ACO – Six-Part Series – Part 5 | Maximising Maintenance for a Water Sustainable Environment
In part five of this six-part series, authored by Terry Wilkinson, Specialist Design & Application Engineer at ACO Water Management, we look at how prioritising maintenance is crucial to a highway drainage system.
All facets of highway drainage systems rely on appropriate levels of maintenance to ensure maximum efficiency. This is even more imperative when working with Sustainable Drainage Systems (SuDS) to ensure environmentally friendly water management can be achieved. Most highways and infrastructure engineers will be aware of the importance of maintenance and upkeep across existing highways drainage systems, but a significant proportion still view this as an afterthought.
Correctly planned maintenance ensures surface water can be properly managed and treated in a sustainable way. SuDS critically rely on maintained drainage networks to be free of sediment and silt build-up to avoid overflows and flooding. Yet, despite the importance of built-in and properly managed maintenance, there still remains a proportion of industry professionals who potentially view the topic as a lower priority or see it as a post-project consideration.
In a survey by ACO, 100 highways and infrastructure engineers were asked whether they were aware of a clear maintenance strategy in place on their project. Positively, there was overall agreement that this was the case, with 67% of respondents confident of a clear maintenance strategy in place post-installation. However, cause for concern arises with 55% of respondents stating they’ve worked on a project where maintenance has not been factored into the design of the drainage system.
This presents an opportunity for industry professionals to prioritise maintenance during the development process and avoid costly remedial work as a result.
Make maintenance a priority
Due to the various elements involved in highways drainage design, maintenance is often overlooked and brushed aside in order to cut costs, meet budget constraints and save time. Without correct maintenance, clogged drainage systems have knock-on effects across the entire drainage system. Not only do road users suffer as a result of unmanaged surface water, with implications in terms of both safety and structural damage to the network, but surrounding habitats and biodiversity can also be negatively impacted due to polluted runoff and sediment build-up.
All drainage systems, irrespective of whether they are proprietary, engineered solutions or natural landscaped features will require regular and planned maintenance. The CIRIA SuDS manual contains detailed and comprehensive guidance covering all aspects of the planning, design, construction and maintenance of Sustainable Drainage Systems.
The apparent lack of attention paid to maintenance is worrying when considering the significant impact this can have on the entire SuDS network. This is where industry leading experts, such as ACO, come in. ACO’s approach to SuDS places maintenance at the heart of efficient scheduling and prioritises accessibility, particularly when deciding on proprietary SuDS solutions.
Collection systems such as combined kerb and drainage or linear channels offer key benefits within a SuDS network as they keep the surface water runoff at a high level, allowing for more scope to utilise the water at source. Water-jetting of these systems should be common practice, and therefore access points are required at appropriate locations to maximise ease and speed. When cleaning, pressure can be controlled to prevent water and debris spraying back out of channel slots onto the highway surface.
Inspection and cleaning can be effectively carried out for geocellular systems using the same type of equipment and can also be aided with CCTV to visually navigate through the structure if required. As with any type of drainage system, close visual inspection on a regular basis is vital.
ACO advocates for a clear scheduling approach to maintenance and upkeep, factoring in the specific components within a system. Other factors such as leaf fall from nearby trees and vegetation can also significantly contribute to the build-up of debris.
Software tools such as ACO’s QuAD Hydraulic Design 2.0 can be used in conjunction with guidance found in the Design Manual for Roads and Bridges (DMRB) CD 523: Determination of pipe roughness and assessment of sediment deposition to aid pipeline design, to help forecast sedimentation rate and density for a maintenance period guideline. Users simply input parameters around sedimentation rate and density which is easily integrated if already using the software in other aspects of highway drainage design.
Prior to using software platforms and online tools such as ACO’s, it is recommended that engineers complete the appropriate training. Free downloadable guidance is available from ACO’s website.
In upcoming editions of this series, we will talk further about other areas of highway design such as environmentally positive drainage solutions and how highways can give back to the wider surroundings.