America's Wastewater Infrastructure is Failing
The Problem
Municipal wastewater systems across the U.S. are aging and deteriorating:
900 billion gallons of untreated sewage discharged annually
Concrete manholes crack, corrode, and leak
Rehabilitation and replacement costs continue to rise
Hydrogen sulfide (H₂S) corrosion is the leading cause of premature failure
Cities need a modern, corrosion‑proof solution that eliminates the failure modes of concrete.
MagnaPlast™ is engineered for that future.
What is MagnaPlast™?
MagnaPlast™ is the only monolithic HDPE sanitary sewer manhole engineered and manufactured in the United States. It’s built using extrusion‑wound HDPE, a proven European technology with more than 50 years of performance in corrosive wastewater environments.
It delivers:
- Uniform wall thickness
- Exceptional hoop strength
- Seamless monolithic construction
- Superior performance vs. concrete, polymeric concrete, and lined systems
Innovation Legacy
Houston PolyTank pioneered this manufacturing method in the U.S., earning the first patent for an HDPE rectangular tank. MagnaPlast™ extends that same innovation into underground infrastructure, delivering a seamless, corrosion‑proof manhole system engineered for a 100‑year service life.
It is the foundation of MagnaPlast’s structural reliability.
The MagnaPlast System
A fully integrated manhole platform engineered for long‑term reliability.
MagnaPlast™ is built as a unified system. Each subsystem works together to deliver structural stability, installation efficiency, and long‑term performance.
The diagram below illustrates how the monolithic core and its integrated components form a complete engineered platform – from the base plate and anti‑flotation system to the riser and cover assembly.
A one‑piece, factory‑assembled HDPE structure built using extrusion‑wound technology and a rotomolded base.
- No joints, seams, or weak points
Factory leak‑tested
Engineered for 100‑year service life
Base Plate & Outlet Assembly
Precision‑formed
flow surfaces and structural interfaces that support leak‑free
performance and long‑term
stability.
- Smooth internal flow surfaces (Manning’s n = 0.010)
- Provides foundational stability for the monolithic core
- Ensures proper load distribution into the concrete‑fill tub
- Integrates directly with the extrusion‑wound cylinder and rotomolded base
- Supports anti‑flotation performance in high water table environments
A 6‑ft HDPE concrete‑fill tub provides the ballast needed to prevent flotation in high‑water‑table environments.
Ships installed as part of the structure
Concrete isolated from all inlets/outlets
Includes proprietary cement for securing threaded risers
Flat‑top version available
Precision grade control for any installation environment.
24"–30" ID threaded riser
8" of vertical adjustment for precise elevation control
Minimum 2" thread engagement for structural stability
SikaFlex® 221 sealant provides a watertight riser interface
Compatible with HDPE grade adjustment rings when required
Up to 9" of field adjustment
Supports cast iron or composite covers
Compatible with direct‑mount or grade‑ring installations, including Cretex PRO‑RING systems
Designed for compatibility with standard municipal requirements.
Cast-iron or composite frame & cover systems
Traffic‑rated designs (H‑20/HS‑25)
Direct‑mount or adjustable configurations
Why Cities, Utilities, and Engineers Choose MagnaPlast™
Built for Municipal Approval
MagnaPlast™ aligns with the engineering standards cities use to evaluate and approve sanitary sewer infrastructure. The system is fully compliant with ASTM, AASHTO, and CSI performance criteria — making it straightforward to specify and easy to approve.
Built for Long‑Term Reliability
MagnaPlast™ eliminates the failure modes that make concrete expensive to own.
• 100‑year corrosion‑proof HDPE construction
• Leak‑free inlet and outlet performance
• No cracking, spalling, or H₂S deterioration
• Smooth internal flow surfaces (Manning’s n = 0.010)
• Traffic‑rated for H‑20 / HS‑25 loading
Faster, Safer Installation
- Lightweight HDPE structure reduces crane dependency
- Ships factory‑assembled and leak‑tested
- Adjustable riser system simplifies grade control
- Anti‑flotation system integrated into the design
- HDPE can be drilled or cut with simple tools for field adjustments
Lower Lifecycle Cost
- Emergency repairs
- Infiltration and inflow (I&I)
- Corrosion‑related failures
- Replacement cycles
- Maintenance budgets
Specifications
Full performance specifications are available in the Resource Hub.
MagnaPlast™ is engineered to meet or exceed municipal requirements for sanitary sewer manholes.
- 100‑year design service life
- Factory‑assembled and factory leak‑tested
- Watertight inlet, outlet, and riser interfaces
- Smooth internal flow surfaces (Manning’s n = 0.010)
- Traffic‑rated for H‑20 / HS‑25 loading
- Engineered for groundwater, buoyancy, and saturated soil conditions
- ASTM, AASHTO, and CSI compliant
MagnaPlast™ vs. Concrete
Concrete manholes have served cities for decades, but they come with predictable failure modes that drive up maintenance budgets, emergency repairs, and long‑term operating costs. MagnaPlast™ eliminates those vulnerabilities with a corrosion‑proof, leak‑free, factory‑assembled HDPE system engineered for a 100‑year service life.
Engineering Standards and Comparison PDF
If corrosion, maintenance, leakage risk, and installation efficiency matter, MagnaPlast™ must be evaluated alongside concrete.
Standards matter and MagnaPlast™ aligns with the criteria cities use to approve products and bid specs.
Installation and Cost Advantages
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MagnaPlast™ simplifies installation and reduces risk for contractors and municipalities.
It installs faster, requires less equipment, and delivers long‑term reliability with minimal maintenance.
Installs in one‑third the time of concrete
No cranes or heavy lifting
Performs reliably in poor soils
Shorter road closures
Lower total installed cost
Corrosion‑proof HDPE = minimal maintenance for decades
Engineering Support
Our engineering team provides project‑specific support from design through installation.
- Detailed installation drawings and foundation/backfill guidance
- Structural design details for traffic‑bearing applications
- Anti‑flotation analysis and groundwater evaluation
- Custom submittal drawings for every manhole
- Inlet/outlet deflection angles, drop connections, and pipe compatibility
- CSI‑formatted performance specification for project documentation