surface and groundwater flows of the South Fen SSSI.
- It will fundamentally alter groundwater flows focussing all on one specific soakaway, changing the chemistry and flows. This cannot be mitigated therefore it is contrary to Policy RE4
- The grant of planning permission is contingent on a proven SUDS/Soakaway design this CAN NOT be a planning condition only as confirmed by the Appeal Inspector of the last application
- Any SUDS/Soakaway is unacceptable, as per Lamberth below
- Pad foundations will be very deep, crushing the aquifers, stopping groundwater flows alternatively pile foundations will piece the impermeable clay base of the aquifers leading to loss of water to the fen
- Building on the Green/Blue Infrastructure Network on a greenfield site will result in harm (Policy G1) it NOT residential garden (G6) and represents a change of land use
- It will remove an ecological corridor, in contradicting to the stated government policy of expanding Natural Recovery Networks with land to the immediate west and east of the SSSI and Site already allocated
- Block recovery of Natural England defined Priority Deciduous Woodland habitat which appears to have been clear-felled in 2009 – granting of permission would reward this
- NPPF policies refer to both habitat and species and their restoration and recovery, this development will destroy both, on the Site and at the Fen
- Will transform part of wildlife and flora habitat to domestic gardens which already are identified as negatively impacting on the Fen
- Fencing will either block wildlife/pollen movement, or alternatively provide an attack vector for pets in the development if left porous
- Surfacewater drainage rates into the sewers will increase leading to a higher probability of foulwater release in the fen (drain runs across), as sewers overflow due to misconnects or order mixed systems
- Excess surface drainage can cause flooding downstream at Cowley Marsh/Iffley or lead to erosion of the fen in flood events, now probable with climate change
- Once implemented, residents will acquire permitted development rights to further damage the SSSI and site (sheds, hard surfaces, landscaping) or create pollution
- Will create a precedent for future developments as per the Inspector’s report
- The Site is an important local amenity as evinced by scores of responses the extensive comments by the previous Inspector to this and prior refused applications
- It makes no contribution to Social Housing
- The Headington/Cowley Area is one of the most green space deprived areas in Oxford
Lye Valley Catchments Overview
The Lye Valley SSSI consists of two Units, the North (Thick Green) and South Fen (Purple). The Thames Water stormwater catchment is marked Orange
The Groundwater catchments described below are marked Green, the Surface Water catchments Blue.
An interactive map of all Lye Valley and other catchments be seen below, click on right square for full screen:
A Set of Natural Ground Water Catchments (Green)
The maps above show the North and South Units of the SSSI and Boundary Brook groundwater catchments in green.
The following shows the groundwater flows running generally NE to SW note the South Fen:
Groundwater catchments are small, with the South Fen the smallest, as is the fen itself.
Rainwater in these catchments that does not enter the storm water drainage system will infiltrate into the ground, flowing according to strata inclination (NE-SW), become calcareous, and nourish the fen by emerging at the springline ABOVE the fens.
Issues are as per Thames Water storm water catchment below, but ADDITIONALLY deprive the Lye Fen of vital groundwater, as all water entering the storm drains is lost to groundwater infiltration. This is the most sensitive area where the most stringent measures must be taken.
Groundwater Catchments: North Fen SSSI Unit, South Fen SSSI Unit and Boundary Brook.
A Set of Surface Water Catchments (Blue)
Risks to the Lye Valley are as per Groundwater Catchment, but flows are dictated mainly by surface gradient.
Water from rooves, driveways, roads and hard surfaces flows into the Thames Water or sewers (two large, one smaller) and then in the Lye Brook at the head of the Lye Valley, shown in Orange.
Additional connections, paved areas and removal of greenery all increase storm flows to the Lye drains and downstream (Cowley/Iffley or Barton Park/Bayswater Brook/Oxford)
The Lye Brook has suffered severe erosion in places due to the irregular and often heavy water discharge from the surrounding urban areas….Any further urban development around the reserve [Lye Valley] would produce increased water run-off discharging through the Lye Brook and exacerbate the already serious erosional problems. (BBOWT PII 1986, 24)
Several sewage pipes cross the valley. If any were to rupture their discharge could seriously pollute the streams.
The South Fen stormwater catchment does not discharge into head of the Lye Valley but still presents the same risk downstream.
The downstream flood risk is further detailed in Appendix A.
