Wyoming Administrative Code › Agency 020 - Environmental Quality, Dept. of › Sub-Agency 0011 - Water Quality › Chapter 11 - DESIGN AND CONSTRUCTION STANDARDS FOR SEWERAGE SYSTEMS, TREATMENT WORKS, DISPOSAL SYSTEMS OR OTHER FACILITIES CAPABLE OF CAUSING OR CONTRIBUTING TO POLLUTION AND MOBILE HOME PARK AND CAMPGROUND SEWERAGE AND PUBLIC WATER SUPPLY DISTRIBUTION SYSTEMS › Part B - MUNICIPAL AND DOMESTIC SEWERAGE SYSTEMS, TREATMENT WORKS, AND DISPOSAL SYSTEM › Section 11-15 - Attached Growth Systems

Current through July 13, 2024
(a) Pretreatment
				  and primary treatment requirements. Attached growth systems shall be preceded
				  by primary settling or fine screening. If fine screening is provided, the
				  screen size shall have 0.06 inch (1.5 mm) or smaller openings.
(b) Trickling filters.
(i) Loading rates. Applied organic loading
				  rates on trickling filters, where not used in series with activated sludge,
				  shall be limited to:
Applied Liquid Rate to Surface
							 of Filter
BOD Loading*
(gpm/sf)
(1pm/m)
(lb/1000ft3/d)
(kg/1000
							 m3/d)
Rock Media
0.1
4.07
10
160
0.2
8.15
12
192
0.3
12.22
16
256
Plastic or
Redwood Media
20
320
*For more than a one-stage trickling filter, the volume of
					 all stages shall be used.
(ii) Recirculation. Recirculated flow to
				  stationary media attached growth systems shall be provided. Recirculated flow
				  shall be sufficient to provide the following minimum wetting rates:
Media
Minimum
							 Wetting Rate
(gpm/sf)
(1pm/m2)
Rock
0.1
4.07
Plastic or redwood
0.75
30.5
(iii) Media. Media may be rock or specially
				  manufactured material made of redwood or plastic. Rocks shall be durable and
				  free from thin, elongated, flat pieces and should have the following size
				  distribution:
Passing 6-inch (15.2 cm) screen
100% by
							 weight
Retained on 4-inch (10.2 cm) screen
95 - 100%
							 by weight
Fabricated media shall be resistant to ultraviolet
					 degradation, disintegration, erosion, aging, all common acids, alkalies,
					 organic compounds, fungus and biological attack. Media shall be capable of
					 supporting a man's weight.
(iv) Flow distribution. Wastewater shall be
				  applied to stationary media by a rotary distributor or a fixed nozzle
				  distribution system that provides uniform distribution. Flow distribution
				  between multiple units of stationary or rotating media systems shall be by
				  weirs, meters and valves, or other positive flow split device.
(v) Depth of media. Rock trickling filter
				  depths shall be between five (5) to ten (10) feet (1.52 to 3.04 m), and
				  manufactured media filter depth shall be between ten (10) to thirty (30) feet
				  (3.05 to 9.15 m).
(vi) Underdrain
				  system. The underdrainage system shall cover the entire floor of the filter.
				  Inlet openings into the underdrains shall have an unsubmerged gross combined
				  area equal to at least 15 percent of the surface area of the filter.
				  Underdrains shall have a minimum slope of one percent.
Effluent channels shall be designed to maintain minimum
					 velocity of two (2) feet per second (0.61 mps). Drains, channels and pipe shall
					 be designed to have maximum depth flow of 50 percent.
(vii) Flushing. Provide valves and
				  structurally capable walls to permit flooding rock media filters. Access shall
				  be provided around the periphery of the underdrain system to allow flushing the
				  underdrains.
(viii) Freeboard. The
				  clearance between rotating distributor and the media shall be at least eighteen
				  (18) inches (0.46 m). The surrounding wall shall extend 2.5 feet (0.76 m) above
				  the distributor.
(ix) Ventilation.
				  All trickling filters shall be provided with ventilation openings to the
				  underdrain. Ventilation openings will be provided with dampers or other
				  adjustable devices to permit adjusting the ventilation rate opening.
				  Ventilation openings shall be a minimum of eight (8) square feet (0.74 m²)
				  per 1,000 lb (454 kg) BOD5/day.
Forced ventilation providing 4,000 cfm (113
					 m3/min) per 1,000 lb (454 kg)
					 BOD5/day shall be provided for covered filters.