Large Diameter Manholes

From the Nyloplast product line

Nyloplast offers a 36” Storm Manhole developed to handle larger pipe diameters, provide access, and meet structural performance standards for traffic applications. This larger diameter manhole was developed with performance, ease of maintenance, and cost effectiveness in mind. 

From the ADS product line

ADS offers the HP Manhole for large diameter structure options for connection to ADS HP polypropylene pipe. The 48” HP Manhole is lightweight for ease of installation and is the perfect solution where corrosion is a concern. It is durable and tested to withstand H-20 traffic loads when installed per manufacturer’s recommendations. Contact your ADS representative to learn more about the HP Manhole.

48" HP Manhole

48" HP Manhole

36" Reducing Plate Assembly Image

36" Reducing Plate Assembly Image

36" Manhole with ladder

36" Manhole with ladder

48" HP Manhole
36" Reducing Plate Assembly Image
36" Manhole with ladder


Lightweight for ease of installation, our Nyloplast Manhole is a perfect solution for installations where water tight performance and corrosion is a concern.

Features and Benefits

  • PVC body, water tight gasketed connections, and accepts a variety of ductile iron inlets and covers.
  • Provides watertight connections for a wide range of pipe connection types and sizes up to 36” (900 mm) diameter. See minimum angle design chart
  • Manhole accepts a variety of 30” (750 mm) diameter manhole covers and inlet grates
  • Structures tested to meet H-20 traffic loading
  • Materials provide long-service life, excellent abrasion and corrosion resistance
  • Lightweight structure constructed from PVC for easy installation
  • Provides significant installed cost savings
  • Design minimum pipe angles comparable to 60” (1500 mm) precast concrete manhole
  • Ladder option provides access to pipe collection system
  • Installs three times faster than traditional precast
  • Structures can be factory built with weirs and other water quality features


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