SECTION 252:656-9-2. Essential facilities

(a)   Emergency power facilities. All plants shall provide standby equipment which will generate electric power to allow continuity of operation, including but not limited to pumping, aeration and disinfection, during power failures.

(b)   Water supply.

(1)   General. Provide potable water under pressure to laboratories, restrooms, offices, drinking fountains and showers. Cross-connections between potable and non-potable water lines is prohibited.

(2)   Direct connections. Potable water from a municipal or separate supply may be used directly at points above grade. Hot water shall not be taken directly from a boiler used for supplying hot water to a sludge heat exchanger or digester heating unit.

(3)   Indirect connections. Where a potable water supply is to be used for any purpose in a plant other than those listed in paragraph (1), above, provide a break tank, pressure pump, and pressure tank. Discharge water to the break tank through an air gap at least six inches above the maximum flood line or the spill line of the tank, whichever is higher. Post a permanent sign at every hose bib, faucet, hydrant, or sill cock located on the water system beyond the break tank to indicate that the water is not safe for drinking. The installation of a reduced pressure zone backflow prevention device will be considered in lieu of the break tank. To allow maintenance on the backflow prevention device, the design shall include a bypass line with equal backflow prevention. Do not locate back-flow devices in a pit or vault where they may become submerged; they must be easily accessible for routine testing for proper operation.

(4)   Non-potable water outlets. Post a permanent sign at non-potable water outlets indicating the water is not safe for drinking.

(5)   Prevention of cross-connections. Do not allow a physical connection between potable water lines, sanitary sewer lines and/or reclaimed water lines unless a break tank is provided. All water discharged to a break tank shall be discharged through an air gap at least six inches (6") above the maximum flood line or the spill line of the tank, whichever is higher.

(c)   Laboratory equipment. All treatment works shall have access to a laboratory for making analytical determinations and operation control tests.

(d)   Sewage flow measurement. Flow measurement devices shall be selected for reliability and accuracy. All flow measurement equipment must be sized to function effectively over the full range of flows expected and shall be protected against freezing. Every primary flow measurement device must conform to the standard guidelines in the Water Measurement Manual, 3^rd Edition, published by the United States Department of the Interior, Bureau of Reclamation. An equivalent set of standard guidelines may be used, if approved by the DEQ. Every primary measurement device, sharp crested weir or flume, must be equipped with an affixed staff gauge to measure the liquid level and placed at the proper head measurement location. For continuous flow measurement, the level sensor must be placed at the proper head measurement location equivalent to the location of the staff gauge so that the head measured using the staff gauge and that measured by the sensor are the same.

(1)   Influent flow. Provide for the measurement of incoming flow at all non-industrial wastewater treatment plants. Where all incoming flow to a plant having a design flow of less than 0.5 mgd is through a single pump station, flow measurements may be satisfied by the calibration of pumps and the installation of run-time meters. Weirs must not be used to measure influent flow.

(2)   Effluent flow. For discharging systems, provide for the measurement of wastewater effluent flow in accordance with the system's OPDES permit and OAC 252:606. For lagoon effluent, a baffle shall be provided to prevent the discharge of surface debris and algae to a depth of at least one foot (1') below the weir crest.

(3)   Land application. For land application systems, effluent flow measurement shall be in accordance with OAC 252:656-25-2(h).

(4)   Closed channel flow measurement. Provide the complete design information and calculations for all closed channel flow measurement devices.

(e)   Housed facilities. Where treatment units are in a housed facility, introduce fresh air continuously at a rate of 12 air changes per hour, or intermittently at a rate of 30 air changes per hour. Provide adequate stairway access to above or below ground installations. All electrical installation in enclosed grit removal areas where hazardous gases may accumulate shall meet the requirements of the National Electrical Code.

[Source: Added at 17 Ok Reg 1140, eff 6-1-00; Amended at 23 Ok Reg 937, eff 6-15-06; Amended at 28 Ok Reg 1282, eff 7-1-11; Amended at 29 Ok Reg 1061, eff 7-1-12]