Surface Water Catchments: Lye Valley and Boundary Brook (Simplified)
An Artificial Thames Water Storm Water Catchment (Orange)
See Appendix B – not relevant to this application.
The South Fen Catchment
The green line around the SSSI South Fen SSSI (Purple) is the groundwater catchment area for the fen. The brown line is the golf course for alignment of source maps only.
The above map shows the Development Site (Red) with T Pin and white label with ground flows marked as red arrows with black heads. (Lamberth 2007, Fig 4) [EN2]
The above map shows the Development Site (Red) with T Pin and white label with ground flows marked as red arrows with black heads. (Lamberth 2007, Fig 4) [EN2]
Groundwater flows DO NOT follow the surface contours but the underlying rock strata from NE to SW. In this case a western flow can be observed but crucially, almost all flows concentrate at the development site marked in Red with a T pin in the centre) which is directly above the South Fen SSSI unit (Purple).
Development here will affect ALL flows from the entire catchment as it is a focal point just above the South Fen.
Groundwater Quality and Flow (South SSSI)
Flows – Objection Summary
- The soakaway fundamentally alters the quality, quantity and flow direction of surface and groundwater this close to the fen
- Removal of much of the limestone on the site will reduce calcification
- Tolerance of fen flora to different pH values are entirely unknown
- The hydrology assessment and SUDS proposed are unworkable, but for this development, ANY SUDS or other mitigation strategy will be unable to where an assessment can demonstrate that there will be no adverse impact on the surface and ground water flow to the Lye Valley SSSI.
Flows – Overview
Hydrology and layout of the Site is shown below with Unit 2 as an example – PRIOR to development:
- A layer of soil (0.3m) allows rainwater to be become saturated with CO2 (either through or over)
- This dissolves more calcium carbonate from the limestone directly below
- Water arrives at the impermeable clay layer and flows down to the Tufa springs which emerge where the clay layer meets the surface which feed the fen immediately below
Diagram is to scale, except springs and fen are at 68m from the road, not as shown at 60m. The water table is at 77.6m at TP3 and will be sloping down slope. (as at Warren Meadow)
The soil and limestone layer are confirmed by the Hydrological Assessment, which indicates that calcification of the water commences immediately on contact. See [EN3 for details]
The developer’s diagrams considerably underestimate the slope.
The Lye Valley is supplied predominantly from water passing through calcareous, base rich Corallian beds. Spring and seepage lines originate from where rocks meet the Oxford Clay. The groundwater has a uniform pH of 7.6 over the fen area. . (BBOWT P1 1986, 70)
Impermeable clay forces groundwater to move laterally to appear as spring-lines on the sides and bottom of the valley. The perpetual seepage of groundwater and permanently water-logged conditions has resulted in peat formation in parts of the valley. (BBOWT P1 1986, 1.1.2)
Surface water plays an important part in tufa formation. Carbon dioxide is formed as a natural process in active soils where the decay of humic material and the effect of plant roots and biological activity generate CO2 from respiration. This CO2 saturates rainwater percolating through the soil. In turn this CO2 rich water dissolved more calcium carbonate from the aquifer. Therefore, it is vital that catchments in the vicinity of a tufa spring have an active soil horizon. Active soil horizons could be grassland, woodland or even an agricultural field but not hardstanding or a conventional SUDS system. Any man made system must have an indefinite lifetime. (Lamberth 2007, 20)
[*] Soil with growing plants, good humus content and aerated by root growth and activity of worms and other soil invertebrates
Site Post Development
Post development the following applies:
- ALL water that would have flowed through soil will now not gain CO2 from the soil as there is no contact at all – a loss of an area of approximately 24m*12m*0.3m.
- Passage through the limestone will be quicker and more concentrated, water may be lost entirely to the fen reducing calcium uptake
- Foundations, approx. 3-4m deep from ground level, will either pierce the clay layer, or compress the layers so that the water resistance will be impossible to overcome, leading to both loss of quality and quantity of water and blocking flows from the entire catchment.
Pile foundations must on no account be used, as these will block flows and piece the thin layers of impervious clay below, leading to groundwater not reaching the fen. [See EN3 for source data]
The Energy Statement (4.14) mentions recycled aggregates usage under the houses – these are essentially industrial waste and should be under no account be used due to contamination and unpredictable effects on both infiltration and groundwater flows. These are not marked on the plans above but in the worst case could extend from the floor level to the natural ground.
