Sitework Estimating: Earthwork, Utilities, and Site Development

Sitework is usually the first trade on site. It’s often the least understood at bid time, too. Earth volumes change as soil is dug, hauled and compacted. Utility depths vary across the site, and soil and groundwater conditions may only be known from a few borings. A sitework estimate needs clear quantities, stated assumptions and a good read of the geotechnical report.

Where Sitework Sits in MasterFormat

In CSI MasterFormat, sitework falls in the Site and Infrastructure subgroup:

• Division 31 Earthwork — site clearing, earth moving (excavation, fill, grading), erosion control, excavation support and protection, and special foundations
• Division 32 Exterior Improvements — bases and paving, curbs and sidewalks, fences, site furnishings, irrigation and planting
• Division 33 Utilities — water, sanitary sewer, storm drainage, and other site utilities

Division 02 Existing Conditions covers surveys, subsurface investigation, demolition and remediation. Those items often come before the sitework package but are usually scoped separately. Check what the bid form puts in your package.

Earthwork Quantities

Bank, loose and compacted yards

The same soil occupies different volumes depending on its state:

• Bank cubic yards (BCY): undisturbed, in place
• Loose cubic yards (LCY): after excavation, in the truck. Soil swells.
• Compacted cubic yards (CCY): placed and compacted as fill. Most soils end up smaller than bank.

Excavation is usually measured in BCY, hauling in LCY, and fill in CCY. Mixing them up is one of the most common sitework errors.

Material	Typical swell (bank to loose)	Typical shrink (bank to compacted)
Sand and gravel	10-15%	5-10%
Common earth / loam	20-30%	10-15%
Clay	30-40%	10-20%
Blasted rock	50-65%	Rock usually bulks rather than shrinks

These are general ranges. The geotechnical report and local experience should drive the factors you actually use.

Average end area method

For roads, channels and long pads, take cross-sections at regular stations, often every 25 to 50 ft, and more where grades change quickly. Volume between two sections = (A1 + A2) / 2 x distance.

Grid (borrow-pit) methods and surface-to-surface comparisons in civil software are more common for building pads and parking lots. Whatever the method, check the result against a rough hand calculation.

Worked Example: Cut Volume, Haul and Fill

Example: a road cut has three stations 50 ft apart. Cut cross-section areas are 120 SF at station 0+00, 180 SF at 0+50 and 90 SF at 1+00. Assumptions: 25% swell, 10% shrink, 14 LCY per truck load.

Bank volume

1. Station 0+00 to 0+50: (120 + 180) / 2 x 50 = 150 x 50 = 7,500 CF
2. Station 0+50 to 1+00: (180 + 90) / 2 x 50 = 135 x 50 = 6,750 CF
3. Total: 7,500 + 6,750 = 14,250 CF
4. In cubic yards: 14,250 / 27 = 527.78 BCY

Haul

1. Loose volume: 527.78 x 1.25 = 659.72 LCY
2. Loads: 659.72 / 14 = 47.1, so 48 truck loads

If reused as compacted fill

1. Compacted volume: 527.78 x (1 - 0.10) = 475.0 CCY
2. Working backward, a pad that needs 600 CCY of fill needs 600 / 0.90 = 666.67 BCY of suitable borrow

Utility Trenching

Utility estimates are usually built per linear foot of pipe by size and depth range, then extended.

• Trench excavation: width x average depth x length. Use actual invert elevations from the profiles, not one assumed depth.
• Protective systems: OSHA’s excavation standard (29 CFR 1926 Subpart P) requires a protective system for trenches 5 ft deep or more unless the excavation is entirely in stable rock. Sloping, benching, trench boxes or shoring affect trench width, production and equipment.
• Bedding and backfill: bedding and initial backfill per the pipe spec, final backfill compacted to the specified density. That is often a percentage of maximum dry density by standard or modified Proctor.
• Pipe, fittings and structures: pipe LF by size and material, plus manholes, catch basins, cleanouts, valves, hydrants and thrust blocks
• Testing: pressure testing, mandrel and camera inspection, and disinfection for water lines where specified
• Surface restoration: pavement patching, curb, sidewalk and landscaping over the trench

Worked example: sanitary trench

Example: 300 LF of 8 in sewer, trench 3 ft wide with vertical sides in a trench box, average depth 8 ft. Bedding and initial backfill zone 1.5 ft deep, full trench width, pipe displacement ignored (a conservative assumption).

1. Excavation: 300 x 3 x 8 = 7,200 CF; 7,200 / 27 = 266.67 BCY
2. Bedding and initial backfill: 300 x 3 x 1.5 = 1,350 CF; 1,350 / 27 = 50.0 CY of bedding stone
3. Final backfill zone: 266.67 - 50.0 = 216.67 CY in place, before accounting for shrink if native soil is reused

Paving and Hardscape

• Asphalt: estimated in tons. A common planning figure is about 110 lb per SY per inch of compacted thickness. Confirm it with the mix density from your supplier.
• Aggregate base: CY or tons by thickness, with compaction considered
• Concrete paving and sidewalks: CY by thickness, plus joints, reinforcement and finish
• Curb and gutter: LF by type
• Striping and signage: LF of striping, counts of stalls, symbols and signs

Worked example: asphalt tonnage

Example: a 20,000 SF parking area with a 2 in asphalt surface course, at 110 lb/SY/in.

1. Convert to square yards: 20,000 / 9 = 2,222.22 SY
2. Weight: 2,222.22 x 2 in x 110 = 488,888.9 lb
3. Tons: 488,888.9 / 2,000 = 244.44 tons, before any waste allowance

Sitework Estimating Checklist

• Read the geotechnical report: soil types, groundwater, rock, unsuitable soils, recommendations
• Confirm existing and proposed surfaces and the source of each
• Separate topsoil stripping, mass excavation, structural excavation and trenching
• Apply swell and shrink factors, and label each quantity BCY, LCY or CCY
• Determine import or export quantities and haul distances
• Take off utilities by size, material and depth range from the profiles
• Include protective systems, dewatering and erosion control
• Include testing, surveying and layout if they’re in scope
• Price paving by course and thickness; include base, striping and signage
• List exclusions such as rock, unsuitable soil removal and contaminated material

Common Mistakes

• Mixing bank, loose and compacted yards. Hauling bank yards underprices trucking.
• One depth for every utility. Inverts change along the profile, and depth drives excavation, shoring and production.
• Ignoring the geotech report. Unsuitable soil, groundwater and rock change the whole approach.
• Missing erosion control and restoration. Silt fence, inlet protection, stabilized entrances and trench patching add up.
• Treating the net cut/fill balance as the quantity. A balanced site still has to be excavated, moved and compacted.

For related scope, see our demolition estimating page and the concrete Division 03 guide.

How F&K Estimatings Can Help

F&K Estimatings prepares sitework takeoffs organized by Divisions 31, 32 and 33, with earthwork quantities labeled by state, utilities by size and depth, and paving by course, along with the assumptions behind each number. See our sitework estimating services, or our industrial estimating service for heavy civil work. Pricing and turnaround are on the pricing page.