Pipe bursting for Indianapolis sewer replacement

Pipe bursting starts with two pits: a launch pit at one end of the lateral, often near the house, and a receiving pit at the other, often near the curb or at the connection to the main. A steel cable or a string of rods is fed through the old pipe from the receiving pit to the launch pit. The bursting head, a cone wider than the old pipe, is attached at the launch end with the new pipe fixed behind it.

A hydraulic puller at the receiving pit then draws the cable back. As the cone moves through the old pipe, it cracks clay, fiber or cast iron into pieces and pushes the fragments outward into the surrounding soil ^[2]. The new pipe, connected directly behind the head, slides into the space the old pipe used to occupy. Some systems use pneumatic heads that hammer forward as well; on house laterals static pull systems are common.

When the head reaches the receiving pit, the full length of new pipe is in place. The crew trims the ends, connects them to the house drain and the main or a short new connector, and the work is inspected before the pits are filled. Because the new pipe is a single fused piece from one pit to the other, there are no joints for roots to find along the way.

Much of Indianapolis was built in two big waves that left two kinds of tired sewer pipe. The first, from the late 1800s to the 1930s, used vitrified clay in short sections ^[5]. The second, the post-war boom of the late 1940s through the 1960s, often used bituminized fiber pipe because it was light, easy to handle and quick to lay ^[4]. Both are now reaching the end of their working life in large numbers.

Clay with roots at its joints can often be lined, but fiber pipe usually cannot. As it ages, fiber pipe absorbs moisture, softens and gradually loses its round shape under the weight of the soil. A liner needs a round host pipe to press against, and a bladder cannot reliably push a deformed fiber pipe back into shape. Bursting does not care about the old pipe's shape: it breaks whatever is there and replaces it.

Bursting also solves the problem of mixed materials. A lateral that starts as cast iron at the foundation, changes to clay under the yard and has a section of fiber pipe that someone repaired decades ago can be replaced in one pull, as long as the head can get through.

Many single-family bursting jobs are completed in a day, sometimes two when pits are deep, the ground is hard or the inspection has to be scheduled. The sewer is out of service from when the old pipe is disconnected until the new one is connected, so plan for no water use for most of the working day.

You will see a length of black pipe laid across the lawn or along the street before it is pulled in. That is normal; it has to be fused into one piece first. The puller and its hydraulic power unit are fairly compact, and the excavator used for the pits is usually a small machine. Noise comes from the excavator and from the power unit while pulling.

Once the new pipe is connected and filmed, the contractor calls for the Citizens inspection. The pits stay open until it passes, then they are backfilled and the surface restored. Compared with an open trench, the yard is left with two patches instead of a long strip.

A pipe bursting job is a replacement, and Citizens Energy Group requires a permit for replacements, repairs, relocations and lining of laterals ^[1]. Only licensed contractors may do the work, and in Indianapolis they must be registered with the City, with insurance and a bond in place ^[1]. After the new pipe is connected, the contractor requests an inspection and leaves the pits open until it passes.

On many older Indianapolis streets, the main runs under the roadway rather than in an alley, and the receiving pit may end up at the curb or in the street. Where the existing tap is sound, the new pipe can often be joined to it with a short connection. Where it is damaged, the connection is rebuilt in the street to the utility's standards, which brings its own coordination.

Local soils play a part too. Central Indiana's clay-rich glacial soils are dense, which helps support the new pipe but can make bursting harder work than in sandy ground. Contractors account for this in their choice of head size and pulling equipment.

High-density polyethylene is tough, flexible and can be joined by heat fusion, which melts the ends of two pipes together into a joint as strong as the pipe itself. That makes it ideal for bursting: it can bend slightly to follow the path, withstand the pulling forces, and arrive in place as a single piece with no gaps. For a homeowner who has fought roots at clay joints for years, a jointless pipe is the main attraction.

Polyethylene does not corrode and resists the chemicals in household wastewater. It is also smooth inside, which helps flow. The connection points at each end are where attention is needed, since that is where the new pipe meets old cast iron at the house and the public system at the main.

If the camera shows a round clay pipe with roots at the joints, cured-in-place lining and bursting can both work; lining may need less digging, while bursting gives an entirely new pipe and can increase the diameter. If the old pipe is deformed fiber, bursting is usually the better trenchless option. If the line has sags, open-trench work is needed for those sections, whatever method is used elsewhere.

The parent page on sewer line replacement explains open-trench replacement in more depth, and the trenchless vs excavation guide compares the approaches side by side.

On a typical older city lot, the launch pit is dug a few feet out from the front foundation wall, where the lateral leaves the basement. That spot is usually lawn or a planting bed, and it is close enough to the house that the new pipe can be joined to the cast iron building drain with a short transition. If the front of the house has a porch or steps over the line, the pit goes to one side and the connection is angled in.

The receiving pit depends on where the main is. Where the main runs under the street, the pit is often at the curb or in the tree lawn, with the final connection made under the pavement. Where houses back onto an alley with a sewer in it, the whole job shifts to the backyard. The camera locate tells the contractor exactly where the line runs and how deep it is at each end, which is what decides how big each pit has to be.

Ask to see the planned pit locations marked on the ground before work starts. If a pit would land on something you care about, such as a favorite shrub or a newer section of walk, there is sometimes room to move it a few feet.

The fragments of the old pipe stay in the soil around the new one. Clay and cast iron pieces are inert, and fiber pipe fragments are compressed into the ground. They do not affect the new pipe in normal conditions. Sharp cast iron shards can scratch the outside of the new pipe as it is pulled, which is why contractors choose wall thicknesses and heads suited to the old material, and sometimes pull a protective sleeve with the new pipe through cast iron sections. If you ever dig near the line later, expect to find broken pieces of the old sewer alongside the new pipe; that is normal and not a sign of a problem.

Before backfill, a camera run through the new polyethylene should show a smooth, continuous wall from the house connection to the main, with no water standing in low spots and clean, aligned fittings at each end. Ask to watch it or receive the file.

Bursting can be done most of the year, but frozen ground makes digging pits slower and wet spring soil can make them muddy and unstable. If the line is still working, scheduling for drier months is sensible.

Most bursting jobs follow years of root clearing, a basement backup, or a camera inspection that found pipe beyond repair. For early signs that a lateral is failing, see signs of a broken sewer line.