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Detail estimate report for sewerage project

Short answer

Sewerage estimate needs survey, population/design flow, hydraulic design, soil/groundwater, drawings/specs, rates, land and environmental data. Sub-heads include preliminary, land, trench excavation, pipes, manholes, house connections, pumping, treatment, road restoration, contingencies and VAT. The specimen scheme totals NPR 25,042,608.

Explain the different data required and sub-heads of sanitary works to be included in the detailed estimation report for installation of sewer in a city (prepare a detailed estimate report for a small sewerage project).

A sewerage project collects and carries the wastewater of a town through a network of pipes to a treatment unit and a safe disposal point. Its detailed estimate is prepared after the survey and design are complete.

Data required

  1. Survey: topographic map, road network, levels and slopes, location of outfall and treatment site.
  2. Population and flow data: present and design-year population (usually 20 years), per-capita water supply (typically 100–135 lpcd in towns), sewage flow = 80% of water supply, peak factor.
  3. Hydraulic design: pipe diameters, gradients (self-cleansing velocity not below 0.6–0.75 m/s, not above about 3 m/s), manhole spacing (30–50 m), depth of cover.
  4. Soil and groundwater data for trench excavation, shoring and dewatering.
  5. Drawings and specifications: layout, longitudinal sections, manhole details, treatment plant design.
  6. Rates: District Rates for excavation, pipes, concrete, brickwork, labour, transport; land and wayleave data; environmental and social data.

Sub-heads of sanitary works

  • Preliminary: survey, investigation, design, supervision.
  • Land and compensation (treatment site, wayleave).
  • Excavation, shoring, dewatering, bedding and backfilling of trenches.
  • Supply, laying, jointing and testing of sewer pipes (trunk, main, lateral).
  • Manholes, drop manholes, inspection chambers, flushing and ventilating arrangements.
  • House connections and gully traps.
  • Pumping station (if gravity flow is not possible) and electromechanical works.
  • Treatment plant (screen, grit chamber, sedimentation, stabilisation pond or similar) and outfall.
  • Restoration of road surface, miscellaneous and contingencies, supervision, VAT.

Specimen detailed estimate report for a small sewerage scheme

Report headings: (1) introduction and project description, (2) design basis, (3) abstract of cost, (4) detailed quantities and rate analysis, (5) specifications, (6) drawings, (7) work programme. Illustrative abstract of cost (quantities and rates are assumed):

S.N.ItemQtyUnitRate (NPR)Amount (NPR)
1Survey, design and investigation (lump)1LS350,000350,000
2Excavation in trenches3,200m³7002,240,000
3300 mm dia. RCC NP2 sewer pipe, laid and jointed1,500m3,8005,700,000
4200 mm dia. uPVC sewer pipe, laid and jointed1,200m2,2002,640,000
5Brick manholes (1.2 m dia., about 1.8 m deep)45no38,0001,710,000
6House connections120no6,500780,000
7Backfilling and compaction2,800m³350980,000
8Road and pavement restoration900m²1,8001,620,000
9Waste stabilisation pond / treatment unit (lump)1LS4,500,0004,500,000
Sub-total20,520,000
Physical contingency 5%1,026,000
Supervision and administration 3%615,600
VAT 13%2,881,008
Total project cost25,042,608

Total estimated cost = NPR 25,042,608.

✓ Answer checked by Claude Opus 5.5 (high effort)

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