811 Before Installing an Irrigation System

What 811 Covers on an Irrigation Job

Your 811 ticket will notify all member utility companies — electric, gas, water, sewer, telecom — and their locators will mark any infrastructure that runs through your planned trench corridors. This is the baseline protection you must have before any digging begins.

On a typical suburban property, an irrigation installation might cross: the gas service line running from the street to the house, the electric feed running underground to a garage or outbuilding, and multiple cable/telecom runs. All of these will be marked.

What 811 Does NOT Cover on an Irrigation Job

This is where irrigation projects get complicated. If you're installing a new system, 811 covers the public utilities. But if you're adding to or repairing an existing system, you also have existing private irrigation lines that are now underground infrastructure — and 811 won't mark them.

• Existing irrigation mainlines — the supply line from your backflow preventer to each zone valve
• Existing zone laterals — the distribution lines running to each sprinkler head
• Landscape lighting wire — frequently runs parallel to or across irrigation zones
• Low-voltage outdoor audio/video — often runs through landscaped areas
• Private drains and French drains — installed by previous owners with no records

Before trenching near any existing irrigation zones, map the existing system first. Locate the zone valves (usually in valve boxes buried near the backflow preventer or in landscape beds), trace the mainline path, and mark existing lateral runs based on sprinkler head locations.

Typical Irrigation Trench Depths

Note that these depths put irrigation lines significantly shallower than public utility service lines — but they put them right in the zone where you'll be trenching. An irrigation trenching machine running at 8–12 inches is above most utility lines, but below existing shallow private lines.

Mechanical vs. Hand Trenching Near Marks

Irrigation contractors typically use one of three tools: a chain trencher (most common), a vibratory plow (for shallow lines), or hand digging. Chain trenchers move quickly and efficiently but cannot be stopped mid-cut if a line is encountered — the operator must watch for marks constantly and stop the machine before entering the tolerance zone of any marked utility.

• Chain trenchers: stop at least 24 inches from any mark, hand trench across
• Vibratory plows: cannot be used within 24 inches of any mark — they pull blind
• Hand trenching: the only method within the tolerance zone of any marked line

Step-by-Step: 811 Process for Irrigation Installation

1. Design the full system before calling 811

   Know your zone layout, mainline path, valve box locations, and controller wiring run before submitting your ticket. The more complete your design, the more accurate the locate for your specific trench paths.

2. Pre-mark all trench corridors in white

   Use white marking paint or flags to mark the full path of every planned trench. For irrigation this can be a significant marking exercise — mark the mainline path, each zone lateral route, and the controller wiring run.

3. Submit 811 ticket describing full trench coverage

   Describe the project as: "Installing irrigation system, trenching throughout [describe area: front yard, rear yard, side yards] at 8–14 inch depth, approximately [X] linear feet total." Include the full property address and the extent of the dig area.

4. Map existing private lines before digging begins

   While waiting for your 811 response window, map your existing private infrastructure. Locate all sprinkler heads and trace their zone runs. Find the valve boxes and mainline path. Check for landscape lighting fixtures and trace wiring. This is work that can be done during the wait period.

5. Walk all trench paths with the locate marks before any equipment starts

   After locators have been out, walk every planned trench with someone who knows the plan. Identify every place where a trench must cross a marked utility. Mark those crossing points clearly — these are hand-dig zones.

6. Hand trench all crossings, then run machine between crossings

   At each utility crossing, hand dig a minimum 3-foot section centered on the mark before the mechanical trencher reaches that point. Once the crossing is confirmed clear by hand, the machine can resume on the other side.

Frequently Asked Questions

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