Mihai Chelmus · Construction Testing, Investigation & Remediation Specialist Email: mihai.chelmus@swantest.co.uk |  Tel: +44 734 228 1981 Construction structural testing, load verification and on-site assessment for buildings, temporary works and safety-critical elements across London.

Industrial and chemical facilities place unusually high demands on concrete infrastructure. Drainage details in particular are exposed to aggressive environments that can accelerate deterioration far beyond what standard repair specifications are designed to withstand.

This case study examines how a targeted, material-appropriate repair strategy was delivered at a live chemical facility in Essex, with the works undertaken by Swantest and coordinated by Mihai Chelmus, Operations Manager. The intervention was designed to address early-stage deterioration in a chemically aggressive environment where conventional concrete repairs would have presented a high risk of premature failure.

Project Context

The works related to the repair of a number of deteriorated drainage manholes within an operational industrial chemical facility. The defect involved breakdown of concrete edges around a drainage opening measuring approximately 1000mm x 1000mm x 300mm deep.

Given the nature of the site operations, the drainage infrastructure is routinely exposed to chemically aggressive conditions. The client identified early-stage deterioration and sought intervention before further loss of section, frame instability, or operational disruption occurred.

Crucially, the works were required to be undertaken:

• within a live site environment
• under a permit-controlled regime
• without prolonged shutdown or loss of drainage function

Technical Challenge

The primary challenge was material compatibility. Standard repair mortars commonly used for drainage reinstatement are not suitable for chemically aggressive environments. In this case, long-term durability depended on the correct integration of:

• acid-resistant repair concrete
• corrosion-protected reinforcement
• replacement of existing steel frames with chemically stable alternatives

In addition, the existing concrete exhibited irregular edge failure, requiring controlled breakout to achieve a sound, well-defined repair interface capable of sustaining both mechanical and chemical loads.

Repair Strategy and Methodology

Following a site visit and review of defect photographs, a repair methodology was developed around controlled intervention rather than wholesale replacement.

The agreed scope included:

Concrete breakout and preparation

• Saw-cutting an 80mm deep perimeter to establish clean repair arrises
• Careful removal of loose and unsound concrete without inducing further damage
• Full exposure of reinforcement at affected edges

Reinforcement treatment

• Mechanical cleaning of exposed rebars
• Application of corrosion-inhibiting primer to restore protective capacity

Structural reinstatement

• Installation of shuttering to control geometry and finished levels
• Use of acid-resistant repair concrete supplied by the client, selected to match site-specific chemical exposure
• Controlled placement, compaction and finishing to reinstate original profiles

Frame replacement

• Removal of existing steel frames from within the drainage opening
• Installation of new GRP frames, selected for improved chemical resistance
• Fixing using stainless steel brackets and fastenings
• Application of epoxy protective coating to exposed steel components

All materials and procedures were selected to ensure compatibility with the facility’s operational environment and maintenance expectations.

Delivery Constraints and Risk Controls

The works were undertaken within a live chemical facility, requiring strict adherence to site safety and access protocols. Key controls included:

• Permit-to-dig and hot-works permits for cutting and grinding activities
• Controlled work zones and exclusion areas
• Full PPE compliance for operatives working with concrete and chemical-resistant materials
• Sequencing to minimise standing water, access disruption and curing risk

The methodology was structured to allow continuous site access and avoid interruption to plant operations.

Programme and Commercial Certainty

The works were delivered on a fixed lump-sum basis, providing cost certainty to the client prior to commencement.

Key parameters included:

• Anticipated site duration of up to four days
• Standard weekday working hours
• No requirement for extended shutdown or out-of-hours operations

The defined scope and clear sequencing reduced the risk of programme overrun and avoided reactive repair escalation.

Outcome

The repaired drainage opening was successfully reinstated with:

• chemically compatible materials
• improved edge durability
• upgraded frame detailing
• reduced future maintenance risk

Importantly, the intervention addressed deterioration before structural compromise or operational failure occurred, extending the service life of the drainage asset without the need for invasive reconstruction.

Lessons for Industrial and Chemical Facilities

This case highlights several wider considerations relevant to asset owners and facilities managers:

• Early identification of drainage edge deterioration allows targeted repairs rather than full replacement
• Material selection is critical, standard repair mortars are often unsuitable in chemically aggressive environments
• GRP frame systems can offer significant durability advantages over traditional steel in specialist settings
• Controlled breakout and detailing can significantly influence long-term repair performance

In environments where chemical exposure is unavoidable, durability is achieved through appropriate specification, not heavier intervention.