2.2 Mandatory Visitation Frequencies & Facility Oversight

2.2 Mandatory Visitation Frequencies & Facility Oversight

[!IMPORTANT] Telemetry is not a visit. North Carolina rules state minimum physical visitation frequencies. SCADA, autodialers, and remote trimming help an operator watch a plant between visits; they do not reduce the number of visits the rule requires.

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Wastewater: 15A NCAC 08G .0204(2)

The ORC shall "visit the system as often as is necessary to ensure the proper operation of the system but in no case less frequently than specified in the following schedule, unless otherwise specified in permit":

Two details are frequently missed. First, the schedule is a floor: the permit may require more, and the rule's opening clause requires visits "as often as is necessary to ensure the proper operation of the system." Second, the ATU exception flips the small-system rule — a 1,000 gpd conventional domestic system is visited twice a year, but a 1,000 gpd aerobic treatment unit with a blower and a chlorinator is visited weekly.

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Drinking water: 15A NCAC 18C .1303

The baseline for every treatment facility

During each oversight visit the supplier of water must ensure the facility receives a routine visual inspection from the source to the point where water enters the distribution system; equipment settings are adjusted and chemical feed tanks filled as necessary; dates and quantities of chemicals added are recorded; and the physical and chemical tests required on the monthly operation report are performed. The supplier must have the ORC or a certified treatment facility operator working under the ORC on site as frequently as necessary to ensure compliance, and at least one visit per week must be performed by the ORC for the treatment facility, or by an operator whose grade of certification corresponds to or exceeds the classification of the facility.

Surface water and GWUDI: the 20 percent rule

Surface water or groundwater under the direct influence of surface water systems must provide an operator as required by 18D .0206 and must have the ORC, or an operator with a grade of certification corresponding to or higher than the facility classification, on site at least 20 percent of the time the facility is in operation, calculated on a weekly basis.

• A plant running 24/7 operates 168 hours per week → 33.6 hours of certified on-site time.
• A plant running 8 hours a day, 5 days a week operates 40 hours → 8 hours of certified on-site time.

Remember this stacks with 18D .0206(b), which requires an operator holding at least Grade C-Surface to be on duty on the premises whenever the surface plant is treating water.

Groundwater and supplemental treatment facilities

• Any facility with any individual parameter rating value of 10 or higher under 18D .0203 — for example gas chlorine (10), caustic soda pH adjustment (10), gravity sand filtration (10), packed tower aeration (10), or reverse osmosis (15) — shall be visited by an operator daily. Note that the trigger is a single parameter at 10 or more points, not the cumulative plant score.
• Facilities with all individual parameter values below 10 follow Table B:

For a three-times-per-week frequency, no more than two consecutive days may pass between visits; for twice per week, no more than three consecutive days.

Distribution facilities and increased frequency

18C .1303(b) states plainly that distribution facilities have no specified standard frequency of oversight visits; the distribution facility is visited as frequently as necessary to operate it, respond to emergencies, and ensure compliance. Under 18C .1303(c), however, a system that fails to maintain any operational parameter, or suffers any treatment or distribution failure that would cause a water quality or treatment standard violation, must be visited daily until it returns to compliance — including any system failing to maintain minimum residual disinfectant concentrations.

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What a real visit covers

1. Intake, wellhead, or headworks. Screens and racks, wellhead sanitary seal and vent screening, raw meters; on the wastewater side, bar screen blinding, grit washing, wet-well grease, and lead/lag pump alternation.
2. Chemical feed. Day-tank levels, drawdown calibration with a graduated cylinder, feed pump stroke and speed, diaphragm and foot-valve condition; for gas chlorine, cylinder scale weight, vacuum integrity, automatic switchover, and scrubber readiness.
3. Process basins. Floc character, clarifier blanket depth by core sampler, weir condition; in activated sludge, the 30-minute settleability test, mixed liquor color, basin dissolved oxygen, and surface foam.
4. Filtration and disinfection. Head loss, individual filter effluent turbidity, backwash triggers, chlorine residual at the entry point, contact time, UV intensity and transmittance.
5. Discharge and documentation. Outfall and receiving stream observation; then contemporaneous logging of arrival and departure times, tests, chemical quantities, and every adjustment made.

[!NOTE] Turbidity benchmarks to check during the visit. For conventional and direct filtration, combined filter effluent must be ≤ 0.3 NTU in at least 95 percent of monthly measurements and never above 1 NTU; a reading above 1 NTU must be reported to the State within 24 hours. Individual filter effluent above 1.0 NTU in two consecutive 15-minute readings triggers reporting, and above 0.5 NTU in two consecutive readings at the end of the first four hours after a filter returns to service triggers an exceedance report.