Hiring for Open-Cut Replacement

When a dig is honest

The method itself, trench to backfill, is described on the lining site's sewer line replacement page. This page is about hiring for it. Start by confirming the dig is justified. The camera footage should show one of a few things: standing water in a low section that no liner or burst can lift; a reverse grade or a dropped joint that needs the pipe re-laid at a new elevation; a collapse with no shape left; or a line so shallow, short and open that trenching is cheaper and cleaner than any alternative. If none of those is present and the contractor still proposes a dig, ask what the trenchless bids were and why they were set aside. An excavation company that does not offer lining or bursting will dig everything, and that is a reason to get a second bid, not a reason to sign.

Trench safety first

Any trench five feet deep or deeper must be protected against cave-in under federal rules, and many residential sewers sit at six to twelve feet. The bid should state the protective method: a trench box, hydraulic shoring, or sloped or benched walls at an angle suited to the soil. It should also name a competent person responsible for the excavation. A contractor who shrugs at this question, or plans to send a worker into an unshored eight-foot cut "for a few minutes," is a contractor whose fatality becomes your liability claim. Shoring costs money and time, and leaving it out is the first way a low bid gets low.

Depth, length and what is above the line

The bid should give the depth of the pipe at the house and at the main, taken from the camera locate, and the length of trench between. Depth drives everything else: the width of the trench, the volume of spoil, the shoring, the size of the equipment, and whether a sidewalk or driveway comes out. The bid should list every surface the trench crosses, since each one is a restoration item later. If the contractor has not located the pipe and is guessing at depth, the depth, and the price, are guesses too.

Groundwater

A trench below the water table fills with water, and pipe cannot be bedded or inspected in it. The bid should say whether groundwater is expected at this depth in this neighborhood, and if it is, how it will be handled: sump pumps in the trench, well points along it, or a stone drainage layer. It should also say where the water will be discharged, because pumping muddy water into the street or the storm drain is a violation in most cities. Dewatering is the second place a low bid gets low, and it is often the first change order.

Bedding, backfill and compaction

New pipe that is laid on lumps and buried with the dirt that came out will settle, and a settled sewer pipe is a new belly. The bid should specify the bedding under and around the pipe, usually crushed stone or sand to a stated depth below the pipe and up to a stated height above it, and then the backfill above that, placed in lifts of a specified thickness and compacted to a specified density. On your own property the standard may be the contractor's, but it should still be written. In the right-of-way it is the city's standard, and the inspector will test it. A bid that says "backfill and compact" with no numbers has left room to drop the spoil back in the hole in one pass.

The pipe

Most new laterals are solid-wall PVC in one of two standard wall thicknesses, joined with gasketed bells; some utilities allow or require HDPE or ductile iron in certain conditions. The bid should name the material, the diameter, the wall class and the standard it meets, and it should match what the utility's specifications allow for new services. It should also list the fittings: the cleanout or cleanouts, the transition fitting at the house, and the connection at the main.

The connection and the inspection

How the new pipe joins the main depends on who owns that segment, and the ownership and permits page explains how to find out. Either way the utility inspects the open trench before backfill, looking at the pipe, the bedding, the slope and the connection, and will not pass a trench it did not see open. The bid should list this inspection and say that backfill waits for it. Some utilities also require an air or water test, and the right-of-way inspector returns after restoration to check the surface. All of these should be in writing, and final payment should follow the last of them.

Restoration is where the money is

Pipe is cheap. Putting the ground back is not. A complete excavation bid itemizes restoration by surface. A lawn gets topsoil and seed or sod. A concrete sidewalk or driveway is replaced to the joint, full panel, matching thickness and finish, because a patch inside a panel cracks. An asphalt driveway is saw-cut, based and repaved. Landscaping, fences and irrigation that have to be removed are listed, and so is who puts them back. A street cut is restored to the city's published standard, which typically means a wider cut than the trench, a specified base depth, a specified pavement depth, and sometimes a mill-and-overlay across the full lane. Many cities also charge a pavement degradation fee on top. The low excavation bid almost always omits some of this, either by not mentioning restoration at all or by saying "rough grade" and leaving the rest to you. Read for it.

Traffic control and the right-of-way

If any part of the trench is in the sidewalk or street, the bid must carry the right-of-way permit, the traffic control plan the city requires, the signs, cones and flaggers that plan calls for, and the right-of-way bond the city holds against the restoration. Steel plates to reopen the street overnight are a line item. So is the permit fee. A plumbing company without a right-of-way bond cannot legally open your street, and it may propose to stop at the property line and leave the public segment to someone else, which is acceptable only if the bid says who.

Change orders for what the ground hides

Rock, boulders, buried concrete, an old abandoned tank, groundwater that was not expected: the ground sometimes surprises everyone. A fair bid handles this with language written in advance. It defines what counts as a differing condition, states the unit rate for rock excavation per cubic yard or per hour, states the rate for additional dewatering, and requires that work stop and you be notified in writing before any extra is incurred. A bid with no change-order language is either going to absorb the surprise, which is unlikely, or present it to you as a verbal number from the edge of the trench. The general bid page covers the rest of the paper.

Checking the contractor

Excavation is where licensing patterns matter most, because in some states a plumbing license covers the trench and in others a utility or underground license is required, and a general excavator with neither is common. Use your state page to see which register to search. Confirm general liability and workers' compensation, since trench work is where injuries happen. Ask when they last had a city inspector reject a trench and what they did about it; the answer tells you whether they have met one. Then compare the bids item by item, and treat the one that left out restoration as the most expensive, because it is.

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