Snow Plow Trigger Depth: 1 Inch vs 2 Inch, Priced and Worded

A snow plow trigger depth is the accumulation that starts plowing, and it decides how many visits a winter holds. NOAA's station normals count the days at 1 inch and at 2 inches, so a 1-inch trigger's extra visits can be priced before anyone signs: at Chicago O'Hare, 11.4 days a year reach 1 inch and 6.6 reach 2 inches. Ice is a separate rule, and the contract says where depth is measured and by whom.

What a snow plow trigger depth is, and what it is not (ice)

A trigger is the snow depth at which you roll, and nothing else. SIMA's article Triggered defines it as "a specific measurement of snow accumulation" reached before service starts, and the seasonal contract post turns NOAA day counts into pushes on it. A trigger is not an ice rule: SIMA's clause to avoid is salt only after 1 inch has accumulated, because "a dusting of snow combined with freezing rain" is slick with the trigger unmet, so salting runs on icy surfaces or a freezing forecast instead.

How many inches of snow before plowing: triggers by surface

Pick the trigger per surface, not per property: the walk a tenant takes at opening needs a lower trigger than the back lot. Belvidere, Illinois' snow plowing policy is tiered: under 1 inch it salts only, from 1 to 2 inches it plows once the storm ends, above 2 inches it plows the driving lanes and re-plows every additional 3 inches. Minneapolis' sidewalk rules give a business 4 daytime hours after the snow stops to clear the full width to bare pavement, and a house 24 hours.

Counting the extra visits a 1-inch trigger adds

The extra visits are the days between 1 and 2 inches, and NOAA counts them: NCEI's 1991 to 2020 normals carry, per station, the average days a year with snowfall at 1, 2 and 3 inches or more, the readme's GE010TI, GE020TI and GE030TI fields (TI is tenths of an inch).

So a 1-inch trigger at O'Hare rolls on 11.4 days a year and a 2-inch trigger on 6.6: 4.8 more plow days, the ones with 1 to 1.9 inches on the ground. The seasonal post shows where to pull your own station's CSV.

2 inch trigger snow removal versus 1 inch: pricing the difference

The per-push price does not change with the trigger; the count does. The per-acre post costs a 1-acre lot in 2 inches at $49.40 and prices it at $76 per push (its assumptions, not a market rate); the seasonal post adds a reserve of 3 pushes at cost before the cap.

Offer both: a customer who sees $1,288 beside $984 picks with the budget in view, or takes 1 inch on the walks and 2 inches on the lot.

In MakeHay, a quote carries up to three packages (Good / Better / Best), so a 1-inch and a 2-inch service level sit side by side and the customer picks one as they approve (packages help). The snow plowing starter list has "Driveway plow, per push", "Commercial lot, per push" and "Salt application" as Each, "Sidewalk and walkway" as Per linear foot and "Pre-season stake and mark" as Flat price; snow removal adds "Pre-treatment" as Each.

Zero tolerance snow contract: what the words buy

Zero tolerance is a service level, not a depth. Phil Harwood's scope of work column in Landscape Management puts it plainly: in a zero-tolerance contract "the contractor has the discretion to do whatever is needed" based on the weather and time of day, and a trigger depth in the same contract "implies the scope of work is something less than zero tolerance", so pick one model per surface. Write down whether the client expects inspections between storms for refreezing and whether your authority to act is unrestricted, since a restriction moves liability.

Price it as pre-treatment plus patrol visits: a brine pass before the snow at the rates in the salt post, a return at each shift change or opening while the event runs, and the refreeze checks between storms, so the line is a per-event price with an hourly rate behind it for long storms.

Snow removal trigger ice: freezing rain and refreeze below the trigger

Ice below the trigger belongs to the salt clause, which runs on conditions. On Minnesota's MPCA winter parking lot factsheet, six of the eight freezing rain rows in the de-icing table read "Apply chemical" with no plowing, and the two that pair freezing rain with snow read "Plow & apply chemical": the plow goes first where there is snow to move, chemical after it. A refreeze after the plow leaves is a salt call, not a push.

Anti-icing is the other half. The factsheet says anti-icing "prevents the bond from forming between pavement and ice" and "must be applied prior to snow fall", at 0.3 to 0.8 gallons of salt brine per 1,000 sq ft before light or moderate snow and 0.3 to 0.6 before frost or black ice. SIMA says the same from the contract side: salt on icy surfaces or a freezing forecast, whatever the depth.

In MakeHay, a repeating "ice check" job with Bill after each visit invoices each salt-only call, and each visit is marked Done or Skip with Weather as a reason (mark a visit done or skipped).

Who decides the trigger was reached: the measurement clause

The contract decides, by naming where depth is read and by whom. Kenton, Ohio's code section 425.13 declares an emergency snow condition at 4 inches on the streets "as determined by measurement by the Safety-Service Director or as determined by the local U.S. Weather Station". Osseo, Minnesota's snow emergency policy has an on-duty Public Services employee or police officer measure 2 or more inches at the Public Works facility parking lot, street address printed.

Kenton's weather station option ties the number to the National Weather Service station whose normals priced the contract: NWS Chicago's snow climatology takes its Chicago normals from O'Hare. Name the station, and add a ruler reading at a named flat spot on site, as Osseo does, for storms that miss the airport.

In MakeHay, every scheduled visit carries the National Weather Service forecast for the job site's own coordinates (US addresses only), and the suggested "Snow event" rule is max rain 50 percent and max temp 34°F, "Salt only" max temp 32°F (plan around the weather). A forecast is not a depth measurement.

Contract wording to copy

Seven clauses cover the arguments, built on the city rules above, Harwood's two questions and O'Hare's season dates.

• Trigger per surface: "Plowing of the parking lot begins when accumulation reaches 2 inches. Sidewalks, entrances and accessible routes are cleared at 1 inch, the entire width, to bare pavement."
• Measurement point: "Accumulation is the snowfall reported by the National Weather Service for [station name], or the contractor's ruler reading at [location on site], whichever is higher."
• Response time: "Plowing begins within [hours] of the trigger being reached. Sidewalks and entrances are cleared within 4 hours of the end of daytime snowfall, the lot within [hours]."
• Salting on conditions: "De-icer is applied when surfaces are icy or the National Weather Service forecasts freezing conditions, after snow is cleared, with no depth threshold. Pre-treatment goes down before forecast snow at the Schedule A rate."
• Season dates: "The season runs December 1 through March 31." At O'Hare the normal first 1-inch snowfall is December 7 and the last March 20.
• Drifting and re-plow: "Drifting over a cleared surface is a new event once it reaches the trigger after [hours] without new snow. A return inside that interval is a follow-up visit at the follow-up rate, outside the seasonal cap."
• Who calls: "The contractor determines that the trigger has been reached at the measurement point above, inspects for refreeze between storms at the Schedule A rate, and notifies [name] before and after each visit."

The seasonal contract post covers the state statutes that void hold-harmless clauses in plow contracts.

Good to know: This is general information, not legal advice. Statutes and rules change; read the current text and ask your state licensing board or a lawyer before you rely on it.