Covers Farm: what we know so far

In 2018 Morants Promotions Ltd startedPlanning application ref. KCC/SE/0495/2018   ‘”Stabilisation and restoration of Covers Farm Quarry using imported engineering materials to restore the site to grassland, including landscape planting and an ecologiial receptor area together with a temporary road and ancillary buildings , at Westerham Kent”.

Key points from the 2018 application:

One truck every 3 minutes 7am – 6pm each weekday  The application involves  84,200 extra tipper trucks bringing construction waste along local roads. That is,  3 trucks per minute for 11 hours each weekday, for 6 years or more.

Claims that the northern lake will flood the Croydon Road  The Gault Clay that once capped the top of the northern quarry face has slid down. It’s assumed though not proven  that this clay is now lining the lake, preventing it from draining into the sand beneath. It’s assumed though not proven  that this clay is now lining the lake, preventing it from draining into the sand beneath. Morants’ (Squerryes’) engineer claims that there is a risk of the large lake overflowing from its north-eastern rim, causing flooding in the Croydon Road  area. A time-frame 10-15 years has been put forward in the latest report (ES Addendum 2021). This is despite the concession made by Mr Warde and the December 2018 “Drop-in” meeting that the water level of this lake goes up and down.

Claims, unsubstantiated of an M25 threat The application has repeatedly alleged that the possibility of  failure in the Gault Clay slope could present a risk to the M25, which at its nearest point runs 60 metres to the north of the quarry. Highways England, the agency in charge of motorways,  have no such risk logged.   They would however want to see a risk register and thorough monitoring of the risks arising from this proposed stabilisation/restoration project.

The proposed solution  Morants’ engineer proposes to build huge dykes, each 20 metres in width across the top, compartmentalising the site into four sections. Please note the extent to which the underpinning structure traces the proposed line of the western end of the bypass in the Which Way Westerham Masterplan with reference to the illustration below.

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Diagram from Which Way Westerham Masterplan showing proposed route of relief road across Covers Farm where it would rejoin the A25.

The dykes are to be built up of end-tipped granular material in a gradual process of displacing the water. The ‘compartments’ would then also be gradually filled. On-site materials combined with imported material would be use to contour the site into the final landscaping.The final contouring of the site would create a single gulley and a series of ponds, channelling surface water to the site of the existing southern lake. There, the theory is that the water would drain into the underlying sand stratum.

KWG comment – Here’s a statistic for you: lowering the contour across the entire site  by 150 mm would reduce the infill required by 64,000 cubic metres, or  about 7,000 fewer lorries on local roads.

The 800,000 cubic metre figure which is the ‘requirement’ for imported material comes from a simple “before and after” comparison of the estimated volume of sand/clay/debris in the pit and the final contouring envisaged by the proposer’s consultants.  It makes no allowance for the fact that much of the material would need to be compacted – therefore more material will be needed, resulting in more tipper trucks on local roads.

The chosen approach requires vast quantities of granular material. Bought to a specification, this is expensive. But Squerryes’ consultant’s  stated preference (“Drop-in”meeting, Dec. 2018) is to import construction waste and screen it on site. At the “Drop-in” meeting it was said that from such  waste, you would derive 20% in  granular material. The rest of the  material would be used elsewhere on site.  Importing construction waste is economically favourable, because the importers pay you.

Among the options put forward in the recent ES Addendum 2021) an importation of one million cubic metres was put forward, with the claim that this would achieve better drainage and better contours for agricultural use (but see paragraph on “Drainage and risk of clog up” below and on the Home Page, the bullet point about the space bored piles option). The actual proposal = 84,200 additional lorries on our roads. The one-million–cubic-metre option could equate to 105,000 additional lorries!

Key points from December 2019 further material

Late in 2019 / early 2020 Morants Promotions Ltd submitted further documents.

  1. The further information used the phrase  ‘ minimum 800,000 cubic metres. If this application is approved and the scheme gets started, Kent County Council won’t be able to say No to  more importation, ie even more lorries.
  2.  The further information did not properly consider other sensible engineering techniques to address the superficial slope failure. Regarding the technique used to address slope failure at Junction 6 of the M25 – a row of submerged bored piles – it quickly claims that is is too costly and unfeasible, despite it being less onerous for residents and road users. The space bored piles technique would take about 9 months and require 400 lorries.
  3.  A “Routing Agreement” was included in which it KCC Conservation Advice recommended that Brasted has no more than 100 lorry movements per day from this project. The result: North Westerham will have to take up any lorry journeys  above the figure of 100 per day.
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Proposed route of tipper trucks to and from Covers Farm Quarry. 100 movements each weekday to and from M25 Junction 5 through Sundridge and Brasted then via Beggars Lane. The ‘Routeing agreement’ document states that this is the absolute maximum through Brasted. 100 truck movements via Biggin Hill and up and down Westerham Hill. All of above would then continue westward onto the “temporary” haul road to arrive at the red arrow on the map. Possibility of 15% of this lorry traffic would come in via Tatsfield and the Croydon Rd. A stoplight is proposed approximately where the tip of the arrow is.

Other key points from December 2019 further material:

The proposed ‘temporary’ road or ‘haul’ road

To spare Westerham High Street from all these lorries, Morants proposes a  ‘temporary’ road  between the BP garage roundabout and the Croydon Road. The Further Information  continues to suggest that this is a single width road with passing places.

Noise, dust and fumes for Churchill School Primary Children

Churchill C of E School Primary pupils will have to endure the construction of the haul road, the construction of the earthworks and then the 5+ years of 84,000  lorries toing and froing between the Croydon Road and the Beggars Lane roundabout.

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Proximity of haul road to the M25 embankment – is it safe?

Squerryes were asked to look at the risk to the M25 embankment slope posed by the proximity of the haul road.  Squerryes’ engineer has looked at this and reported on it in his Ground Investigation Report (Further Information, Appendix 6). Advising KWG, Professor Edward Bromhead MICE, C Eng, PhD, has said that the geotechnical assumptions and methodology described in Reports 1, 3, 4 and 5 have major shortcomings and fail to support the claim in the GIR that the haul road would be safe.

Dangerous convergence at the BP garage roundabout

The haul road is single width. The traffic figures suggest that there would be a lorry every three minutes. Where do the arriving lorries, waiting to join the haul road, park up?  As they wait in the mornings for the quarry site to open, where will they park up?

Danger of lorries on Westerham Hill

The “Routeing proposal” currently implies that there could be more than an extra 100 lorries per day connected with Covers Farm.  Having a maximum gradient of 18% (average 9%) there are no passing places on this winding hill.  Bromley Borough Council made an objection to this application.

Croydon Road – dangerous stop light location

Where the 200 daily lorry journeys would intercept the Croydon Road, at Point B above, a stop light is proposed.   You can see that this in the 60 mph limit zone, on a bend where it emerges from the M25 underpass. A lorry every three minutes. The haul road is wide enough for single file  traffic only. We shall leave you to comment on the risks of all of this.

Drainage and risk of clog up

In the finished scheme  in order that the groundwater drained away from the site, an area on one side of the southern lake would need to be excavated so that there was adequate connectivity with the underlying sand stratum. The application does not say who would be responsible for monitoring or maintenance of this infiltration (ie  for keeping it free of silt and clay fines) or for how far into the future they should be doing this.

Potential drinking water issue

Connection to a drinking water site.  The sand stratum chosen as the infiltration is part of a Principal Aquifer. The specific site is what’s called a source point (reference SPZ3) from whence groundwater could discharge to a drinking water borehole 530 metres to the west at Westwood Pumping Station.

 

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