Rock removal · Line drilling · Vibration control
Taking out ledge five feet from an occupied brick building
A developer's new building needs about eight feet of rock taken out for its basement and footings, and the rock starts just below the topsoil. Five feet from the edge of the cut stands a c. 1900 three-storey brick building with people living in it. Breaking that rock with a hydraulic hammer beside old masonry is how a job ends up paying for cracked plaster, so the rock nearest the building comes out another way.
Illustrative example — composite site, not a completed ESC project.
- Neighbor
- c. 1900 three-storey brick building, occupied throughout
- Gap
- 5 ft from the building to the new rock face
- Rock
- Hard conglomerate or argillite, 2–3 ft below grade (typical; to be mapped)
- Cut
- To about 10 ft below grade, most of it in rock
- Water
- None expected in the cut
- Lot
- 50 ft × 90 ft
The situation
The ledge surfaces just under a thin cover of fill across the whole lot. The new building's basement and footings go about ten feet below grade, so most of the cut is rock.
On the left, a c. 1900 brick building stands five feet from where the rock face will be. Its footings very likely sit on the same ledge, and the building stays occupied the whole time.
The rest of the lot is open. The far side of the cut is thirty feet or more from anything that matters.
What drives the design
The rock is continuous
Ledge carries vibration a long way, and a building whose footings sit on the same rock feels every blow of a hammer. Distance, and the way the rock is broken, are what bring that down.
People inside
Vibration limits, working hours and notice to the occupants shape the method as much as the rock does.
A clean face at the property
The rock face nearest the building is also the edge of the new basement. Line drilling gives a planned, clean break there instead of overbreak reaching toward the neighbor's footing.
Measured, not guessed
A seismograph on the neighbor's wall records every event against the limit the engineer of record sets. The readings decide how close the hammer may come.
Line-drill the face beside the building, drill and split the rock next to it, and hand the far side to the excavator's hammer.
- Rock probes first, so the rock surface along the face is mapped before anything is priced.
- Line drilling: a row of 3-inch holes at about 6-inch centers along the face nearest the building, taken to the bottom of the cut. The rock breaks to that line, and the open slot also interrupts some of the vibration headed for the building.
- Drill and split: within about twenty feet of the face, the rock is drilled on a grid and broken with hydraulic splitters or non-explosive expansive grout, then mucked out by the excavator.
- Past that, the excavator's hammer takes over, only as close as the monitoring allows.
- A pre-construction survey of the building and a seismograph on its wall before the first hole.
Illustrative example — composite site, not a completed ESC project.
- Note 1: Occupied brick building, its footings on the same ledge
- Note 2: Seismograph on the wall nearest the work
- Note 3: Line-drilled face: 3 in holes at about 6 in centers, to the bottom of the cut
- Note 4: Drill-and-split zone: rock broken with splitters or expansive grout
- Note 5: Hammer zone: only as close as the readings allow
- Note 6: Top of rock, mapped by probes before pricing
Illustrative example — composite site, not a completed ESC project.
- Lot line
- Neighboring building
- New building footprint
- Drill-and-split zone
- Line-drilled rock face
- Gap that decides the design (measured on the drawing)
- Synthetic lot for illustration: 50 × 90 ft, with rock close under the whole lot.
- Line drilling along the whole face on the neighbor's side: about 66 LF.
- Drill and split within about 20 ft of that face; hammering beyond it, inside the vibration limit.
- A seismograph on the neighbor's wall for as long as rock is being broken.
The order of work
- 01Week 0. Rock probes along the face to map the rock surface; the neighbor surveyed and a seismograph set.
- 02Days 1–3. Compact track drill in; line-drill the face beside the building.
- 03Week 2. Drill and split the zone next to the face while the excavator mucks out.
- 04Then. The excavator's hammer takes the far side, inside the vibration limit.
Who carries what
ESC
the earth-support subcontractor
- Rock probes to map the rock surface
- Line drilling along the face
- Drill and split beside the face
- Our own drill cuttings
General contractor
or the builder
- Notice to the occupants and working hours
- Footings, pits and foundation concrete
- Site access and street permits
Excavator
often the GC's own crew
- Mucking out the split rock
- Hammering in the open part of the lot
- Loading and trucking the rock
Engineer of record
designs and signs
- Vibration limits for the neighbor
- Rock face and footing levels
Others
- Monitoring consultant: seismograph and reports
- Surveyor: pre-construction survey of the neighbor
Budget range
Budget range · budget, not a quote
$8,750–$18,250
Computed from ESC’s published unit prices, book rev 1 issued September 14, 2026 and valid through December 13, 2026: the low quantities at the book’s low rates to the high quantities at its high rates, rounded out to the nearest $250. It is a budget for this composite site, not a quote for yours.
The basis, line by line
Compact track drill to site and back, one visit
$8,750–18,250
1 LS × $8,750–18,250
One continuous visit for the probes, the line drilling and the splitting.
Book row MOB-COMPACT
Rock work: line drilling and drill-and-split
Priced per job
Not in the current price book. Priced per job once probes have mapped the rock surface and the drawings fix the face.
Not in this range
- Mucking out, loading and trucking the broken rock (excavator)
- Hammering in the open part of the lot (excavator)
- Vibration monitoring and the neighbor's survey (owner's consultant)
- Vibration limits and footing levels (engineer of record)
- Footings and foundation concrete (builder)
Where a real job lands
The range covers getting the drill to the site and back, once. The rock work itself is priced per job: the rock surface and the drawings set the quantities.
Low end: open site, repetitive work, good ground, larger quantities. High end: tight access, obstructions, variable ground, small quantities. Book rates carry prevailing wage.
Every rate in the published bookWhat we’d need to firm it up
- Borings or test pits that reached the rock, and its type
- Footing plan with bottom-of-footing and slab levels
- The vibration limit set for the neighbor
- Rock probe results along the face (we can run them)
- The working hours the occupants' situation allows
More on the techniques
Send us the address and drawings
We'll send back how we'd approach yours: the support we'd use, the order of work, and a budget range from our published prices. We work for builders, GCs and developers.
Or email plans to bids@earthsupportcorp.com