Installation, testing, winterization, and startup

Trenching Specifications, Depths, and Utility Clearances

Excavating trenches for landscape irrigation requires balancing frost protection, mechanical shielding from lawn maintenance equipment, and code-mandated separations from underground utilities.

Cover and separation

Burial depth depends on pipe function, frost exposure, traffic, maintenance equipment, local requirements, and the approved plan. Typical residential mainline and lateral depths are planning examples, not statewide legal minimums. Measure cover from final grade and allow for future aeration or cultivation.

Review potable and nonpotable separation rules, utility clearances, crossings, and bedding before trenching. Locate facilities and use the required excavation precautions. Do not impose one twelve-inch clearance on every utility type or assume irrigation pipe can share a trench with electrical service without an approved detail.

Utility protection

Notify Oregon 811 within the required window, confirm operator responses and markings, investigate private facilities, and use required careful excavation within the twenty-four-inch tolerance zone. The zone is measured from the facility's outside edges, not merely a paint centerline.

Separation at crossings follows the specific utility, potable/nonpotable, electrical, and local requirements. Use the approved crossing detail; do not apply one twelve-inch horizontal and vertical clearance to every facility. If actual locations conflict with the design, stop and obtain a correction.

Pipe Assembly and Solvent Welding Chemistry

Solvent welding PVC pipe is not a gluing process; it is a chemical fusion that temporarily dissolves the surface polymer chains of the pipe and fitting socket, fusing them into a single monolithic plastic joint.

Solvent-cement joint sequence

Cut square, remove burrs, and chamfer as directed. Check pipe and fitting compatibility and fit, clean and prepare surfaces, apply the required primer and correct cement, insert fully using the product's prescribed method, and hold against pushout for the instructed time. Primer color, coat count, rotation, and hold time follow the applicable code and manufacturer rather than a universal generic recipe.

Use fresh compatible materials and protect joints during cure. Contamination, incomplete insertion, premature pressure, and wrong cement can cause failures. Check the actual cure chart for diameter, temperature, humidity, and pressure. Threaded and solvent-welded joints require different procedures.

Cure before water pressure

Solvent-cement cure depends on pipe diameter, product, temperature, humidity, and test pressure. Use the actual cement manufacturer's chart. A two-hour fill and twenty-four-hour test rule, or tripling times below forty degrees, is not valid for every joint.

Inspect square cuts, deburring, cleaning, primer where required, cement coverage, insertion, and hold time. Keep incompatible solvents and joint types separate. Never pressure-test PVC with compressed air or gas; use an approved water-based test procedure and observe the manufacturer's pressure limit.

Head Connections: Triple-Elbow Swing Joints and Funny Pipe

Connecting a sprinkler head directly to a rigid lateral pipe tee with a threaded PVC riser is a severe design defect. When lawn mowers, maintenance vehicles, or pedestrians strike the head, the rigid riser acts as a lever arm, snapping the riser threads or cracking the buried lateral pipe.

Pre-Assembled Triple-Elbow Swing Joints

Standard specification for commercial turf installations and large gear-driven rotors:

• Constructed using three Schedule 80 threaded street elbows linked by threaded nipples.
• The three swivel elbows provide 360-degree rotational movement in all three geometric planes (X, Y, and Z axes).
• When a mower wheel rolls over the sprinkler, the swing joint rotates downward, absorbing the load without transferring bending torque to the lateral tee.
• Enables precise vertical and angular adjustment flush with finished sod grade.

Flexible Spiral-Barb Tubing ("Funny Pipe" / Swing Pipe)

Standard specification for residential and light commercial spray heads:

• Consists of thick-walled, high-density polyethylene flexible tubing ($1/2"$ ID) connected to spiral-barb insert street elbows.
• No Clamps Required: The aggressive spiral barbs thread into the flexible PE tubing, locking under line pressure up to 80 PSI.
• Flexible tubing length should be between 12 and 18 inches (lengths over 24 inches cause excessive friction loss).

