Introduction

Inflow and infiltration (I&I) through manholes can overwhelm wastewater systems, drive unnecessary treatment costs, and trigger regulatory risk. Hinterland Group delivers MIC/H2S‑resistant manhole rehabilitation that seals every leak path, extends service life, and minimizes disruption using proven trenchless methods backed by in‑house crews and rapid response across the Southeast. See capabilities in Services, Repair and Replacement, and Inspection.

How we stop I&I in manholes

Hinterland’s approach combines structural restoration, chemical/physical sealing, and corrosion protection.

Condition assessment and cleaning: high‑pressure cleaning, debris removal, and CCTV to document defects before/after (Inspection).
Seal the chimney/frame area: internal mechanical chimney seals; external wraps where appropriate.
Grade ring reset: remove failed rings, reset with non‑shrink grout or polymer rings to restore elevation and seal frame/cover interface.
Rebuild benches/inverts: reshape flow channels to eliminate standing water and reduce turbulence‑induced H2S.
Penetration/joint sealing: hydrophilic seals and chemical grouts at pipe penetrations, lift holes, and barrel joints.
Structural lining: apply MIC‑resistant calcium‑aluminate or spray‑applied geopolymer lining for uniform corrosion protection and leak sealing (Repair and Replacement; Services).
QA/QC: spark/holiday testing (as specified), adhesion checks, dry‑film thickness verification, and post‑rehab CCTV. Ongoing Maintenance programs are available.

Quick reference: defects and fixes

Manhole defect/leak path	Rehabilitation action	Preferred material/system
Leaking chimney/frame	Internal mechanical chimney seal; optional external wrap	Stainless/EPDM seal systems; external wrap
Failed/settled grade rings	Remove/replace and reset elevation	Non‑shrink grout or polymer composite grade rings
MIC/H2S corrosion of cone/barrel	Resurface and line for structural/chemical resistance	Calcium‑aluminate mortar; spray‑applied geopolymer
Infiltration at joints/penetrations	Chemical grout; hydrophilic seals	Acrylamide/polyurethane grouts; hydrophilic waterstops
Deteriorated benches/inverts	Rebuild channels; seal surface	Calcium‑aluminate or geopolymer

MIC/H2S resistance: why it matters

Microbially Induced Corrosion (MIC) occurs when hydrogen sulfide (H2S) off‑gasses in sewer atmospheres and oxidizes to sulfuric acid, rapidly attacking traditional cementitious substrates. Hinterland mitigates MIC by:

Installing calcium‑aluminate lining systems that resist acid attack and provide structural restoration (Hinterland’s use of Refratta calcium‑aluminate is referenced in Repair and Replacement).
Applying spray‑applied geopolymer linings for high‑build, low‑permeability protection with strong adhesion and crack‑bridging (see Services).
Eliminating leak‑driven turbulence by rebuilding benches/inverts to reduce H2S generation.

Materials and system selection

Hinterland performs all trenchless methods in‑house, enabling unbiased selection of the most effective solution for each structure (Pipe Rehabilitation).

Calcium‑aluminate lining: rapid set, MIC‑resistant, high early/ultimate strength; ideal for severe H2S environments and structural rebuilds (Repair and Replacement).
Spray‑applied geopolymer: high‑build corrosion barrier and structural enhancement; conforms to complex geometries (Services).
Mechanical chimney seals: stainless/EPDM systems to stop annular leakage at the frame interface.
Chemical grouting/hydrophilic seals: stops infiltration through cold joints, penetrations, and annular spaces.
Grade ring materials: polymer composite or properly bedded non‑shrink grout to restore elevation and seal interfaces.

Scope elements frequently included

Traffic control, bypass coordination, and confined space safety led by OSHA‑certified management (About).
Surface prep to manufacturer spec; moisture and substrate temperature checks prior to lining.
Thickness/coverage targets per design; transitions detailed at frames, steps, service laterals, and penetrations.
Final inspection package with photos, measurements, and recommendations for Maintenance Plans.

Warranty language (typical terms)

The following are example terms commonly used in municipal manhole rehabilitation contracts; actual project warranties are finalized in contract documents.

Materials and workmanship: 1‑year minimum; extended terms available by material system.
Lining adhesion and integrity: 3–5 years typical for cementitious/calcium‑aluminate or geopolymer systems, when operated within design envelopes (no chemical exposures beyond spec, no structural loading beyond design, no unmanaged groundwater surcharging).
Chimney seals: 5 years against leakage at the frame/chimney interface, subject to proper frame/cover fit and traffic loading.
Exclusions/owner responsibilities: maintain covers/frames, avoid chemical exposures beyond specified limits, and sustain drainage to prevent continuous submergence where not designed.

Stop I&I: municipal outcomes and ROI (illustrative examples)

These example scenarios illustrate how targeted manhole rehab can reduce wet‑weather flow. Actual results depend on site conditions, groundwater, upstream defects, and verification via metering/CCTV.

Basin A (Florida coastal city, 120 manholes): chimney sealing, grade ring resets, calcium‑aluminate lining in severe MIC structures, and penetration grouting. Result: peak wet‑weather flow reduction modeled at 22–28% at basin meter; treatment O&M avoided via reduced dilution and fewer surcharge events. Service approach aligns with Hinterland’s Services and Maintenance.
Basin B (Southeast municipality, 85 manholes near high groundwater): mechanical chimney seals, geopolymer lining of cones/barrels, bench/invert rebuild, and external wraps at recurring leak points. Result: average base‑flow reduction modeled at 15–20% with measurable decrease in rainfall‑dependent I&I. Methods reflect in‑house trenchless capabilities described under Pipe Rehabilitation and Inspection.

Why municipalities choose Hinterland for manhole rehab

In‑house trenchless portfolio (CIPP, geopolymer spincast, grouting, sliplining, pipe bursting) enables best‑fit solutions, not one‑size‑fits‑all (Services; Pipe Rehabilitation).
MIC‑resistant manhole coating experience, including Refratta calcium‑aluminate processes for structural protection (Repair and Replacement).
24/7 emergency response with rapid mobilization and large fleet coverage across Florida and the Southeast (Markets We Serve).
Safety excellence: OSHA‑certified leadership and a mature safety culture (About).
Lifecycle support: inspection, rehabilitation, and maintenance under one partner (Inspection; Maintenance Plans).

Next steps

Request a basin‑level I&I screening, including CCTV review and scope/budget options for chimney sealing, grade ring reset, joint/penetration grouting, and MIC‑resistant lining.
Coordinate a pilot area with pre/post metering to validate reduction. Contact the team at Contact Us.

Manhole Rehabilitation to Stop I&I (MIC/H2S Resistant)