SuDS in London - a guide
sustainable-urban-drainage-november-2016
sustainable-urban-drainage-november-2016
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
5.14 Goldhawk Road<br />
Location<br />
Shepherd’s Bush<br />
<strong>London</strong> Borough of Hammersmith & Fulham<br />
Extent<br />
0.27ha<br />
Cost<br />
£100,000 (construction only)<br />
Date<br />
2015<br />
Credits<br />
<strong>London</strong> Borough of Hammersmith & Fulham<br />
Robert Bray Associates<br />
McCloy Consult<strong>in</strong>g<br />
GreenBlue Urban<br />
FM Conway<br />
<strong>SuDS</strong> components<br />
Kerb <strong>in</strong>lets<br />
Tree pit attenuation<br />
Flow control<br />
Summary<br />
Tree trench plant<strong>in</strong>g for attenuation.<br />
Project description<br />
Street tree plant<strong>in</strong>g with<strong>in</strong> the pavement<br />
on a busy <strong>London</strong> high street us<strong>in</strong>g a modular<br />
structural tree soil system, comb<strong>in</strong>ed with<br />
kerb <strong>in</strong>lets and flow-control devices.<br />
Objectives<br />
To provide <strong>SuDS</strong> functionality and to<br />
protect the comb<strong>in</strong>ed sewer.<br />
Actions and results<br />
• Each tree is planted with<strong>in</strong> a 1.8m x 1.8m<br />
tree pit with tree grille, located with<strong>in</strong><br />
a much larger soil-filled root<strong>in</strong>g zone<br />
beneath the pavement, aim<strong>in</strong>g to provide<br />
between 10-20m³ of soil per tree<br />
• Dur<strong>in</strong>g heavier ra<strong>in</strong>fall, when the tree<br />
pit fills above the weir level, the water<br />
flows <strong>in</strong>to a sub-base replacement layer<br />
cover<strong>in</strong>g the root<strong>in</strong>g zone just beneath<br />
the pav<strong>in</strong>g build-up. This distributes<br />
the water over the whole root<strong>in</strong>g zone,<br />
allow<strong>in</strong>g it to <strong>in</strong>filtrate <strong>in</strong>to the soil<br />
• Specialist soil with a 25% void<br />
ratio allows ra<strong>in</strong>water storage<br />
• Perforated pipes <strong>in</strong> the base of the<br />
construction collect water and direct<br />
it to a flow control chamber, which<br />
discharges to the comb<strong>in</strong>ed sewer.<br />
The flow control chamber allows<br />
water to build up <strong>in</strong> the root<strong>in</strong>g zone<br />
when it ra<strong>in</strong>s to be released slowly<br />
once the peak <strong>in</strong> runoff has passed<br />
Image courtesy of George Warren<br />
Under construction<br />
• Runoff from the adjacent road and<br />
footpath flows directly <strong>in</strong>to the tree pit<br />
at road level, via a custom kerb <strong>in</strong>let<br />
• The soil level <strong>in</strong> the tree pit is lower than<br />
the road. It is surrounded by a raised<br />
polypropylene weir to allow <strong>in</strong>itial water<br />
storage. This ensures the trees get water<br />
every time it ra<strong>in</strong>s and allows sediments<br />
and litter to drop out of the water<br />
• Integrated protected overflows ensure the<br />
system can discharge freely to the sewer<br />
once storage capacity has been reached.<br />
Flow rates are designed to reduce the<br />
risk of comb<strong>in</strong>ed sewer overflow events<br />
103 5 Case studies