Client: South Tyneside Council
Location: Lizard Lane, South Shields
South Tyneside Council (STC) commissioned Lynas Engineers to design and implement a scheme to combat ongoing speeding issues and mitigate major carriageway flooding issues exacerbated by overland flows from adjacent fields. The existing traffic calming measures needed to be redesigned as they failed to have an impact on vehicle speeds along Lizard Lane.
STC had a very small footprint to work in when considering the location of new drainage infrastructure as it needed to be positioned within the eastern verge of Lizard Lane.
A series of surveys were undertaken including a CCTV survey of the existing drainage infrastructure; trial holes to establish the utilities on site; a GPR survey to establish the depth of the bedrock and location of utilities; and a geotechnical investigation to ascertain the porosity and make-up of the soil. Testing and analysis concluded that infiltration would be a viable drainage method for the scheme.
LIDAR data was used to obtain the areas which contributed to the carriageway flooding along Lizard Lane. These areas were used to calculate the overland flow rates. By combining the LIDAR information along with the topographical survey, the route of the overland flows was established and identified the points where it and the carriageway surface water runoff combined to cause flooding issues. MicroDrainage software was used to calculate the maximum volume of attenuation which could physically fit in the available verge space. Traditional soakaways were disregarded due to the volumes required, as well as the cost of materials, excavation, and disposal of spoil. Various products were investigated and presented to STC with associated costs. An innovative SuDS drainage product called Hydrorock was recommended to STC, which was accepted and installed by the Council’s delivery team.
Challenges:
Reduce speeds in an existing 20mph zone.
Improve pedestrian and equestrian safety.
Reduce on carriageway flooding issues.
Provide attentuation for overland flow.
Successes:
A combined traffic calming and drainage scheme.
Provided attentuation in a small footprint whilst working near existing underground utility apparatus.
Safer pedestrian crossing points were provided.
The scheme included the first use in the UK of an innovative SuDS drainage product called Hydrorock.
Hydrorock is an artificial aquifer which offers an excellent void ratio, flexible sizing, as well as being easy to handle and install. It is widely used in the Netherlands to address surface water issues.
