Purple Haze Quarry
Purple Haze in relation to Moors Valley Country Park.
Key: 1= excavation areas (dark purple). 2 = whole site area (light purple) 3 = processing plant area which would be excavated to 3-metre depth.
The site is bounded on its South side by the Sandy track – the extension of Pine Avenue. On its North side the overall site is bounded by the Ringwood-Verwood Road (B3081).
​The map shows the location of existing gravel roads, foot paths, tracks and the Through the Forest bike track. The 'Wide Ride', is a green lane that is a favourite of dog walkers and horse riders. The Wide Ride runs through the site parallel with the Ringwood-Verwood Road (B3081) and would become adjacent to the quarrying works. It seems that the Wide Ride would remain open once the quarry is working. During the opening up of the site, the Wide Ride would likely be closed for safety reasons.
A hazard from day-one of site development would be a road (see Zone map further down the page) constructed across the Wide Ride for heavy lorry access to the first stage of excavation – the site for sand processing plant (see zone plan below). The North section of the site, '2', is not a proposed extraction area but would be selectively felled with the objective of opening up the area (further) to become mixed heathland.
The site: highest point
The highest point of Purple Haze – at 52-metres AOD (above sea level) – featuring an unscheduled tumulus and an Ordnance Survey trig point.
The site: lowest point
The Ebblake end of the Purple Haze site.
This area, apart from a section West of the existing Eastern track, would not be excavated according to current plans. The area would be created as a 'reptile & Nightjar Habitat enhancement area', established at the outset of operations. It is not clear how the existing terrain would be altered, or not, by tree planting or felling – or changes in natural vegetation.
The site: interior
Purple Haze viewed from the Sandy Track at its highest point
A challenging track at the heart of Purple Haze
Pre-excavation: what happens to trees?
The existing woodland between Wide Ride (the track to the North of the Purple Haze extraction site) and the busy B3081 road.
The Wide Ride. Trees to right of the picture (North East) may be candidates for felling. The extraction site to the left would be cleared of trees.
The developer's Outline Restoration Proposals plan appears to contradict an earlier plan for clear felling of areas of trees between the Wide Ride and the Ringwood-Verwood road. If trees are felled here the relative tranquility enjoyed by walkers would be marred by road noise as well as quarry-working noise. Also, excavation areas, once restored, would be subjected to noise, which again would not be absorbed or screened by vegetation.
It is not apparent how tree clear-felling on the Purple Haze extraction area would be timed. Would the whole area be cleared prior to excavation? Or would felling be carried out on a zone-by-zone basis? Disruption and damage to the Wide Ride by heavy plant moving timber would be considerable during felling operations. Trucks or tractors removing timber would be a hazard to walkers, although it is probable that the Wide Ride would be closed (for a considerable time) as a safety measure. No provision, for renovating what will be a heavily-rutted Wide Ride after tree-felling, appears to have been made. What happens to the carpark at the North West corner of the Purple Haze site?
The Sandy Track with Purple Haze to left side.
Pre-excavation: fencing and site boundaries.
The proposed boundary of the quarry area: fencing of an unspecified height and type which would be external to a low mound of earth.
The developer plans to maintain an 8-metre buffer zone of natural vegetation between tracks and a newly-installed fence.
The fence would be located 3-metres from an earth bund (mound) formed at the perimeter of the excavation area. Existing habitat would also be retained between fence and bund. It is not clear at what point the fence would be erected prior to starting of quarry working: would it enclose the entire site or be erected on a staged basis? It is also not clear how long the fence would remain after the beginning of restoration, given the apparent intention to exclude the public from areas while a new habitat is establishing itself.
Pre-excavation: Through the Forest bike track
The Sandy track runs along the South side of the Purple Haze site. Here the Through the Forest bike track enters Purple Haze (on right)
At this point (pictured above), the bike track would be closed off and 'short-circuited' to join up with the track's existing exit point from Purple Haze. This means that one of the most exciting, undulating sections of the bike track will be destroyed and only re-created decades later when site restoration work is completed.
Excavation: plant
The £6 million Power X state-of-the art wash plant at Grundon's New Barn Farm quarry. This system can separate out silica fines, wash and 'spin dry' them – and then add them back into the sand product. This apparently eliminates the need for silt ponds, reduces the volume of spoil generated and increases the volume of product for sale. It is possible that this type of plant would be used at Purple Haze.
Excavation details & important quarry related questions
IMPORTANT. The objective of this section is to pose questions of a technical nature regarding proposed quarry excavation and other works. Data are provided in good faith but no reliance should be relied upon statements made or numbers quoted, until confirmed (or not) by the developer or expert consultants.
An understanding of the topology of the Purple Haze site as it is, as it would be after excavation and on completion of the proposed restoration is important for the general public if they are to be able to truly visualise the impact of a quarry. As a result, we hope the drawings will demonstrate the magnitude of problems – visual, environmental, technical and community-related that result from having a large and deep hole in the ground replace a forest for decades.
