Challenge
During maintenance in Manhole 154, a worker sustained injuries when a large fragment of deteriorated concrete separated from the manhole wall. Prior inspections had documented advanced spalling, exposed reinforcing steel, and structural degradation. However, remediation attempts were limited to patchwork repairs, and no comprehensive rehabilitation strategy was implemented.
The incident highlighted three primary concerns:
- Inadequate inspection practices – Evaluations were not conducted under NASSCO MACP™ protocols, resulting in incomplete documentation of the manhole’s condition.
- Improper rehabilitation methodology – No evidence of compliance with ASTM F2551, ASTM F3240, or ICRI concrete repair standards was identified.
- Worker safety deficiencies – No OSHA-compliant Lockout/Tagout (LOTO) procedures or overhead protection systems (scaffolding/shoring) were in place at the time of entry.
Technical Analysis & Recommended Approach
Back Municipal Consulting performed an expert analysis of the manhole’s condition, contractor submittals, and project records. Key findings included:
- Structural Integrity – The manhole exhibited advanced chemical corrosion and material degradation consistent with hydrogen sulfide attack. Proper rehabilitation should have included full surface preparation (ASTM D4262/D4259), corrosion treatment of exposed rebar, and installation of a structural liner or geopolymer mortar system.
- Inspection Deficiencies – Without MACP Level 2 or 3 inspections, deterioration stages were not properly classified, preventing a defensible rehabilitation plan.
- Contractor Oversight – “Spot patching” was insufficient given the degree of structural deterioration. A full rehabilitation (cementitious or geopolymer lining per ASTM F3240) would have been the correct engineering approach.
- Safety Failures – Entry into a structurally compromised manhole without overhead protection introduced avoidable risk. OSHA 1910.146 (Permit-Required Confined Space) and 1926 Subpart P requirements were not followed.
Outcome & Industry Implications
BMC’s technical review determined that the accident was preventable with:
- Proper MACP inspections and documentation.
- Specification and enforcement of ASTM-compliant rehabilitation techniques.
- Implementation of OSHA-compliant confined space procedures.
The incident underscores the importance of engineer-reviewed specifications, QA/QC oversight, and adherence to ASTM/NASSCO protocols in manhole rehabilitation projects.
BMC’s Role
BMC provided expert witness testimony supported by ASTM standards, NASSCO MACP inspection requirements, and OSHA regulations. Our findings demonstrated how improper inspection, inadequate rehab methods, and safety lapses directly contributed to structural failure and worker injury.
With more than 30 years of experience in manhole rehabilitation, CIPP, lateral connection lining, and trenchless design, BMC continues to support municipalities, engineers, and contractors with technical consulting, specification development, and expert analysis to ensure compliance and prevent recurrence of similar failures.