The site surface flows are shown above (prior to development). Flows are evenly spread either going directly to the fen or to a ditch to the east which in turn wets the fen via installed log dams.
Water will infiltrate into the ground, mostly evenly over the site, and become calcified as the calcium layer is directly below the top soil.
The yellow area of the development will be lost, and be directed only to a small soakaway as discussed above.
The Hydrological Assessment concentrates almost exclusively on the local and downstream flood risks, NOT on the far more important issue of the quality of groundwater to the fen. No analysis of groundwater flows or geology has been performed either for the quality, quantity or direction of the flows or the effects this development would have.
Only three pits were dug between 2 and 2.5m depth.
Therefore it is wholly inadequate as any basis for evaluating the effects on groundwater. In particular, no details of the proposed foundations are given.
Policy RE4 – Extract
The following applies to the surface and ground water catchments:
Surface and ground water flow and ground water recharge:
Planning permission will not be granted or development that would have an adverse impact on ground water flow.
The City Council will, where necessary, require effective preventative measures to be taken to ensure that the flow of ground water will not be obstructed. (Ref: RE4)
Within the surface and ground water catchment area for the Lye Valley SSSI development will only be permitted if it includes SuDS and where an assessment can demonstrate that there will be no adverse impact on the surface and ground water flow to the Lye Valley SSSI.
Policy – Lamberth Recommendations
The following applies to the groundwater catchment:
Ground water protection zones are not fully mitigated by the use of SUDS therefore development within these areas must be restricted or eliminated. (Lamberth 2007, 39)
Can The SUDS/Soakaway Design Be a Condition?
This very issue was considered by the Inspector (previous application) who concluded that a complete SUDS design and hydrological assessment for the effect on the fen acceptable to Natural England would be required …for the grant of planning permission
I conclude on the second main issue [Groundwater Impact] that there is insufficient information before me to properly assess the likely impact upon the SSSI. As this matter could not be addressed by way of any suitably worded planning conditions, I find that the proposal would be at odds with the objectives of CS policy CS12. (Appeal 21)
Put simply, it was too important an issue to be a mere Planning condition as it is fundamental to grant.
South Fen Fragility and Vulnerability
The groundwater catchment area is very small (approx. 20ha) almost all of which is heavily urbanised.
The Fen (0.53ha) is already below the minimum viable size, cut off from the other surviving fen in the North SSSI
The key points from the Natural England Assessment and OCC Management Plan (BBOWT 1986) quoted below are in summary:
- Exceptionally rare and fragile rare species habitat
- Substantial damage to the South Fen has already occurred by gardens to the west of the Lye Valley Road (the development location)
- Any adverse hydrological change either of quality or quantity of groundwater could result in severe damage or loss of fen
- Foulwater or mixed sewers could burst and destroy parts of the fen due to overloading
- The fen is at or below minimal viable size
Conclusion: ANY development this close to the fen will damage the water supply to the fen as there is no margin of error, the damage from domestic gardens alone is well documented
The alkaline fen habitat at Lye Valley is an exceptionally rare and fragile habitat. …, as well as protection of water supply to ensure the underlying peat remains waterlogged. There has been significant input of resources to protect this site …. An exceptional list of specialised plants has been confirmed as being present – many of these are extremely rare in Oxfordshire and some are at their southerly limit in the UK. Notable species present include [list]. This is a truly remarkable plant assemblage. The habitat is now also in very good condition to support specialised wetland invertebrates associated with alkaline mire. The area is very small and isolated in the landscape and remains extremely vulnerable to damage from a variety of pressures. In particular, it will be important to ensure that management input is maintained and water supply and water quality is protected. (Natural England Citation – Lye Valley SSSI – South Unit)
The damage already by 1986 by only gardens (on the western side of the Lye Valley Road and the Site on the eastern slope) was noted:
The development of gardens on the eastern slope of the valley in the 1950s [Lye Valley Road, Site], appears to have had widespread damaging effects on the fen flora. Partitioning of this area has resulted in damage not only by improvement of land in some gardens but also through its neglect in other, which has allowed the spread of the alder carr. (BBOWT PI 1986, 70)
If these fen areas are to survive it is important that the present hydrological stability continues. Lowering of the water table or pollution of the ground water supply could seriously damage the fen areas
At the southern end of the valley [ie South Fen] some areas of calcareous fen within private gardens [ie Lye Valley gardens and Site] extending onto the proposed reserve [now SSSI] have been destroyed by mowing and the planting of commercial grasses, hedgerows and trees. This has led to a serious loss of fen flora in places, with only a few survivors such as Juncus effusus.
