The Warren Crescent Housing Development – Risky, Reckless and Ruthless
Isn’t This Worth Saving?
Gallery F1: Rare Plants of The Lye Valley – Under Threat From Oxford City Council
It is hard to think of a more environmentally destructive, reckless, ruthless, cruel, socially damaging and financially wasteful development managed with such overweening apparent incompetence than the still unbuilt 10 house development at Warren Crescent, Headington on the Lye Valley slope.
Overwhelming evidence has been presented that the scheme is simply not fit for purpose, yet the Council persists in pursuing it against all logic.
Clear evidence that the Lye Valley West Fen is, far from “cleared reeds”, now mostly restored and teeming with rare species, and was and is worthy of the highest level of protection has been ignored by The Council, which seems to have forgotten that even after granting itself planning permission under false premises, it still has a statutory duty to protect it.
Although advised by SDS Consultancy of the fundamental flaws in the SUDS system, pivotal in the grant of planning permission, Oxford City Council (OCC) is still proceeding with a damaging, defective, unworkable and largely pointless design that will rob residents of the last vestige of green space rather than face public scrutiny via a planning variation which would have forced the abandonment of the entire scheme and a very probable unresolvable objection by Natural England regardless of the design adopted. Natural England withdrew its objection based on the functioning of this SUDS system, and as this does NOT work, the scheme must be halted.
If we accept the logic of the Planning Officer below, if the SUDS cannot work, then Planning Permission, or discharge of conditions, were not correctly granted as this was the basis on which Natural England withdrew its objection.
Further, it must provide a dignified and healthy environment for its citizens now, as COVID has taught us, more than ever.
Subsequently, at time of writing, repeated FOI requests have revealed OCC does not hold ANY detailed designs other than those released as part of the planning process, which, in particularly in the case of the SUDS, are not sufficient to progress with a build, therefore OCC CANNOT have done any risk assessment at all – at least of some of the final designs.
Planning has granted itself the right (At EABC 04/08/20) to make any changes it chooses without further reference or consultation, which given the unresolved and unresolvable issues below, this must be of the utmost concern as stated in my objection at the EAPC meeting.
Fundamentally, this scheme is reckless of the environment and ruthless towards citizens with NO access to private green space living in blocks of flats, and financially senseless, negatively impacting the delivery of housing, and places OCC at risk of damage both financially and reputationally in the event of environmental harm to the Fen.
The only honourable and logical outcome is for the Council to abandon this crazed scheme before any more damage is done and money wasted.
- The development will interrupt the groundwater flows from the whole catchment to the West Fen, which the Council described as “reeds” so no meaningful risk assessment was undertaken
- The site is ABOVE, not near the Lye Valley
- The Made Ground under it is dangerously unstable, presenting a danger of slippage of land, houses and a clear H&S danger to workers on the site
- The SUDS system proposed is dangerous, infeasible, and unfit for purpose
- The Council preferred to continue with a defective SUDS system design and waste taxpayers’ money rather than resubmit to public scrutiny by a planning change
- Public Green Space is being taken from the Green Poor in blocks of flats with NO private space and privatised for the exclusive use of the new development, contrary to the Social Equality Act of 2010, leaving children to play in the road
- The secluded and wild feel to the Lye Valley will be permanently defaced by highly visible buildings
- The footpath on open Warren Meadow with its beautiful views of the Lye will be reduced to a back alley and then set back from the edge at the SUDS
- It reduces Oxford’s housing supply by wasting money on expensive and infeasible development rather than spending it efficiently on producing cheaper, and more, homes, any gain is far outweighed by the damage done
- The lack of design overview and lack of public consultation is of deep concern, all current information must be released.
For earlier and more in-depth articles refer to Headington Heritage, Lye Valley Menu.
