Virginia Administrative Code › Title 9 - ENVIRONMENT › Agency 25 - STATE WATER CONTROL BOARD › Chapter 790 - VIRGINIA POLLUTANT DISCHARGE ELIMINATION SYSTEM (VPDES) PERMIT REGULATION › Part III - Manual of Practice for Sewerage Systems and Treatment Works › Article 7 - Effluent Polishing and Disinfection Processes › Section 9VAC25-790-810 - Polishing ponds

Current through Register Vol. 40, No. 24, July 15, 2024
A. On-line
					 effluent polishing ponds (OLEPP) can be provided to receive discharges at
					 locations where use of the receiving water requires a degree of performance
					 reliability exceeding that provided by the design, operation and maintenance of
					 the sewage collection system and treatment works. The design and construction
					 of OLEPP's may be similar to that of stabilization ponds.
B. Useage. All sewage treatment works
					 designed to produce a secondary effluent quality of 24 mg/l or more of BOD or
					 suspended solids that discharge to shellfish waters such that shellfish
					 harvesting restrictions may be imposed, shall be provided with an OLEPP, or
					 sufficient off-line emergency storage, unless an exemption is granted by the
					 director subsequent to a public hearing held to discuss the impacts of the
					 discharge. An OLEPP should be required for all sewage treatment works (i) for
					 which the design either does not achieve Class I reliability requirements, or
					 is considered nonconventional in accordance with this chapter; (ii) that
					 discharge to critical waters; or (iii) that are located where water quality
					 conditions dictate the need for maximum protection of public health and
					 welfare.
1. These effluent polishing ponds
					 may be required for any Class I reliability discharge from treatment works that
					 are not daily attended by operational personnel for a minimum period of 16
					 hours.
2. Those sewage treatment
					 works for which sufficient information is provided to the department verifying
					 that adequate performance reliability will exist in the form of continuously
					 available operational staff and supplemental systems and resources, so that
					 water quality and resources will not be damaged in a manner that produces
					 socio-economic losses, may be granted an exception to the requirements for an
					 OLEPP or emergency storage.
3. An
					 OLEPP can be utilized in instances where an additional removal of
					 BOD5and suspended solids up to a maximum of 3.0% is
					 desired from the effluent of a properly operated and properly loaded secondary
					 treatment facility.
4. An OLEPP can
					 be utilized to control residual chlorine through natural processes such as
					 oxidation and UV light irradiation. The chlorine dosage applied to the pond
					 influent shall be monitored and controlled.
5. A closure plan shall be provided in
					 accordance with this chapter and standards contained in this chapter, prior to
					 issuance of an operating permit.
6.
					 Effluent from an effluent polishing pond shall be disinfected in accordance
					 with this chapter, unless adequate disinfection can be provided for the pond
					 influent, so that effluent disinfection is not deemed necessary.
7. Adequate disinfection of a three-day
					 capacity effluent-polishing pond influent may require special consideration
					 such as:
a. A minimum flow path
					 length-to-width ratio within contact tanks of 40:1.
b. Expansion of detention volume to 60
					 minutes residence time.
c. Use of
					 mixing devices for chlorine dosing to replace or supplement standard
					 diffusers.