Ohio Admin. Code 3745-42-05 Design Flow and Waste Strength Requirements For Treatment Works Sized For One Hundred Thousand Gallons Per Day Or Less

• Library: Ohio Administrative Code
• Edition: 2023
• Currency: Current through all regulations passed and filed through December 25, 2023
• Citation: Ohio Admin. Code 3745-42-05
• Year: 2023

(A) Except as provided in paragraphs (A)(1) to (A)(5)(A)(6) of this rule, the minimum design flows and waste strengths in table A-1 of this rule shall be used to design a treatment works sized for one hundred thousand gallons per day or less. The design flow and the waste strength shall be based on the existing and proposed services at the facility, and the justification for the proposed design flow and the proposed waste strength shall be submitted with the permit to install application. In addition to table A-1 of this rule, the director may also consider additional relevant engineering design data, including flow monitoring data, computer flow modeling data, flow equalization facilities, potential impacts to upstream sewers and sampling data for waste strength characterization.

[Comment: If the place to be served by a wastewater treatment works is not listed in table A-1 of this rule, the applicant or consultant should discuss the design flow with an Ohio EPA district office representative so that a proper flow value and waste strength can be chosen.]

(1) Flow monitoring. The director may consider flow monitoring data in addition to the minimum design flow requirements in table A-1 of this rule when evaluating the design of a treatment works sized for one hundred thousand gallons per day or less provided that the flow monitoring data is obtainable and documented on a daily basis.(a) The flow monitoring data shall be submitted with the permit to install application and shall conform to either of the following (i) Be from the facility for which the treatment works is being designed, and be representative of the range of operating conditions that are expected to occur, which includes considering the months, days and hours of operation; or. (ii) Be from a place of like kind, like usage, and located in a similar climate, and be representative of the range of operating conditions that are expected to occur which includes considering the months, days and hours of operation. (b) For facilities that operate year-round, at least twelve months of flow monitoring data shall be provided For seasonal facilities, flow monitoring data shall be provided for the entire operational period within a calendar year.

(2) Computer flow modeling. The director may consider computer flow modeling data in addition to the design flow requirements in table A-1 of this rule when evaluating the design of a treatment works sized for one hundred thousand gallons per day or less. The computer flow modeling data shall be submitted with the permit to install application.

(3) Flow storage and equalization facilities. The director may consider flow equalization facilities at the treatment works or upstream of the treatment works in addition to the design flow requirements in table A-1 of this rule, when evaluating the design of a treatment works sized for one hundred thousand gallons per day or less For facilities that have significant variations in daily flow for each day of the week, the director may allow the storage facilities to equalize the flow over several days. The values in table A-1 shall be used to determine the storage volume needed and the design flow of the treatment units following the storage facility. If a facility has a significant variation in daily flow through the week, month or season and lagoon treatment is proposed, the director may allow the proposed lagoon design to be based on an average daily flow and average daily organic loading that is lower than the peak flow values and organic strength values in table A-1, provided sufficient flow monitoring data is provided for the director's consideration. The flow equalization data shall be submitted with the permit to install application.

(4) Potential impacts to upstream sewers. The director may consider potential impacts to upstream sewers in addition to the design flow requirements in table A-1 of this rule when evaluating the design of a treatment works sized for one hundred thousand gallons per day or less. Any information regarding the potential impacts to upstream sewers shall be submitted with the permit to install application.

(5) Sampling data for waste strength characterization. The director may consider sampling data in addition to the organic loading concentration ranges in table A-1 of this rule when evaluating the design of a treatment works. Sampling data shall be provided that is indicative of normal operations. For seasonal operations, the data shall be reflective of the time when the facility is most used. This data shall include the following: daily raw data, seven-day averages and thirty-day averages. This shall be submitted along with the permit to install application and, either of the following: (a) Be from the facility for which the treatment works is being designed, and be representative of the range of operating conditions that are expected to occur; or. (b) Be from a place of like kind, like usage, and located in a similar climate, and be representative of the range of operating conditions that are expected to occur.

(6) Water efficiency or water saving devices. The director may consider a reduction in the design flows for a wastewater treatment works, as established in table A-1 of this rule, of up to thirty per cent based upon the installation of low flow fixtures or water saving devices installed at the source of wastewater generation. The following scenarios are eligible for the up to thirty per cent reduction in design flows, established in table A-1: (a) A wastewater treatment works serving an operation or facility where the sources of the sewage are all new construction, occurring after the effective date of this rule. In general, this provision does not apply in situations where an extensive collection system is installed as well (e.g. mobile home parks recreation parks or campgrounds, etc.). (b) A wastewater treatment works serving an operation or facility where all of the sources of sewage are being remodeled after the effective date of this rule and low flow fixtures or water saving devices are replacing existing water use features. As a condition of the permit application, the applicant shall submit data or necessary information verifying that appropriate low flow fixtures or water saving devices are being installed throughout the operation. In general, this provision does not apply in situations where an extensive collection system is installed as well (e.g. mobile home parks, recreation parks or campgrounds, etc.). Flows may be reduced through the scenarios in this paragraph, and the wastewater treatment works design shall accommodate organic and solids loading established utilizing the original design flows contained in table A-1. [Comment: The NPDES regulations at paragraph (d) of 40 CFR 122.45 (effective July 1, 2011) require that all permit limits be expressed, unless impracticable, as both average-monthly limits (AMLs) and maximum-daily limits...