Bobbin House, Whitefriars, Back Lane, Blakeney, NR25 7NR

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Ground Conditions & Geology Location The Landranger reference for the site is TG031441 which should be 52° 57'.18N, 01° 01'.18E. This is grid reference 603018,344037. General Ground Conditions The general ground conditions as determined by the digging of three trial holes of 2.2 to 2,45m deep is: The site is overlain by approximately 600mm to 700mm of black topsoil, overlying approximately 800mm of orange-brown loose soft sand and gravel, overlying a white chalk sub-strata. The chalk horizon shows initially as a weathered remoulded chalk putty matrix becoming harder with depth and containing greater amounts of chalk gravel. At lower depths the chalk contained occasional medium to large flint cobbles and became more difficult to excavate. Geology The site is located close to the coastal marshes and is probably 20-30m above sea level. The nearby marshes are behind the coastal sea defences and are probably freshwater marshes. The geological maps indicate natural drift geology of sand and gravel overlying the sold chalk substrata. There is an outcrop of the chalk substrata at Blakeney quay level running westwards towards Morston, indicating that the chalk could be close to the ground level in adjoining areas on a similar contour. This is in agreement with with information from Building Control. Building Control stated that the load bearing strata in this part of Blakeney is generally chalk, which can be weathered near to ground level. According the the Building control officer there are not, to his knowledge, any buildings in Back lane that required special foundations and generally most of the residential buildings are founded on traditional concrete footings onto the sold chalk strata. Environment Agency Following discussions with the Environment Agency, it appears that there are not any source protection zones locally that affect us regarding the use of a water borehole for an Open-Loop borehole-based to drive a Ground Source Heat Pump (GSHP). British Geological Survey The BGS staff have been very helpful. The following information was garnered in conversations with BGS staff. We also paid for a Water Prognosis Report (around £300) and a Ground Source Heat Pump (Basic) (around £50) where more specific information is given. This seemed very worthwhile. They believe the geology to be sand and gravel on upper chalk. It is likely we will find the water has 50 to 100 parts per million of chloride (table salt is sodium chloride) which is below the recommended limit of 250 parts. I have gleaned the following from the BGS staff that local boreholes in Blakeney (The Manor Hotel being the nearest) are no longer used. Much if not all of the following information is accessible for free on the BGS website. Information on local (but disused) boreholes is: Manor Hotel 40' deep, 4" diameter borehole 700 gallons/hour (0.9l/second) Beacon Cottage, Little Lane Well with bucket, disused 1960 Water table 57' below well-head. Council Houses Borehole drilled in 1937 and disused in 1960. Water table 56' below well-head 136' deep, 4" borehole 900/gallons/hour (1.1l/second) Red House Abandoned due to saline contamination (Red House is next to the quay and therefore, like Manor Hotel it is only just above sea level). 500 gallons/hour Very hard water.

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