Trench Volume Calculator

Calculate excavation volume, import backfill, and spoil haul for a trench. Accounts for pipe void and soil swell.

Trench length (LF)

Trench width (ft)

Trench depth (ft)

Pipe OD (inches)

Bedding thickness (inches)

Soil swell factor (%)

Import backfill needed?

Notes: Swell factor of 25% is typical for clay/silty soils. Sandy/granular: 10–15%. Rock: 30–40%. Import backfill volume = excavation volume minus pipe void.

Concrete Volume Calculator

Calculate concrete volume in cubic yards for slabs, walls, footings, and cylindrical structures (manholes, vaults).

Length (ft)

Width (ft)

Thickness (inches)

Waste factor (%)

Concrete strength

Asphalt Tonnage Calculator

Calculate asphalt tonnage for pavement, patching, or trench restoration. HMA density ~145 lb/CF.

Area (square feet)

Thickness (inches)

Mix density (lb/CF)

Price per ton ($/ton)

Waste factor (%)

Typical densities: Dense-graded HMA: 140–150 lb/CF. SMA: 148–152 lb/CF. Open-graded: 110–120 lb/CF.

Pipe & Fittings Quantity

Calculate pipe, fittings, and bedding quantities for a pipeline. Add additional line items as needed.

Pipe length (LF)

Pipe diameter (inches)

Pipe material

Joint length (ft)

90° elbows

45° elbows

Tees

Couplings / repair sleeves

Bedding depth below pipe (inches)

Trench width at pipe (ft)

Pipe Flow Calculator (Manning's Equation)

Calculate flow capacity and velocity for gravity-flow pipes: storm drains, sanitary sewer, culverts.

Pipe diameter (inches)

Pipe slope (ft/ft)

Manning's n coefficient

Flow depth ratio (d/D)

Manning's Equation: Q = (1/n) × A × R^2/3 × S^1/2 — where A = flow area, R = hydraulic radius, S = slope. Maximum hydraulic capacity occurs at ~93–94% full, not 100%.

Minimum Pipe Slope

Find the minimum slope required to maintain self-cleaning velocity (2.0 ft/s minimum, 2.5 ft/s recommended) for gravity sewer and storm drain.

Pipe diameter (inches)

Manning's n

Target velocity (ft/s)

ASCE Standard: Minimum 2.0 ft/s at design flow for sanitary sewer per ASCE MOP 36. Many agencies require 2.5 ft/s. Maximum velocity: 10–15 ft/s to prevent scour.

Trench Safety – OSHA Requirements

OSHA 29 CFR 1926 Subpart P sloping, benching, and shoring requirements by soil type and depth. This is a reference tool — always consult a competent person on site.

Trench depth (ft)

Soil type

Protection method

Disclaimer: This tool provides general OSHA Subpart P reference information only. All excavation safety decisions must be made by a competent person on site per OSHA 29 CFR 1926.651. Conditions vary — shoring or shielding may be required regardless of soil type.

Thrust Block Sizing

Calculate thrust force and minimum bearing area for concrete thrust blocks at pipe bends, tees, and dead ends.

Pipe diameter (inches)

Test pressure (PSI)

Fitting type

Soil bearing capacity (PSF)

Formula: T = 2 × P × A × sin(θ/2) for bends. T = P × A for dead ends and tees. Bearing area = T ÷ soil bearing capacity. Always verify with project engineer for design pressure.

Grade & Slope Calculator

Convert between percent grade, ft/ft slope, rise/run, and degrees. Calculate elevation change over a given distance.

Grade (%)

Distance (ft)

Compaction Calculator

Calculate compaction requirements: passes needed, lift thickness, and relative compaction from Proctor test data.

Max dry density – Proctor (pcf)

Field dry density (pcf)

Required compaction (%)

Common requirements: APWA/AWWA trench backfill: 95% Standard Proctor within 3 ft of surface, 90% below. Check project specs — requirements vary by owner and pavement class.

Markup & Bid Price Calculator

Calculate bid price from direct cost using separate overhead and profit markup. Works from cost-to-bid or bid-to-cost.

Direct cost ($)

Overhead (%)

Profit (%)

Overhead vs. markup: Overhead is applied to direct cost first, then profit is applied to the overhead-loaded cost. Typical heavy civil overhead: 10–15%. Profit: 8–15% depending on risk and competition.

Unit Price Builder

Build a unit price from scratch — material, labor, equipment, subcontractor, and markup per unit of work (LF, CY, EA).

Unit of measure

Material cost per unit ($)

Labor cost per unit ($)

Equipment cost per unit ($)

Subcontractor cost per unit ($)

Overhead (%)

Profit (%)

Quantity (for total)

Change Order Calculator

Calculate change order value: T&M or unit price basis. Includes labor burden, equipment, materials, markup.

Superintendent hours

Superintendent rate ($/hr)

Laborer hours

Laborer rate ($/hr)

Equipment hours

Equipment rate ($/hr)

Material cost ($)

Overhead & profit (%)

Bond rate (% of bid, optional)

Production Rate Calculator

Calculate daily output, cost per unit, and project duration from crew size, hours, and production rate.

Work type

Production rate (units/day)

Unit of measure

Total quantity

Crew size (workers)

Avg crew rate ($/hr all-in)

Hours per day

Equipment cost ($/day)

Typical production rates (heavy civil): 8" waterline in average soil: 150–300 LF/day. 8" sewer: 100–200 LF/day. Trench excavation: 300–600 LF/day. Backfill: 400–800 LF/day.

Crew Day Cost Calculator

Calculate total daily crew cost including labor, equipment, and overhead burden. Useful for T&M pricing and daily report tracking.

Labor

Equipment

Small tools / consumables ($)

Overhead burden (%)

Construction Unit Converter

Common unit conversions for heavy civil: volume, area, weight, pressure, length.

Pipe Reference Table

Outside diameter, wall thickness, weight, and pressure class for common pipe materials used in underground utility work.

Filter by material:

Material	Nom. Size (in)	OD (in)	Wall (in)	Weight (lb/ft)	Pressure Class	Standard

Manning's n Reference Values

Roughness coefficients for common pipe and channel materials. Use in Manning's equation for open-channel and partially-full pipe flow.

Material / Condition	n (low)	n (typical)	n (high)	Notes
Concrete pipe (RCP)	0.011	0.013	0.015	New, good joints
PVC pipe	0.010	0.012	0.013	Smooth interior
HDPE (smooth interior)	0.009	0.011	0.013	Profile wall varies
Ductile iron pipe	0.013	0.015	0.016	New; use 0.017–0.020 for aged/tuberculated
Steel pipe	0.012	0.014	0.017	Welded; smooth interior
Corrugated metal pipe (CMP)	0.020	0.024	0.030	Standard corrugations
CMP – annular corrugated	0.022	0.027	0.033
Vitrified clay pipe (VCP)	0.011	0.013	0.015	Good condition
Cast iron pipe	0.012	0.013	0.015	Old; increases with age
Open Channels
Concrete lined channel	0.012	0.013	0.015	Troweled finish
Riprap lined channel	0.020	0.030	0.040	Varies with D50
Earth channel – clean	0.020	0.025	0.030	Regular section
Earth channel – weedy	0.025	0.035	0.045	Light vegetation
Natural stream – clean	0.025	0.030	0.033	Straight, uniform
Natural stream – irregular	0.035	0.045	0.060	Stones, weeds

Source: Chaudhry (2008), Ven Te Chow (1959), ASCE manuals of practice. Values for design use — verify with project-specific conditions.