FLOOD CONTROL & SUDS 39
OUR BROWN AND PLEASANT LAND
Will Allen of ACO explains why, given the in-depth specification needs that are associated with brownfield remediation, sound awareness of the surface water management criteria that must be met is essential to an effective and successful planning application.
requiring pre-development remedial work, coupled with the ‘up-sell’ advantages of a desirable location. However, in line with the Government’s 2017 White Paper on the housing market, green belt boundaries will now only be amended in exceptional circumstances, once local authorities have examined all other reasonable options for meeting identified housing targets. In short, green belt land will be much more difficult to build on.
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AN INTEGRATED SEAL PROMOTES QUICK AND EFFECTIVE INSTALLATION
However, the same report details Government plans to maximise the contribution of brownfield and surplus public land, to provide an accessible solution to the land availability crisis. While it does represent a viable solution, brownfield land still presents developers with a number of issues, particularly surrounding the cost of remediation.
FAIL TO PLAN, PLAN TO FAIL
Key to the successful redevelopment of any brownfield site is managing the risk of pollution to the surrounding land, both during and post-construction. Water resources are of particular concern, as if sufficient pollution or contamination were to occur, not only would it add significant cost to the remediation process, but it could threaten the suitability of land for redevelopment.
Under the National Planning Policy Framework (NPPF) guidelines, developers must show that all submissions fulfil the planning requirements for the specific intended end-use. This includes the management of surface water run-off
during the construction period, to prevent the contamination of surface and groundwater resources, as well as the post-construction removal or isolation of potential sources of contamination to water bodies.
This notion is reinforced by the Environment Agency’s Guiding Principles for Land Contamination 1 (GPLC1), which outline the requirement that successful plans must be able to evidence a disruption between the potential source of contamination (be it construction debris, vehicle brake dust or road salt chlorides), the pathway, surface water and the receptor (either groundwater or a water resource). From a specification perspective, there is a highly effective way to prevent a potential contaminant entering into a natural watercourse during, and after the development of a brownfield site: that is, using drainage channels with an integrated seal.
DELIVERING WATER TIGHTNESS One of the biggest risks of secondary (manually) sealed channels is that the
integrity of the seal is not assured. A compromised seal will affect the channel’s water tightness, and thus its ability to meet the necessary planning requirements.
According to BS EN 1433/DIN
19580, drainage channels must remain waterproof for 30 minutes ± 30 seconds. However, manual sealing relies on a number of variables, including the contractor, the quality of the sealant and the operating conditions, to deliver an effective seal. Just because a secondary sealed channel may be able to conform to BS EN 1433 on paper, does not necessarily guarantee it will perform in practice if it has not been installed properly. Junctions between channels, as well as sump pumps and outlets, represent a major risk of egress into the substrate. Poor sealing – or worse still, the use of no sealant whatsoever – could significantly hamper the chance of a developer satisfying the necessary planning criteria. Using a system with an integrated seal dramatically reduces this risk.
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reen belt land has long been the much-prized goal for developers, given its low likelihood of
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