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BROCKWELL PARK - AGRONOMY REPORT

Agrostis Sports Surface Consulting

Tel: 01359 259361 E-mail: [email protected] Website: www.agrostis.co.uk

Agrostis Sports Surface Consulting aims to assist clients in matters concerning sports surfaces. All recommendations are offered free of bias. Agrostis has no commercial connections or obligations to any manufacturer, supplier or contractor.

Agrostis Turf Consultancy Ltd. Registered office: Eldo House, Kempson Way, Bury St Edmunds, Suffolk, IP32 7AR. Company No: 6675140. VAT Reg No: 889 4960 43.

23 May 2018 TAL

BROCKWELL PARK - FIELD DAY ADVISORY REPORT

1 INTRODUCTION ...... 1 2 EXISTING CONDITIONS ...... 2 2.1 Brockwell Park Gardens ...... 2 2.2 The Event ...... 3 2.3 The assessment ...... 4 2.4 Ground cover ...... 5 2.5 Soil profile ...... 6 2.6 Drainage ...... 7 2.7 Geology and soil type ...... 8 3 DISCUSSION ...... 9 4 CONCLUSION ...... 11

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1 INTRODUCTION

An advisory visit was requested to assess the general ground and surface conditions from an agronomic perspective of the area of a public park to be used for a significant outdoor event. The event is to take place between 1 and 3 June 2018. Site construction had commenced on the day of the visit, 21 May. The site was to be cleared by 10 June 2018.

The event was to take place over an area of Brockwell Park Gardens, , south east . Appraisal before the event was necessary partly in order to pre-determine what measures should be undertaken beforehand and to anticipate what renovation procedures are likely to be required to restore the ground conditions afterwards to their previous state.

Agrostis’ employer is… Waxarch Ltd 30 Leicester Square London WC2H 7LA

… and the report was commissioned by , Operations Manager of BroadwickLive.

Camden Wharf 28 Jamestown Road London NW1 7BY

The site inspection was undertaken on 21 May 2018 in the company of , Site Manager and .

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2 EXISTING CONDITIONS

2.1 Brockwell Park Gardens

Brockwell Park is a 50.8 hectare (125.53 acres) park located between , and in . The nearest post code is SE24 9AF. It is bordered by the roads Brixton Water Lane, Norwood Road, Tulse Hill and Dulwich Road.

The park commands views of the skyline of the city and , and hosts almost 4 million annual visits. At the top of the hill within the park stands Brockwell Hall.

The entirety of Brockwell Park is a Site of Importance for Nature Conservation (SINC) of Borough Importance (Grade I), with mature trees including ancient oaks, substantial lawn areas set to meadow, and a series of lakes. As well as adding to the landscape value, these support a variety of birds and bats. The Park’s eighteenth century agricultural past may still be discerned in the hedge lines and mature oak trees.

Brockwell Hall was built between 1811-1813. The land and house were acquired by the and opened to the public in 1892. In 1901, the LCC acquired a further 43 acres (17 ha) of land north of the original park. In the 1920s, there were 13 cricket pitches in the park. During World War I it is recorded that Brockwell Park grazed a large flock of sheep. During World War II, three sites in the Park were set aside for wartime food production.

Figure 2-1 Brockwell Park entrance display

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Brockwell Park - Field Day

2.2 The Event

The Event requires the enclosure of a part of the Park shown in the Google Earth image of Figure 2-2. This represents an area of approximately 14.41 hectares.

Figure 2-2 Area occupied by the Event

The Event plan, shown in Figure 2-3, was provided. This indicates the location of various features to be incorporated including 5 stages, numerous bars and eating establishments, toilets, VIP areas etc.

Figure 2-3 Event plan (reduced version of provided drawing)

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Brockwell Park - Field Day

2.3 The assessment

The assessment of ground conditions was undertaken by means of a walk over the area of the Event, noting features of the ground cover and possible soil-related factors. The route taken over the site is shown in Figure 2-4, shown on both Google Earth imagery and the Event plan.

Figure 2-4 Route of observation walk

In addition to the general observations made during the walk itself, ground cover and species composition was assessed by eye and photographed at each of the 13 locations shown in Figure 2-5. The soil profile was also examined at the location shown.

Figure 2-5 Ground cover assessment and excavation locations

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Brockwell Park - Field Day

2.4 Ground cover

The ground cover of areas subject to regular mowing and not subject to such mowing were examined. Typically, areas of longer grass are maintained along the boundaries of the various fields and within more heavily wooded areas. One area, that had been left to grow and in which a daffodil colony had been maintained, it was assumed would be mown at some point, the daffodil flowering season having come to an end.

