What is it?

This will be the concrete pipe with the manifolds, rings etc. that you never see unless during construction. This the parts under the manhole covers. This is a pretty good … and simple explanation of the system. We see the Manhole access and the Sanitary Sewer running off of the base. Just looking at the drawing I would “guess” that this pipe is about a foot in dia. We see drains from the house sanitary system drain into the Sanitary Sewer while paralleling is the storm drain system fed by a Catch Basin.

The sanitary sewer is a system of underground pipes that carries sewage from bathrooms, sinks, kitchens, and other plumbing components to a wastewater treatment plant where it is filtered, treated and discharged. The storm sewer is a system designed to carry rainfall runoff and other drainage.

The storm sewer is a system designed to carry rainfall runoff and other drainage. It is not designed to carry sewage or accept hazardous wastes. The runoff is carried in underground pipes or open ditches and discharges untreated into local streams, rivers and other surface water bodies. Storm drain inlets are typically found in curbs and low-lying outdoor areas. Some older buildings have basement floor drains that connect to the storm sewer system. 1

Concrete Base, Risers, Cones etc.

I’m going to be simplifying everything to some extent .. this is for a model after all.

Looking at the diagram to the left the manhole cover and ring are all that we normally would see. Everything else is out of sight. The frame sits on a grade ring – which can be from 2″, 3″, 4″, 8″ and 12″ heights (Oldcast Precast® diagram used throughout this discussion)

Next down is the cone which can be Eccentric or Concentric. This connects the narrow cylinder of the access to the much larger riser.

The riser sits between the cone and the base. It is shown as 5′ for Oldcast Precast® units

At the bottom is the Base which is also 5′ for Oldcast Precast® units. It shows as round but I have seen drawings of rectangular units (I *think*)


I used the cross-sectioned drawing above to create an Eccentric cone, Riser and Base in O scale. Happily, I was able to print these on my Prusa i3 MK3 FDM printer

The Base in the drawing shows a sewer pipe holes in the sides. A cross-sectional drawing can only go so far. In this case the drawing shows a pipe 10″ in dia with the center of the pipe a little over 11″ from the bottom of the base. This gives us about 6″ from the bottom of the sewer pipe to the bottom of the base.

I was looking around and found that reinforced concrete pipe runs from 12″ to 144″ diameters. It seems that ‘ordinary’ (for uses of the word) sewer pipe ranges from 24″ to 36″ in dia. Since this is for use in a 1:48 model scene it seems reasonable to me to use readily available tubing to represent the pipe. Evergreen tubing is readily available and the sizes are found online so I will that for the design. Evergreen #228 has a .250″/6,3m OD and a .194″/4,9mm ID.

We have to remember that the actual size of the sewer pipe depends on how much drainage is require, the distance it has to flow, what other systems may connect together down the line. This is way above my pay grade so as modelers we have to .. to a great extent .. model what ‘looks’ right. The one measurement that to me is important is the 6″ between the bottom of the sewer pipe and the bottom of the base – where we find the compacted bedding.


Here we have the early stage of prototyping.

  • The Riser and Eccentric Cone printed fine … the Manhole Cover Ring not so much – it printed but not very crisp. I used a .4mm nozzle for the prints so not surprised. On the flip side .. the ring usual sits buried in the asphalt and you only see the upper surface around the manhole cover.
  • VectorCut – unfortunately not in business now. The laser cut items were top of the line
  • Rusty Stumps – also not in business any more. This was Walt Gillespie’s test run for a manhole cover

Ver 2

I got to taking measurements and found that the prior versions were oversized . I … *think* I was using a O scale manhole cover that was itself oversize .. but I can’t prove that so .. continue mission.

The one on the far left came out pretty good .. I had to tweak it a bit (the others were earlier prints) simply as I had the tolerances too close for a good fit with the FDM printer.

These scale to a 5′ OD with a 4′ ID .. that matches drawings I found online – the Oldcast Precast® units at the top of the page.

  1. http://msu-water.msu.edu/wp-content/uploads/2014/06/Storm-vs.pdf[]

3 thoughts on “Sanitary/Storm Systems”

  1. These are something to be had !! I’ve always searching for something like this and would add a great detail to my layout

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