Phase 1 Desk Study and Environmental Risk Assessment · assessed as LOW to NEGLIGIBLE. The desk study has identified potential sources of contamination within Phase 1, Phase 3, Phase

Phase 1 Desk Studyand Environmental Risk Assessment

at North East Sector, Crawley, West Sussex

for Persimmon Homes Ltd and Taylor Wimpey Ltd

Report Reference : LP369 Report Date : 31st July 2012

LP369 North East Sector Crawley

TABLE OF CONTENTS

1 Introduction ..................................................................................................................................... 1

2 Environmental Setting .................................................................................................................... 2

2.1 Site Location and Description ............................................................................................ 2 2.2 Site History ............................................................................................................................. 2 2.3 Geology ................................................................................................................................... 5 2.4 Quarrying and Mineral Sites ............................................................................................... 6 2.5 Hydrogeology ......................................................................................................................... 6 2.6 Hydrology and Surface Water Resources ....................................................................... 6 2.7 Sensitive Land Uses ............................................................................................................... 7 2.8 Current Land Use ................................................................................................................. 7 2.9 Neighbouring Land Use ....................................................................................................... 7 2.10 Fuel Stations ........................................................................................................................... 7 2.11 Landfill and Waste ................................................................................................................. 7 2.12 Mining and Ground Stability ............................................................................................... 8 2.13 Other Regulatory Records ................................................................................................. 8 2.14 Radon ....................................................................................................................................... 9 2.15 Summary of Previous Investigation Reports ................................................................... 9 2.16 Phase 1 Environmental Desk Study Report ................................................................. 10 2.17 Crawley NE Sector New Neighbourhood – Contaminated Land Investigation . 11 2.18 Environmental Assessment Forge Farm Crawley ....................................................... 12 2.19 Validation Report of Forge Farm .................................................................................... 13

B Conceptual Site Model and Initial Environmental Risk Assessment .................................... 16

2.1 Conceptual Site Model ...................................................................................................... 16 2.2 Sources ................................................................................................................................. 16 2.3 Receptors ............................................................................................................................. 18 2.4 Pathways and Potential Pollutant Linkages ................................................................... 18

3 Conclusions and Recommendations for Further Work .................................................... 19

3.1 Conclusions ......................................................................................................................... 19 3.2 Recommendations for Further Work ........................................................................... 20

APPENDIX A – Figures

APPENDIX B – Landmark Envirocheck Report


EXECUTIVE SUMMARY

This report presents the results of a desk study and preliminary geo-environmental risk assessment including a review of the previous investigations that have been carried out on part of the site by others between 1997 and 2000. It is proposed to redevelop the site with mixed residential and commercial properties with areas of public open space, allotments and a school.

The site extends to approximately 108 hectares and is located on the north eastern side of Crawley, approximately 3km from the town centre with the M23 motorway to the east and the London to Brighton mainline railway to the west. It is proposed to redevelop the site in four phases.

Historically the majority of the site has been used for farming, and comprises undeveloped fields and some woodland. However Forge Farm located in the centre of the Phase 1 and 3 parts of the site was used as a Knacker’s Yard, Abattoir and Processing Works. This part of the site was remediated in 2000. An historic landfill is shown within the Phase 4 section of the site.

A gas holder, crematorium, railway line, motorway and industrial estate are all located in the immediate vicinity of the site. There is a landfill located off site to the east of Phase 4.

The site is mapped as being underlain by the Upper Tunbridge Wells Sand with Terrace Gravels along the western boundary of the site. Alluvium is mapped adjacent to the Gatwick Stream.

The site is underlain by a Secondary A Aquifer. The site is not situated within a Groundwater Source Protection Zone.

The nearest surface water feature is the Gatwick Stream running through the site between the proposed Phase 1 and Phase 3 parts of the redevelopment.

The majority of the site comprises open fields/woodland and has remained undeveloped during its recent history. The risk of contamination on the majority of the site is therefore assessed as LOW to NEGLIGIBLE. The desk study has identified potential sources of contamination within Phase 1, Phase 3, Phase 4 and in the vicinity of the site which may represent a risk to human health, however with appropriate remedial measures the risk would be reduced. The former abattoir in Phase 1 and 3 was remediated extensively in 1999 and in general the standards applied at that time are applicable at the present time.


Therefore the risk of contamination within this area is assessed as LOW to MODERATE, and overall may be classed as LOW subject to limited additional validation testing.

There is a possible LOW risk to the groundwater resource from any contamination on the subject site however this risk would reduce following remedial works. There is a MODERATE potential for made ground on site. There is a small landfill in Phase 4 and landfills located off site of Phase 2 and Phase 4 to the east therefore there is a MODERATE potential risk of land gas affecting parts of the subject site.

On the basis of the above, intrusive investigation into contamination issues for the proposed development will be necessary prior to redevelopment which can be carried out as part of the wider site investigations that will be required to provide geotechnical design parameters for the proposed construction.

