Mimmshall Brook flood alleviation work
The Environment Agency held an exhibition at the RVC on 24 October which was attended by many residents of Hawkshead Lane, Warrengate Road, Swanland Road, the PA of our MP Melanie Johnson, and one of our Parish Councillors. Eleven members of the project team answered questions etc.
This project started in 1991, and there have been various planning applications relating to it. Construction work should start in February 2003 and finish in August.
New metal floodgates will be installed on Warrengate Road, just north of the junction with Hawkshead Lane.
Metal shoring will raise the west bank of the brook from the new gates to near Bradmore Lane. By this point the roadway has risen sufficiently not to be flooded.
Some brook-side trees will be removed but a new 'nature area' will be created as compensation. The metal shoring may have some sort of cladding to reduce its visual impact.
When flooding is forecast the gates will be closed manually (by Highways?) to form a 'V' shaped barrier across the roadway, with the point facing south. The dip at the bottom of Hawkshead Lane will still flood, so will Warrengate Road south of the floodgates.
The water pressure south of the gates, from the north flowing brook, will keep the gates closed like canal lock gates. The gates and shoring will prevent water getting onto the road and flooding the houses north of the gates - the objective of the works.
‘Road closed' and diversion signs will direct through-traffic away from Warrengate Road and Hawkshead Lane to a route through Brookmans Park, Welham Green and Swanland Road. There will be access to Warrengate Road and Hawkshead Lane properties.
Computer modelling has shown that the new flood barriers should not increase the flood levels at the Bradmore Lane bridge or at the bridge to the pumping station and two houses.
The flood plain south of the new gates will be slightly larger but no houses will be affected. Flood levels in Warrengate Lane (link road between Swanland Road and Mutton Lane) should not be any worse than now. The Environment Agency said it is uneconomic to carry out flood alleviation work on Warrengate Lane.
by Bob Horrocks, North Mymms Greenbelt Society
You can discuss this issue in this site’s Forum.
October 26, 2002
Flood defence public meeting - October 9, 2002
Homes evacuated following flooding - October 30, 2000
Warrengate Road flooding photogallery - October 30, 2000