Groundworks
Drainage and underground services
Install stormwater, wastewater, water, power, gas, data, and service sleeves before they are buried or covered by slabs and landscaping.
drainageserviceswatercareunderground6 common trades
What happens in this stage
- Confirm service locations, connection approvals, pipe routes, gradients, bedding, inspection openings, separation, and protection.
- Install and test underground drainage and service sleeves before backfill.
- Photograph routes with measurements to fixed points before burial.
Before work starts
- Confirm the latest issued-for-construction and consented documents for drainage and underground services are on site, including Drainage plan.
- Check Drainage specification, approved product data, RFIs, minor variations, and amendment status before work starts.
- Confirm the subcontractor understands the scope, hold points, access, protection requirements, H&S controls, and quality evidence required.
- Check the programme sequence so this stage does not start before earlier work, inspections, testing, or concealed-work photos are complete.
- Confirm materials delivered to site match the specification, are dry/undamaged, and are stored according to manufacturer instructions.
During the work
- Walk the work face early, mid-shift, and before close-up. Compare actual work with the consented drawings, specification, and manufacturer details.
- Check set-out, levels, falls, clearances, penetrations, fixings, bracing, waterproofing, or protection points that will be difficult to see later.
- Ask trades to show their own quality checks rather than only saying the work is complete.
- Keep weather, site condition, delivery, delay, inspection, RFI, variation, and safety notes in the daily report.
- Photograph any work before it is covered, backfilled, lined, clad, tiled, painted, or otherwise hidden.
After the work
- Complete a close-out walk with the subcontractor and mark defects immediately while access is still available.
- Confirm required inspection bookings, council results, producer statements, LBP Records of Work, warranties, test certificates, or installer declarations are obtained.
- Update as-built notes where service routes, drainage, fixings, penetrations, or dimensions differ from the design.
- Confirm the area is protected from weather, other trades, impact damage, contamination, or premature loading.
- Update the lookahead programme and tell affected trades what is ready, what is blocked, and what must not be covered.
Common problems and step-by-step solutions
Incorrect trench depth
- 1Stop the affected drainage and underground services activity if continuing could hide defective work, create unsafe work, or move away from the consented design.
- 2Photograph the condition from wide, medium, and close-up angles. Include a tape, level, datum mark, gridline, or drawing reference where useful.
- 3Check the latest consented architectural, structural, civil, services, and specification documents before giving an instruction.
- 4Ask the subcontractor to explain the cause, proposed fix, timing impact, and whether the fix changes consented work.
- 5Escalate to the builder/project manager, designer, engineer, council inspector, or client when the fix affects structure, weathertightness, drainage, H1, fire/safety, cost, programme, or consent.
- 6Record the decision, responsible person, drawing/RFI/variation reference, photos, and follow-up inspection in the daily report.
Service clash
- 1Stop the affected drainage and underground services activity if continuing could hide defective work, create unsafe work, or move away from the consented design.
- 2Photograph the condition from wide, medium, and close-up angles. Include a tape, level, datum mark, gridline, or drawing reference where useful.
- 3Check the latest consented architectural, structural, civil, services, and specification documents before giving an instruction.
- 4Ask the subcontractor to explain the cause, proposed fix, timing impact, and whether the fix changes consented work.
- 5Escalate to the builder/project manager, designer, engineer, council inspector, or client when the fix affects structure, weathertightness, drainage, H1, fire/safety, cost, programme, or consent.
- 6Record the decision, responsible person, drawing/RFI/variation reference, photos, and follow-up inspection in the daily report.
Failed drainage inspection
- 1Stop the affected drainage and underground services activity if continuing could hide defective work, create unsafe work, or move away from the consented design.
- 2Photograph the condition from wide, medium, and close-up angles. Include a tape, level, datum mark, gridline, or drawing reference where useful.
- 3Check the latest consented architectural, structural, civil, services, and specification documents before giving an instruction.
- 4Ask the subcontractor to explain the cause, proposed fix, timing impact, and whether the fix changes consented work.
- 5Escalate to the builder/project manager, designer, engineer, council inspector, or client when the fix affects structure, weathertightness, drainage, H1, fire/safety, cost, programme, or consent.
- 6Record the decision, responsible person, drawing/RFI/variation reference, photos, and follow-up inspection in the daily report.
Source / Where to check
Check stormwater, surface water, drainage paths, and council/engineer stormwater design.
Check hot/cold water supply requirements, plumber producer statements/certificates where applicable, and consented plumbing layouts.
Auckland Council explains local building consent processes, CCC, related certificates, producer statements, LBP notification, and whether resource consent may also be needed.
Consented drawings and specifications
The issued consent drawings, stamped specifications, engineering drawings, RFIs, minor variations, and amendments control the specific project.
Manufacturer specification
Use the exact current installation manual, warranty requirements, BRANZ/Appraisal information where applicable, and product data sheet for the product on site.
Insufficient data to verify
Insufficient data to verify — check the consented drawings, project specification, relevant NZ Standard, or council requirement.
Common inspections required
- Council drainage inspection
- Pressure/water test
- As-built drainage survey where required
Common risks
- Incorrect falls
- Pipe damage during backfill
- Service clash
- Future access impossible
- Cross-connection
Common mistakes
- Backfilling before inspection
- No photos/as-built measurements
- Wrong pipe route due to old drawing
Required documentation
- Latest consented drawings and specifications
- Relevant RFIs, site instructions, amendments, minor variations, and variation approvals
- Subcontractor scope, QA checklist, delivery dockets, product data, and installation records
- Inspection booking/result records and photos before cover-up
- Daily site report notes covering labour, weather, progress, delays, risks, and decisions
Photos or diagrams needed
- Wide photo showing where drainage and underground services is happening on the site
- Close-up photos of critical details, fixings, laps, seals, penetrations, clearances, levels, or falls
- Photo of product labels, batch numbers, delivery dockets, and installer marks where relevant
- Marked-up drawing or simple diagram showing any changed location, clash, defect, or agreed remedial detail
Construction manager checklist
- 1Scope, drawings, specification, product data, and latest revision confirmed
- 2Trade briefed on hold points, tolerances to verify, evidence required, and inspection sequence
- 3Access, storage, protection, temporary works, and safety controls in place
- 4Work checked against drawings during installation, not only at completion
- 5Photos and records captured before work is concealed
- 6Defects, RFIs, delays, and variations recorded with owner and due date
- 7Inspection/producer statement/warranty/Record of Work requirements tracked for CCC
Questions to ask the subcontractor
- Which drawing, detail, or manufacturer instruction are you working from?
- What needs to be checked before this is covered or handed to the next trade?
- What could stop you today: weather, access, materials, information, inspections, or other trades?
- Does anything on site differ from the drawings or specification?
- What evidence will you provide for the quality file and CCC file?
Red flags to stop work
- Work differs from consented drawings or specification and no approved variation/RFI exists
- A structural, weathertightness, waterproofing, drainage, fire/safety, or H1 detail is unclear
- The trade wants to cover work before inspection, testing, or photos are complete
- Specified materials are missing, substituted, damaged, wet, expired, or installed outside manufacturer instructions
- A safety control is missing for excavation, heights, plant movement, electrical work, asbestos, silica, or public protection
What to record in the daily report
- Exact location and quantity of work completed
- Trade headcount, company names, plant used, deliveries, and material batch/product details
- Weather, site conditions, delays, instructions received, RFIs raised, and inspections booked/passed/failed
- Photos taken before cover-up and any defects or non-conformances found
- Next-day lookahead, blockers, and who is responsible for each action