OK Water/Wastewater Operator cheat sheet

Oklahoma public water systems are classified by population served and treatment complexity; a system serving 3,300 or fewer people with conventional treatment falls in Class C/D categories, while large surface-water plants with filtration are Class A/B.

Maximum contaminant levels (MCLs) are enforceable limits; secondary standards (e.g., iron 0.3 mg/L, manganese 0.05 mg/L) are aesthetic and non-enforceable.

Disinfection CT concept: CT = disinfectant residual concentration (mg/L) × contact time (minutes); required CT varies with pH, temperature, and log inactivation of Giardia or viruses.

Total coliform rule: if any routine sample is total-coliform positive, the system must run repeat samples at the same and adjacent taps; an E. coli-positive repeat is an acute violation requiring public notice within 24 hours.

Lead action level is 0.015 mg/L at the 90th percentile; copper is 1.3 mg/L; exceedance triggers corrosion control, public education, and lead service line replacement planning.

Stage 2 Disinfectants/Disinfection Byproducts: TTHM MCL 0.080 mg/L and HAA5 MCL 0.060 mg/L, calculated as locational running annual averages.

Operator certification in Oklahoma is graded by system class (A highest through D) and discipline (water, wastewater, or both); an operator may only serve as chief at or below their certified class.

Static head equals elevation difference; pressure in psi ≈ feet of head ÷ 2.31. A 100-foot column of water produces about 43.3 psi.

Biochemical oxygen demand (BOD5) measures oxygen consumed over 5 days at 20°C; typical untreated domestic wastewater is about 200–250 mg/L BOD5, 200–250 mg/L suspended solids.

Secondary treatment standards: 30-day average effluent limits of 30 mg/L BOD5 and 30 mg/L TSS (45 mg/L where the 30-day/7-day percent removal alternative applies).

Activated sludge F/M ratio typically 0.2–0.5 lb BOD per lb MLSS per day; sludge age (SRT) = MLSS inventory ÷ solids leaving per day.

Return activated sludge (RAS) concentration is roughly 5,000–10,000 mg/L; wasting rate controls SRT and prevents bulking.

A combined sewer overflow (CSO) or sanitary sewer overflow (SSO) must be reported to the Oklahoma Department of Environmental Quality; SSOs require public notice and corrective action.

NPDES permit effluent monitoring uses flow-proportioned composite samples for most parameters; pH and fecal/ E. coli indicators may be grab samples.

Oklahoma stormwater construction general permit requires a Stormwater Pollution Prevention Plan (SWPPP) and best management practices (BMPs) before land disturbance above the permit threshold (typically 1 acre).

Chlorine residual in effluent is typically maintained at 1–2 mg/L before dechlorination; total residual chlorine discharge limits protect aquatic life.

Oklahoma DEQ issues construction permits for water and wastewater facilities; plans must be sealed by a licensed professional engineer before submittal.

A public water supply system must obtain a permit to construct before building or modifying treatment, storage, or distribution mains; operating without permit is a violation.

Water main separation: minimum 10 feet horizontal separation between water mains and sanitary sewers; if not achievable, sewer must be encased and water main pressure-tested.

Vertical separation: water mains crossing above sewers need at least 18 inches clearance; crossing below requires encasement of the sewer.

Backflow prevention: an air gap is the only absolute protection; reduced-pressure-zone assemblies are required for high-hazard cross-connections and must be tested annually.

Storage tank design requires overflow, vent, and drain provisions; a 4-log virus inactivation or equivalent is required for groundwater under direct influence of surface water.

Construction permit applications typically require design calculations, hydraulic profiles, and a capacity analysis; permit issuance precedes construction and an inspection is required before operation.

Land disturbance permits tie to stormwater; erosion and sediment controls must be installed before grading and maintained until final stabilization.

A watershed is the land area draining to a common point; delineate using topographic maps or digital elevation models following flow paths.

Time of concentration (Tc) is the travel time from the hydraulically most distant point to the outlet; used in the Rational Method Q = CiA.

Rational Method: Q (cfs) = C × i (in/hr) × A (acres); C is a runoff coefficient (0.1–0.95) reflecting land cover.

Total maximum daily load (TMDL) allocates pollutant loading among point sources, nonpoint sources, and a margin of safety; Oklahoma DEQ develops TMDLs for impaired waters on the 303(d) list.

Source water protection plans identify potential contamination sources within a wellhead or surface intake area and set management strategies.

Impervious cover increases peak flow and runoff volume; a common planning threshold is 10% imperviousness for stream degradation and 25% for severe impairment.

Nutrient criteria for lakes and streams address phosphorus and nitrogen; Oklahoma uses ecoregion-based reference conditions for numeric criteria.

Green infrastructure (rain gardens, permeable pavement, bioswales) reduces runoff volume and pollutant loading; credit is often given in stormwater permits.