(a) The term “hydraulic barking” means a wood processing operation that removes bark from wood by the use of water under a pressure of 6.8 atm (100 psia) or greater.

(b) The terms “cubic feet” or “cubic meters” of production in subpart A means the cubic feet or cubic meters of logs from which bark is removed.

(c) The term “process wastewater” specifically excludes non-contact cooling water, material storage yard runoff (either raw material or processed wood storage), boiler blowdown, and wastewater from washout of thermal oxidizers or catalytic oxidizers, wastewater from biofilters, or wastewater from wet electrostatic precipitators used upstream of thermal oxidizers or catalytic oxidizers installed by facilities covered by subparts B, C, D or M to comply with the national emissions standards for hazardous air pollutants (NESHAP) for plywood and composite wood products (PCWP) facilities (40 CFR part 63, subpart DDDD). For the dry process hardboard, veneer, finishing, particleboard, and sawmills and planing mills subcategories, fire control water is excluded from the definition.

(d) The term “gross production of fiberboard products” means the air dry weight of hardboard or insulation board following formation of the mat and prior to trimming and finishing operations.

(e) The term “hardboard” means a panel manufactured from interfelted ligno-cellulosic fibers consolidated under heat and pressure to a density of 0.5 g/cu cm (31 lb/cu ft) or greater.

(f) The term “insulation board” means a panel manufactured from interfelted ligno-cellulosic fibers consolidated to a density of less than 0.5 g/cu cm (less than 31 lb/cu ft).

(g) The term “smooth-one-side (S1S) hardboard” means hardboard which is produced by the wet-matting, wet-pressing process.

(h) The term “smooth-two-sides (S2S) hardboard” means hardboard which is produced by the wet-matting, dry-pressing process.

(i) The term “debris” means woody material such as bark, twigs, branches, heartwood or sapwood that will not pass through a 2.54 cm (1.0 in) diameter round opening and is present in the discharge from a wet storage facility.

(j) For the subcategories for which numerical limitations are given, the daily maximum limitation is a value that should not be exceeded by any one effluent measurement. The 30-day limitation is a value that should not be exceeded by the average of daily measurements taken during any 30-day period.