Job in progress: a 5-foot tall segmental block wall holding back a slope with the customer's driveway 4 feet behind the top.

Stop everything. Do not place the cap. Do not backfill another bucket.

This wall is being built as a failure waiting to happen. You have three critical code/engineering violations (IRC R404.4, NCMA standards):

1. No Drainage (The Killer): Native clay backfill + no drain stone + no perforated pipe = hydrostatic pressure. Clay holds water. A 5-ft wall holding a slope + driveway surcharge will generate massive lateral load when saturated. IRC R404.4 requires drains for all retaining walls. Without a 12-in. stone column and daylighted 4-in. perforated pipe at the base, this wall will bow, crack, or blow out.
2. No Geogrid Reinforcement: A 5-ft gravity wall (segmental block only) cannot resist the active pressure from a backslope + 4-ft driveway surcharge (live load ~250 psf). You need geogrid layers (typically 60–80% of wall height long) starting at the 2nd course. Check the block manufacturer’s specs—most max out at 3–4 ft without grid on level ground. You are double that load.
3. Inadequate Base/Embedment: "Scraped grade" is not a base. You need 6 in. compacted crushed stone (ASTM No. 57) minimum, with 1 course (6–8 in.) buried for embedment against kick-out.

Immediate Action:

1. Strip backfill back to the block.
2. Excavate base trench: 24 in. wide, 6–12 in. deep below front grade.
3. Install 6 in. compacted stone base. Set first course level, buried.
4. Install 4-in. perforated pipe (socked) at base rear, daylights to low point.
5. Backfill only with ¾-in. clean stone (12 in. wide min.) wrapped in non-woven fabric.
6. Install geogrid per engineer/manufacturer layout (likely every 2nd course, 4–6 ft long).
7. Compact stone lifts (max 8 in.) with plate compactor—keep heavy equipment 3 ft back.

If the crew/owner refuses: Walk away. Document with photos. This is a structural liability. A 5-ft wall with surcharge requires an engineered design in most jurisdictions.

Stop the job immediately. This wall is being built in violation of basic segmental retaining wall (SRW) engineering principles and poses a significant risk of failure.

Critical issues to stop:

1. No drainage: Backfilling with native clay without drainage aggregate (typically ¾” clean crushed stone) or a perforated drain pipe at the base traps water. Clay retains water, creating hydrostatic pressure behind the wall. For a 5-ft wall, this can exceed design limits and cause sliding, overturning, or blowout. → Required: Minimum 12” of drainage aggregate behind the wall, connected to a drain pipe at the base (per NCMA guidelines and most manufacturer specs).

1. No geogrid reinforcement: A 5-ft wall with a surcharge (driveway 4 ft behind the top = ~2-ft equivalent soil surcharge) almost certainly requires reinforcement. Segmental block walls over 3–4 ft tall, or with any surcharge, typically need geogrid layers per design. → Required: Check the block manufacturer’s design charts or hire an engineer. For clay soil and driveway load, grid is likely needed at multiple levels.

1. No base preparation: “Scraped grade” is insufficient. Base must be excavated, compacted gravel (typically 6” of crushed stone), level, and extend beyond the wall front and back.

1. No compaction control: Backfilling with native clay in lifts without proper compaction (and moisture control) leads to settlement and uneven loading.

What to do now:

• Halt backfilling.
• Remove improperly placed clay backfill.
• Install proper base: 6” compacted crushed stone, level.
• Install drain pipe at base, wrapped in filter fabric, draining to daylight or dry well.
• Backfill with drainage aggregate (not native soil) in 8” lifts, compacted.
• Determine if geogrid is needed: consult block manufacturer’s specs or hire an engineer for a 5-ft wall with driveway surcharge.
• Cap only after correct construction.

This is not just substandard — it’s unsafe. A failure could damage the driveway, property, or injure someone. Do not proceed until corrected. If the crew lacks SRW expertise, involve a licensed contractor or engineer. (Reference: NCMA Design Manual for Segmental Retaining Walls, Section 3.2; IBC Section 1807.2 for retaining walls.)