King Alfred Way drainage (2)

For those of technical bent, there are many examples of BRE Digest 365 available on the internet, of which 3 random ones are shown below, each presenting it in slightly different ways.  I believe that BRE Digests are available to order from local libraries if further study is needed:

http://www.plymouth.gov.uk/bredigest365.pdf

http://www.capitasymonds.co.uk/pdf/06%20Soakaway%20Tests.pdf

http://www.broxbourne.gov.uk/PDF/BRE%20DIGEST%20365.PDF