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TITLE 30ENVIRONMENTAL QUALITY
PART 1TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
CHAPTER 217DESIGN CRITERIA FOR DOMESTIC WASTEWATER SYSTEMS
SUBCHAPTER BTREATMENT FACILITY DESIGN REQUIREMENTS
RULE §217.36Emergency Power Requirements

(a) Reliability of existing commercial power service.

  (1) An owner shall determine the reliability of the existing commercial power service for a facility from the power outage records obtained from the appropriate power company.

  (2) The records must:

    (A) be in writing;

    (B) be on the utility's letterhead and bear a signature of a utility employee;

    (C) identify the location of the wastewater treatment system or off-site lift station(s) being served;

    (D) list the total number of outages that have occurred during the past 24 months; and

    (E) indicate the date and duration of each recorded outage.

(b) An owner shall submit an power reliability determination and all backup documentation in the report for the approval of the executive director.

(c) If the executive director determines a power supply is unreliable:

  (1) the owner will be notified in writing;

  (2) the facility shall incorporate an on-site, automatically starting generator, capable of ensuring continuous operation of all critical wastewater treatment system units for a duration equal to the longest power outage in the power records; and

  (3) any off-site lift station must incorporate an on-site, automatically-starting generator capable of ensuring continuous operation of the lift station for a duration equivalent to the longest power outage on record for the past 24 months.

(d) Exceptions to the auxiliary power generator requirements for wastewater treatment facilities are:

  (1) The requirements for on-site, automatically starting generators for wastewater treatment facilities may be reduced as follows:

    (A) Facilities may use lift stations and collection systems to store wastewater in lieu of on-site generators when the report calculations show that sufficient storage volume exists in the lift stations, upstream gravity wastewater collection system lines, and manholes to store the volume of wastewater during a peak diurnal event equal to the longest outage in the power records.

    (B) If storage is used in lieu of backup power generators, the report must show that the hydraulic grade line of a collection system is such that in no case will wastewater be allowed to bypass the treatment facility during a peak flow event equal to the longest outage in the power records.

    (C) When upstream storage is used as a means of ensuring complete treatment of the influent wastewater, a design must include the following:

      (i) Storage is prohibited as a substitute for on-site generators if any of the flow to the treatment facility is gravity flow.

      (ii) If the influent storage is less than two hours and power outage records indicate a maximum outage of less than two hours, the on-site, automatically starting generators need only provide sufficient power to operate all components of the disinfection system.

      (iii) If the influent storage is at least two hours but not more than four hours and the power outage records indicate an outage of at least two hours but not more than four hours, a generator need only supply sufficient power to operate all or components of the disinfection system. Auxiliary generators are also required to supply power for return activated sludge pumps if the report does not show sufficient volume in the clarifiers for storage of sludge.

  (2) Off-Site Lift Stations. Off-site lift stations may substitute portable generators or pumps in combination with collection system storage for on-site generators if the following criteria exist:

    (A) the firm pumping capacity of a lift station is less than 100 gallons per minute;

    (B) a station includes an auto-dialer or telemetry system with battery backup;

    (C) operators knowledgeable in acquisition and startup of the portable generators and pumps are on 24-hour call;

    (D) a station is accessible during a 25-year flood event;

    (E) reasonable assurances exist as to the timely availability and accessibility of the proper portable equipment; and

    (F) a station is equipped with properly designed and tested quick connections.


Source Note: The provisions of this §217.36 adopted to be effective August 28, 2008, 33 TexReg 6843

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