Culverts and Headwalls in Casper, Wyoming

Dry gulches in this country are dry until they are not. A drainage way that carries nothing for ten months can carry a road away in ten minutes. The culvert under the road decides which of those happens. If it is the right size, set at the right grade and protected at both ends, the road stays. If any of those three is wrong, the water finds the weak spot.

A culvert is a pipe or a box that passes water under a road, drive, rail spur or yard. A headwall is the concrete or masonry face at the end of the pipe that holds the fill, guides the flow and keeps the pipe from being undercut. Together they are among the oldest pieces of civil work, and among the easiest to get wrong because the failure happens during a storm, long after the crew has gone.

We install culverts and headwalls for private drives, lease roads, industrial yards and public roads. We set them to the engineer's grade, protect the ends and make sure the water goes where the design says it should.

Pipe, box and end structures

The culvert may be reinforced concrete pipe, corrugated metal, HDPE or a precast concrete box, depending on the opening, the cover and the load. Small drive culverts are single pipes. Larger crossings use multiple barrels or a box that spans the whole channel. We install the bedding, set the sections, make the joints watertight and place the backfill in compacted lifts on both sides at once.

End treatments finish the job. A cast-in-place or precast headwall holds the embankment, and wingwalls guide the water in and out. A concrete apron or riprap pad at the outlet absorbs the energy that would otherwise carve a hole. Cutoff walls under the headwall stop water from running under the pipe. Where concrete is formed on site, the trade partners for rebar placement and forming build the walls in place and tie them to the pipe collar.

Flash flows, ice and the ground that moves

The terrain around Casper sends water downhill fast. Casper Mountain rises to 8,130 feet, roughly 3,000 feet above the city, and runoff from slopes like that reaches the plain in a hurry. Out west on US 20 and 26, Hell's Half Acre is a 320 acre scarp of deep ravines and eroded earth exposing Wind River Formation rock, a plain look at what moving water does to this soil. Soft, erodible ground at a culvert outlet is a scour pit waiting for a storm.

Winter adds ice. A culvert that freezes shut forces spring melt over the road. Pipe sized with some margin, laid on a continuous grade without sags and kept free of debris is less likely to ice up. In very cold stretches we recommend an inlet that can be steamed or thawed by the owner. Geometry matters too. A skewed crossing is harder to form and needs longer pipe, and we price that honestly.

Set it right, protect both ends

We set the pipe on a firm, shaped bed at a uniform grade. Sags hold water and silt. High spots dam the flow. After the sections go in, we check the joints and the alignment before any backfill touches the pipe. Backfill goes in both sides evenly, because lopsided fill pushes the pipe out of line.

The ends get as much attention as the barrel. The headwall footing goes below scour depth and below frost where the design calls for it. Concrete is placed in forms, vibrated and cured, and the outlet gets rock sized to the flow velocity. We lay a filter fabric under the riprap so the soil beneath does not wash through the stones. Disturbed ground around the structure is seeded or armored right away, with help from our erosion control and stormwater measures.

Where culverts are needed in this metro

Culverts show up everywhere. Subdivision streets, county roads, ranch drives and highway approaches all cross drainage. Lease roads that serve the Salt Creek Oil Field and other oil and gas sites cross draws on their way to well pads, and operators in oil, gas and midstream depend on those roads staying open in a storm. The Salt Creek Oil Field area is a case in point, where heavy trucks use the same crossings every day.

Public owners have their own needs. Counties, towns and the state replace failing culverts as part of road maintenance, and the construction crews that do that work need pipe set quickly, with a detour or a staged lane closure. Public agencies and government and municipal buildings with long entrance drives and site drainage use the same details.

Working in a channel without flooding the site

Culvert replacement means diverting water while the pipe goes in. If the channel is dry, we build in the dry and keep a pump ready. If it carries flow, we dam, pump around or divert with a temporary pipe. We watch the forecast closely during the work, because a storm upstream can send a surge through an open cut.

Weather limits the window. Midwest, north of Casper, has recorded a high of 106 F and a low of minus 42 F, which shows the range the construction trade partners work in. Concrete headwalls need warm enough weather to cure, and pipe sections are easier to set in the dry season. We aim for late spring through early fall for new crossings and keep winter work to emergency repairs. Where the road base also needs rebuilding, road subgrade preparation follows the pipe. Precast headwalls and box sections shorten the time a crossing stays closed, and for roads with heavy traffic we recommend them for that reason.

Walk the crossing with us

Send the drainage plan, or just the location and the pipe size. We will walk the crossing, check the downstream ground and tell you what the culvert needs to survive a real storm.

Questions Owners Ask

How do I know what size culvert I need?

An engineer sizes it from the watershed, the rainfall, the slope and the allowable water level at the road. Undersized culverts overtop the road in a storm, and oversized ones cost more than they need to. We build to the engineer's size and tell you if field conditions suggest a problem, such as a larger channel than the plan shows.

What is the headwall actually for?

It holds the soil around the pipe end, directs flow into the barrel and stops water from undermining the fill. Without one, the pipe end can float, shift or be crushed. The headwall also gives a clean edge for rails, guardrail posts and slope protection.

Can a failing culvert be repaired without replacement?

Sometimes. Pipe lining, sliplining and spot repairs can extend the life of a culvert that has not collapsed. We evaluate the condition by inspection and, when it makes sense, recommend repair. If the pipe is crushed or undersized, replacement is the right answer.

Do you work for oilfield operators on lease roads?

We build crossings for lease and access roads, usually for an operator or a road contractor. These jobs need quick turnaround, strong pipe and end structures that can take heavy traffic. We coordinate access and safety requirements with the operator before mobilizing.

How long does a culvert replacement take?

A small drive culvert can be done in a day. A county road crossing with a headwall may take several days, especially if concrete must cure before fill goes on. Large box culverts take longer. We stage materials in advance so the crossing is open only as long as it has to be.

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