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We ask how big and deep is this hole in the ground? We attempt to answer this ourselves . . .
Excavation depths. The drawing below shows the undulating terrain rising steeply from either end of the site. If the Wide Ride (which runs adjacent to the excavation site) is taken as ground level, the maximum excavation depth (as indicated by the restoration plan) is ten metres below ground level at the Eastern end of the site, two metres at the Western end and twenty metres at the Wide Ride's highest point. It is accepted that actual excavation depths would be greater or lesser, subject to water table levels.
Pre-excavation site contour plan
Site pre-excavation as at January 2024.
Contour heights: metres AOD (above sea level). Contour heights are shown in red and OS spot heights in black. Trig point at the highest point of Purple Haze is shown by a red triangle. Dashed line shows point of cross-section used by the sectional drawings below. Source: developer's planning application drawings 2022/23​
Indicative excavation levels
Estimated site excavation levels based on OS data and planning drawing DR-0006 9 Feb 2023
With 8*million tonnes of sand and gravel going out of Purple Haze and, according to the developer, nothing coming in, the topography of the site would be significantly changed. The developer states that actual excavation levels will be decided on the basis of the water table. According to the developer's restoration plan, there would be 16 metres difference in height comparing highest peaks before and after the development. This is equivalent to just under the height of four London buses stacked on top of each other.
* HCC estimates a total of 8 million tonnes of sand and gravel can be extracted, with 3.4 million tonnes sand & gravel extracted by 2040 (source HCC Minerals & Waste Plan-Partial update).
Indicative quarry cross sections: before / after excavation (showing highest point of site: section AA)
An indicative section at point AA on the contour plan above. This section is taken at the highest point of the site, viewed from the South West.
The drawings above are derived from OS contour data in the developer's 2023 restoration plan, thus indicating the profile of proposed landscaping. Proposed excavation depths appear to vary between 4 and 20 metres with an average depth, according to the developer, of 8.5-metres. The excavated site drawing shows a typical 1:2 gradient for the quarry faces which may vary for this development. The developer has not provided a drawing of post-excavation contours. For the restored site sectional drawing, the in-fill (shown in grey) is understood to be created from materials on site eg spoil, original topsoil, overburden and possibly vegetative matter. Fortunately the use of inert waste and externally sourced 'artificial soil' as a mix with on-site material has subsequently been rejected by HCC. It is considered to be technically impossible to resurface the quarry bed with soil that is suitable for restoring the original habitat.
Excavation: quarry zone plan
The proposed quarry plan showing excavation zones numbered in order of proposed excavation.
The developer indicates that quarrying work would be carried out in 21 phases, worked zone-by-zone – with each phase lasting 12 to 15 months. This means quarry works will continue for 22 to 28 years. Each zone is about four acres
(2 hectares). The zone numbering in the illustration above shows the proposed sequence of excavation work – with the processing plant area and zone 1 excavated as one phase. The process plant area is about six acres (2.4 hectares) and, we understand, would be in the same location for the duration of the project.​ Note the plant access road to be constructed across the Wide Ride – connecting the site directly with the main road.
Restoration site contour plan
The plan shows primary contour heights in red. Contour heights: metres AOL (above sea level).
Restoration: what we do and don't know
Our understanding is that a sand quarry – to achieve maximum sand extraction might be excavated with steep perimeter gradient in the range of 1:2. The restoration plan shows some retention of steep quarry faces but generally illustrates sloping embankments with gradients of 1:3, 1:5, 1:8 etc to achieve attractive landscaping features. This means a considerable amount of material is needed to create such landscape features. Will there be enough material on site to achieve this, given that the developer has indicated that no materials will be brought to site? According to HCC's draft minerals & waste plan, 8 million tonnes of sand and gravel would be extracted from the site. It is understood that, traditionally, the amount of spoil/silt/ fines after sand processing falls within the average range of 10 to 15%. (source Harrison et al 2001). Based on an extraction of eight million tonnes of aggregate, this means 800,000 to 1.2 million tonnes of spoil, along with over-burden, wood chips, green waste and top-soil could be available on site. The situation is complicated by the fact that the quarry operator, Grundon, might use the same plant as it employs at its New Barn Quarry, whereby cleaned, dried silt is reintroduced to the sand product. In which case the volume of spoil would be reduced. No calculations have been published as to how much material would actually be needed to achieve the planned landscape. It could be that externally-sourced material would be required. From the commercial viewpoint the only economical / practical source would be suitable waste. Given what FoRF has learnt recently about the HCC’s waste (landfill) policy in relation to Purple Haze, there is a possibility that such externally-sourced material could include inert waste (what this comprises is explained below). However, there is a risk that a mix of available on-site material and inert waste would not support the soil conversion structure required for the intended habitats. The developer has stated that the amount of top soil and subsoil on the Purple Haze site is limited – which worsens this situation. Research on quarry waste as a medium for plant growth demonstrates the criticality of achieving the correct proportions of materials to achieve effective soil conversion. Expert opinion on Purple Haze in particular, is that restoration will fail on several counts if inert waste is used (see Risks page). The use of PAS100 organic waste to augment materials on-site has not been discussed. The use of this material would almost certainly be ruled out because of cost, availability and further impact on truck movements on the Ringwood-Verwood Road. Clearly, given the above, together with the high cost of restoration, the commitment of subsequent management / maintenance and possibility of failing to meet environmental standards, adds up to an acute risk for the developer, community and biosphere.
