For: The Trustees of the Estate of the Late Ronald Marsland Heap

Transcription

1 DESK STUDY AND SITE INVESTIGATION REPORT Site at Fowlers Farm Black Lane Nateby Nr. Preston. Survey Date: 06 th April Weather Conditions: Mixed sun/showers For: The Trustees of the Estate of the Late Ronald Marsland Heap CONTENTS 1 SCOPE 2 SITE LOCATION & PROPOSALS 3 SITE HISTORY 4 EXISTING CONDITIONS 5 SUB-SOIL SURVEYS 6 CONTAMINATION/RADON/FLOOD RISK 7 PRELIMINARY CONCEPTUAL SITE MODEL (CSM) 7.1 GENERAL 7.2 GROUND CONDITIONS 7.3 CONTAMINATION 7.4 HAZARDOUS SOILS & GASES 7.5 SUMMARY OF POTENTIAL POLLUTANT LINKAGES 8 FOUNDATION PROPOSALS 9 RECOMMENDED FURTHER WORKS AND INVESTIGATIONS. 10 APPENDICES

2 Dear Sirs, 1. SCOPE In accordance with your verbal instructions, we confirm that we have undertaken a desk study and walk-over survey of the above proposed development site The purpose of these investigations are to obtain preliminary information as to the presence /level of contaminants and harmful gases within the sub-soil and to identify whether any specific precautions need to be taken to isolate the buildings from toxic/dangerous chemicals and gases. 2. SITE LOCATIONS AND PROPOSALS 2.1. The site is situated in a rural setting within a plot bounded by open farmland and accessed directly off the main carriageway, Black Lane, to the north. The land slopes down towards the north with the nearest significant watercourse being Pilling Water 500m to the West of the site The proposals are to carry out conversion works to the existing building to form a new dwelling No new carriageway works are associated with the development of the buildings It is likely that any re-development of the buildings will include garden areas attached to the dwelling.

3 3. SITE HISTORY 3.1. Historical information from maps and aerial photographs together with verbal reports indicate that no definite evidence existed for significant ground contamination at the site From historical maps, the application site has remained largely unaltered in the nature of its use since 1847 although there is evidence of the removal and addition of buildings over the past 150 years We have referred to records published by Lancashire County Council and observed historic maps and photographs of the area. The 1:10,560 (6-inch) first edition O.S. map surveyed (published ) shows a single building in the location of the farmhouse and adjoining barn. It is likely that the building shown is the existing dwelling. That building which existed in 1847 also appears on the :2500 O.S. map and a further building had been constructed to the south of the farmhouse which is likely to be the existing brick barn A building is evident within the location of the existing shippon (north-east of the farmhouse) in an aerial photograph taken in the 1940 s. The existing shippon is of more recent construction and appears to be slightly larger than the structure shown on the 1940 s and it is assumed that the shippon has been constructed on the site of that former building The most significant development within the vicinity of the site since the first edition O.S. map is the alterations and expansion of Sullom Side Farm 140m to the South of the site boundary. The farmhouse at Sullom Side Appears to be similar in size, appearance and age as the existing house on the application site The aerial photograph from the 1960 s shows the site largely as it is today There was no evidence of any other significant development within close proximity of the site.

4 3.8. Agricultural vehicles or machinery were not stored in the buildings and land forming part of the application, nor were any materials that are likely to give rise to the presence of contamination That area of the site to the South of the existing buildings was laid out as a garden and there is no indication that it had been put to any other use or previously developed Ordnance Survey Map - Dated This map indicates that the land was occupied by a building of a residential scale which is annotated on the map as Fowlers Farm. This building was evident on the later O.S. map of 1890 and the existing brick two-storey barn has appeared by this date Aerial Photographs 1940s and 1960s These maps show the site was developed with the addition of several buildings and by the 1960 s it appeared largely as it exists today.. 4. EXISTING CONDITIONS (Refer To Photographic Records) During our walk-over survey of the site it was noted that the yard to the North and East of the existing dwelling was concreted. The concrete does not appear to have been laid recently and there is no indication that the form of the yard and access way have changed over the years. There is no evidence of recent disturbance of the yard area The land beyond the farm buildings to the East, West and South is agricultural grassland.