The mowing regime and an indication of the extent of ground cover, provided by both grass and broad leaved species, is shown in Table 2-1. Note that all of the un-mown sampling locations were assessed as supporting 100 % ground cover.

Assessment Mowing regime Notes location 1 Un-mown 2 Un-mown 3 Un-mown 4 Un-mown Daffodil colony 5 Mown 60 % ground cover 6 Mown 100 % ground cover 7 Un-mown 8 Mown 75 % ground cover 9 Un-mown 10 Mown 100 % ground cover 11 Mown 100 % ground cover 12 Mown 40 % ground cover 13 Mown 40 % ground cover

Table 2-1 Ground cover status of the 13 assessment locations

Examples of the appearance of the sward are shown in Figure 2-6.

The great majority of the site supported a full cover of healthy grass, often growing quite vigorously, as determined by the quantity of grass clippings left by the last mowing operation.

The areas around sampling points 5, 8, 12 and 13 provided examples of the lower ground cover north and south of the copse in the large, northern field.

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Brockwell Park - Field Day

Figure 2-6 Example ground cover samples, (clockwise from top left - 2, 5, 11, 12)

The species represented in the sampling points included perennial ryegrass which was present in all of them, generally the main contributor to ground cover where a full cover of mown grass occurred. Annual meadow grass tended to be found in the mown areas of reduced ground cover and Timothy and rough-stalked meadow grass occurred in some areas showing signs of prolonged wetter conditions, notably to the north of the site.

White clover was apparent in most locations and red clover in many of the areas of un-mown grass. Also common in mown areas was dandelion, and plantain, their abundance often increasing as ground cover generally declined. Buttercup was also noted in some areas likely to be wetter.

2.5 Soil profile

Examination of the soil profile at the point indicated in Figure 2-5 showed a well-structured, organic sandy loam that extended to approximately 250 mm and contained few stones. A layer of fibre, around 20 mm, had accumulated in the surface at a location where grass cover was dense and vigorous. The topsoil also supported a good deal of worm activity.

This overlay a sandy clay with gravel and larger stones.

The profile was relatively dry throughout the depth of the excavation.

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Brockwell Park - Field Day

Figure 2-7 Excavation profile

2.6 Drainage

Along the entire route of the site investigation, no waterlogged or even generally wet ground conditions were encountered. It was reported, however, that the area to the north of the copse in the large northern field, and to a lesser extent to the south of this, was prone to waterlogging during the winter months in particular.

Evidence of a field drainage system was apparent in the large northern field and in that to the east of this. The lines of land drains could generally be discerned in the dry grass and in the light of this the plan of possible drain trench locations shown in Figure 2-8 was drawn up. There is a certain amount of guesswork here but the likelihood of three herringbone drainage systems being installed at some stage in the past, with laterals at approximately 20 metre centres, seems fairly great. At least one inspection chamber was noted almost certainly to be associated with this system.

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Brockwell Park - Field Day

Figure 2-8 Estimated location of main and lateral land drains

Figure 2-9 Appearance of land drains

2.7 Geology and soil type

The British Geological Survey has classified the solid geology on which the northern part of the Park is located as being of the London Clay Formation - Clay And Silt. Sedimentary Bedrock formed approximately 48 to 56 million years ago in the Palaeogene Period. Local environment previously dominated by deep seas.

The superficial or drift deposits are described as Head - Clay, Silt, Sand And Gravel. Superficial Deposits formed up to 3 million years ago in the Quaternary Period. Local environment previously dominated by subaerial slopes.

Unfortunately, the Soil Survey of England and Wales does not record the soil type due to its predominantly urban setting.

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3 DISCUSSION

Soils and grass surfaces respond differently to the processes of wear and compaction depending on their moisture content. At the time of the site appraisal, and during the course of the Event, it is more than likely that the soil profile will remain dry and firm in all locations. Any but the most torrential rain falling over this period will be absorbed at or near the point of impact by the dry, cracked and pervious topsoil. Consequently, the structural qualities of the topsoil are unlikely to alter significantly as a result either of rainfall or of the footfall that can be expected to pass over it.

Very intense rainfall, that is significant storm events, will tend to run over the surface and accumulate in low-lying or generally flat areas. All of the Event features appear to be located on, sometimes quite steeply, sloping ground. Storm event rainfall is likely therefore, if it is not absorbed at the point of impact, to runoff to locations not included in the Event and in the manner it would do when no activities are taking place in the Park at all.

