Lambeth Council has revealed that it is to seek a guarantee from the Mayor of London or Transport for London that the borough will not become liable for any costs if the Garden Bridge Trust fails to meet its obligations.
News of the proposed guarantee comes as the council prepares a deal with with Coin Street Community Builders and the Garden Bridge Trust to enable the bridge to be built on council-owned land on The Queen's Walk.
The South Bank end of the proposed Garden Bridge will be on land held by Coin Street Community Builders on a long lease from Lambeth Council.
According to a council report published this week, Coin Street Community Builders have indicated a willingness to be part of a tripartite arrangement with Lambeth Council and the Garden Bridge Trust for the construction of the bridge and the south landing building.
The council will grant CSCB an extended lease of 200 years at a pepercorn rent, and CSCB will in turn grant an under-lease to the Garden Bridge Trust for the same term.
A final decision on the grant of a new lease will be taken by Lambeth's cabinet in due course.
The Lambeth report says: "The council will not incur any financial liabilities arising from the construction/maintenance of the south landing building and the surrounding area in the event of GBT failing to fulfil its obligations.
"A guarantee is sought from TfL/GLA to meet the obligations of the GBT for the ongoing maintenance and upkeep of the bridge and is incorporated into the head of terms."
Lambeth's move to seek a guarantee from City Hall follows the City of Westminster's decision to require the maintenance of the bridge to be underwritten by a third party as a condition of granting planning permission.
The Lambeth report also notes that "the estimated projected footfall of 7 million visitors annually (approximately 3 million visitors are estimated to be new visitors to the area) may impact adversely on the immediate area" and explains that under the terms of the planning permission granted by the council, the Garden Bridge Trust will contribute up to £250,000 a year to meet cleaning and maintenance costs on the South Bank.
This annual payment will be administered and spent by the South Bank Employers' Group.
According to the council report: "There is no certainty that this payment of £250k will be adequate for the upkeep of the surrounding public realm.
"It is therefore proposed that adequate guarantee should be provided under the lease.
"The intention is that there will be no cost implications for the council resulting from increased footfall of visitors arising from the new bridge."
The report also notes that the extra visitors attracted by the bridge will have an impact on crime and the risk of terrorism.
"As an iconic location attracting additional visitors in an area that is already crowded, it presents a terrorist threat. Additionally it is located within the Government Security Zone.
"There will need to be a comprehensive counter terrorism strategy developed, and counter terrorism measures put in place to mitigate risk, and these will need to be constantly maintained and reviewed."