Temporary Works Surface Water Management
Surface water management is a critical and increasingly scrutinised element of UK construction, both during the temporary works and in the permanent condition.
During construction, uncontrolled runoff can mobilise sediment and pollutants, exceed the capacity of receiving watercourses and trigger regulatory intervention.
OGI provides the hydrological, hydrogeological, and design expertise required to manage surface water effectively across the construction lifecycle.
What are the Risks?
Pollution Incidents
Uncontrolled runoff carrying sediment, fuel, or concrete washings into nearby watercourses constitutes a pollution incident, exposing clients to enforcement action by the relevant environmental regulator, financial penalties, and reputational damage.
Flooding On and Off Site
Inadequate temporary drainage can result in flooding of working areas, loss of plant productivity, and damage to partially completed works. Off-site flooding caused by uncontrolled discharge from a construction site is a frequent source of third-party claims.
Regulatory and Planning Risk
Surface water management strategies submitted with limited supporting evidence are likely to attract requests for further information from the lead local flood authority (LLFA), the planning authority, or the relevant environmental regulator, with consequent programme delay.
Surface Water Management Solutions
Integrated, Compliant and Practical
Effective surface water management depends on understanding the catchment, receiving environment, discharge constraints and construction sequence as a single connected system.
A drainage measure that performs well in isolation may be ineffective if the catchment area changes during construction, or if the receiving watercourse cannot accommodate the proposed discharge.
OGI’s approach is to base every surface water strategy on site-specific catchment and water quality data, interpreted with appropriate engineering judgement, and to design measures that remain effective as the construction sequence progresses.
Where a project combines surface water discharge with groundwater abstraction, dewatering, or infiltration-based drainage, OGI coordinates the hydrological, hydrogeological, and water quality evidence across all elements so that the overall water management strategy is working together.
What We Do
We provide surface water management support from concept drainage strategies through to implementation.
We assess the site catchment, receiving environment and regulatory requirements to define the design and assessment work needed to deliver an effective surface water strategy, including water quality sampling and hydraulic assessments where required.
Early engagement is critical. By identifying assessment and design requirements at the earliest project stage, OGI ensures surface water strategies are evidence-based and efficiently integrated into the project, so mitigating construction or regulatory risks.
Our Temporary Surface Water Management Services
Temporary Works Drainage Design
Design of construction-phase drainage, including temporary drainage, cut-off ditches, settlement lagoons, silt fences, and treatment measures, sized for defined sub-catchments and to discharge water within receiving-environment limits.
Hydrological Assessment
Catchment delineation, runoff estimation, and design rainfall analysis using industry-standard methods. This includes allowances for climate change to establish design flows that the system is required to convey and attenuate.
Water Quality Assessment
Baseline and operational monitoring of receiving watercourses, with pollution-risk assessment of proposed construction activities to inform treatment measures and demonstrate compliance with discharge consent conditions.
Discharge Consent Applications
Assessment of discharge options and preparation of surface-water discharge consent applications, including hydraulic and water-quality evidence and engagement with the relevant regulator throughout the determination process.
Some of Our Solutions
1. Sustainable Drainage Systems (SuDS)
2. Drainage networks (‘V’ Ditches, French Drains etc.)
3. Attenuation Lagoons/Ponds
4. Silt Management
5. Treatment and Pollution Control
Key Outputs
Temporary Works Drainage Design
A complete design package for the construction-phase drainage system, including sub-catchment delineation, sizing of drainage ditches, pipes and attenuation lagoons, treatment and pollution control measures, and operational arrangements to maintain performance throughout construction.
Discharge Consent Application
An application package for submission to the relevant environmental regulator, including assessment of the proposed discharge location and receiving waterbody, supporting hydraulic and water quality evidence, and a technical case demonstrating that discharged surface water will not adversely affect the receiving environment.
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