Project Case Study. Richmond Hill. Walk-up basement foundation excavation. Free on-site assessment: 416-317-3090
Richmond Hill Foundation Excavation — Walk-Up Basement Add-On
A Richmond Hill homeowner wanted to convert their basement into a legal rental unit. The only viable second egress was a walk-up cut into the south foundation. Eight working days on site, one buried surprise, and a clean square excavation handed back ready for the forming crew. What we quoted, what we found, what it cost. Free assessment on a similar job: 416-317-3090.
Project Snapshot
- Location: Bayview Avenue corridor, Richmond Hill (street only, homeowner privacy)
- Job type: New walk-up basement excavation, south elevation, existing foundation
- Crew: 3 (operator, ground lead, labourer) plus P.Eng site visit day one
- Timeline: 8 working days on site, 6 weeks lead time from quote to start
- Equipment: Yanmar SV40 (6 ft. tracks, fit through the rear gate), Vio17 (38 in. tracks, 39 in. side-gate buffer at the gas meter), GEHL RT135 for haul-out
- Approximate cost: $24,000-$31,000 all-in for excavation scope (excludes forming, waterproofing, concrete, framing)
- Permits: Richmond Hill building permit, Ontario One Call locates, no Section 41 trigger
- Soil: Aurora-Newmarket Till. Stiff clay over silty till, typical north-GTA shelf
The Setup
1962 side-split bungalow on a 50 ft. lot. Under Richmond Hill’s second-unit by-law the owner needed separate egress, minimum ceiling height, and a separate entrance. A walk-up against the south foundation was the only configuration that did not eat interior square footage. Footprint to cut: 12 ft. long by 8 ft. wide by 8 ft. deep at the wall, stepping back at 1:1 to grade.
Two constraints set the equipment plan. The side yard between house and neighbour’s fence is 41 inches at the narrowest, past the gas meter. The SV40 at six feet wide could not fit. We planned the Vio17 (38 in. tracks, about 3 in. clearance each side) for inside-the-gate work, with the SV40 in the rear yard after we pulled a fence section. The neighbour also has a mature silver maple about 9 feet off the lot line, and the city has a tree-protection by-law on private trees over a set trunk diameter.
Soil: Aurora-Newmarket Till. Stiff brown clay in the top metre, denser silty till below. Good for short-term unsupported faces. Heavy per cubic yard, so haul-out gets planned tight.
The Plan
Bid the dig at 8 ft. depth at the foundation, stepping back at 1:1 to daylight, with a flat 4 ft. by 6 ft. landing pad. Volume: roughly 22 yards in place, about 28 loose. Three tandem dump loads, fourth on standby.
Shoring: not required at this depth in this soil on this geometry. Stiff clay at 8 ft. with a 1:1 lay-back falls inside Ontario Regulation 213/91 Type 2 allowances for an unsupported face, and we were not under-mining the existing footing. We confirmed footing depth day one with a hand-dug pit: 7 ft. 6 in. to the bottom, giving 6 in. of headroom below the new dig. Shallower footing would have meant soldier pile and lagging or stepped underpinning.
Drainage: site grades to the rear. Temporary swale cut to push runoff away from the open hole. Two electric submersibles on the truck for contingency. No paid dewatering on the quote: this site sits well above the water table per regional MOECC well logs.
The Execution
Day 1. Locates verified. Fence panel pulled. Plywood track-mats laid from rear gate to dig face. P.Eng on site at 10 a.m. to confirm the footing pit and sign off slope geometry. Turning ground by 2 p.m., 4 yards out before sundown.
Day 2-3. Bulk excavation. Vio17 worked the side-yard corridor against the foundation, SV40 worked the rear stepped slope. Two tandems loaded day two, one day three. End of day three: within about 18 inches of finished depth across the footprint.
Day 4. The surprise. About 5 ft. down against the foundation, the SV40 pulled up a rusted steel cap, then a section of corroded 2 in. steel pipe. Buried abandoned oil tank fill line, almost certainly leading to a tank under the original walk-up that was paved over decades ago. Job stopped. We called the homeowner and the TSSA-registered tank-removal contractor we use, and pulled the crew back from that quadrant. Soil sampling came back clean. The tank itself was not in our dig zone, just the fill pipe. Full day lost waiting for clearance and pulling the line. Cost passed through at the sub’s direct rate, no OCM markup on emergency work.
Day 5-6. Bulk dig finished. Hand-trim of the foundation face to expose 6 in. of footing for the new wall tie-in. The neighbour’s maple gave us one root, about 2 in. diameter, cleanly cut at the lot line with an axe (not torn by the bucket), wound dressed, photographed for the file. No root over 2 in. was severed, the threshold the local arborist by-law uses.
Day 7-8. Final grading. Landing pad compacted. Temporary plywood barrier and orange snow fence around the open dig. Sign-off with the building inspector. Forming crew scheduled for the following Tuesday.
The Result
Final dig: 12 ft. long by 8 ft. wide at the foundation, 8 ft. deep, stepped 1:1 back-slope, 4 ft. by 6 ft. flat landing pad. Footing exposed cleanly. No water in the hole at handover. Fence reinstated where the forming crew did not need it open, track-mats pulled same day. Eight working days end to end, including the buried-tank lost day. Homeowner walked it the morning of day nine and signed off.
Cost Breakdown
Rough ranges below for a comparable Richmond Hill walk-up excavation in stiff clay at 8 ft. depth on a tight-access lot. This job landed in the middle of the all-in range.
| Phase | Cost Range | Notes |
|---|---|---|
| Site setup, locates, track-mats, fence panel | $1,400-$2,200 | Ontario One Call coordination |
| Bulk excavation, hand-trim at footing, slope grading | $11,000-$14,500 | SV40 + Vio17 + GEHL RT135, 6 working days |
| Hauling, 28 yd. loose clay till | $3,200-$4,800 | 3 tandem loads to clean fill site |
| Dewatering (contingency, not used) | $0-$1,800 | Two submersibles on standby |
| Buried oil tank line removal (pass-through) | $2,400-$3,400 | TSSA-registered sub, no OCM markup |
| Restoration, barricade, lawn repair | $900-$1,500 | Topsoil and seed in spring |
| All-in excavation scope | $24,000-$31,000 | Excludes forming, waterproofing, concrete, framing |
What We Would Do Differently
Pre-dig a 2 ft. inspection trench along the full foundation face on day one, before bulk excavation. We hand-dug the footing pit at the planned tie-in but not along the rest of the south wall. That is where the tank fill line was waiting. Two extra hours of careful hand work day one and we would have surfaced the steel cap before the SV40 found it, lined up the tank sub the same morning, saved a full shift. On every walk-up against a pre-1980 foundation now, we trench the full face before the big machine swings the first bucket.
Want a Similar Project Done?
OCM Excavation runs residential foundation work, walk-up cuts, basement lowering, and underpinning across Richmond Hill, Markham, Vaughan, Aurora, Newmarket, and the rest of the GTA. We quote on site, free, within 24-48 hours of your call. Tight access, older foundation, second opinion before you sign with anyone — that is the conversation to have. Call 416-317-3090.