Flushing and Hydrostatic Pressure Testing

Before backfilling trenches and installing fragile nozzles, two vital commissioning procedures must be conducted:

Line Flushing Protocol

1. Assemble lateral piping and install pop-up sprinkler bodies, but do not install nozzles or internal filter screens.
2. Install temporary threaded flush caps (or leave top caps open).
3. Open the zone control valve and flush water at full velocity for 1 to 2 minutes until discharge runs completely clear.
4. Flushing clears dirt, trench stones, plastic shavings, and primer residue that would otherwise instantly clog nozzle orifices and jam rotor drive gears.

Water testing and inspection

Use the approved test pressure, duration, isolation method, and acceptance criteria, keeping pressure within every included component's rating. Remove or isolate equipment that must not receive the test pressure. Fill slowly and purge air before testing with water.

Inspect exposed joints and fittings. Pressure changes can reflect a leak, trapped air, or temperature, so diagnose the result rather than label every small gauge change proof of a leak. Record the test conditions and corrections before concealing the work. Compressed-air winterization is a different operation and does not justify air pressure testing of plastic piping.

Winterization Blowout Procedures & Compressed Air Safety

Throughout Oregon—from the Willamette Valley to the sub-zero winter regions of Central and Eastern Oregon—undrained water trapped inside irrigation components will freeze, expand by approximately 9% in volume, and can create damaging internal stresses. This shatters PVC lateral pipes, cracks brass backflow bodies, and splits plastic valve bonnets.

Winterization airflow and pressure

Follow the installed equipment's winterization instructions, or use draining methods where the system is designed for them. A regulated airflow can remove water from suitable irrigation zones, but pressure, volume, duration, and sequencing depend on the components. Published limits for a particular sprinkler or pipe should not be presented as one statewide fifty-psi threshold.

Compressed air stores energy and can create dangerous failures. Keep people clear of discharge and components, wear suitable protection, avoid overheating dry-running equipment, and never leave the compressor operating unattended. Use the lowest pressure and appropriate volume specified for the system. Blowout is not a substitute for draining trapped water from components that require manual drainage.

Dedicated Blowout Port Location

The compressed air blowout port (typically a 3/4" or 1" brass tee with a quick-connect fitting or ball valve) must be located downstream of and isolated from the backflow assembly, according to the approved detail.

Spring Startup Recommissioning Protocols

Recommissioning an irrigation system in the spring requires a disciplined startup sequence to protect components from pressure surges:

Backflow inspection and testing

Inspect for damage and follow the manufacturer's startup sequence. Restore shutoff and test-cock positions correctly, fill slowly, and arrange the required test under the water supplier's program. Annual testing is required, but Oregon does not universally fix the annual test date to spring startup. Installation, repair, and relocation also trigger testing requirements. Do not confuse an LCP's installation authority with tester qualification.

Fill slowly and vent air

Use the manufacturer's controlled filling procedure and approved venting points. Rapid filling and trapped air can produce damaging transients; the magnitude depends on the system rather than a universal three-hundred-to-five-hundred-psi range.

Verify that air can escape safely, fill at a controlled rate, and inspect for leaks before normal operation. A ball-valve handle percentage does not directly establish a flow percentage. After filling, operate zones and check pressure, flow, closure, and sensor function.

Zone-by-Zone Operational Audit

• Manually activate each zone from the controller to verify solenoid actuation.
• Inspect pop-up sprinkler risers to ensure they pop up fully and retract cleanly without sticking.
• Clean clogged nozzle filter screens; adjust spray arcs to eliminate overspray onto sidewalks, roadways, and building siding.
• Inspect drip zones for punctured tubing, displaced emitters, and flush the distal ends of drip laterals through manual flush valves.
• Test rain sensor operation by pressing the manual test spindle to verify the controller suspends watering.