Contrived ‘improvement’ of these gardens will result in further loss of habitat. (BBOWT PII 1986, 24-25, extracts)
The size of the calcareous fen community has decreased considerably in the last 50 years during which time some species of plant have become extinct.
The minimum size for a sustainable fen community may have been reached.
It is therefore paramount to maintain the fen areas at their present sizes and if possible increase them
Species richness is heavily dependent on the size of the site. Topographical, land-use and hydrological changes to the Lye Valley, mostly as a result of neighbouring urbanisation, have all combined to reduce the size of the calcareous fen area. .. there has been a marked decrease in species diversity, particularly since 1964. Between 1964 and 1978 23% of Bowen’s indicator species had disappeared, and between 1978 and 1985 a further 15%.
In order to ensure a high level of species diversity within the valley all the existing habitat types must be conserved. Of particular importance is the very species rich calcareous fen. This area must be maintained at least at its present size and preferably expanded.
Fenland habitats are very susceptible to disturbance due to the particular environmental conditions that form and maintain them.
(BBOWT PII 1986, 3-10 extracts)
In the annotated map below (BBOWT PII, Fig 13), the areas of active peat formation in 1986 are shown below (dark brown), with the past areas shown as brown stiped, indicates the severe damage done to the fen to 1986, which previously stretched unbroken from the current North Unit in the Lye Valley to the South Fen.
Much of the area to the immediate north of the Site (Red) marked as active peat formation, has now been lost or severely degraded: (Yellow)
Green Space – Policy
11 …. there is no dispute between the main parties that this is a greenfield site. (Appeal 11)
The Site is part of the Blue and Green Infrastructure Network:
Green and open spaces …. of the Green and Blue Infrastructure Network are protected for their social, environmental .. functions and are defined on the Policies Map.
G1 Planning permission will not be granted for development that would result in harm to the Green and Blue Infrastructure network, except where it is in accordance with policies G2- G8 .
The view from the Town Furze/Lye Valley junction is clearly of great importance to the community:
Any loss … other facilities that enable the enjoyment of the blue infrastructure network, must be replaced by a facility in another equally accessible and suitable location
Policy G6 – Residential Garden Land, which permits some development does NOT apply. The land is NOT a residential garden as per the Local Plan glossary definition as below:
Local Plan Glossary – Residential Garden Land
The development Site does NOT conform to the Local Plan Glossary definition of “Residential Garden Land”:
Outdoor land within the private or shared curtilage of a residential property or properties, which has been or is used primarily for relaxation, growing plants, drying clothes and other private domestic activities . This includes gardens, patios and terraces for houses, flats, houses in multiple occupation (HMOs), guest houses, residential care homes and any other building that was originally built as a house which has not been substantially altered .
Residential garden land includes all landscaped areas, whether turfed or planted, or otherwise, and all paths, domestic sheds, private driveways and small ancillary outbuildings . However it excludes large communal car parking areas and large communal storage or utility buildings
Further, such a change would represent a change of land use.
Even if this land were “residential garden land” under Policy G6 it would fail all conditions required – character and appearance, biodiversity and habitat creation and improvement.
Policy G2: Protection of biodiversity and geo-diversity
Development that results in a net loss of sites and species of ecological value will not be permitted .
Sites and species important for biodiversity and geodiversity will be protected. Planning permission will not be granted for any development that would have an adverse impact on sites of national or international importance
This development will build ON the green/blue network and habitats, so this is directly contrary to the objectives of the network.
Objection Summary – Wildlife Habitat
- The development will be contrary to Policy G2 not only due to the severe threat to the South Fen SSSI, but CAN NOT be built with destroying protected habitat
- The Site is an important part of the blue/green network or wildlife corridor as per the Local Plan and NPPF policies below
- Clear-felling in 2009 destroys species but NOT the protected habitat
Habitat – Networks and Corridors
The terminology of network (G1) and corridors (NPPF) is critically important to understanding the importance of this land as a wildlife corridor as shown in the following maps, policies which are in essence:
Making Space for Nature, A review of England’s Wildlife Sites and Ecological Network1, published 2010, set out the essence of what needs to be done to enhance the resilience and coherence of England’s ecological networks. The report proposed that this could be summarised in four key words: more, bigger, better and joined.