This report has been prepared by Leap Environmental Ltd on the basis of information received from a variety of sources which Leap Environmental Ltd believes to be accurate. Nevertheless, Leap Environmental Ltd cannot and does not guarantee the authenticity or reliability of the information it has obtained from others.

Leap Environmental Ltd has used all reasonable skill, care and diligence in the design and execution of this report, taking into account the manpower and resources devoted to it in agreement with the Client. Although every reasonable effort has been made to obtain all relevant information, all potential contamination, environmental constraints or liabilities associated with the site may not necessarily have been revealed.

The conclusions reached in this report are necessarily restricted to those which can be determined from the information consulted, and may be subject to amendment in the light of additional information becoming available. These conclusions may not be appropriate for alternative schemes.

This report is confidential to the Client, and Leap Environmental Ltd accepts no responsibility whatsoever to third parties to whom this report, or any part thereof, is made known, unless formally agreed by Leap Environmental Ltd beforehand. Any such party relies upon the report at their own risk.

Signed :

Sarah Cook MSci

Countersigned :

Georgina Donbroski BEng MSc DIC


Date :

31st July 2012

Revision: Final


1 Introduction

Leap Environmental Ltd (hereafter referred to as LEAP) has been appointed by Persimmon Homes Ltd and Taylor Wimpey Ltd to undertake a Phase 1 desk study and preliminary risk assessment of a site referred to as North East Sector Crawley. The instruction was given in an email from John Childs of Persimmon Homes Ltd.

The site has been split into four phases for redevelopment as shown in Figure 1. The majority of the site is farmland. Phase 1 comprises fields in an area between Steers Lane on its eastern boundary, the Gatwick Stream on the western boundary and Radford Road on the northern boundary. Phase 2 is located between the M23 on its eastern boundary and Balcombe Road on the western boundary, and comprises fields and woodland with Phase 4 to the north. Phase 2A is located to the south of phase 1 and is currently a field. Phase 3 is located to the west of Phase 1 on the western side of the Gatwick Stream, with the railway line running along the western boundary, Radford Road to the north and Crawley Avenue to the south. Phase 4 is located north of Phase 2 and comprises fields with Toovies Farm on the southern boundary between Phase 2 and Phase 4 and some properties along Balcombe Road on the western boundary.

It is proposed that the eastern half of Phase 1 will be redeveloped with housing, a local centre and a school. The western half of Phase 1 is to be left as public open space. It is proposed to redevelop Phase 2 with housing and Phase 3 with housing, commercial, public open space and allotments. Phase 4 will be redeveloped with housing and commercial properties with playing fields on the southern boundary.

The objectives of this assessment are to:

Provide information on the environmental quality of the ground present on the site and summarise the extensive historic information on the site and

To assess the potential health and other environmental risks posed by the site to the proposed development and other specifically identified receptors and

To assess the potential for offsite contamination to adversely affect the proposed development.

This report includes a desk study which is based on the following sources of information

Envirocheck database report

Envirocheck historical map search

Interrogation of the Environment Agency web site on 19/07/12

Previous site investigation reports.


2 Environmental Setting

2.1 Site Location and Description

The site, extending to approximately 108 hectares is located on the western side of the M23 motorway, approximately 3.5km north east of Crawley town centre. The approximate National Grid Reference of the centre of the site, where Steers Lane and Balcombe Road meet is TQ 297 393.

2.2 Site History

The history of the site and surrounding area has been deduced from historical maps, historical aerial maps, and environmental searches.

2.2.1 Historical Map Evidence

2.2.2 Phase 1

1879 – 1:10,560 The majority of the phase 1 part of the site is shown as fields. Forge Farm is located on the centre of phase 1and the buildings are separated by a stream. Worth Park is located to the south of the Phase 1 and Phase 2a area with a large fish pond in the grounds. 1899 – 1:10,560 Additional buildings are now shown at Forge Farm. There has been some development along the road on the northern boundary of the site. 1912- 1:10,560 There are no changes to the site or surrounding area. 1919- 1:10,560 There are no changes to the site or surrounding area. 1946 – 1:10,560 There are additional buildings shown at Forge Farm. There has been further residential development to the east of Phase 1 along Radford Road. 1974-1979 – 1:10,000 There is an abattoir located close to the Gatwick Stream in the centre of Phase 1. A drain is shown close to the abattoir. A Crematorium is located in Forge Wood to the south of the site. A gas holder is located 50m off to the site to the south of Phase 1 and 3.


1983 -1:10,000 The abattoir has been extended to the south. Crawley Avenue has now been built to the south of the site with housing to the southern side of the road.

2006 – 1:10,000 No buildings, including the abattoir are shown at Forge Farm.

2012 – 1:10,000 There have been no changes to the site or the surrounding area.

2.2.3 Phase 2

1879 – 1:10,000 The map shows fields across Phase 2.

1887 – 1:2,500 Forge Wood is located off the western boundary of Phase 2. Properties forming Rickman’s Green are located off the western boundary. Heathyground Farm is located along the south western boundary of the site.

1898 - 1899 – 1:10,560 There are no changes to the site or surrounding area.

