823 - Water Mains
GENERAL
Water mains are a conduit or pipe that is constructed to convey treated water for consumption or to provide water for emergency services such as Fire Departments. The pipes, which are typically cast iron, are run under pressure to provide a continuous supply of water when performing such tasks as washing dishes.
Water mains are typically maintained by local municipalities and in some instances, regional entities.
MATERIALS
Pipe
Pipe material is per Section 923 of the Standard Specifications for Construction. Pipe material is typically bituminous and cement lined cast iron material with male and female ends. The bituminous lining, which is applied to the outside of the pipe helps to mitigated corrosion of the cast iron pipe as well as the cement lining which is applied to the inside of the pipe. Each section of pipe can either come with push-on joints or be bolted mechanically. Note that there may be additional material requirements as specified by the maintaining agency for the water main.
The Inspector should verify the material is acceptable for incorporation into the project by comparison to approved Material Source Lists and delivery tickets.
Figure 1Example of mechanical joint restraint
Figure 2 Pipe with flange pipe fitting
Water Services
Water service material is per Section 923 of the Standard Specifications for Construction. Water services are a smaller diameter water line, usually made of copper, that feeds off the main water main line to a house or businesses.
Gate Wells
Gate wells material is per Section 909 of the Standard Specifications for Construction. Gate wells are typically precast concrete structures that provide access to gate valves. Refer to special details associated with the water main work as maintaining agencies have different requirements for gate wells.
Gate Valves
Gate valves material is per Section 923 of the Standard Specifications for Construction. Gate Valves are installed along water main runs and are intended to provide isolation points to full open or fully close a run of water main. Gates valves are operated by turning the stem to open or close the valve as you would with a household spigot. Refer to special details associated with the water main work as maintaining agencies have different requirements for gate valves.
Tapping Valves
Tapping valves material is per Section 923 of the Standard Specifications for Construction. Tapping Valves are installed along a water main that is in in place and can be installed if the pipeline service cannot be suspended. Refer to special details associated with the water main work as maintaining agencies have different requirements for tapping valves.
Valve Boxes and Curb Boxes
Valve and Curb Boxes must meet the material requirements per Section 923 of the Standard Specifications for Construction. The boxes, made of cast iron, are installed over gate valves that are used for service shut offs or hydrants. Refer to special details associated with the water main work as maintaining agencies have different requirement.
Figure 3Valve Box
Corporation Stop and Curb Stop
Corporation stop and curb stop must meet the material requirements per Section 923 of the Standard Specifications for Construction. Corporation stop’s screw into the municple water main and a curb stop is what is used to shot of water to residence. Refer to special details associated with the water main work as maintaining agencies have different requirements.
Figure 4 Corporation stop with double strap saddle
Service Saddle
Service Saddles must meet the material requirements per Section 923 of the Standard Specifications for Construction. Service Saddles are intended to secure a service lead to the water main, see Figure 2 for a picture of a service saddle. Refer to special details associated with the water main work as maintaining agencies have different requirements.
Hydrants
Hydrants must meet the material requirements per Section 923 of the Standard Specifications for Construction. Hydrants serve as discharge points so that water can be delivered from the distribution system. Hydrants serve as an important means of assisting emergency services. Refer to special details associated with the water main work as maintaining agencies have different requirements.
Figure 5 Hydrant installation, with gate valve
Backfill material
Granular material will be used as per Section 902 of the Standard Specifications for Construction and as noted in applicable standards associated with the water main work.
The Inspector should verify the granular material is acceptable for incorporation into the project by comparison to approved Material Source Lists and delivery tickets.
Polyethylene Encasement
Polyethylene Encasement, also commonly called Polywrap, will be used as per Section 923 of the Standard Specifications for Construction and as noted in applicable standards associated with the water main work. Polywrap is common method used to protect ductile iron pipe from corrosion in certain types of soil The material works by depleting oxygen in the water trapped under the wrap and thereby reducing corrosion.
EQUIPMENT
The following list of equipment can be used for water main work:
- Excavators
- Backhoes
- Front end loaders
- Occasionally bulldozers and riding vibratory rollers for aggregate compaction
- Plate compactors
- Ho-Pac attachments
- Gas powered rammer tamping machines
- Air powered pogo thumper hammers
- Sand/stone boxes
- Portable cement mixers
- Cement/mortar mixing tubs
- Portable generators
- Electric submersible pumps
- Trash pumps
- Pipe lasers
- Transit or laser levels
- Leveling/grade poles
- Electric impact wrenches
- Pipe/spud bars
- Small hand tools (shovels, levels, pipe “chop” saws, etc.)
- Direct tap machine for water main taps
PRECONSTRUCTION
- Prior to the start of construction, the Inspector should review the plans to verify the location of the water main work.
- Verify the Contractor has requested the maintaining agency to stake existing water infrastructure.
- Verify the licensed surveyor has provided stakes for the work. Typically survey stakes are offset 5 and 10 feet from the centerline of the work. There is potential that paint marks will be placed on pavement due to limited room or inability to place offset stakes. If the water main work requires the removal of existing pavement, verify the limits of the pavement removal have been marked.
- The Inspector should review the plans and the Special Provision for Maintenance of Traffic. There may be restrictions or staging requirements for the installation of the water main. This is typically associated with staging requirements on a project and access to side streets and driveways.
- Verify all materials are approved for use and verify that stockpiled materials are protected. Obtain photographs of material labels, storage method, and their location.
- An onsite meeting with the maintaining agency should be conducted. The following topics should be discussed at the meeting: staging requirements, services, locations of valves, and exercising of valves outside the work area. Exercising existing valves within the work area and also outside of the work area should be done several weeks in advance of the work. If valves cannot be closed when exercised a discussion with the maintaining agency and Engineer will need to be conducted to determine if there are any impacts to the proposed work.
- Discuss with the Contractor the methods that will be used to construct the water main.
- Residents and businesses should be contacted if there will be disruptions to services. Coordination by the Contractor with impacted users may be required if disruption is necessary.
CONSTRUCTION
The Contractor will begin with the removal of existing pavement or aggregate material to the required depth and grade of the proposed water main work.
Once the excavation is completed per the project plans, the Contractor will lay a bedding material to rest the water main on. Individual pipes will be laid in the trench and assembled using a come along or pry bar. The installation of all pipe, fittings, and appurtenances should be in accordance with the manufacturer’s recommendations. It is important at this time that the Contractor make every effort to avoid debris from entering the water main as it is being placed.
The Contractor will place backfill material and compact the material with a hand operated compactor to receive required density. After that, the Contactor will place the remaining backfill per the plans, and will compact the fill by mechanical means.
After the completion of the installation of the water main, the Contractor will then perform a pressure test and bacteriological test on the water main. This test, which is done in conjunction with the maintaining agency, will confirm that the water main is ready to be connected to the distribution system. This process of testing can take up to two weeks.
MEASUREMENT AND PAYMENT
-Reserved-