Oxford City Council (OCC) has granted itself planning permission to build 10 houses and an associated SUDS system:
13/01555/CT3 | Erection of 10 x 3-bed dwellings (use class C3) together with associated car parking, cycle and bin storage. Diversion of public footpath. (Amended plans and description) | Land East Of Warren Crescent Oxford Oxfordshire OX3 7NQ
Council Failure -West Fen Is Habitat!
PBA advised OCC that the West Fen was “reeds” so the flows from the development (West) side of the catchment did not matter:
The SSSI designation (covering both Fen sides) and protection is as a SITE of Special Scientific Interest is to protect the fen environment.
Its degraded state in 2013 was NOT relevant, and it was quite wrong to apparently suggest did not matter as it was not part of the “main fen” although it is approximately 50% of it, and then to claim that flows under the development were therefore not contributing to a unilaterally declared “Main Fen” on the East side of the Lye.
PBA marked the East Fen (Fig R2 right) as “an area of extensive fen habitat”, but the West Fen (left) as an “area of restoration reed” and “cutting scrub removal”. (Fig R1) “Habitat” is that which supports fen flora not the flora itself – This was an ELEMENTARY error. Even were this argument accepted, the West Fen is now home to many rare flora such as over 40 Marsh Helleborine orchids, and almost no reeds still exist.
Under pressure from the FOLV, a hydrological assessment of the flows ON and FROM Warren Meadow was conducted, but the focal role of the development site in the Lye Valley hydrology of flows UNDER AND THROUGH the West Fen from ALL of the west catchment was simply ignored. NO assessment of the crushing effects of 10,000s of tons of foundations on the delicate rock layers though which water flows was undertaken.
Groundwater Flows – Why They Matter
Rain falls in the whole catchment, infiltrates through limestone, and becomes vital calcareous groundwater on which the Lye Valley SSSI depends:
This concentrates and flows UNDER the development site (Fig F1 Red) as shown with blue arrows, via a perched water table and layers of rock picking up the correct calcium content. Flows will be blocked as shown above (Fig F1)
It then emerges ABOVE the West Fen (Fig 3 Green) at the springline (Fig 3 Blue) as shown below:
How The Development Affects Flows
Development Site – Pre 1956
Rain falls on the entire catchment infiltrating into the ground and down to the Perched Water Table/Aquifer. Importantly flows move both down and towards the viewer and the West Fen as shown in Fig F2.
For the section location below, see (Fig O2, B-B1/B’)
Fig D1: Development Site – Pre Development – Infiltration To Springs
Development Site – Warren Meadow – 1956 Approx
Fig D2: Warren Meadow From 1956 to Present
In approximately 1956, the builder’s rubble, probably from site levelling for the Town Furze estate, was used to create Warren Meadow and an artificial and unstable slope ( brown line)
The natural Lye Valley slope (green) was covered with Made Ground (or Tipped Embankment), destroying almost all the fen below. Flows were weakened (not shown).
The flows moving towards the viewer and which emerge in the Lye under the development site.
This is the current situation.
Development – Warren Crescent Development – 2021
Fig D3: Post Development showing aquifer crushing and rupture
The Warren Crescent development will require deep foundations (black) to reach the solid natural slope (green) of the Lye Valley at 1-3.5m below the artificial flat surface of Warren Meadow, requiring foundations to 4m+ for a level surface.
This will be effectively a giant underground 80m * 20m dam corresponding to the blue outline shown in diagram above (Fig F1 – Catchment Flows Through the Development Site) blocking ALL flows from the ENTIRE west catchment
These impose massive weight on the delicate water bearing layers below, either rupturing them or crushing them so water is either blocked, or simply leaks below the level of the fen and is lost.
The West Fen, deprived of calcareous groundwater will then die.
Made Ground – The Steep Slope
The artificial slope formed by the Made Ground to the Lye Valley is between 32-42 degrees, as measured by Dr Curt Lamberth.
 See also Fig V2: below for bank steepness at the housing area.
The Slope Stability report (GEO) determined the slope was dangerous to a point approximately 3-4m from the edge. The nearest houses will be located within 8m from the cliff edge.