1962 - 1:2,500 Residential properties have been built to the south west along Barcombe Road. Sussex and Surrey Crematorium is now shown to the west of the Phase 2 area within the woods.

1974- 1975 -1:10,000 The M23 has been built along the eastern boundary of Phase 2 and the junction is shown on the section of site to the south of Phase 2.

1975 – 1:2,500 A refuse tip is shown to the east of the M23.

2.2.4 Phase 3

1879 – 1:10,000 The map shows fields across Phase 3 with a pond located in the centre of the western boundary. The Brighton Mainline railway runs along the western boundary of Phase 3.

1887 – 1:2,500 There are smaller fish ponds and springs marked to the south of the Phase 3 area of the site.

1897 - 1899 – 1:10,560 Gatwick Race course and Gatwick Station are located 1500m to the north of the site.


1912- 1:10,560 There are no changes to the site or surrounding area.

1919- 1:10,560 The pond along the western boundary is now smaller.

1946 – 1:10,560 There has been no change to this area of the site. There has been some residential development to the south west of the railway line.

1959 – 1:1,250 There have been no significant changes to Phase 3, there are a number of factories and works located to the west of the railway line. 1962 – 1:2,500 There is a works marked in a gap along the southern boundary between Phases 2 and 3. There are disused filter beds marked on northern side of the pond, to the south of Phase 3. 1963 -1:10,560 The pond along the western boundary is now called Ballast Hole. There have been no other changes to the site.

1969 – 1:2,500 There has been no change to the phase. There has been further development to the west of the railway line with further factories including a coal yard, a coal concentration depot, battery works, a plastics factory, printing works and electrical engineers closest to the railway line and western boundary of Phase 3.

1974-1979 – 1:10,000 There has been further development at Forge Farm, with additional buildings now located on the western side of the Gatwick stream as well as the eastern side of the stream.

1983-1988 – 1:10,000 There are works and warehouses shown immediately to the north and south of the Radford Road junction part of the site.

There are no further significant changes to Phase 3 or the surrounding area to the present mapping.

2.2.5 Phase 4

1879 – 1:10,560 The map shows fields across Phase 4 with Heathyground Wood located off site to the east. Toovies Farm is located in the centre of the phase. There is a road running along the western boundary of Phase 4.


1897 - 1899 – 1:10,560 There are 2 ponds shown around Toovies Farm. Heathyground Pond, located off site to the east extends across a small section at the southern end of Phase 4. There are a number of residential properties along the road to the north of the phase.

1933 – 1:10,000 There have been no changes to the site. There has been some residential development in Copthorne to the east of the site.

1968 – 1:10,000 Heathyground pond is now a small pond and the rest appears to have been filled in. There are houses to the south east of the site.

1975 1:10,000 The M23 has now been built along the eastern boundary and through the section of site to the south of Phase 4.

1992 -1:10,000 The A264 slip road to East Grinstead has now been built to the east of Phase 4.

2.2.6 M23 Junction The earliest historical map shows the motorway junction to be open fields and this remains as fields until 1972 - 1975 when the M23 is built.

2.3 Geology

The geology of the site has been ascertained by reference to the 1:50,000 British Geological Survey Sheet 302. The site is shown as underlain by Upper Tunbridge Wells Sand in the east, with River Mole Terrace Gravels overlying the Upper Tunbridge Wells Sand along the western boundary of the site. Alluvium overlies the Tunbridge Wells Sandstone close to the Gatwick Stream. Clay within the Upper Tunbridge Wells Sand outcrops along the northern part of the site close to the northern boundary of Phase 1, Phase 3 and Phase 4.

2.3.1 Alluvium The alluvium associated with the Gatwick Stream is an interbedded soft, locally very soft grey and grey brown silty clay and loose grey silty gravelly sand with pockets of sandstone gravel.

2.3.2 River Terrace Gravels The River Mole Terrace Gravels comprise predominately ferruginous Wealden siltstone and sandstone gravel and sands and are usually a maximum thickness of 3m.

2.3.3 Upper Tunbridge Wells Sand The Upper Tunbridge Wells Sand unit comprises a complex succession of interbedded thinly bedded silty mudstones, siltstones, silty sandstones and fine-grained sandstones which are laterally persistent over long distances. Sandstones, which form prominent scarp and dip


slope features, are typically fine-grained and quartzose, weathering to a pale yellowish grey or brown colour. They are locally ferruginous in the St Leonard's Forest area where three sandstone beds are sufficiently persistent to be named Shelly Plain Sandstone, Colgate Sandstone and Roffey Park Sandstone (Gallois and Worssam, 1993). Clay ironstone occurs locally, notably in the Horsham-Crawley area (Worssam, 1972). Here, grey and greenish grey silty mudstones and siltstones, red-mottled in part, dominate in the lower part of the unit, whereas pale grey to yellowish grey sandstone mostly appear in the upper part.

2.4 Quarrying and Mineral Sites

There is record of a mineral site located on the western side of Phase 3. This was for the removal of sand and gravel and has ceased operation. The quarry is now a lake.

