Subsidence Repair for Harrow Council – Saving £500k through a new approach to subsidence repair
A block of flats with 12 units, owned and managed by Harrow Council, had suffered from structural movement due to the clay shrinking beneath the foundations. This resulted in cracks in the brickwork, internal walls and ceilings meaning it would require underpinning repairs and the tenants would need to relocate.
The standard approach to this issue was followed: a site investigation to understand the issue, a structural engineer’s recommendation for underpinning works, and a tender process to identify contractors and delivery. The tender process began in May 2022, with 20 weeks of work to commence in September 2022.
However, contractor Geobear approached Harrow Council to propose an alternative to underpinning – ground improvement using geopolymer injection. This innovative approach, developed by Geobear in 1980, uses an innovative ground injection technique to minimise structural movement in buildings affected by shrinking clay soil. Crucially, it could be delivered in ten days without tenants needing to relocate for up to 20 weeks.
The benefits of the Geobear alternative to underpinning were so great that Simba Manjonjori, Interim Planned Investment Manager at Harrow Council, put a case forward to the senior management. He argued that there needed to be a change to the procurement approach to enable them to capitalise on the benefits. The request was granted and the scheme delivered benefits to Harrow Council, the residents, and the local community.
Benefits of Innovative Subsidence Repair
The benefits of using Geobear to deliver the subsidence repairs are quantitative and qualitative.
Benefits for Residents:
- Residents would not need to vacate the property during work. Many tenants in the units were elderly or disabled, and relocating during underpinning works for 20 weeks would have significantly impacted their mental and physical well-being.
- Relocation would mean residents being moved away from friends and family for 20 weeks, disrupting the support many depend on for day-to-day living.
- The Geobear works are all outside the property and minimally intrusive. The residents are unaffected and have full access to the entrance and garden areas.
- No excavation/digging means minimal noise pollution to residents in properties.
Benefits to the Community and Environment:
- The Geobear work is minimally intrusive – just two vehicles needing parking. With underpinning, major heavy machinery would have been required to be in the area for 20 weeks going backwards and forwards through tight residential areas with difficult access.
- Excavation and machinery would ruin the local green spaces and leave mud and dirt throughout the neighbourhood. The noise of digging and excavation from underpinning would affect the neighbourhood for 20 weeks. Geobear has no impact.
- The carbon footprint of an underpinning scheme is 70% greater than the Geobear method of ground improvement. This is verified in a Carbon Footprint report comparing Geobear’s solution on a residential property to a traditional underpinning scheme.
- With underpinning schemes, there is a requirement for the cutback of vegetation and tree removal. The Geobear solution does not require the removal of trees, leaving the green space unaffected.
Benefits for Harrow Council:
- Up to £320,000 saved on the costs of relocating tenants into hotels, plus costs associated with vacant stock.
- Reduced administration time/cost. Staff resources at Harrow would have spent several weeks arranging the relocation and logistical aspects of the original scheme.
The total financial savings for Harrow Council over 20 weeks was almost £500,000. This sum includes both direct savings on the cost of work and indirect savings from requiring no alternative accommodation. The cost savings for Harrow Council could be invested in other urgent property maintenance projects.
In terms of indirect cost savings, these can be calculated based on losses due to void unit costs to Harrow Council, plus the alternative accommodation costs. The cost of tenants to be moved to temporary accommodation is approximately £4000 per month – per family room. Therefore, a total temporary accommodation cost for 12-16 units (as there were some households with children), during the 20 weeks of underpinning, would have equated to £240,000 – £320,000.
The benefits and overall savings of the scheme have been widely recognised within Harrow Council and similar asset maintenance schemes are now being re-evaluated to ensure value is maximised.
Removing Barriers
Many procurement processes are standardised and unchallenged. This case provides an excellent example of how and why existing procurement should be considered to maximise the value of local government and housing association budgets.
Harrow Council had a standard procurement process that was challenged by their housing maintenance team. The argument for using Geobear’s innovative approach was quantified, illustrating the cashable benefits to the council and qualitative benefits to the community.
Other organisations may have a similar approach to asset maintenance and procurement that has been unchanged for many years. This can prevent new ideas and improvements to existing, tried and tested approaches that deliver increased value.
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