Detailed Surface & Foul Water Drainage Strategy
Civilistix Consulting Engineers were appointed to prepare a detailed surface and foul water drainage package and highway design input for a residential development consisting of 12 units including associated hardstanding, access, and POS areas.
Our sustainable drainage strategy for this development utilised 4 different types of SUDS.
Permeable paving was utilised to all private hard standing areas.
To maintain the usable area of public open space but also utilise it to accommodate attenuation, we created an innovative solution which used geo-cellular storage tanks with a shallow depression above. Storm water from storm events below the 1:30 Annual Exceedance Probability (AEP) were kept fully within the geo-cellular storage structure. Storm water from storm events exceeding the 1:30 AEP however, were designed to flow up from the geo-cellular storage crates into the above depression essentially acting like a high level overflow basin. This approach meant we could significantly reduce the amount of geo-cellular storage crates required and was also seen as in-fitting with the natural environment / SuDS philosophy.
To the south of the site, we designed a roadside swale draining to an attenuation basin. The swale meant run off could be treated in accordance with current guidance and the basin provided the downstream attenuation for the access road and SuDS structures upstream of it.