Council Failure Summary – Slope Opposite The Houses
The stability report failed to address:
- The excavation disturbance which will be far greater, and nearer to the edge, than the final foundation footprint
- Damage to tree roots at the cliff edge caused by contaminated soil removal and replacement, coppicing, and tree removals causing further instability
- Groundwater seeping under the foundations, undermining the bank
- The effect on the land being split between the foundations and the cliff edge, which will become unstable
- Evidence of previous landslips at this location
- The H&S risks to construction workers
- Critically, it did not address the slope stability at the SUDS, a dangerous part of the development
It is sheer folly to rely on trees to maintain the structural integrity of the bank.
The unstable part of the bank in front of the houses is shown below (orange hatching), before and after a landslip, which could include the houses themselves (not shown)
Fig D4: Post Development With Unstable Ground
Fig D5: Post Development After a Landslip
A SUDS (Sustainable Drainage System) is designed to retain water to prevent downstream flooding and mimic the natural drainage environment.
The SUDS – Council Failure Summary
- It does NOT mimic natural flows, instead concentrating all flows to one point at the headwall of the SUDS, starving the West Fen of groundwater
- It will be dangerously unstable leading to bank collapse both due to leakage and pressure on Made Ground from a top heavy unsupported structure in addition to slope issues highlighted above
- 90% of it is completely pointless as flows will never reach it
- It does not regulate the pH of the groundwater, key to Fen survival
- It is unmaintainable due to poor design
- Deprives locals of desperately needed green space for NO gain
- Has a completely pointless bund, adding to the instability of the slope
- It is dangerous to build, creating serious H&S issues
- May block flows directly as the structure will be “keyed in” to the original slope which is AT the water table level at this point (approx 87m)
- May compromise the structural integrity of the adjacent 33-55 Warren Crescent block of flats
- Coppicing to keep the SUDS free of leaves, and removal of trees will weaken the bank, and make housing (33-55 Warren Crescent) visible from the Lye Valley
The SUDS – Its Importance
The SUDS design was absolutely critical to the grant of Planning Permission by overcoming Natural England’s objection.
The importance of the SUDS system and concern about the damage to the hydrology of the fen is clearly set out by a Planning Officer to the applicant’s contractor:
“I appreciate that your client may be looking to reduce costs, [by presenting a better SUDS design] but there is a considerable history to this site, the planning permission, and even the allocation for housing which you need to bear in mind. There was considerable local interest in this site, and particularly the impact on the SSSI. This required a specific solution to ensure that the development did not impact on the hydrology to the fenn.[sic] There was a particular objection from Natural England to developing this site that was only removed once we agreed to allocate it for development in the Sites and Housing Plan and provide a caveat that a suitable drainage solution was provided.
The application through pre and post application discussions developed a strategy which enabled the removal of Natural Englands objection to the planning application. Therefore we cannot accept changes which undermine the purpose of this strategy which amongst other things was to maintain the right level of PH of the water.
This strategy was so integral to the scheme that the Council would not have obtained planning permission without it, and therefore we cannot accept changes to the strategy without a new application or at the least a formal application seeking variation of the condition. This will be subject to public consultation and will open up all the previous issues raised.” (Ref: SDS, Appendix B, Planning Officer email)
That SDS found it necessary to include this and other email exchanges below between the Council and other parties would imply it was deeply uncomfortable with the “dictated” design imposed by the Council.
Failure – The SUDS Does Not Mimic Greenfield Runoff
The originally approved SUDS design was produced by PBA who stated:
The “proposed permeable paving and swale has been designed to mimic the existing greenfield drainage regime” (PBA)
Fig S2: SUDS/Swale Horizontal – Showing Water Loss by Vertical Discharge
Fig S3: SUDS – Showing pointlessness of remaining SUDS
This was reviewed by SDS (4980-RP01) as part of the Planning Condition 11 discharge, who observed:
“SDS note that surface water flows are to enter the swale and disperse over the first erosion control mattress. This entails that surface water flows will discharge directly into the underlying limestone fill and essentially flow along the length of the sub surface of the swale. It is unlikely that surface water flows will discharge along the length of the swale due to the direct discharge into the limestone beneath the swale thus making the implementation of the swale redundant….