There are a further four mineral sites listed within 250m of the site. The nearest is located 64m north east of the site and was an opencast pit for the extraction of ironstone. This has ceased production.

2.5 Hydrogeology

The bedrock across the majority of the site, where the Upper Tunbridge Wells Sand is outcropping is mapped as a Secondary A Aquifer (Minor Aquifer of Intermediate leaching potential). Where Clay within the Upper Tunbridge Wells Sand is outcropping, along the northern parts of Phase 1, Phase 3 and Phase 4, the site is mapped as unproductive strata.

The overlying superficial deposits across Phase 3 are also mapped as a Secondary A Aquifer.

The site is not situated within a Groundwater Source Protection Zone (SPZ).

2.6 Hydrology and Surface Water Resources

The nearest surface water feature is the Gatwick Stream running through the site. The Gatwick Stream runs along the boundary between the Phase 1 and Phase 3 parts of the site.

The centre of the site, along the western Phase 1 and eastern Phase 3 boundary is within an area at risk of flooding without defences (zone 3) with the eastern half of Phase 3, the western half of Phase 1 and the south west corner of Phase 2A are in an area at risk of extreme flooding without defences (zone 2) according to the Envirocheck report.

The Envirocheck database search indicates that there was one discharge consent located on site, revoked in 1992, for the discharge of surface water to a freshwater stream from the sewerage network. There are a further two discharge consents within 250m of the site, the nearest is 53m north east of the site and is for the discharge of final treated effluent into the Gatwick Stream from the crematorium.


2.7 Sensitive Land Uses

The site is mapped as situated within a Nitrate Vulnerable Zone. There is an area of adopted Green Belt 59m to the north east of Phase 4. A local nature reserve is located 71m south of the Phase 3 area of the site.

2.8 Current Land Use

The site currently comprises fields and woodlands with some farm buildings in the centre of Phase 4 and some residential and commercial properties along the western boundary of Phase 4. There is a pond along the western boundary of Phase 3 called Ballast Hole. The M23 Junction 10 and Radford Road Railway Bridge are included within the site for the purpose of the highway modifications.

2.9 Neighbouring Land Use

The Envirocheck database report lists numerous active contemporary trade entries within a 150m radius of the site as a whole, the most significant of which are listed below:

Contemporary Trade Directory Entry Distance from site

Direction from Phase

Bus and Coach Operators 83m W - Phase 3

Cemetery and Crematoria 108m SE - Phase 1

Bus and Coach Station 108m NW - Phase 3

Asphalt and Macadam Suppliers 109m W - Phase 3

Tyre manufactures and Distributors 109m W - Phase 3

Mechanical Engineers 109m W - Phase 3

2.10 Fuel Stations

There are no fuel stations listed within a 250m radius of the site.

2.11 Landfill and Waste

The Envirocheck report lists two historic landfills on site. Blackcorner Wood is a small landfill located on the western side of the Phase 4 area of the site and received waste, including inert waste, in 1980.

There are three historic landfills within 250m of the site listed below:


Landfill Waste Received Phase Distance from site

Direction

The Oaks Waste including inert waste

4 190 SW

Wakehams Green farm

-1985

Inert and Industrial 2 250m W

Heathy Ground Wood

1982 - 1989

Inert, Industrial Commercial and Household.

This landfill is also listed as a local authority landfill site

2 215m N

There is also a local authority landfill listed on site, within the Phase 4 area, to the south of the historic landfill. The Envirocheck database has no further information on the landfill however this appears to correspond with the location of the historic Blackcorner landfill.

There are four registered waste transfer sites located within 250m of the site. The nearest is 30m south west of the site.

There is a licensed waste management facility located 245m south west of the site for the treatment of waste to produce soil.

2.12 Mining and Ground Stability

The Envirocheck database indicates that there is a low risk of ground stability hazards on site.

There are records of mining for iron in the local area, with Forge Farm highlighted as an Iron Age foundry and forge. Bell Pits have been identified to the south of the site, on the southern side of Crawley Avenue and therefore there is a possibility of a mining hazard on site, particularly infilled bell pits.

2.13 Other Regulatory Records


The Envirocheck Report indicates that there is one Local Authority Pollution Prevention and Control listed within the Phase 1 area of the site at the former Forge Farm. This is for air pollution control at Crawley Abattoir and is listed as Revoked.

The Envirocheck report indicates that there are records of four pollution incidents to controlled waters on site.

Three of the pollution incidents are located within the Phase 1 area of the site. These are all listed as category 3 minor incidents that occurred between 1990 and 1998. There is also a pollution incident located within Phase 3; this is listed as a category 3 minor incident for the discharge of oils to the Ballast Hole in 1998.

Given the date of the incidents and that they were all classified as category 3 – minor incidents it is unlikely they will have had any long term impact on the site.

2.14 Radon

According to the Health Protection Agency the site is not in an area for which radon protection measures are required (refer BRE report: Radon – Guidance on protective measures for new buildings. 2007 edition).

