In the summer of 2019, SSP staff in Mukwonago, WI were invited by We Energies to participate in field training for a firsthand look on how natural gas mains and fittings are installed. SSP provides data services to We Energies and part of that offering involves translating GPS main and fitting data into GIS every day; however, drawing them is only one aspect of mapping. To map a gas distribution system correctly, one must know how mains, services, and fittings operate collectively in the physical world. Understanding the role of each piece and how they function together as an ensemble creates a new perspective for GIS editors. This viewpoint allows SSP to accurately represent what is in the ground and produce a reliable map for field crews and decision makers to use.

The first training location was a jobsite in a residential subdivision where a large main replacement project was in progress. We watched a crew member prepare two pipe segments for fusion by cutting the ends with a rotational pipe cutter to provide a clean cut for even alignment The outside of the pipe wall was peeled using a scraping tool to remove the surface layer, which is exposed to oxidation and other contaminants (Figure 1).  After the pipes were properly scraped, the Electrofusion Coupling, a fitting with built-in heating elements, was placed over both ends of the pipe with clamps on each side to prevent the pipe from moving during the fusion process. Electrofusion is the process of joining PE pipe together by using electric voltage to heat coils inside the coupling that melt the plastic material to the point where it fuses together with the PE main material. After the fusion process and the allotted cool time, the joint was visually inspected and determined successful. Afterwards, tracer wires for locating purposes were run along both pipe segments and tied together.

The next stop brought us to a residential neighborhood where the crew was finishing up a tie-in to an existing main. The new main had several fittings installed, such as valves, couplings, elbows, a reducer, and an in-line tee, which was preassembled above the excavation. Preassembled sections of pipe make installation in the trench easier in scenarios where several fittings are required over a short distance (Figure 2). We spoke to the inspectors about the difficulties they encounter in collecting GPS data in situations where there are lots of fittings in a restrictive area. Depending on the GPS accuracy, the location of fittings can vary. Therefore, SSP GIS Specialists, work directly with the inspectors to ensure the GIS reflects the exact locations and relationships of the pipe and fittings. When unsatisfactory GPS accuracy is encountered, the inspectors take pictures and create dimension lined sketches of the work that was done and attach these as supplemental as-built information to the GPS attribute data. This equips the editor with the necessary information to accurately update the GIS.

The field training concluded with a site visit to a business and residential area where the team observed the installation of 8-inch HDPE (High Density Polyethylene) pipe. At this location a butt fusion machine was being used to fuse HDPE pipe and fittings together. A heating iron and hydraulic force were used to form symmetrical beads around the inner and outer edges of the pipe end and fitting. This widely used technique produces a permanent connection called a butt fusion joint. After the pipe segments and fittings successfully fused together, a six-person team hoisted the large section of assembled pipe into their arms and carried it to the trench (Figure 3). The long, heavy winding piece of plastic piping was lowered into the pit and crew members began their next steps to tie into the existing main.

The SSP staff working on the We Energies project greatly benefited from the field training. Such benefits that have a lasting effect are:

1. Seeing main installations in person helps editors to visualize the process and relationships involved. Additionally, it brings context to what we are mapping and aids in identifying data inaccuracies/inconsistencies.
2. Being able to meet with inspectors and contractors who we normally only speak to on the phone or through email. Interacting with them allowed us to discuss the data in terms of how we see it digitally in GIS versus how it physically is in the ground.
3. Having the opportunity to ask questions on the individual functions of mains, services, and fittings, and learning how they collectively enable the operation of a gas distribution system.

The field training gave us a unique and different perspective about how simple points and polygons plotted on a 2D map represent a series of complex underground natural gas facilities. The team continually applies the information learned from the field to map with greater accuracy and efficiency due to this excellent opportunity.