6″ x 24″ Locking Watertight Manhole Frame and Cover

The 6″ x 24″ Locking Watertight Manhole Frame and Cover is a heavy-duty cast iron access assembly engineered to provide secure, watertight access to sanitary sewer systems, wastewater treatment facilities, lift stations, utility vaults, pump stations, and other underground infrastructure. Manufactured from ASTM A48 gray cast iron and designed for AASHTO H-20 highway loading, this assembly combines the strength of a municipal-grade manhole casting with the added security of a bolted locking system and watertight gasket seal.

Unlike conventional manhole covers, locking watertight assemblies are specifically designed to prevent unauthorized access, reduce infiltration and inflow (I&I), minimize odor migration, and protect underground systems from surface water intrusion. These features make them ideal for flood-prone areas, environmentally sensitive locations, treatment plants, coastal regions, and municipal sewer systems where infiltration control is critical.

Product Features

• Heavy-duty cast iron construction
• 24″ clear opening
• 6″ deep frame design
• Locking bolt-down cover system
• Watertight gasket seal
• ASTM A48 Class 30 gray iron construction
• AASHTO H-20 highway loading
• Precision-machined seating surfaces
• Corrosion-resistant design
• Prevents groundwater infiltration
• Helps reduce sewer system inflow and infiltration
• Available with custom utility markings
• Available with municipality-specific logos
• Long service life in harsh environments

Common Applications

The 6″ x 24″ Locking Watertight Manhole Frame and Cover is commonly specified for:

• Sanitary Sewer Systems
• Wastewater Treatment Plants
• Lift Stations
• Pump Stations
• Force Main Systems
• Combined Sewer Systems
• Utility Vaults
• Electrical Infrastructure
• Telecommunications Facilities
• Stormwater Control Structures
• Coastal Infrastructure
• Flood-Prone Installations
• Industrial Facilities
• Municipal Infrastructure Projects

Why Use a Watertight Manhole Cover?

Traditional manhole covers allow air exchange and may permit surface water infiltration during heavy rain events or flooding. Watertight manhole covers utilize compression gaskets and bolted locking mechanisms to create a positive seal between the cover and frame.

Benefits include:

• Reduced inflow and infiltration (I&I)
• Protection against stormwater intrusion
• Reduced treatment plant loading
• Improved environmental compliance
• Odor containment
• Increased system security
• Protection from floodwater contamination

Many municipalities utilize watertight castings to reduce excess groundwater entering sanitary sewer systems, which can significantly increase wastewater treatment costs.

Technical Specifications

Manufactured from municipal-grade cast iron, this assembly is designed to provide long-term performance under repeated traffic loading while maintaining a watertight seal.

Material Specifications

Municipal watertight castings are commonly manufactured using ASTM A48 cast iron and neoprene gasket systems designed to resist environmental degradation and maintain long-term sealing performance.

H-20 Highway Loading

This assembly is suitable for H-20 traffic loading and can be installed in roadways, highways, parking lots, industrial facilities, and other locations subject to vehicular traffic.

H-20 remains one of the most widely recognized traffic loading classifications for municipal utility castings and underground infrastructure access systems. Properly installed castings distribute traffic loads efficiently while protecting the supporting concrete structure.

Locking System Benefits

The locking mechanism provides several advantages over conventional manhole covers:

Enhanced Security

Locking covers help prevent unauthorized access to underground infrastructure, reducing vandalism, theft, and safety concerns.

Public Safety

Bolt-down covers reduce the risk of cover displacement due to traffic vibration, flooding, or accidental movement.

Infrastructure Protection

Critical utility systems remain protected from tampering and environmental exposure.

Regulatory Compliance

Many utility authorities and treatment facilities require locking covers in sensitive or high-security applications.

Watertight Gasket Performance

The integrated gasket system creates a compression seal between the cover and frame.

Benefits include:

• Reduced groundwater infiltration
• Reduced inflow during storm events
• Odor containment
• Corrosion protection
• Improved system performance
• Extended infrastructure life

Neoprene gasket systems are commonly used throughout municipal wastewater and utility infrastructure because of their durability and resistance to chemicals, moisture, and environmental exposure.

Available Cover Markings

Amercast can supply cast-in lettering including:

• SANITARY SEWER
• STORM SEWER
• WATER
• ELECTRIC
• COMMUNICATIONS
• TELEPHONE
• FIBER OPTIC
• RECLAIMED WATER
• MUNICIPAL LOGOS
• CUSTOM TEXT

Custom logos and utility identification markings are available upon request.

Custom Manufacturing Options

Amercast specializes in custom municipal castings and can provide:

• Locking Covers
• Watertight Covers
• Bolt-Down Covers
• Hinged Covers
• Ductile Iron Options
• Utility-Specific Castings
• Municipality-Specific Castings
• Custom Logos
• Custom Markings
• Project-Specific Designs

Our engineering team routinely manufactures products to city, county, DOT, utility authority, and consulting engineer specifications.

Related Products

• Manhole Frames and Covers
• 6″ x 24″ Heavy Duty Manhole Frame and Cover
• Adjustable Manhole Risers
• Manhole Risers and Extension Rings
• Catch Basin Grates
• Municipal Castings
• Septic Covers

Industry Resources

For additional information regarding wastewater infrastructure design, infiltration control, and sanitary sewer system best practices, engineers and municipalities can reference the Water Environment Federation:

Water Environment Federation (WEF)

Why Choose Amercast?

Amercast manufactures heavy-duty cast iron manhole frames and covers engineered for municipal infrastructure, utility systems, treatment facilities, and industrial applications. Our locking watertight castings are designed to provide superior durability, security, and infiltration protection in demanding environments.

Whether your project requires standard municipal castings, custom markings, utility-specific designs, or complete watertight systems, Amercast has the manufacturing capabilities and industry expertise to deliver a solution tailored to your specifications.

Request a Quote

Need pricing, shop drawings, CAD files, custom markings, or engineering assistance?

Contact Amercast today to request a quote for the 6″ x 24″ Locking Watertight Manhole Frame and Cover. Our team can assist with municipal, wastewater, utility, commercial, and industrial projects throughout North America.