5 4.3. It was evident that the site was used for residential purposes and has operated as a small farming unit. There was no evidence that the site had been used for any other purposes in the recent past There are ponds within the vicinity of the site indicated on the historical maps and the likelihood of landfill being present cannot be excluded Grid Reference No: SD Altitude approx. 8.5m AOD 4.7. The site is approximately rectangular. There are a variety of walls, trees, fencing and hedgerows surrounding the site This site slopes downwards from the South towards the North A walk-over survey was undertaken and revealed nothing to indicate that the land has been used for anything other than agricultural grazing or that the buildings have been put to any use other than agricultural storage and housing livestock. There were no signs of contamination or disturbance The site occupies a position which is elevated in relation to the carriageway to the North. The Agricultural land to the South falls towards the site. Adjacent land is not considered to pose any risk of contamination to the site. No contaminants from adjacent land are expected to enter the site other than the potential from small-scale infilling of pits as mentioned earlier.

6 5. SUB-SOIL 5.1. The Institute of Geological Sciences Survey Drift Map of the area - sheet 67 indicates that the sub-soil below the site is likely to be glacial till/ clay, Till, Devensian - Diamicton. Superficial Deposits formed up to 2 million years ago in the Quaternary Period. Local environment previously dominated by ice age conditions. Formed in cold periods with Ice Age glaciers scouring the landscape and depositing moraines of till with outwash sand and gravel deposits from seasonal and post glacial meltwaters. The substrate is Sandstone. Sedimentary Bedrock formed approximately 229 to 271 million years ago in the Triassic and Permian Periods. Local environment previously dominated by rivers. These rivers depositing mainly sand and gravel detrital material in channels to form river terrace deposits, with fine silt and clay from overbank floods forming floodplain alluvium, and some bogs depositing peat; includes estuarine and coastal plain deposits mapped as alluvium The farm and associated land is almost surrounded by land with a peat sub-soil.

7 6. CONTAMINATION/RADON/FLOOD RISK 6.1. The historic maps and photographs do not suggest that the land has been used for any purpose that may have caused significant direct contamination of the subsoil From historical maps, the use of application site has remained largely unaltered since 1847, the risk assessments indicate that there are no potential contaminated additional sites within 500m of the site, nor are there any indications of any registered recorded landfill sites, waste transfer or regulated industrial sites within 500m of the site The historical maps of the area do not suggest that the land has been used for any purpose that may have caused significant direct contamination of the subsoil With reference to the Health Protection Agency (formerly the National Radiological Protection Board) published data; the site is outside any areas at risk of radon gas - copy of map attached The Building Research Establishment published data indicates that a basic level of Radon gas protection is required. -copy of map attached Enquiries made to the Environment Agency reveal that the site is not located within an area at risk of flooding.

8 7. PRELIMINARY CONCEPTUAL SITE MODEL (CSM) 7.1. General This conceptual site model describes the significant characteristics and processes at the site which have relevance to the likely risk of contamination related to the proposed development work and future site use The site consists of a historical and present use that has involved no recent development. Activities on the site appear to have been restricted to historical minor agricultural use and associated storage of livestock and fodder with a purely residential use in the recent past The main target receptors for this project will be that of human health of the occupiers of the buildings, the buildings themselves and the natural environment Minor uncertainties exist these are: The occurrence and concentration of any significant contamination at the site due to activities from the initial occupation of the land. The presence of any concealed contamination beneath the concrete floor slabs It should be emphasised that no evidence of contamination exists and the possibility of significant contamination having occurred is expected to be relatively low A summary of the potential pollution linkages at the site with regard to the proposed development and end use is presented in the following table referenced Table 7.1.

9 7.2. Ground Conditions The geological map indicates the site to be underlain by boulder clay over Mercia mudstones. The sections are not of sufficient accuracy to predict the clay depths The historic maps indicate that the site may have been used for agricultural activity at one time with a residential use during the recent past Contamination At this stage no contamination testing has been carried out There was no indication of any debris or deleterious waste that would give cause for concern There are no industrial buildings within close perimeter of the site Based on the findings of the desk study review it is not anticipated there will be any significant contamination on the site. The only issue could be deposition of contaminated materials / fluids from fertilizer etc from surrounding farmland, together with the possibility of minor landfill where ponds have been in-filled The boulder clay sub-soil will provide a barrier to prevent leakage of contaminants from sources away from the site. Therefore there is a low risk setting with regard to controlled waters Hazardous Soils/Gases.