2.15 Summary of Previous Investigation Reports

The area known as Forge Farm, within the Phase 1 and Phase 3 parts of the site has been the subject of previous desk study and intrusive investigation reports. The Forge Farm site was demolished and remediated between 1999 – 2000 and a validation report was produced for this work.

The previous reports are as follows:

Phase 1 Environmental desk Study Report, Crawley North East Sector, Crawley, West Sussex for Crawley North east Sector Land Owners Consortium by Graham Consulting group in May 1997, Reference CHP102544300.

Crawley NE Sector New Neighbourhood Contaminated Land Investigation for Beazer Homes by WSP Environmental Ltd in August 1998, Reference 80129/R

Environmental Assessment Forge Farm Crawley for Beazer Homes Reigate Ltd by Waterman Environmental in March 1999, Reference R/EN1329.AG.1.1.8

Validation Report, Site Remediation and Demolition Works, Forge Farm, Steers Lane Crawley for Beazer Homes Ltd in December 2000, Reference R/EN1329.RS.3.1.6


2.16 Phase 1 Environmental Desk Study Report

A Phase 1 Environmental Desk Study Report was carried out by Frank Graham Consulting Engineers Ltd in May 1997 (Ref CHP/102544/300). This report covers all four phases of the site but focuses on Forge Farm.

As part of that study, a walkover was carried out in April 1997 across the site. At that time Forge Farm was occupied by Crawley Abattoir Sussex Limited, a knacker’s yard and processing works, including an incinerator. These activities were housed in various buildings, outbuildings and stables. It was reported that the area of the knacker’s yard comprised apparently disused and partially collapsed stables of brick and wood construction. In the area of the stables there were piles of animal hides and blood staining on the concrete floor.

The incinerator comprised a portal frame building with iron cladding. Fuel tanks and skip containers containing animal wastes were located near the abattoir entrance and incinerator.

The areas around the Knacker’s Yard, incinerator and internal roads were littered with various old cars, scrap metal and pallets along with numerous fuel tanks and drums and bags of chemicals.

To the east of the abattoir there were various properties which comprised Forge Farm farmhouse and other houses. To the west of the Gatwick Stream, beyond the abattoir building was a World War II anti-aircraft gun emplacement and lookout tower. To the south of the World War II building there was a large grassed mound, possibly a World War II defence structure approximately 200m in length and 2m in height running in a northeast-southwest direction.

The area to the south of the abattoir comprises open farmland and wooded areas with a gas holder to the south. The embankment of Crawley Avenue forms the southern boundary of the site.

The remainder of the site was occupied by fields and bounded to east by the M23. There are various drains and ditches crossing the site which flow to the Gatwick Stream.

The walkover also identified potential contamination sources around the abattoir and slaughter house including:

Oil Spills

Bags of fertilizers

Chemicals in drums

Car batteries

Organic wastes including animal blood

Scrap metal

Asbestos cement sheeting


In the area around Toovies Farm (Phase 4) there were numerous fuel tanks, oil cans and drums with obvious signs of spillage.

2.17 Crawley NE Sector New Neighbourhood – Contaminated Land Investigation

A contaminated land investigation was carried out by WSP in August 1998 (ref 80129/R). This was carried out across the proposed Phase 1 and Phase 3 parts of the current site.

A total of 14 window sample boreholes and 97 trial pits were excavated up to 4m below ground level across the site in 50m grid spacing. Monitoring wells were installed in eleven of the window sampler boreholes for groundwater and gas monitoring.

The soils encountered comprised made ground, particularly in the vicinity of the abattoir over Alluvium, which was encountered adjacent to the Gatwick Stream up to 3.3m deep over Upper Tunbridge Wells Sand which was encountered across the site. The Upper Tunbridge Wells Sand comprised silty clay underlain by siltstone or mudstone. Groundwater was encountered in some of the trial holes between 0.5 – 2.5m depth in the Alluvium in the vicinity of the Gatwick Stream.

A significant amount of made ground was noted in the main abattoir area, up to 2.6m deep of silty clay made ground with much ash, clinker, foundry slag, brick, concrete, metal, glass and wood. The bund to the south of the World War 2 structure was noted to generally comprise loose brown sandy clayey silt with much flint gravel with clinker, ash, tarmac, wood, scrap metal, glass and brick fragments.

A number of the holes were noted to have occasional animal bones at the surface and within the near surface soils. Testing for anthrax was negative.

Elevated levels of heavy metals (arsenic, mercury, cadmium, nickel, zinc and copper) were encountered in the near surface made ground soils around the abattoir. Localised elevated levels of total petroleum hydrocarbons were also encountered around the abattoir and were thought to be a result of leakages from tanks and spillages.

The groundwater samples tested were not found to contain significant levels of the compounds tested.

The report recommended that the upper 500mm of spoil within the abattoir area of the site should be removed, including any drains or structures encountered. This would also allow the identification of oil hotspots. Any voids should be infilled with suitable imported fill and the abattoir area covered with 300mm of topsoil.