What is inert waste? Inert waste is defined by the Landfill Directive as material that does not undergo any significant physical, chemical or biological transformations. Inert material will not dissolve, burn or otherwise physically or chemically react, biodegrade or adversely affect other matter with which it comes into contact in a way likely to give rise to environmental pollution or harm human health.
Site restoration: the plan so far
An interpretation of the developers restoration plan. It should be regarded as indicative only.
Yellow in the plan represents areas of created mosaic lowland heathland. Borders of the site, in places, are sloped down from the levels of the existing tracks bordering the site – as indicated by the contour lines (gradients vary from 1:3 to 1:8 ie steep to gentle). These slopes would be mainly wooded on the Southern side. New planting on the Northern side would be sparse in comparison. The highest point within the restored site is a small wooded area
The developer indicates that restoration would start at a relatively early stage, with work linked to completion of excavation in one or more zones. Such work would include substantial landscaping works and planting of vegetation and trees.
Is there a flaw in the quarrying and restoration plans?
We think the answer is yes, there is a substantial flaw. The zone plan shows how quarrying work would progress in a straight line, along one half of the site (Northern side), starting from the processing plant. This methodology is, understandably, needed for production practicality and efficiency. As we'll see, it's the opposite of what's needed for transforming a quarry into an attractive and environmentally successful landscape. The process is termed 'restoration'.
The restoration plan explained / interpreted
As explained above, excavation starts with zone 1 and with the processing plant area to the South of it. The processing plant, it is understood, remains in the same area throughout the project, so that trucks can transport sand away via the road constructed across the Wide Ride for that purpose. Excavators would (presumably) dump extracted sand into hoppers on the processing plant or, as work progresses, into hoppers on a conveyor system that progressively extends along the site. At 12 to 15 months per zone, the far end of the site (Zone 8) is reached in 8 to 10 years. Once excavation reaches the West end of the site, the direction of work reverses along the second, Southern, half of the site (starting with zone 9). Sand extracted from the Southern side of the site has to travel back to the processing plant along the Northern side. As a result, no restoration work eg landscaping with heavy plant is possible until several zones are excavated on the Southern side. For instance, to reinstate the Through the Forest bike track, it would be necessary to have excavated up to and including zone 15 and then completed landscaping and planting work on zones 1 to 15. The plant processing plant zone presumably needs to remain as-is until the end of the project. Thus the bike track could only open after 16 to 20 years – plus the time tken to landscape, plant trees, vegetation etc. Even then, the bike track would be passing through freshly planted trees: hardly exciting! Strangely, for access to the procesing plant it would seem zones 21, 20 and 19 would need to be excavated before zones 16, 17, 18. But it seems not. The apparent impossibility of starting restoration at an early stage means some current users of the forest won't see completion in their life time. And a lot more current users won't see maturity of vegetation on the site in their life times either.
It has to be said that we may have misunderstood what is planned for restoration: in which case it will be easy for the developer to demonstrate that we are wrong by providing information that should have been supplied during the years since planning permission was first sought.
More information from the developer is essential. It is therefore suggested that additional documentation be provided so as to clarify what is proposed and what is feasible in terms of restoration timing. Such documentation would include 3D renders of existing site, fully excavated site and restored site. In addition, it is suggested that dimensioned sectional drawings at key points on the site be provided for the above three phases. The project timing is not clear and a timetable of projected key events is necessary from pre-excavation work to maturity of planting and when public access is allowable.
Relationship of excavation zones and proposed restoration works
Tree restoration
The Ebblake end of the Purple Haze site
Trees are of course a major factor in restoration work. Areas of dark green in the restoration plan above show wooded areas. In some cases these would consist of coniferous and Scots pine woodland that was not part of the proposed clear-felling scheme. Other areas would consist of newly-planted mixed woodland which would, of course, require decades after planting to get to a reasonable state of maturity (fast-growing pine trees typically have a growth rate of 300 to 600mm per year and could take over 30 years to grow to typical house height). It has been suggested that public access to zones in post-restoration habitat-development would be restricted or disallowed. Is this correct we ask?