No flows occur the length of the swale. The swale will only have water within the swale due to the back of flows from the sub base limestone, this occurs during the 1:100 year storm events.” (Ref: SDS)
To put it more bluntly, 95% of the SUDS is pointless. (S2 purple, 50m) and does not achieve the stated aim, the only reasonable explanation for proceeding with a defective or at least redundant design as reported by SDS, on valuable green space appears to be the reluctance of the Council to have to justify the unjustifiable as part of a new Planning Variation which would subject the risk to the Fen to public scrutiny.
So the SUDS will achieve the exact opposite of natural, diffuse infiltration of rainwater, and ensure most runoff from rooves and the estate is concentrated at the headwall of the SUDS where it discharges vertically (S2 blue, S3 blue) so water flows directly down through the artificial limestone bed of the SUDS and falls down in a concentrated manner 100m from where it is needed at the West Fen.
This water is far less likely to percolate along part of the perched water table as it will create an erosion channel and small spring, or will infiltrate directly down to the Lye Brook level below, reducing the flows to the West Fen, and causing a landslip as advised:
Consideration should be given to the drainage of the proposed development, additional or concentrated discharge of water in close proximity to the slope should be avoided. The use of soakaways in the rear gardens, for example, is inadvisable. (Ref: GEO 10)
This is exacerbated by complex geology meaning that water could arrive on either Beckley Sands or Limestone doggers and be lost.
It is equally unclear what purpose the bund serves other than to block one of the prettiest paths in Headington, it will never retain water, and even if it did, would probably contribute to the slope collapse due to its weight.
Council Failure – The Slope Near The SUDS Will Be Unstable
Fig S4: SUDS – Unstable Made Ground After SUDS implementation (Fig S2 S-S1)
A very large portion of the ground near the slope (Fig S4 above) is weakened by:
- Pressure from the imposition of a top heavy structure on Made Ground with an artificially steep slope are shown above.
- Root damage due to the SUDS construction extensive coppicing required to keep the entirely pointless SUDS free of leaves, and imposition of the entirely pointless bund
- The SUDS outfall as above
No ground stability report has done undertaken for this area.
The specification requires the SUDS limestone base to be keyed into the bedrock, however, it is entirely unclear how deep will need to be, as NO proper site survey has been done. A BGS borehole in the vicinity identified Made Ground of 5.5m depth, this has been ignored.
Council Failure – SUDS Maintenance Will Be Impossible
The design and depth of the SUDS, as pointed out by SDS :
“Note that the current PBA / WSP design which gives a significant depth of limestone to the Beckley Sands does not consider future maintenance or inspections. … The PBA / WSP design entails that the full length and depth of the limestone would need to be removed and replaced in the event of a spillage / pollution incident”. (Ref: SDS, email)
Council Failure – No SUDS pH Regulation
Planning Officers emphasise the importance of the SUDS system to ensure the water is the right pH for the SSSI:
“The site is adjacent to the Lye Valley triple SSSI, an area of fen particularly sensitive to changes in water quantity, quality and also water chemistry/changes in pH. In order to maintain the correct pH, it is necessary for particular materials to be used, i.e. the limestone.” (Ref: SDS Planning Officer App B)
The SUDS is supposed to deliver calcified water of the correct pH to the fen, however:
- It has no regulatory mechanism, so over or under supply of calcium and resultant damage to the Fen, is possible
- There is no target pH given
- No knowledge of the plant pH tolerances
- No calculation indicating how specifically the SUDS would operate (noting that 90% of it is completely useless with only a very small part of the limestone actually wet)
SDS Consulting questioned the non existent requirements for the target design of the SUDS as below, Red is as in original text, not markup:
“o What level of PH is to be achieved? Natural England Requirement?
o What depth of percolation through the limestones needs to be provided to achieve the PH requirement (if evident that there is a requirement)? “
Natural England Requirement? (Ref: SDS Appendix B)
The underlying assumption that a bit of limestone will be a good thing is an intellectually lazy and unfounded assumption that finds no support in any of the documentation – it is astonishing this was not clearly addressed before any design work was conducted.
