October 29, 2026
This week’s photo is courtesy of- Western Hydro Engineering- Cochise, AZ, USA .
Safety Focus
Part 4 of 4: Respiratory Protection Program
Everything this week comes together in one document. Where respirators are required, 1910.134(c)(1) says the employer "shall establish and implement a written respiratory protection program with worksite-specific procedures."
What goes in it. The written program covers how respirators are selected, medical evaluations, fit testing, use in routine and emergency situations, cleaning, inspection, maintenance, and storage, breathing-air quality for supplied-air units, training on the hazards and on the respirator itself, and how the program gets evaluated.
Who runs it. A program administrator, qualified by training or experience to match how complex the program is.
Who pays. The employer provides respirators, training, and medical evaluations at no cost to the employee.
Training that sticks. Each worker must be able to show they know why the respirator is needed and how a bad fit, misuse, or poor maintenance cuts its protection; its limits; what to do in an emergency or if it fails; how to inspect it, put it on, take it off, and seal check it; how to maintain and store it; and how to recognize medical signs and symptoms that can limit its use. Retraining comes every year, and sooner when the job, the respirator, or the worker's knowledge changes.
Keep it honest. The employer evaluates the workplace as often as needed to make sure the program is actually working, and keeps a written copy of the current program.
One element gets its own two days: medical evaluation, which comes before fit testing and before anyone wears the respirator on the job. Friday and Saturday's Health Focus covers why.
Key Takeaways:
• Required use means a written program with worksite-specific procedures.
• A qualified administrator runs it, and the worker pays nothing for respirators, training, or medical evaluations.
• Training repeats every year, and sooner when anything changes.
• Medical evaluation comes before fit testing and use.
Sources:
Knowledge Share
Part 4 of 4: Formation Sieve Analysis
A perfect sieve analysis on a bad sample gives you a precise picture of the wrong formation. The Bureau of Reclamation's specimen-size study made the point itself: getting a representative sample, reducing it properly, and using proper procedures can affect results much more than specimen size does.
Here is where curves go wrong before they reach the bench.
Mixed depths. A USGS guide for logging cuttings notes that samples from fluid drilling generally contain variable amounts of fragments from overlying units, and that sample lag becomes appreciable at depths of 200 feet or more. If you do not account for lag, the bag labeled 240 feet may hold material from somewhere else.
Lost fines. In a USGS test well in San Diego, a San Diego State University study found the drill cuttings lacked the silt and clay present in core shoe samples from the same hole. Drilling fluid carries fines away.
Think through what that does to the curve. Lose the fines and the curve shifts coarser, so D10 goes up. The formation looks coarser and cleaner than it is, and a slot or pack picked from that curve can end up too coarse for the real formation. That is the logic of the curve, not a measured result from the study.
Composites across layers. One bag that spans two different layers produces a curve that describes neither one. The 1963 USGS design example analyzed its sample zones separately, 65 to 115 feet and 115 to 127.5 feet.
A100-20 gives the purchaser room to ask for this: its foreword lists additional formation samples and sample delivery among the items a purchaser can specify.
What to consider on your next bid:
• Write the sampling interval and method into the bid, and split samples at every change in formation (a crew practice, not a code requirement).
• Account for lag time, especially past 200 feet with fluid drilling.
• Treat a cuttings curve as likely low on fines, and say so on the design sheet.
Sources:
• U.S. Bureau of Reclamation: Minimum Test Specimen Mass for Gradation Analysis (GR-88-2)
• USGS / San Diego State University: Evaluation of Drill Cuttings Using Particle-Size Analysis in a Water Test Well, San Diego (Polis)
• AWWA: ANSI/AWWA A100-20, Water Wells
Recommended Print References:
• Hydraulics of Wells: American Society of Civil Engineers
• Handbook of Ground Water Development- Roscoe Moss Company
• Groundwater & Wells, Third Edition- Edited by Robert J. Sterrett, Johnson Screens
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