Decision details

Proposed Decision:

To agree to provide delegated authority to the Corporate Director of Growth, Environment and Transport to award a contract for environmental remediation works at North Farm Closed Landfill Site.

Background:

Under the Environmental Protection Act 1990 (EPA90), Kent County Council (KCC) is responsible for managing the impact of its closed landfill sites on both the environment and human health.  KCC Waste Management therefore undertakes a programme of managing, control and monitoring of landfill gas and leachate waters at the North Farm closed landfill site. Environmental Monitoring Reports are updated on a rolling 18-to-24-month programme with subsequent reporting defining risks and identifying remediation works necessary.

Such works will include those required to be compliant with Part 2A of the EPA90 (Contaminated Land) but will also seek to provide engineered solutions to ensure the site is operated in a safe and efficient manner. At the same time ensuring best value for money in terms of liability and risk to KCC continue to be applied.

Environmental issues requiring attention:

Leachate: - Significant and increasing levels of Leachate (reflecting general higher rainfall volumes nationally) is produced as rainfall permeates the landfill capping materials into the waste before being collected via a series of leachate collection drainage ditches where it is collected and pumped to the Southern Water’s Wastewater Treatment Works (WWTW) off-site but close by. These arrangements cost KCC in the region of £100k annually, however recently the volumes have further increased, and it would be unlikely for these limits to be raised.

Landfill gas escape to atmosphere - Landfill gas is predominantly methane and carbon dioxide, both powerful greenhouse gases. To control the migration of this gas, a collection/control system, is in place with the network of collection pipes terminating at a gas flare where it is safely burnt off.  A recent audit has identified a number of age-related issues with the collection system such that it is becoming increasingly more difficult to maintain a fully functioning compliant system. Furthermore, capping soils laid when the site was closed are not able to prevent surface emissions to atmosphere across the entire site.

Alternatives considered and rejected:

1.            Do nothing. This is not considered to be a viable option, as there are environmental issues that need addressing.  Doing nothing has the potential for harm to the environment or human health to be realised.  In this instance, the site may then be officially classified as Contaminated Land and remediation costs imposed upon KCC.

2.            Install Geosynthetic Clay Liner (GCL) across the top of the site to minimise leachate generation and also upgrade gas collection system to help to reduce harmful greenhouse gases. Whilst there is an initial works cost to install the GCL installation this will result in lower revenue costs through savings realised by a reduction of discharging leachate to the treatment works.

3.            Install storage to attenuate leachate on site during heavy periods of rainfall and upgrade gas collection system. This option will also decrease the risk of KCC breaching its discharge consent, but it will not reduce revenue costs and not offer a sustainable solution to mitigate against increasing levels of rainfall.

The recommended Preferred Option is No.2 for the authority to award a Contract for environmental remediation works comprising installation of a GCL and upgrade of the gas collection system. This will be the most cost effective and will seek to address the environmental issues identified and reduce risk to KCC.

How the proposed decision meets the priority actions of Setting the Course: Kent County Council’s Interim Strategic Plan (December 2020):

The contract if awarded will meet the following priority actions:

• Use technology to improve efficiency and reduce cost
• Delivering our target to achieve net-zero emissions for the Kent Estate by 2030 and protect or enhance biodiversity.
• Target resource where it has the greatest impact

As Cabinet Member for Environment, I agree to provide delegated authority to the Corporate Director of Growth, Environment and Transport to award a contract for environmental remediation works at North Farm Closed Landfill Site.