In addition the following NPPF Policies apply:
a) Identify, map and safeguard components of local wildlife-rich habitats and wider ecological networks,
b) promote the conservation, restoration and enhancement of priority habitats, ecological networks and the protection and recovery of priority species; and identify and pursue opportunities for securing measurable net gains for biodiversity. (NPPF 179 a, b)
b) development on land with in or outside a Site of Special Scientific Interest, and which is likely to have an adverse effect on it (either individually or in combination with other developments), should not normally be permitted.
c) development resulting in the loss or deterioration of irreplaceable habitats(such as ancient woodland and ancient or veteran trees) should be refused, (NPPF 180)
The presumption in favour of sustainable development does not apply where the plan or project is likely to have a significant effect on a habitats site (NPPF 182)
d) minimising impacts on and providing net gains for biodiversity, including by establishing coherent ecological networks that are more resilient to current and future pressures; (NPPF, 174)
Survival of Habitat, not only species is required
The following images show the Natural England Land Designations of SSSIs, Local Nature Reserves, Woodland and other green designations. (Click right)
Natural England has designated the Site as priority deciduous woodland habitat, with land designated for Network Enhancement Zones in lime green on either side of the Site. These are areas targeted for “joining up” of ecological networks: (Natural England MAGIC)
Clear Felling of Protected Woodland
All the properties to the West of the Lye Valley Road have very vegetated gardens, however the Development Site appears to have been clear-felled in approximately 2009 as below: (click right)
[*]The clearing of the SSSI was a separate action designed to restore the fen habitat. Blue diagonal lines show Boundary Brook flow.
Therefore the Planning Developer statement below that “there are not statutory designations upon the site (Planning Statement 4)” is not correct:
The entire site is shown on Natural England’s Priority Habitat Inventory as “Deciduous Woodland” with the “Confidence in Main Habitat Classification” being listed as “low”. The site is however not a woodland and the inventory is incorrect. (Habitat Assessment, 5)
Is misleading as the inventory is incorrect due to apparent clear-felling in 2009.
Green Space Amenity
The very considerable amenity afforded by the views out of the Site are attested to by the very high number of resident submissions, therefore the development will be contrary to G1 as above, but also:
Policy RE7: Managing the impact of development
Planning permission will only be granted for development that:
a) ensures that the amenity of communities, occupiers and neighbours is protected;
and the following NPPF policies:
Planning policies and decisions should ensure that developments:
c) are sympathetic to local character and history, including the surrounding built environment and landscape setting, (NPPF 130)
Planning policies and decisions should contribute to and enhance the natural and local environment by:
a) protecting and enhancing valued landscapes, sites of biodiversity or geological value and soils (in a manner commensurate with their statutory status or identified quality in the development plan); (NPPF 174)
and Local Plan 2036 – Policy DH2: Views and building heights:
The City Council will seek to retain significant views..
Amenity Value Recognised By Inspector
The value of this landscape is specifically addressed for the Site by the Inspector in the previous appeal:
Appeal Decision APP/G3110/W/18/3203669
Moreover, as I noted during my visit, its unspoilt, green open qualities make a pleasing contribution to the street scenes of Town Furze and Lye Valley. The site assists in softening the impact of neighbouring built development and also affords views south across the city. It adds to the quality of the local environment
Together with adjoining land to the west and on the southern side of Lye Valley, .., the site forms an area of greenspace that provides an attractive landscape setting to the houses to the north. It is also evident from the well-worn public rights of way that bisect the land to the south and west, as well as the numerous representations made by interested parties at application and appeal stage, that the site forms part of a valued area of local greenspace.
The proposed houses would be designed and finished to match neighbouring dwellings. A sizeable part of the site would also remain open for use as private gardens and a swale. However, the new dwellings, garage and parking spaces would considerably erode the unspoilt, green open qualities of the site. When looking south along this section of Town Furze, or south and south east from properties in Lye Valley, the proposed development would significantly encroach into this area of local greenspace. It would markedly detract from the setting of neighbouring houses and the quality of the local environment.