Note that these very positive predictions would not apply were the event to be taking place during the winter. At that time the soils will be at or approaching saturation and would behave very differently. They would be much more prone to compaction and far less able to absorb water following even relatively light rainfall events.

Due to the arrangement of the Event features, the area to the north and south of the copse in the main field to the north may be subject to higher levels of wear than elsewhere in the Park. This area was also reported to be prone to poorer drainage qualities, a phenomenon that becomes apparent during the winter months. This has almost certainly contributed to the areas of locally reduced ground cover that exist here. Also, it is not unlikely that soil structural qualities will have been adversely affected. This may result in slower permeation of rainwater and the consequential increased likelihood of more significant runoff following major storm events. This had been anticipated by the Event organisers, however, and it was reported that mechanical aeration work was scheduled to be undertaken at some point beforehand. Verti-draining of this area of the Park in particular should be sufficient, provided it is accomplished with appropriate intensity, to mitigate against the possible consequences of intense rainfall taking place during the Event.

It was interesting to note the existence of land drains in the northern part of the Park. Those land drains are probably very old and so their condition may be somewhat questionable. The spacing of the laterals, approximately 20 metres, is also too wide to intercept sufficient ground-water to make a very substantial difference to the performance of the surface during the winter months. However, the system will be achieving some positive effects at that time of year. At all other times the pipes will, in all probability, remain completely dry. If there were an intention to improve the accessibility of this part of the Park during the winter months it is likely that the incorporation of an improved and extended pipe drainage system would be very effective. Such a system would also enhance the effectiveness of measures taken in relation to the topsoil to improve drainage at other times of the year, should such improvements be called for.

Turning to the consequences of covering the ground for a period of what could be up to 19 days, it is certain that this will affect the health of the grass. Structures that do not allow any air movement

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Brockwell Park - Field Day

at all to take place over the grass leaves, for example a metal plate, will probably kill the grass over this time period. Most ground protection structures have a small space between the actual surface that is trafficked over and the ground and this will improve the survival chances of the grass very considerably. When all of the Event features are removed, by 10 June, what is likely to be seen is a patchwork of various degrees of pale, thinner ground cover with smaller, scattered, areas (probably less than a metre across) of dead grass and exposed soil. Ironically, wet weather would then accelerate the recovery of the affected grass, most of which should eventually achieve a full recovery, possibly within just a few weeks. A period of drought would slow this recovery however.

Areas of dead grass, and of course bare ground, would require over-seeding in order to restore ground cover. In this respect, the timing of that over-seeding work would be very significant. Such work should take place in mid August in order to maximise the success of establishment. At that time intense heat sufficient to kill young seedlings is unlikely to be experienced, significant rainfall can be anticipated and yet ground conditions will still be warm; ideal circumstances to maximise seed germination and establishment.

The most effective approach would be to review the condition of the site once more some three or four weeks following the Event to determine the nature and extent of any renovation works that may be required. Note that, apart from the resumption of mowing, there are no operations that would be appropriate or effective to be carried out during the weeks immediately following the Event.

Over-seeding work need only be carried out on affected areas. It is worth pointing out, however, that it could be extended to cover the areas that are already thinner due to the effects of winter saturation as discussed above. This would increase the area requiring the work very considerably but the consequences for the Park as a whole would be very beneficial, particularly in association with the verti-drain work that will also be undertaken.

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4 CONCLUSION

In conclusion;

• It is unlikely that the Event will have any consequences for the ground cover of the Park that cannot be fully rectified within the remainder of the current growing season, before, say, November. • Most of the consequences will be resolved within a few weeks of the Event. • At that time, a review of the site to determine appropriate renovation works would be appropriate. • Verti-draining prior to the Event will be very helpful in accelerating the recovery and mitigating against the effects of intense rainfall taking place during it. • A provisional requirement to carry out over-seeding of thin and bare ground that has persisted until mid August would be appropriate.

Longer term observations include:

• The incorporation of a more substantial and appropriately designed pipe drainage system would greatly enhance the amenity value of the northern sections of the Park during the winter and early spring. • In association with appropriately timed aeration work, a more extensive over-seeding of certain areas of the Park would lead to significant improvements in the appearance and amenity value of the surfaces.

Signed:

Director Agrostis Sports Surface Consulting

23 May 2018

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