2.18 Environmental Assessment Forge Farm Crawley

An Environmental Assessment Report was carried at Forge Farm for Beazer Homes in March 1999 by Waterman Environmental (Ref R/EN1329.AG.1.1.8). The primary purpose of which was to assess the potential environmental and health risks to the site owners and site clearance and demolition contractors at Forge Farm and the associated abattoir, knacker’s yard and processing works.

The Forge Farm site, prior to demolition and remediation, comprised a number of vacant industrial buildings including an abattoir, stables, knacker’s yard, processing works and some residential buildings surrounded by open grassland.

The report indicates that planning permission for expansion at the animal processing works between 1955 and 1992 included the addition of a boiler house, a building for offal cleaning and dressing, a processing plant, a building for hides, skins and fellmongering and an extension to the boning and packing rooms.

On the eastern side of the Gatwick Stream were residential properties, a slaughterhouse/abattoir and old knacker’s yard. On the western side of the stream are the processing works and a new knacker’s yard. There was also a stock car race track.

An assessment of the concerns on site included:

The presence of offal in the cold stores, animal remains (skin hair legs tails) tanks containing oils and processed animal wastes.

Animal remains, bones, hair and skin, rendered fats in drums and on ground, burnt animal remains, oil in storage tanks and DDT which was found in Forge Farm garage along with other veterinary medicines and chemicals.

The abattoir closed down in December 1998.

As part of the study a number of agencies were contacted for information on the site Crawley Borough Council, MAAF and the Environment Agency all supplied information,

Crawley Borough Council Environmental Health had a number of concerns about the site including:

Potential ash deposition from incinerator

Potential ground contamination from the use of some land for stock car racing

The fact that animal blood spreading had taken place on land by Steers Lane.

Limited evidence that anthrax cows had been incinerated and the ash buried on site.

Crawley Borough Council Planning Department were also contacted. Between 1950 and 1998 over 60 planning applications relating to expansion of the animal processing works and other proposed uses had been made.


A letter from Environmental Health included in the planning files indicated that less than 2% of the cattle incinerated were suffering from BSE.

A letter from MAFF contained in the report dated 10th March 1999 indicates that they have no record of any animal carcase burial on site.

A very limited intrusive investigation was carried out in the mounds to the south of the buildings on the eastern side of the Gatwick Stream. In one excavation metal drums with animal fat, bone and hair were encountered. An area of poor vegetation growth was also investigated and found to contain a depression infilled with soil, brick rubble and bone meal. No significant animal remains were discovered by the limited intrusive investigation carried out.

2.19 Validation Report of Forge Farm

The remediation of the Forge Farm area of the site was carried out between November 1999 and July 2000. These works were designed to reduce the perceived environmental and health risks associated with the former abattoir knackers yard and processing works (including incinerator).

The works included the removal of all surface contaminated material from the central area of forge farm and an investigation into the potential of any buried anthrax contaminated remains, the removal of surface rubbish and any identified soil contamination.

Prior to demolition buildings were located on both sides of the Gatwick Stream (in both the Phase 1 and Phase 3 area of the site).

The report suggests that the incinerator was used to destroy cows infected with BSE, and according to MAFF, most of the cattle, which would have arrived dead would have been confirmed as positive cases. However the animals arrived in sealed lorries and were then generally incinerated whole, any blood was mixed with straw and also incinerated meaning the risk of any residual BSE (prion protein) contamination was rated as low

Asbestos containing material was present in many of the buildings across the site mainly in roof sheets and wall panels. Amosite was found in the Old Knackers Yard, in the processing works and in one of the residential buildings.

Further investigation with regard to blood spreading on the land close to Steers Lane confirmed there were no records of the required license to carry this out and furthermore the previous owners had confirmed to MAFF that they had never spread blood on the land.

The remediation that took place across Forge Farm comprised the removal of all animal remains encountered. These were treated as biohazardous and securely bagged and removed for incineration. All buildings were also disinfected prior to demolition. The hardstanding and all surface soils were removed to a depth of 200mm so that the underlying natural soil was exposed.


Two animal processing waste tanks which were located adjacent to the Gatwick Stream were removed to landfill.

Two underground brick chambers in the vicinity of the abattoir were found to contain brick rubble and some standing water. Once the water had been removed the structure and any contaminated clay surrounding the structure was removed and disposed of to landfill.

A site strip of the upper 200mm of soil was carried out across the farm. The total volume of material disposed off site from the surface strip of the processing works and knacker’s yard was 2775m3. An area of ash to the west of the perimeter fencing of the processing works was excavated also to 0.2m.

During the ground works a number of areas around former oil tanks were found to be visibly contaminated with hydrocarbons. This material was excavated and the excavations validated.

Unconfirmed anecdotal evidence from a former employee had indicated that the potential anthrax infected animal remains may be buried on site. Two samples of the made ground were taken from each of the suspected locations and sent for testing. No anthrax spores were detected in either of the samples.

