Section 435.33 - Pretreatment standards for existing sources (PSES)(a)PSES for wastewater from unconventional oil and gas extraction. Except as provided in 40 CFR 403.7 and 403.13 , any existing source subject to this section, must achieve the following pretreatment standards for existing sources (PSES). (1) There shall be no discharge of wastewater pollutants associated with production, field exploration, drilling, well completion, or well treatment for unconventional oil and gas extraction (including, but not limited to, drilling muds, drill cuttings, produced sand, produced water) into publicly owned treatment works.(2) For the purposes of this section, (i)Unconventional oil and gas means crude oil and natural gas produced by a well drilled into a shale and/or tight formation (including, but not limited to, shale gas, shale oil, tight gas, tight oil).(ii)Drill cuttings means the particles generated by drilling into subsurface geologic formations and carried out from the wellbore with the drilling fluid.(iii)Drilling mud means the circulating fluid (mud) used in the rotary drilling of wells to clean and condition the hole and to counterbalance formation pressure.(iv)Produced sand means the slurried particles used in hydraulic fracturing, the accumulated formation sands, and scales particles generated during production. Produced sand also includes desander discharge from the produced water waste stream, and blowdown of the water phase from the produced water treating system.(v)Produced water means the fluid brought up from the hydrocarbon-bearing strata during the extraction of oil and gas, and includes, where present, formation water, injection water, and any chemicals added downhole or during the oil/water separation process.(3)Compliance deadline for existing sources. Existing sources discharging into publicly owned treatment works on or between April 7, 2015 and June 28, 2016, shall comply with the PSES by August 29, 2019. All other existing sources shall comply by August 29, 2016.(b)PSES for Wastewater from Conventional Oil and Gas Extraction. [Reserved] 81 FR 41857 , June 28, 2016, as amended at 81 FR 88127 , Dec. 7, 2016 81 FR 41857, 6/28/2016; 81 FR 67192, 11/29/2016; as amended at 81 FR 88127, 12/7/2016