The site. A property at Ashley Farm, Grafton, just south of Hereford, with no mains foul drainage. A treatment plant needed a drainage field.
What we did. Infiltration testing to the BS 6297 method used under Part H to size a foul drainage field.
What we found. Infiltration was very low to negligible. The ground would not accept effluent at a usable rate.
What it meant. A drainage field wasn’t viable. The foul drainage needed another solution, and the test gave the engineer the evidence to justify it.
The lesson. Herefordshire’s red mudstone and clay are often slow. Test before choosing the treatment system, not after.