Ground Works
Work Inside an Active Excavation (Foundations, Walls, Scaffold, Pours)
Excavation controls do not end when foundations, basement walls, formwork or scaffolding begin — they layer. Covers retained excavation controls, activity-specific release controls, SIMOPS coordination, the cumulative permit/release stack and the formal tests for reducing or withdrawing excavation controls.
v2.1Updated 9 Aug 2026ADOSH-SF v4.1 (February 2026)Learning Objectives
- Explain the layering rule: an excavation stays an active deep excavation until the temporary-works designer formally releases it.
- List the excavation controls that remain in force while permanent works proceed.
- Identify the additional design checks, ITP hold points and specialist permits for each activity inside the excavation.
- Apply simultaneous-operations rules where pours, lifting, scaffolding and dewatering share the same excavation.
- Use the five-level cumulative permit and release stack correctly.
- Apply the five release tests before any excavation control is reduced or withdrawn.
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1. The Operating Rule — Controls Layer, They Do Not Stop
The rules do not stop when foundation, retaining-wall or basement work begins — they layer. Until the temporary works designer formally releases the excavation support and the permanent works have assumed the intended stability function, the work area remains both a construction work zone and an active deep excavation. Shoring integrity, dewatering, groundwater monitoring, access and egress, edge protection, plant and surcharge control, inspection, emergency readiness and the controlling excavation PTW all remain in force. The foundation, wall, scaffolding, formwork or other activity adds its own design checks, inspection releases and specialist permits; it does not replace the excavation safety case. Never treat a completed base slab or first lift of wall as an automatic release of temporary shoring or dewatering — the approved construction sequence must state precisely when the permanent structure can resist the relevant earth, water and construction loads, and when each temporary support or pump may be changed or removed.
2. Retained Excavation Controls
Approved shoring and temporary-works design: no strut, waler, tie, anchor, pile, capping beam or internal brace may be cut, loosened, loaded, bypassed or removed unless the temporary-works designer or consultant has issued the relevant staged release or change instruction. Dewatering and groundwater control: keep the excavation dry, maintain the approved internal/external groundwater condition, and continue duty/standby pump tests, discharge controls, piezometer review and high-water contingency — changing the pumping regime can increase base-heave, piping, inflow, uplift or wall-movement risk, and Dubai's bylaw requires shoring and dewatering designs to be compatible and to avoid impacts on adjacent structures. Monitoring and inspection: continue the approved inclinometer, piezometer, settlement/asset and visual-inspection plan; a pour, backfill, heavy lift, scaffold load or pump change is a potential stage change — review the trend and revalidate the release before and after it. Access, egress and fall protection: maintain engineered stairs, ramps, ladders, protected routes, lighting, edge protection, barriers and rescue access; scaffold or formwork must not block evacuation routes or access to pumps, instrumentation or emergency equipment. Surcharge and plant control: treat concrete trucks, pumps, crane outriggers, material stacks, scaffold loads, rebar bundles and formwork panels as construction loads affecting wall stability and place them only within the approved loading/surcharge plan. Excavation PTW and SIMOPS: the excavation/ground-disturbance PTW remains the controlling permit and must be revalidated after shift change, changed conditions, a trigger breach, a weather or water event, an emergency, or an altered simultaneous operation.
3. Foundations, Basement Walls and Falsework
Foundation formation, blinding, rebar and base slab: confirm formation level, bearing condition, blinding/working-platform condition and dewatering status under the approved inspection-and-test plan, and obtain the consultant or geotechnical confirmation required before casting. Do not place rebar cages, concrete skips or material stacks where their load was not included in the shoring design. Interface: foundation/formation ITP hold point and consultant release, the existing excavation PTW, and a lift plan where cages, skips or plant are lifted. Basement retaining/permanent walls: use the designer-approved pour sequence, construction-joint and waterproofing arrangement, and check the emerging wall has the required concrete strength, connection or diaphragm action and waterproofing/anti-uplift performance before changing any temporary restraint or pumping. Interface: reinforcement/formwork and pre-pour ITP hold points, waterproofing inspection, and a temporary-works change/release before any strut or anchor alteration. Falsework and formwork: design for wet-concrete load, construction loads, access and stability; supports must sit on a confirmed load-bearing base and must not transfer unapproved load into temporary shoring, weak blinding or unverified ground. Inspect and release formwork before the pour and control striking to the approved sequence. ADOSH-SF CoP 40.0 — Falsework (Formwork) applies in Abu Dhabi.
4. Scaffolding, Concrete Placing and Lifting
Scaffolding and working platforms: scaffold needs competent design, erection, inspection and handover plus a stable verified bearing base. Confirm it does not obstruct access/egress, reduce the effective width of the base, overload the excavation formation, impose unapproved load on shoring, or create a falling-object route over workers; tie only to a permanent element where the designer has accepted the tie and load path. ADOSH-SF CoP 26.0 — Scaffolding and CoP 23.0 — Working at Heights apply in Abu Dhabi; use a scaffold handover tag and after-event inspection, and link work-at-height rescue to the excavation emergency plan. Concrete pumping and placing: develop a pour plan covering pump/boom location, bearing and outrigger load, truck route, pipe restraints, hose recoil, exclusion zone, communications, lighting, washout and emergency stop. A pump, truck or outrigger must not be placed near the excavation edge or over disturbed or filled ground unless ground-bearing and shoring-surcharge checks have been accepted. CoP 38.0 — Concrete Placing Equipment requires approved formwork suitability and precautions for pumps near excavations. Lifting rebar cages, formwork, precast or pumps: create a lift plan covering load path, crane/telehandler location, outrigger bearing, exclusion zone, tag-line control and conflict with workers below; check plant positions and temporary storage against the approved surcharge plan and never lift over occupied excavation work areas. CoP 34.0 — Safe Use of Lifting Equipment applies.
