October 21, 2026
This week’s photo is courtesy of- Roscoe Moss Company- Los Angeles, CA, USA.
Safety Focus
Part 3 of 4: Heat and Cold Stress
Knowing the signs is half the job. Today is about keeping the crew out of trouble in the first place.
Cold. OSHA’s cold stress guidance for employers comes down to a handful of habits:
• Schedule frequent short breaks in warm, dry areas so the body can warm up.
• Schedule work during the warmest part of the day.
• Use the buddy system (work in pairs).
• Provide warm, sweet drinks, and avoid alcohol.
• Use engineering controls such as radiant heaters.
• Avoid touching cold metal or wet surfaces with bare skin.
OSHA also calls for training workers to choose proper clothing for cold, wet, and windy conditions. On a rig, that means dressing for wet. Adjustable layers, a wind and water shell, and spare dry gloves and socks in the truck are common crew practice, not an OSHA checklist. Change wet gloves before your hands go numb, not after.
Heat. Water, rest, and shade are the base. The control most often skipped is acclimatization, letting the body adjust to heat over several days. NIOSH recommends that new workers start at no more than 20 percent of a normal day’s heat exposure on day 1, and increase by no more than 20 percent each day after. Workers coming back from time away should go 50 percent on day 1, 60 percent on day 2, 80 percent on day 3, and 100 percent on day 4. The new hand and the helper back from two weeks off are both new to the heat.
The crossover. A crew that started on a cold morning can be overdressed and sweating by mid-afternoon. OSHA notes that dampness "even from body sweat" speeds heat loss, so sweat-soaked layers make the evening and the next cold morning worse. Shed a layer before you sweat through it.
Key Takeaways
• Short warm breaks, warmest-hours scheduling, the buddy system, and warm, sweet drinks (OSHA).
• Dress for wet and keep dry spares in the truck (crew practice).
• Build heat tolerance: new workers 20 percent on day 1 and no more than 20 percent more per day; returning workers 50, 60, 80, 100 (NIOSH).
Sources:
• OSHA: Cold Stress
• NIOSH: Heat Stress: Acclimatization
Knowledge Share
Part 3 of 4: Domain 1 Review
Today we run one problem end to end, the way it would come off a constant-rate test. This is a screening exercise with idealized assumptions: a confined, uniform aquifer of large extent, fully penetrating wells, and a steady pumping rate. Real tests rarely behave this cleanly.
The test. A well pumps a constant 500 gpm. An observation well sits 100 feet away. On semi-log paper, the observation-well drawdown falls on a straight line with a slope of 5 feet per log cycle, and the line crosses zero drawdown at 0.5 minute. Saturated thickness is 100 feet.
Step 1, transmissivity. T = 264 × Q ÷ Δs = 264 × 500 ÷ 5 = 26,400 gpd/ft, or about 3,529 ft²/day.
Step 2, storativity. S = 0.3 × T × t₀ ÷ r², with t₀ in days: 0.5 minute ÷ 1,440 = 0.000347 day. S = 0.3 × 26,400 × 0.000347 ÷ 10,000 ≈ 0.00028. A value that small points to a confined aquifer; unconfined specific yields run orders of magnitude higher.
Step 3, hydraulic conductivity. K = T ÷ b = 26,400 ÷ 100 = 264 gpd/ft², about 35 feet per day (roughly 11 meters per day).
Step 4, check the method. Cooper-Jacob only works when u is small. With consistent units, u = r²S ÷ 4Tt works out to about 0.28 ÷ t, with t in minutes. At 10 minutes u is about 0.028; at 30 minutes, about 0.009. Fit the line from 30 minutes on and u stays below 0.01, the conservative cutoff. Early points do not belong on the line.
Step 5, use it. Superposition says drawdowns add. If your well draws itself down 20 feet and a neighbor’s well adds 3 feet at your location, plan for 23 feet.
What to consider on your next bid
• Convert units before you plug in numbers.
• Check u before you trust the straight line.
• These are aquifer numbers; drawdown inside the pumping well also includes well loss.
Sources:
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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