10 The site lies outside an area where radon protective measures are required. Naturally occurring radioactive radon gas is a breakdown product of radioactive uranium in the Earth's crust. It is a known carcinogen and poses a chronic toxicity hazard to man. Geological studies and maps can only provide a rough guide to heavy pockets of the gas and never an accurate figure on the radon level in any one specific home or workplace Based on the recorded ground conditions, it is considered that the potential for Landfill type gases in association with the natural soils on the site is considered to be low Pathways Underground: The British Geological Survey drift map sheet 67 suggests that the site is located on till (boulder clay). There are no fault lines indicated within the vicinity of the site Above ground: Above ground pathways exist as direct contact with onsite personnel and via run-off to the fields at the southern, western and eastern boundary of the site or to the carriageway at the northernern boundary of the site Air-borne movement of dust on and off site could constitute a pathway Receptors On site: During site development, on-site receptors could include construction workers. Following development on-site receptors could include residents of the dwelling Off site: Off-site receptors could include: Waters within the drainage ditches of the adjacent farmland Residents of dwellings in the locality of the site.

11 7.5. Summary Of Potential Pollutant Linkages Table 1: Summary of Potential Pollutant Linkages Target / receptor Potential source / pathway Potential linkage identified by desk study? Human health Uptake of contaminants by food plants grown in YES (proposal is for residential use with domestic garden) contaminated soil Human health Ingestion YES (as above) Human health Dermal contact YES (as above) Human health Inhalation of soil derived dusts YES (as above) Human health Inhalation of vapours LIMITED (potential for localised hydrocarbon contamination but believed to be diesel range organic compounds) Human health Irradiation NO Human health Fire and explosion NO Buildings Fire and explosion NO Buildings Chemical attack on building NO materials and services including risk to potable water supplies Natural Environment Phytotoxicity YES (proposal is for residential use with domestic garden) Natural Contamination of surface water NO Environment Natural Environment Contamination of ground water NO Note: The transient risks to construction workers will be addressed by the adoption of appropriate health and safety measures in accordance with the Health and Safety at Work Act 1974 and regulations falling under the Act (eg. COSHH regulations)

12 Qualitative Risk Assessment Risk interpretation and evaluation The risk of adverse effects on all possible receptors related to current site use is considered to be very low However, given the uncertainties as to the risk of contamination and possible pathways, the proposed development work could result in an elevated risk of adverse effects from contamination during the construction phase This would be specifically due to the exposure and subsequent mobilisation of material within the ground that may be contaminated. The limited degree of development or activity upon the site reduces the likelihood of such material being present Following the construction phase, the risk of longer-term infiltration of methane gas within the completed building is possible owing to the apparent proximity of in-filled ponds Accordingly a gas-proof membrane should be installed within the floor construction and any voids within the structure must be ventilated to prevent accumulation of gas Risk reduction operations should consider the following points: Excavations should be restricted to periods with little or no rainfall. Monitor the material beneath any concrete floor slabs when removing the concrete for signs of concealed contaminants. If contamination is found to exist a further quantitative risk assessment using the results of the CLEA model and soil analysis should be undertaken in order to ascertain procedures to follow during construction and to establish subsequent risk reduction measures to adopt given the intended use of the site.

13 RECOMMENDED FURTHER WORKS AND INVESTIGATIONS Based on the findings of the desktop study revue, only a negligible potential for contamination exists within the proposed development site According to the published data from the Building Research Establishment and the Health Protection Board there is no potential risk of radon gas being present.

14 8. APPENDICES

15 Appendix 1 : Location Plan (not to scale)

16 Appendix 2 : First Edition Ordnance Survey Map extract (not to scale)

17 Appendix 3: 1890s Ordnance Survey Map extract (not to scale)

18 Appendix 4: 1940s Aerial Photograph

19 Appendix 5: 1960s Aerial Photograph

20 Appendix 6: recent Aerial Photograph

21 Appendix 7: Health Protection Agency Radon Map

22 Appendix 8: Building Research Establishment Radon Map 17

23 Appendix 9: Environment agency Data showing historic landfill presence at North Woods Hill Farm approximately 900m from the application site