5. Temporary Electrics, Hot Work and Backfill/De-propping
Temporary electrical works, lighting, vibrators and dewatering pumps: use protected, inspected temporary distribution, control water/electrical interfaces, and route leads and pipes so they do not create trip or rescue obstructions. Any pump isolation is controlled by a linked electrical isolation certificate and LOTO procedure, and a tested standby arrangement must exist before isolating a duty pump where loss of pumping could affect stability — CoP 15.0 Electrical Safety, CoP 21.0 Permit to Work Systems and CoP 24.0 Lock-out/Tag-out. Hot work, cutting/welding and waterproofing: assess combustible waterproofing, vapours, poor ventilation, fire spread, gas accumulation and conflicts with pumps and hoses; maintain fire watch, extinguishers, ventilation and access. A low, poorly ventilated excavation can require atmospheric testing and may meet the project's confined-space trigger — CoP 28.0 Hot Work Operations with a linked hot-work PTW, and CoP 27.0 Confined Spaces only where the space meets the definition. Backfilling, removal of struts/anchors and demobilising pumps: this is a structural sequence, not housekeeping. Backfill, de-propping, tie or anchor removal and pump reduction proceed only in the approved permanent-works/temporary-works sequence, with monitoring review after each stage, a designer release or change instruction, consultant approval, a revised monitoring and dewatering plan and an updated PTW.
6. Simultaneous-Operations Rules
A SIMOPS plan is necessary whenever people, loads, plant, concrete pumping, lifting, scaffold/formwork erection and dewatering are active in the same retained excavation. The Principal Contractor nominates one coordinating person for the shift and documents work boundaries, routes, no-go zones, priority of emergency access, communications and stop-work authority. Concrete pour plus excavation access: prevent hoses, pipeline supports, trucks and washout from blocking primary or secondary egress or access to duty/standby pumps, and set an exclusion zone for hose recoil and line cleaning. Scaffold/formwork erection plus shoring monitoring: keep instrumentation casings, targets and wall access clear, and record readings before erection, after erection and after major loading or pour events where the monitoring plan requires. Lifting plus people working below: segregate the lift zone, never work beneath suspended loads or inside the fall zone, and coordinate crane positions with surcharge and ground-bearing controls. Dewatering maintenance plus permanent works: do not isolate duty pumping without a proven alternate arrangement and clear authority — any water-level rise or pump fault is a trigger for immediate work review, not routine maintenance. Hot work plus waterproofing/formwork materials: separate combustibles, control vapours, provide fire watch and keep egress unobstructed; suspend hot work if a changing groundwater or flooding condition compromises controls. Wall or structural pour plus support change: treat placement and strength gain as part of the temporary-to-permanent transition — the support-removal decision stays with the approved designer sequence.
7. The Cumulative Permit and Release Stack
The documents are cumulative, not alternatives. Level 1 — the controlling excavation/ground-disturbance PTW, owned by the authorised person and issued against the approved shoring, dewatering and monitoring regime. Level 2 — the temporary-works stage release or change instruction, signed by the temporary-works designer or coordinator and consultant. Level 3 — activity release: foundation formation or pre-pour ITP, scaffold handover, formwork/falsework release, lift plan, pump placement and bearing check, waterproofing inspection, signed by the relevant design, QA/QC, scaffold, lifting or temporary-works competent person. Level 4 — specialist PTW or certificate: hot-work PTW, electrical isolation/LOTO certificate, confined-space permit where applicable, critical-lift authorisation, issued by the authorised person or specialist competent person. Level 5 — authority or permit-condition evidence: e-permit inspection request, named third-party review, dewatering/discharge evidence or authority-specific stage document, submitted only where the issued municipality or development-authority permit or written direction requires it.
8. When Can Excavation Controls Be Reduced or Withdrawn?
Controls can only be reduced in the approved sequence — not merely because a permanent element has been cast. Obtain a formal designer or consultant decision after all five tests are satisfied. Structural substitution: the permanent foundation, base slab, wall and connections have reached the specified strength and completed configuration required to take the relevant earth, water, construction and temporary loads. Water and uplift condition: waterproofing, drainage and anti-uplift or structural provisions are complete enough for the approved permanent state, and any dewatering reduction is supported by groundwater data and the design. Temporary-works change: the temporary-works designer has issued the de-propping, anchor or strut removal, backfill or shoring-removal sequence. Monitoring decision: monitoring shows acceptable behaviour before and after the change, and the designer has revised the frequency and trigger schedule if required. Safe-work transition: access, lighting, edge protection, emergency routes, scaffold and formwork and all activity permits are updated for the new configuration.
Knowledge Assessment
1. When foundation and basement wall work begins inside a deep excavation, the excavation controls:
2. A completed base slab or first wall lift means:
3. Who may authorise cutting, loosening or removing a strut, waler or anchor?
4. Concrete trucks, crane outriggers, rebar bundles and scaffold loads beside the excavation are:
5. Which ADOSH-SF CoP governs falsework/formwork in Abu Dhabi?
6. Concrete placing equipment near excavations is covered by:
7. Before isolating a duty dewatering pump you must have:
8. In a SIMOPS excavation, the Principal Contractor should:
9. The permit and release stack is:
10. Which is NOT one of the five release tests for reducing excavation controls?
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