The Geotech Set Your Price and Never Signed It
You priced pumps, fuel, and rental days against a gallons-per-minute number pulled from borings somebody else paid for, and the subsurface came in wetter.
Other trades price quantities they can measure on a drawing. You price a subsurface behavior somebody else modeled, and the variance between the model and the site conditions falls entirely into fuel and rental, the two lines almost no one reviews weekly. By the time the overrun is visible in the monthly financials, the pumps have already run the extra days.
The size of it
Flow materially above the modeled rate turns a profitable lump sum into a loss with no contractual recovery, and it registers as fuel and rental days rather than as a change order anyone will read.
Your commodity exposure here is diesel and pumping duration. The lump sum was built against an assumed gallons per minute and an assumed run length, both taken from a geotech report you didn't commission and can't cross-examine. If flow comes in above the model and the drawdown target doesn't change, you add pumps and burn fuel and rental days for no more money. HDPE header and discharge pipe is resin-priced, so that moves on you too. Specs commonly say nothing about who owns a groundwater condition worse than assumed, and escalation or flow-rate qualification language rarely survives a subcontract review.
Three moves, in order
Step 04: Estimating system
The estimate maps one to one onto the job cost codes, so variance means something the day it appears.
What else costs dewatering contractors money
The same mechanism in other trades
What dewatering owners ask
Who pays when dewatering flow is higher than the geotech report assumed?
You priced pumps, fuel, and rental days against a gallons-per-minute number pulled from borings somebody else paid for, and the subsurface came in wetter.
What does it cost?
Flow materially above the modeled rate turns a profitable lump sum into a loss with no contractual recovery, and it registers as fuel and rental days rather than as a change order anyone will read.
What do I do first?
Write the assumption into the proposal in plain numbers: gallons per minute, pump count, and run length, citing the boring log and report date you priced from. That single sentence is what converts a wetter hole into a conversation.
What are dewatering contractors supposed to be making?
No survey separates dewatering, so there is no figure of its own. The nearest comparable trade in the reference is Excavation, which runs 21% gross margin, 14% overhead and 7% net profit before taxes at $1M–$5M, with a CFOS target of 10.5% net. Those are derived figures, not dewatering's own. Read them as the neighbourhood, and read your own job costing as the answer.
Which part of the system fixes it?
The step is number 04, estimating system. The estimate maps one to one onto the job cost codes, so variance means something the day it appears. It comes from chapter 4 of CONTROL: The Construction Financial Operating System.
Everything on this page is something you can install yourself, andCONTROL is the order to do it in. If you would rather buy the finished result, SPM The Construction CFO does this work for dewatering contractors as a service. It is a separate firm, Sulphur Prairie Management, LLC, run by the same author.
Wrote CONTROL, the 8 step system behind these figures. More about the author.