How long should a residential drainage site assessment take?

Using modern workflows with pre-visit desktop analysis and structured field verification, a residential drainage site assessment should take 75 to 120 minutes of active work time. Traditional manual methods typically require 4 to 8 hours for the same scope of work.

What free tools can I use for drainage site assessment?

QGIS (free GIS software) for terrain analysis, USGS 3DEP for high-resolution elevation data, NRCS Web Soil Survey for soil classification, NOAA Atlas 14 for local rainfall data, and Google Earth for aerial imagery and historical comparison. Combined, these free tools can replace thousands of dollars in survey equipment for preliminary analysis.

Is desktop elevation data accurate enough for residential drainage design?

USGS 3DEP LiDAR data is typically accurate to within 10-20 centimeters vertically at 1-meter horizontal resolution. This is sufficient for identifying slopes, flow directions, and low points on residential lots. However, field verification of critical measurements — especially foundation-to-grade relationships — is still essential.

What calculations are needed for a residential drainage estimate?

Most residential drainage estimates require the Rational Method (Q = CiA) for peak runoff calculation, Manning's equation for pipe sizing, and basic volume calculations for trench dimensions and material quantities. These calculations can be automated in a spreadsheet to produce results in under a minute.

How can I improve my drainage estimate close rate?

Deliver estimates within 24 to 48 hours, include annotated aerial photos and site maps, provide clear scope descriptions with specific measurements, and present a professional formatted document. Contractors who implement these practices typically see close rate improvements of 10 to 20 percentage points.

Do I need a surveyor's license to use elevation data for drainage estimating?

Using publicly available elevation data for preliminary drainage assessment and estimating does not typically require a surveyor's license. However, if your jurisdiction requires stamped grading plans or engineered drainage designs for permitting, those documents must be prepared by a licensed professional engineer or surveyor.

Cut Site Assessment & Drainage Estimating Time by 70% | Guide

Learn proven strategies to reduce residential site assessment and drainage estimating time by 70%. Digital tools, workflows, and templates that save hours per job.

By Low Point Labs

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