Texas Administrative Code

Texas Administrative Code

TITLE 30	ENVIRONMENTAL QUALITY
PART 1	TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
CHAPTER 217	DESIGN CRITERIA FOR DOMESTIC WASTEWATER SYSTEMS
SUBCHAPTER E	PRELIMINARY TREATMENT UNITS
RULE §217.128	Flow Equalization Basins

(a) A wastewater treatment facility must be designed with a flow equalization basin if:

(1) the total daily influent flow volume or total daily influent organic loading occurs during a period less than or equal to ten hours; or

(2) the wastewater treatment facility receives an influent flow of less than 10% of its design flow or an influent organic loading less than 10% of its design organic loading during a period of time equal to or greater than 48 hours in any period of seven consecutive days.

(b) A flow equalization basin must have an upstream screening device or grinding device.

(c) A flow equalization basin must include an aeration system sized to maintain a dissolved oxygen level of at least 1.0 milligram per liter (mg/l) throughout the flow equalization basin.

(d) A flow equalization basin must include a mixing system sufficient to prevent solids from settling.

(e) The size of a flow equalization basin must be based on diurnal flow variations and the size and capacity of downstream process units. The engineering report must include the calculations justifying the size of a flow equalization basin.

(f) For pumped flow to an equalization basin, the effluent from the basin must be controlled by a flow-regulating device capable of maintaining a flow rate that allows downstream process units to operate as designed.

(g) For pumped flow from an equalization basin, a variable-speed pump or multiple pumps are required to deliver a constant flow to downstream treatment units.

Source Note: The provisions of this §217.128 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254