The proposed dwellings by virtue of their height and massing would also disrupt views south across the city.
I conclude ..that the proposal would harm the character and appearance of the area and conflict with the provisions of SHP policy HP9 and LP policies CP1, CP8 and the objectives of NE15. [Now updated as discussed] This harm weighs heavily against granting planning permission.
Landscape and Visual Appraisal
The report does not account for views from the Golf Course except from the very base. More importantly, it attempts to minimise the very important views the Site provides both of itself and to Lye Hill on the opposite side.
Gardens v. SSSI Buffer and Feeder Zone
Policy H16, Outdoor Amenity Space Standards, is in direct conflict with the requirements of the SSSI in that as much vegetation as possible should be retained to enable groundwater infiltration. On a steeply sloped plot, either destructive landscaping and/or full clearance will be required (with some retained trees)
All the gardens west of the Lye Valley Road will be developed if this proposal is approved, as they benefit from G6, Residential Garden Land as acknowledged by the Inspector:
Whilst I have determined this appeal on its own merits, if it was allowed, it could increase pressure for development on neighbouring land, which the LPA could have difficulty in resisting. In turn, this could result in cumulative harm to this area of greenspace and to the quality of the local environment.
Opinions expressed are mine alone, I do not represent anyone other than myself.
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Appeal – Appeal Decision APP/G3110/W/18/3203669 for same site
Lamberth – Investigation of the possible hydrological effects on the Lye Valley Sites of Special Scientific Interest and the riparian zones of the Lye and Boundary Brooks as a result of development on Southfield Golf Course, A Pre-EIA Assessment, Oct 2007, Dr Curt Lamberth
Thames – MWH Global report to Thames Water, 2011, Modelling Report, Appendix A (Map Thames Water stormwater catchment)
BBOWT – A Draft Management Plan For The Lye Valley,BBOWT & Oxford City Council, 1986
Natural England Citation https://designatedsites.naturalengland.org.uk/UnitDetail.aspx?UnitId=1002529&SiteCode=S1002848&SiteName=&countyCode=&responsiblePerson=
Documents above available on request
EN1– Map Derived from Lamberth, Thames Water
EN2 – Map created by overlay of Lamberth catchments and flows with Google Maps, golf course outline used for alignment
EN3 – The diagram is derived from the contours shown in the arboricultural survey, and development position on the plan, and the hydrological data as supplied. Geological strata are assumed below 2m based on (Lamberth and BBOWT and BGS data – in particular the impermeable clay layer may be at any depth above 77.8m, be multiple thin layers, single, and any downward angle.
Also available at:
Headington Heritage Web Site, Lye Valley, Maps:
Natural England SSSI Citation
All catchments above ultimately drain below the Lye Valley into the Iffley/Cowley area where water will contribute to urban flooding.
In the area shown below, water will either go north to Bayswater Brook/Cherwell/Oxford (north of London Road) or via Boundary Brook below the fen, so full offsets (SUDS etc) are required in ALL areas to increase groundwater and reduce surface water flows to reduce downstream flooding.
Groundwater, whether in the Lye catchment or not, will reduce flooding by retention and slow release as opposed to urban development.
Misconnects where surface drains are connected to foul can lead to pollution release in storm conditions as the foul drains respond to storm events both the the Lye and downstream.
Appendix B – Thames Storm Water Catchment
Water from rooves, driveways, roads and hard surfaces flows into the Thames Water sewers (two large, one smaller) and then in the Lye Brook at the head of the Lye Valley, shown in Orange
Additional connections, paved areas and removal of greenery all increase flows to the Lye drains and downstream (Cowley/Iffley or Barton Park/Bayswater Brook/Oxford)
The Thames Water surfacewater drainage network has the effect of greatly enlarging the natural catchment, mostly northwards. This, and intense urbanisation, has led to scouring of the Lye Brook meaning the Fens cannot be wetted via the Lye Brook as water now flows UNDER the fens.
All water entering the Thames Water system will also exacerbate flooding in Cowley Marsh, Cowley and Iffley areas where Boundary Brook discharges into the Thames. (Possible reason for flood Oct 2020)
Connections, if existing to the household, will not be subjected to, or be reported to, Thames Water, leading to incremental pressure on the system unless made a condition by Oxford City Council.