Culvert Installation in Lancaster, PA

A driveway culvert is a pipe buried under the drive that carries a roadside ditch or small stream from one side to the other. This service is for homeowners whose driveway crosses running water, whose old pipe has rusted, crushed or clogged, or whose ditch overflows in heavy rain.

What a driveway culvert does and when you need one

A culvert lets water keep moving where your driveway crosses a ditch. Without one, water backs up against the drive, floods the ground upstream, or cuts through the driveway edge and carries gravel away. Culvert work is one part of Yard Drainage, and it is the part where water already runs in a defined channel instead of spreading across the lawn.

Most calls fall into three situations. A new driveway has to cross an existing ditch. An old pipe has rusted through, crushed under traffic or sunk at one end. Or the pipe is simply too small and the ditch overtops the drive every time it rains hard.

Culvert pipe materials compared

The right pipe depends on the load above it, how long it needs to last, and how much equipment can reach the site.

Corrugated HDPE pipe

Double-wall polyethylene pipe with a smooth interior is light, does not rust, and joins with simple coupling bands. It moves water well and can be set without heavy lifting. It needs firm bedding and enough cover over the top, and the exposed ends should be protected from mowers and sun.

Galvanized or aluminized corrugated steel

Steel pipe carries heavy loads with shallow cover, which helps where the driveway sits close to the ditch bottom. The weak point is the invert, the bottom of the pipe, where standing water and road salt eat the coating. In a ditch that stays wet, expect it to rust out sooner than plastic or concrete.

Reinforced concrete pipe

Concrete pipe is heavy, strong and long-lived, and it suits wide drives or stream crossings that carry trucks. It takes a machine to place, and the joints must be sealed so soil does not wash in. Concrete costs more in labour and equipment, so it is usually kept for the larger crossings.

How to size a culvert pipe

Sizing comes from the land upstream, not from the width of your driveway. A ditch draining a small roadside strip needs far less pipe than one collecting runoff from several fields or a neighbour's lot. We look at the area draining to the crossing, the slope of the ditch, the length of the run under the drive, and how the inlet is shaped.

Residential driveway culverts commonly run from about 12 to 24 inches across, and stream crossings go larger. A pipe that is too small acts like a dam in a storm. Sizing up is cheaper than digging the driveway open a second time.

Cover matters too. Every pipe has a minimum depth of soil or stone over the top before it can take vehicle loads, and the manufacturer publishes it. A stream crossing may also need approval from your township or the county conservation district, so check before any digging starts.

How a culvert installation goes, step by step

The order of work is the same on most driveways, whether the pipe is new or a replacement.

Setting the grade

We mark the ditch line and set the pipe invert at the ditch bottom, with a steady fall from inlet to outlet. A pipe set too high leaves a pool of standing water at the inlet. One set too low silts up.

Excavating the crossing

The driveway is cut or the old pipe is dug out, and the trench is opened wide enough to bed and compact on both sides of the pipe. Soft or soggy spots in the trench floor are removed and filled with compacted stone.

Bedding and laying the pipe

A layer of clean crushed stone goes down as a firm bed. The pipe sections are laid from the downstream end, banded at each joint, and checked for line and fall before anything covers them.

Backfilling in lifts

Stone or approved fill goes in around and over the pipe in thin layers, each one compacted. Dumping it all in at once leaves voids that settle later and show up as a dip in the driveway.

Restoring the driveway

The surface is rebuilt with gravel, asphalt or whatever was there before, crowned slightly so water sheds off it and does not run down into the trench line.

Headwalls, endwalls and inlet and outlet protection

The ends of a culvert fail first. Water scours the soil around the inlet, undercuts the pipe, and the end collapses or drops. A headwall or endwall of stone, block or poured concrete holds the soil back and keeps the pipe from shifting. A simple apron of rip-rap stone at the outlet slows the water so it does not dig a hole below the pipe.

Where the ditch above the culvert is shallow, narrow or washed out, reshaping it with a drainage swale lets water reach the inlet cleanly. If the banks downstream are already eroding, yard erosion control at the outlet protects the ground beyond the pipe.

Signs your existing culvert needs replacing

Look at the pipe after a heavy rain, and again when it is dry.

• Water stands at the inlet or flows over the driveway instead of through the pipe.
• The pipe is flattened, cracked, or the top has rusted into holes.
• The driveway has a dip or sunken strip directly above the crossing.
• Soil or gravel is washing out around either end of the pipe.
• Daylight shows through rust at the bottom of a steel pipe.
• The ditch upstream has silted up or stays wet long after the rain stops.

Culverts and wet weather around Lancaster

Lancaster averages about 42 inches of precipitation a year, and September is the wettest month. That is steady water for a ditch to carry, and a culvert that coped in a dry summer can overtop in a fall storm. Winter adds freeze and thaw, which heaves shallow pipe and cracks old concrete ends.

The city sits in the Piedmont, north of the Conestoga River, and the surrounding county has many drives that cross small roadside ditches and creeks. If your culvert backs up after a storm, that is the time to have it looked at, before the next wet month arrives.