After the rough grading, the first set of utilities to go underground is typically the wet utilities. The wet utilities consist of installation of pipe for sewer, storm drain, and water systems.
In this post we will be discussing:
- Sewer Mainline
- Storm Drain
- Water Mainline
- Sewer “Laterals” & Water “Services”
- Points of Connection
SEWER MAINLINE
The sewer pipe used is typically PVC and the color is green to differentiate it from the water pipe. (Other material used can be vitrified clay pipe, or “VCP”). Sewer is usually the first utility because they are typically the deepest. The reason for this is so the waste won’t leak into any of the other lines.
The sewer system mainly relies on gravity to help move the sewage from the homes to an off-site treatment facility. Although, sometimes a pump system can be put into place if the flow line is too flat.
STORM DRAIN
The storm drain directs all excess rain water away from your site and discharges it into canals, rivers, lakes, reservoirs, seas, or oceans. It can also discharge into large basins (which we’ll talk about in another section).
The material most commonly used around here is reinforced concrete pipe, or “RCP”. Other material used can be corrugated metal, corrugated plastic, or HDPE (High Density Polyethylene).
Storm Drain (RCP) Storm Drain Pipe & Manhole
The stormwater first enters the storm drain system through the catch basins located on the sides of the street. The water will then exit the site via concrete outlet structures (designs vary from site to site).
Storm Drain Catch Basin Storm Drain Outlet Structure
WATER MAINLINE
Similar to the sewer line, PVC is the “go-to” material typically used for the water system. (Other material that can be used is ductile iron). It’s generally the most shallow utility line so that leaks in the sewer or storm drain lines won’t penetrate people’s drinking water.
The water installation also consists of fire hydrants, backflow preventers, and blowoff assemblies (which we’ll cover in more detail in a separate post).
Water mainline (PVC) Water mainline installation
SEWER LATERALS & WATER SERVICES
The main sewer and water pipe that runs under the streets is known as the “mainline” (or “sewer/water main”). All the individual lines that break away from the sewer mainline to service the houses are called “sewer laterals”. And the laterals for the water are actually “water services“. The wet utility sub will typically install the laterals/services up to a certain point beyond the curb and gutter before the house plumber will come in later and extend it all the way to the house.
When the wet utility sub stubs out the laterals and services, they usually leave them above ground until the plumber is ready to connect them to the homes and the meter boxes are ready to be set in the ground. This is also known as being left “wild“.
Water service breaking off the mainline (left “Wild”) Copper Water Services & PVC Sewer Laterals (left “Wild” behind the curb)
“POINT OF CONNECTION”
When bringing the wet utilities in to your site, you have to connect to the existing mainlines located somewhere off-tract. This is your “POC” (“Point of Connection”). This could also be referred to as your “pick up point” or your “tie-in” location.
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