Pipe bursting. When the pipe needs replacement and trenchless is still possible.

§ I · How it works

Two pits are excavated, each approximately 4×4×6 ft deep — one at the basement-side end of the lateral, one at the curb-side end where the lateral meets the city main. The host pipe is exposed in each pit. A steel pulling cable is fed through the host pipe from the curb-side pit to the basement-side pit using a CCTV crawler with a tow hook. The bursting head — a tapered conical fragmenting tool fitted with replaceable carbide blades for clay or with cutting wheels for cast iron — is attached to the basement-side end of the cable. The head is sized one trade size larger than the host bore (a standard upsize: 4-in. host → 6-in. new line; 6-in. host → 8-in. new line). A new fusion-welded HDPE line is attached to the trailing end of the head.

A hydraulic pulling rig at the curb-side pit then winches the cable, pulling the head through the host pipe. As the head advances, the carbide blades split the host pipe longitudinally and the conical taper drives the fragments radially outward into the surrounding soil. The new HDPE line, fused to the head, follows directly behind, occupying the displaced bore. Pulling forces in residential bursts typically run 8 to 18 tons static; pneumatic-style equipment uses a percussive head and lower static cable load. We use a TRIC Tools M-100 static-pull rig, which is the smaller of the two units we own and the one that fits in a Buffalo driveway.

Once the head reaches the curb-side pit, the new HDPE line is in place. We connect to the basement plumbing on one end with a fusion-welded HDPE-to-PVC transition coupling and a code-compliant cleanout assembly; we connect to the city main on the other end with a saddle tap or a direct fusion to the existing tap stub, depending on the BSA inspector's preference and the geometry of the original tap. The pits are backfilled with select fill in 8-inch lifts, compacted, and restored. Total time on site: typically 10 to 14 hours start-to-finish, executable inside a single working day.

§ II · When it's the right answer

• Multiple major joint offsets beyond CIPP tolerance (>15% of nominal).
• Undersized pipe — original 4-in. clay laterals on houses with two bathrooms and a basement laundry hookup are often capacity-limited; a burst to 6-in. HDPE solves the diameter problem and the structural problem in one operation.
• Material mismatch — a stretch of cast iron transitioning to a stretch of clay with a poorly sealed coupling at the transition. The burst replaces both with a continuous HDPE run.
• Recurring failures on a host pipe that has been spot-repaired three times. The customer is paying $2,800 every two or three years; an $11,000 burst ends the cycle.
• Lender or buyer documentation requirements when CIPP lining is rejected by the lender's inspector.

§ III · When it isn't

• The host pipe has a severe horizontal misalignment (a "dogleg" exceeding the bursting head's pulling tolerance, typically >15° of cumulative bend in any 10-ft segment). The cable will not track.
• The lateral runs directly under a structural foundation footing at depth. The radial soil displacement (typically 2–4 in. of ground heave at the surface during the burst) can transfer to the foundation.
• The host pipe is directly adjacent to a parallel utility (a gas service, a water service, or a fiber-optic conduit) within the burst's displacement envelope. The displacement does not respect the existence of the neighbor.
• A foundation entry is not bell-and-spigot but glued PVC into a poured wall — pulling forces can crack the foundation entry. This is a 1970s-vintage problem; clay and cast iron interfaces tolerate the operation.

§ IV · The locate-before-burst rule

We do a full utility locate on every burst, not just the routine 8-1-1 ticket through Dig Safely New York.² We pay for a private utility locator (Buffalo's GPRS office) on every job because the public locate covers public utilities only — gas, water, electric, telecom — and not private utilities like irrigation lines, septic transitions, or 1962 oil-tank fills. A nineteen-cent saved phone call has cost crews in this trade their entire week's revenue. We do not skip it.

§ V · Cost & warranty

The posted range for a 40–60 ft residential lateral burst, 4-in. host upsized to 6-in. HDPE, in our service area, is $8,400–$13,500. The variable is mostly access (private locate cost; pit excavation in a hand-dug yard versus a track-loader-accessible drive; restoration of decorative concrete or paver patios). The price includes both pits, both connections, the BSA permit, the post-install CCTV verification, NYS sales tax, and a 1-year workmanship warranty. The HDPE line itself carries a 50-year design life under PPI TR-3;³ the fusion-welded joints have no measurable failure mode under ordinary service conditions.