PPS 15 Planning and Flood Risk (Revised)·Page 77·E6
Deeper foundations
Foundations may be deepened to prevent flood water and groundwater infiltration, particularly in permeable ground types like sand and gravels, using cut-off trenches and toe walls to deeper impermeable layers to block flow paths.
This may be appropriate in permeable types of ground, such as sand and gravels, where high ground water and flood water is able, under pressure, to infiltrate into the property from below the foundation level. Cut off trenches and toe walls to deeper impermeable clay / rock ground to block flow paths may also be considered.
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