Water Sources, Hydrology, and System Planning
Core concepts
A Class II operator must know where water comes from and how systems plan for it. Understand the difference between surface water (rivers, lakes, reservoirs - variable quality, high turbidity risk, needs full treatment) and groundwater (wells and aquifers - usually lower turbidity and stable temperature, but vulnerable to contamination and affected by pumping drawdown). Know basic hydrology vocabulary: watershed/drainage basin, runoff, infiltration, recharge, permeability, and safe yield (the sustainable withdrawal rate that does not deplete an aquifer or harm users).
Planning and demand
Familiarize yourself with demand forecasting (population projection, per-capita use, peaking factors), source water protection, and wellhead protection areas. A candidate should understand maximum day demand versus average day demand and fire flow requirements for sizing sources and storage. Recognize the role of regulatory programs such as source water assessments and wellhead protection ordinances.
Traps to watch
- Confusing safe yield with maximum pumping capacity - safe yield is a sustainability concept, not a pump rating.
- Assuming groundwater is always clean; it can carry contaminants without turbidity.
- Mixing up peak hour, max day, and average day demand when sizing components.
- Forgetting that surface water quality changes seasonally (algae, runoff, turnover).
Rule of thumb / worked example
If a community has 5,000 people using 120 gallons per capita per day, average day demand = 5,000 × 120 = 600,000 gpd = 0.6 MGD. With a max-day peaking factor of 1.8, max day ≈ 1.08 MGD. Always apply the correct peaking factor to the correct baseline before comparing to source capacity.