14.3 Main Installation, Tapping & Service Line Installation

Open-Cut Installation Sequence

1. Locate existing utilities. Call 811 (Underground Service Alert) at least two working days ahead, verify markings, and pothole (daylight) critical crossings before machine excavation. Damaging a gas line or a fiber trunk is the most consequential single mistake a water crew can make.
2. Traffic control and excavation safety. Set the traffic control plan; establish the trench protective system before anyone enters (Section 14.6).
3. Excavate to line and grade with the specified trench width - wide enough to compact the haunches, narrow enough to limit load on the pipe.
4. Prepare the foundation and bedding. Over-excavate unstable material; place and shape bedding; dig bell holes.
5. Inspect and lay pipe. Check each length for damage; clean bell and spigot; lubricate with approved lubricant; insert to the depth mark; check line and grade continuously.
6. Install fittings, valves, and hydrants with thrust restraint (blocks against undisturbed soil, or restrained joints).
7. Haunch and backfill in compacted lifts.
8. Pressure and leakage test.
9. Disinfect, flush, and sample.
10. Tie in, restore surface, and update the map with a red-line as-built.

Separation Requirements

Under 22 CCR 64572: at least 10 feet horizontally from and 1 foot vertically above any parallel sewer, never in the same trench; crossings at no less than 45 degrees, 1 foot above, with no joints within 8 horizontal feet; 100 feet from a landfill, wastewater pond, or hazardous waste site; 25 feet from a cesspool, septic tank, leach field, or seepage pit. All distances are measured from the nearest outside edge of each pipe barrel.

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Trenchless Methods

Trenchless controls that matter: accurate utility locating and potholing along the entire bore path, monitoring and limiting pull force so the pipe is not overstressed, managing drilling fluid to avoid an inadvertent surface return (frac-out) into a street or a waterway, and verifying depth and alignment as the bore progresses.

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Tapping

Wet Tapping (Live Tap)

A wet tap connects a new branch to a pressurized, in-service main with no shutdown and no customer outage:

1. Install a tapping sleeve around the main and bolt a tapping valve to it.
2. Pressure test the sleeve and valve before cutting - a leak found afterward means an unplanned shutdown.
3. Mount the tapping machine on the valve, open the valve, and advance a shell cutter through the main wall.
4. The cutter's retaining pilot holds the coupon so it is withdrawn rather than left in the main.
5. Retract the cutter, close the tapping valve, remove the machine, and connect the branch.

Key discipline: account for the coupon. A coupon dropped into a main can lodge in a valve, a meter, or a service and cause a failure nobody can explain later.

Dry Tapping and Direct Tapping

• Dry tap - the main is shut down and drained; a hole is cut and a fitting installed. Requires a shutdown and requires disinfection and coliform sampling before return to service.
• Direct tap - a corporation stop threaded directly into the pipe wall. Acceptable in ductile iron of adequate wall thickness. Not acceptable in PVC or thin-wall pipe without a service saddle, which distributes the stress; a direct tap into PVC creates a stress riser that can split the pipe.
• Tap spacing - keep taps away from bells and joints and from one another, per the manufacturer's minimums (a common rule is at least 18-24 inches between taps and at least 18 inches from a joint), and stagger taps around the circumference rather than lining them up along the top.

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Service Line Installation

From main to meter:

1. Corporation stop at the main, on a saddle where required
2. Goose-neck or expansion loop to absorb ground movement - historically these were lead, which is why they are a separate service line inventory category
3. Service line - copper (type K soft is common), HDPE, or PEX; record the material, because the Lead and Copper Rule service line inventory requires the material of both the utility-owned and customer-owned portions
4. Curb stop in a curb box at the property line - the utility's single-customer isolation point
5. Meter setter, meter, and backflow protection appropriate to the hazard
6. Trace wire on non-metallic service lines so the line can be located later

[!IMPORTANT] Never connect new copper to remaining lead. A partial lead service line replacement creates a galvanic couple that accelerates lead release and physically disturbs accumulated scale. If a lead line is encountered, the correct action is full replacement, and the customer must receive flushing instructions and a certified point-of-use filter plus follow-up sampling.

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Pressure and Leakage Testing

Per AWWA C600 (ductile iron) and C605 (PVC), typically:

• Test pressure is commonly 150 percent of working pressure or a specified value such as 150 or 200 psi, held for a defined period (often 2 hours)
• Expel all air before testing - trapped air makes the test meaningless and dangerous
• Allowable leakage is computed from a standard formula based on pipe diameter, length, number of joints, and test pressure; zero leakage is not the standard for gasketed pipe, but the measured makeup water must be at or below the allowable

$L = \frac{S \times D \times \sqrt{P}}{148{,}000}$

where L is allowable leakage in gallons per hour, S is the number of joints, D is nominal diameter in inches, and P is test pressure in psi.

• Nobody stands in line with a cap, plug, bend, or dead end during the test.

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Disinfection and Return to Service

22 CCR 64580 requires that prior to use, newly installed water mains, or mains taken out of service for maintenance or repair, be disinfected and sampled for bacteriological quality in accordance with AWWA Standard C651-05, and that samples from new mains be negative for coliform bacteria before the main is placed into service. The methods and the sampling protocol are covered in Section 15.1.