A delightful footpath (SP80) runs across the site, officially, diagonally across the development, but in reality along the treeline.
This footpath will be retained as a “permissive” path, but boxed in by rear gardens, losing the open feel.
This is currently subject to a planning inquiry re the footpath “diversion” (removal) with objections to be lodged by March 9th 2021 – email author for details. See this article.
Removal Only Useable Green Space
The housing development and SUDS system will result in NO usable remaining green space, where residents can enjoy the basic dignity exercising, relaxing or playing on ANY grassed surface – it will entirely fenced off depriving the local community of even a tiny vestige of remaining green space.
Most in the local community have NO access to private green space, living in the blocks of flats on the estate, leaving local children, including those from the development’s 10 “Family Homes” to play on the roads.
The alternatives to Warren Meadow, except for a tiny tots playground on polluted Girdlestone Road are shown below:
Contrary to the Social Equality Act 2010, this development represents the transfer of public green space from the green space poor to create a new class of green rich who will have private gardens at the expense of the rest of the community to maximise Oxford City Council’s financial position.
Views from the Lye Valley
The sequestered and secluded feel to the Lye Valley, where it is possible to imagine you are no longer in a big city, with housing almost entirely set back from the Lye will be permanently destroyed:
In addition, coppicing of trees opposite the SUDS will make the three storey blocks of flats visible from the Lye (33-55 Warren Crescent)
Negative Impact on Desperately Needed Housing
Oxford has a housing crisis – this ill thought out, very expensive, environmentally unfriendly, socially destructive project is diverting money that can be better spent elsewhere. How many Oxford families will go homeless due to the money wasted here?
The Site Plan Is Unrepresentative
Throughout the entire Planning Permission phase of the development, the Swale (SUDS) was presented (including at the Committee meeting of 05/08/2021) as being an irregular pond sown with wildflowers:
At the EAPRC Planning Committee meeting of 05/08/20, Planning asked for permission to alter plans for the footpath only and produced this presentation showing ONLY that change (Fig L1)
However a supplemental, and contradictory, plan (Fig L2) was added to the EAPC record showing the pond now as an ugly and angular SUDS system, but this was NEVER presented to the members who were led to believe it would be an attractive, irregular and water filled feature. This represents the ONLY SUDS system that was ever proposed by PBA – the pretty pond could never have existed or been planned for as the SUDS occupied the same space.
Neither the pretty pond or the SUDS system would EVER hold water except for very limited timeframes, so the portrayal of both these a water features is entirely unrepresentative.
It is perfectly clear from the evidence presented above that continuing with a scheme would be environmentally inexcusable and financially unviable, the Council must immediately halt this and let Warren Meadow be part of the Lye Valley for the enjoyment and recreation of citizens now and the time to come in an increasingly crowded city.
Thanks for proof reading and input from Dr Judy Webb.
Warren Crescent, Oxford, Discharge of Planning Condition, Condition 11 (SuDS), Report SDS, Ref: 4980-RP01 ISSUE 03 – September 2019 (SDS)
Warren Crescent, Oxford, Slope Stability Appraisal, Geotechnical, Report Ref: 36045 (GEO)
Warren Crescent, Technical Note Ecology, SUDS and Groundwater Quality 2015, Project Ref: 27920,Rev: 01 Date: January 2016, Peter Brett and Associates (PBA)