Chalk above, clay below
East and West Horsley parishes run from the crest of the downs across the chalk, then the Thanet and Woolwich Beds, and finally onto the London Clay. Near the top, clay with flints caps the chalk in places and can make a soakaway behave unpredictably. Further north, the London Clay is dense and slow to take water.
Because water moves through chalk quickly, a failing septic tank on the higher ground is more than a smell problem. Keep it emptied on schedule, and if you think it’s leaking, a septic tank survey will show what’s going on.
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