America's Wastewater Infrastructure is Failing
The Problem
Municipal wastewater systems across the U.S. are aging and deteriorating:
- Concrete manholes crack, corrode, and leak
- Water and sewage leak into the collection system or out into the surrounding environment
- Hydrogen sulfide (H₂S) gas and sulfuric acid corrosion are major drivers of concrete manhole deterioration and premature failure
- 900 billion gallons of untreated sewage is discharged annually
- Rehabilitation and replacement costs are climbing as cities work to manage risk and keep up with tightening regulations
Cities need a modern, corrosion‑proof manhole solution that eliminates the cracking, infiltration, and structural failure modes inherent to concrete and polymer concrete structures.
MagnaPlast™ is engineered for that future.
What is MagnaPlast™?
MagnaPlast™ is a 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 for consistent, engineered structural performance.
- Exceptional hoop strength to resist backfill, groundwater, and soil loads.
- Seamless, monolithic HDPE construction that eliminates internal joints and common leak paths.
- Superior performance vs. concrete, polymer concrete, and lined systems in corrosive sewer environments.
- Integrated anti-flotation design to prevent uplift in high groundwater and poor soil conditions.
- Flexible partial-bury and full-bury installation options with UV-inhibited materials for exposed sections.
- Traffic-rated configurations for H20 / HS25 loading to support street and roadway installations.
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 or weak points
Factory pressure and vacuum leak‑tested
Engineered for 100‑year service life
A 7‑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
Tub provides stability to lateral ground forces
Threaded Adjustable Riser, Direct Frame & Cover Mount, or Grade Adjustment Ring.
Precision grade control for any installation environment.
- 24 in 27 - 30 in ID risers
- Up to 9 in of vertical adjustment for precise elevation control
- Proprietary sealant provides a watertight riser interface
- 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
- 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
- Up to 31 different inlet, outlet, pipe stub configurations
MagnaPlast™ Base
Looking down into the MagnaPlast base
Inlet Detail
A close-up of inlet connection detail Illustrating the smooth, precision-formed surface that supports leak-free performance and long-term minimal maintenance.
High-Density Polyethylene Manhole
The complete MagnaPlast™ manhole system
Why Cities, Utilities, & Engineers Choose MagnaPlast™
Built for Municipal Approval
MagnaPlast™ aligns with the engineering standards cities use to evaluate and approve sanitary sewer infrastructure and integrates seamlessly into existing concrete manhole sewer systems, so engineers and municipal reviewers do not have to redesign their networks. It is engineered in accordance with core ASTM (including F1759, D3350, D2321, F477) and AASHTO trafficloading criteria, and its lightweight HDPE construction can often be installed without heavy lifting equipment — making it straightforward to specify, easy to approve, and practical to build with on constrained urban sites.
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, H₂S, or sulfuric acid deterioration
- Smooth internal flow surfaces (Manning’s n = 0.010)
- Traffic‑rated for H‑20 / HS‑25 loading
Applications
MagnaPlast™ is engineered for the environments where concrete and polymeric concrete consistently fail. Its monolithic HDPE construction, corrosion‑proof performance, and factory‑assembled reliability make it ideal for municipal, industrial, and high‑risk wastewater applications.
Municipal Wastewater Systems
Sanitary sewer collection systems
Interceptor and trunk lines
Lift station transitions
Gravity sewer networks
High‑H₂S environments
Areas with chronic I&I problems
High-Corrosion Environments (H₂S, MIC)
Force main discharge points
Downstream of pump stations
Industrial wastewater zones
Warm‑climate sewer systems with high biological activity
High Water Table & Poor Soil Conditions
Coastal regions
Flood‑prone areas
Saturated soils
Soft or unstable sub-grades
Urban & Roadway Installations
Streets and intersections
High‑traffic corridors
Urban reconstruction projects
Tight construction windows
Industrial & Process Wastewater
- Food processing
- Chemical manufacturing
- Petroleum and refining
- Mining wastewater
- Steel and metals industries
Greenfield and Replacement Projects
- New sanitary sewer construction
Replacement of failing concrete manholes
Rehabilitation avoidance (no coatings or liners needed)
Standardized municipal specifications
Specifications
Download the MagnaPlast™ Technical Overview, then request the full engineering package for standard details, specifications, and design support.
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
System Compatibility
MagnaPlast™ can be integrated into existing concrete manhole and sewer systems, allowing engineers to upgrade problem locations without redesigning their networks.
MagnaPlast manholes in assorted heights
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
Key Benefit: Ensures smooth permitting, faster approval, and long‑term performance.
MagnaPlast™ is engineered in collaboration with strategic partner Dan Early, P.E., of Infrastructure Dynamics, a specialist in structural plastic solutions for municipal water and wastewater infrastructure. This partnership brings deep HDPE and manhole design expertise to every MagnaPlast project, strengthening our ability to help engineers and municipalities replace failing concrete manholes with a proven, next‑generation solution.