Validation sampling was carried out across the stripped levels. A total of 58 samples were tested and the results have been reanalysed to current soil guideline values as shown in the table below:

Determinant

mg/kg

Arithmetic Mean

(mg/kg)

UCL U95

(mg/kg)

Evidence Level

%

Tier 1 GAC

Residential with plant

uptake

Samples which exceed GAC

Arsenic 11 14 100 32 None

Cadmium 1.3 2.5 100 10 None

Copper 42 66 100 2330 None

Lead 59 86 100 450 None

Mercury 0.6 1.2 100 170 None

Nickel 29 39 100 130 None

Zinc 135 199 100 3750 None


At the completion of the validation works all buildings and foundations, drainage and hardstanding had been removed from the central areas along with tanks and underground chambers. This part of the site had been stripped and any additional sub surface contamination removed. Anything considered unsuitable to remain in situ but not contaminated was also removed.

In the open field areas, soil mounds including the soil mound to the south of the World War II building and stockpiled waste was removed and an isolated sub surface pocket of contamination was removed. Items dumped in the Gatwick Stream were also cleared.

The report stated that any domestic garden areas located on this part of the site may require additional remedial action.

A plan showing the remediated areas is attached as Fig 3 Appendix A.


B CONCEPTUAL SITE MODEL AND INITIAL ENVIRONMENTAL RISK ASSESSMENT

2.1 Conceptual Site Model

A risk based approach is used to assess contaminated or potentially contaminated land within the UK. For a potential risk to exist then there must be in place a pollutant linkage, i.e. there must be a source of contamination, a potential receptor and a pathway linking the two. The purpose of the Conceptual Site Model, in this instance, is to identify all of the potential pollutant linkages, by considering in turn, the potential sources, receptors and pathways.

2.2 Sources

2.2.1 Onsite Sources The following potential sources of contamination have been identified on site:-

Source Phase Contaminants of Concern

Abattoir (Remediated 1999 – 2000)

1 Heavy metals, Total Petroleum hydrocarbons (TPH), Polyaromatic Hydrocarbons (PAHs) Asbestos, Anthrax, Animal waste, solvents.

Processing Plant (remediated 1999 – 2000)

3 Heavy metals, solvents, TPH, PAH, pathogens, land gas, asbestos, anthrax

Car racing/storage (remediated 1999 – 2000)

1 Heavy metals, TPH, PAH

Agricultural land ALL Heavy metals, Pesticides

Land fill 2 and 4 Heavy metals, asbestos, petroleum hydrocarbons, VOCs, SVOCs, Land gas

Made Ground All Heavy metals, PAH, land gas

An abattoir, knacker’s yard and processing works with incinerator were located in the former Forge Farm on the Phase 1 and Phase 3 areas of the site. This area of the site has been remediated between 1999 – 2000 with a 200mm strip of soils being removed from this area of the site along with the removal of any hydrocarbon impacted soils identified around fuel storage tanks and ash deposits. The results of the validation testing have been


compared to current soil screening values and indicate that the soils are free from significant contamination with respect to the contaminants tested, as such it is likely that any residual soil contamination present will be limited.

There is record of a historic landfill on site that has potentially received household waste. The date of input is recorded as 1982 and is therefore may still be actively gassing. Possible made ground may also be encountered across the site, particularly around former farm buildings which may be a source of landfill gas.

2.2.1 Offsite Sources The desk study has highlighted some current and historic commercial land uses in the vicinity of the site. The most significant potential off site sources of contamination are listed below:

Source Distance from Site (m)

Contaminants of Concern

Gas Holder 4m

(Phase 1 and 2A)

Heavy metals, asbestos, petroleum hydrocarbons, VOCs, SVOCs, Chlorinated Solvents, Asbestos

Crematorium 108m

(Phase 1 and 2)

Heavy metals (mercury), asbestos, petroleum hydrocarbons, VOCs, SVOCs

Railway Line Western Boundary (Phase 3)

Heavy metals, TPH, PAH

M23 Motorway 2 and 4 Heavy metals, TPH, PAH

Historic Landfill Eastern boundary (Phase 2 and 4)

Land gas, heavy metals, TPH, PAH, leachate.

Generally migration of contamination from the above off site sources would be via the groundwater/land gas migration pathways.

The crematorium is located between Phase 1 and Phase 2 part of the site. The risk of contamination from this source is unlikely, however it has been present since 1962 and it is possible that there may have been historic contamination from ash deposits across the southern part of Phase 2.

There are a large number of factories and engineering works located to the west of the site however given the presence of the railway line embankment and the geology of the site it is


considered unlikely that significant contamination from these sources would migrate onto the site.

Potential off site sources of land gas have been identified as the landfills to the east of Phase 2 and 4, the closest of which was infilled up to 1985 and therefore it may still be actively gassing.

The M23 is a potential source of heavy metal and petroleum hydrocarbon contamination however given there is an undeveloped zone between the motorway and Phase 2 and Phase 4 it is unlikely to be a source of contamination. The railway, along the western boundary of Phase 3 is also a potential source of contamination, but similarly low in risk for the aforementioned reason.

