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A

sewer rehabilitation team from Lanes Group

has met challenging working time frames to

complete a project that has reduced sewer

flooding risks in a Scottish city.

The company was commissioned by Scottish Water

to clean and line a combined sewer downstream of the

Fisherman’s Car Park close to Inverness town centre,

and right alongside the River Ness.

The 300 mm diameter clay pipe had been identified

as being at high risk of contributing to localised flooding

during heavy rainfall, inconveniencing local people and

creating a pollution risk for the river.

A major challenge was to complete all work within

tight daily time frames to minimise their impact on

nearby businesses and essential services. Lanes’ no-dig

sewer rehabilitation expertise was key to achieving this.

Ian Phillips, Project Manager for Scottish Water, said:

“The use of specialist trenchless technology

allowed the rehabilitation of this sewer to be

completed quickly with minimal impact on the

Ness Walk and Bishops Road areas.”

Jon Close, Senior Project Manager for Lanes Group’s

Sewer Renovation Division, said:

“The car park is close to the city centre and

located near a hospital, a hospice and Inverness’s

main theatre.

“Quite rightly, it was important that these

facilities, as well as commuters, were not incon-

venienced, so the traffic management needed

to allow us to work could only be in place be-

tween 6.30pm and 11.30pm.

“This gave us a five-hour window to set up

over-pumping to divert sewer flows, carry out

our work, and then clear the site. Our teams had

to work particularly efficiently and quickly, while

maintaining the highest health and safety stand-

ards to achieve this.”

The main cause of the higher flood risk was tree roots

infiltration into the sewer.

Over three evenings, drainage engineers from Lanes

Aberdeen used high pressure water jetting equipment

to cut away the roots, guided by HD video footage re-

corded by a CCTV drainage survey team using a robotic

camera.

In some places, the tree roots had grown so large

they had to be removed using a KA-TE cutter - a robotic

cutting tool that can grind through wood, concrete and

metal.

CCTV survey footage was used by Scottish Water to

assess the condition of the sewer and decide how much

of its length needed to be lined to strengthen it and

prevent further root ingress.

Over three more evenings, a team from the Sewer

Renovation Division then installed three liners - two 70

m long, and the third 60 m long - in three separate sec-

tions of the sewer pipe along Ness Walk and Bishops

Road.

Ultra violet (UV) cure in place pipe (CIPP) lining was

selected because it suited the very short working time-

frame available.

Unlike conventional hot water CIPP lining, the UV

lining equipment could be set up quickly, the lining pro-

cess was fast, and no hazardous waste water was creat-

ed, which largely eliminated the risk of polluting the

River Ness.

Jon Close said:

“Once the UV liners were installed, they could

be cured within one hour. We could then cut out

lateral connections with the KA-TE cutter. This

meant each pipe could be lined and reinstated

within the five-hour window.”

Lanes Group

UV Lining TeamMeets

Challenge To Cure Flooding

Contractors World UK Ireland Vol 6 No 2

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