| S.No. | Checkpoint | IS Requirement | Status |
|---|---|---|---|
| A. TRENCH DIMENSION & DEPTH | |||
| A1 | Trench width adequate for pipe OD + working space (min. 0.6 m each side of pipe) Acceptance: Width ≥ Pipe OD + 1.2 m, measured at multiple points, documented | Cl. 5.1 — Width specification | |
| A2 | Trench depth matches design (typically 0.5-2.0 m depending on street level and connections) Acceptance: Depth measured at inlet/outlet/mid-span, matches design ±5cm, recorded on drawing | Cl. 5.2 — Depth verification | |
| A3 | Invert level verified at design (elevation of pipe inside bottom); gradient slope per design Acceptance: Invert level checked with theodolite, gradient 0.3-2.0% typical, documented | Cl. 5.3 — Invert level | |
| B. TRENCH BOTTOM PREPARATION | |||
| B1 | Trench bottom is firm and stable; no soft spots or mud; loose soil excavated and compacted Acceptance: Bottom firm, no pooling water, no soft clay layers visible, CBR ≥5 preferred | Cl. 5.4 — Bottom condition | |
| B2 | 100mm sand/gravel cushion layer placed on trench bottom for pipe support Acceptance: Cushion layer 100mm, compacted, free from large stones, even distribution | Cl. 5.5 — Cushion layer | |
| C. WATER MANAGEMENT | |||
| C1 | Ground water level checked; if below invert, no additional dewatering needed; if above, sump/pumping arranged Acceptance: GWT measured, if above invert: sump pump arranged, water controlled during laying | Cl. 5.6 — Groundwater control | |