2.3 Receptors

The site is to be redeveloped with mixed land uses including residential properties, allotments and a school.

The closest surface water feature is the Gatwick Stream running through the site and Ballast Hole pond on the western boundary of the site. There are also numerous drainage ditches and small unnamed streams located across the site.

Potential Receptors are therefore summarised as follows:

Future occupants of the site,

Construction workers

Groundwater (Secondary A Aquifer)

Surface Water (Gatwick Stream, Ballast Hole, drainage ditches and streams)

The material construction of the buildings themselves.

2.4 Pathways and Potential Pollutant Linkages

The proposed residential end use is considered to be one of the most sensitive end uses. The majority of the site has a history of use as farmland/open fields and as such the potential risk of significant contamination being present is considered to be low to negligible for the majority of the site. However, several potential sources of contamination have been identified within the site boundary. These sources are shown in Fig 2 Appendix A

The Forge Farm abattoir was situated within Phase 1 and 3 of the site. The risk of significant pollutant linkages involving human health from the abattoir and associated uses would be rated as Low, as whilst contamination was identified within the Forge Farm site during the previous intrusive investigations, this part of the site was remediated in 1999 - 2000.


While the Phase 4 area of the site is close to the M23 there is a buffer between the residential development and the motorway therefore the risk of contamination from the motorway is likely to be low to negligible.

A historic landfill has been identified on the western side of Phase 4. The nature of the backfill is unknown. Any made ground may be a potential source of contamination, and at this stage a moderate risk of impact on the proposed development should be assumed pending intrusive investigation and monitoring.

The site is underlain by a Secondary aquifer. Hence there is a potential pathway for leachate from soil pollutants and for mobile liquid contaminants to enter the groundwater. However, the site is not situated within a Source Protection Zone. In addition, the shallow soils on site will likely comprise relatively impermeable clays and silts. Therefore the risk of significant pollutant linkage involving the subject site and local groundwater is rated as low.

The Gatwick Stream is located along the boundary of Phase 1 and Phase 3. The abattoir, knacker’s yard and processing plant located adjacent to the stream have been remediated, there has been no other development close to the river. The other surface water features located on site are not located in areas that have previously been developed. The risk of contamination to surface water is therefore considered low.

An historic landfill has been identified in Phase 4 and also adjacent to the eastern boundary of Phase 4. On the basis of the information gathered to date the risk of landfill gas migrating to Phase 2 and 4 is considered moderate. Made ground was also encountered in Forge Farm in the Phase 1 and Phase 3 areas of the site during previous investigations however this was removed as part of the remediation. Some made ground may be encountered in other areas of the site however the risk of land gas migration across the remainder of the site is low.

Construction workers are at risk as a result from direct contact/ingestion of soil and inhalation of dust. These risks may all be mitigated by applying the appropriate health and safety precautions on site.

Construction materials and the building itself are at risk from direct contact with organic contaminants and sulphates.

3 Conclusions and Recommendations for Further Work

3.1 Conclusions

Potential on site and off site pollutant linkages have been identified. The site has a history of use as farmland with an abattoir, processing works and knacker’s yard located within the Phase 1 and Phase 3 part of the site. Remediation has been carried out to this part of the site however further investigation is recommended in this area to ensure it has been


remediated appropriately for the final sensitive residential land use. There are records of landfilling in Phase 4 and the previous investigations have identified some potential sources of contamination around Toovies Farm and therefore intrusive investigation will be required in these areas.

The majority of the site comprises open fields/farmland. There is therefore the potential for pesticide contamination to be present on site, although from previous experiences the risk is considered low.

Potentially infilled land has been identified in the vicinity of the site. As part of the detailed design, gas monitoring will be required.

3.2 Recommendations for Further Work

A full phase II site investigation report will be required for the redevelopment of the subject site to provide geotechnical design parameters. With regard to the environmental issues detailed above, the intrusive investigation should target the potential point sources of contamination the landfill and Toovies Farm in Phase 4, the remediated abattoir, processing plant and knacker’s yard in Phase 1 and Phase 3, the motorway and railway along the eastern and western boundaries and to get a good coverage across the remainder of the site. Gas monitoring will also be required.

Contamination testing at this stage should include for a broad suite of contaminants including asbestos, heavy metals, pesticides, polyaromatic hydrocarbons (PAH), volatile and semi volatile organic compounds and petroleum hydrocarbons (TPH).


Figures

APPENDIX A

Site

Crawley NE Sector Client

Persimmon Homes Taylor Wimpey

Project ID

LP00158

Figure No.

1 Title Phase Locations

Site



Project ID

LP00369

Figure No.


Forge Farm – See Fig 3

Landfill

Toovies Farm

Site



Project ID

LP00369

Figure No.



Landmark Envirocheck Report

APPENDIX B

Documents

Phase 1 Desk Study and Environmental Risk Assessment · assessed as LOW to NEGLIGIBLE. The desk study has identified potential sources of contamination within Phase 1, Phase 3, Phase