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 E - STANDARDS FOR THE APPLICATION OF BIOSOLIDS AND THE REUSE OF TREATED NON-DOMESTIC WASTEWATER › Section 11-50 - Site Requirements

Current through July 13, 2024
(a) The method for
				  determining the size of a particular land site for accomplishing the treatment
				  level necessary to comply with an NPDES permit or to maintain a groundwater
				  aquifer within its present class shall be based on the number of acres
				  (hectares) required to reduce the waste constituent identified as requiring the
				  largest land area, based on soil assimilative capacity. The ratio used for this
				  determination is expressed as:
Required Land Treatment Area = G/C Where:
G = generation rate = the yearly amount of the controlling
					 constituent to be applied for land treatment. G is listed in kilograms per year
					 (kg/yr) or pounds per year (lbs/yr).
C = plant-soil assimilative capacity = the yearly amount of
					 the controlling constituent that can be assimilated by plant uptake, soil
					 adsorption and accumulation, transformation or degradation, and allow survival
					 and maintenance of indigenous or crop plant species. C is listed in kilograms
					 per hectare per year (kg/ha/yr) or pounds per acre per year (lbs/ac/yr).
Wastewater constituents or categories of constituents from
					 which the land-limiting factor will be selected are generally grouped as:
Organics
Nitrogen
Phosphorus
Heavy metals
Salts, acids and bases
Water
Oil and grease
(b) Slope. Slow rate irrigation systems
				  (generally less than 4.0 inches/wk application rate) will not be developed on
				  slopes greater than 15 percent unless the site is terraced, gated pipe is
				  placed on the contour, or vegetation, application rate and soil infiltration
				  rate are such that runoff and erosion would not result.
Overland flow systems will not be developed on sites having
					 less than two percent or greater than eight percent slope.
(c) Soil profile. The minimum depth of
				  unsaturated soil strata on which a land treatment system may be developed is
				  five (5) feet for a slow rate system and ten (10) feet for a rapid infiltration
				  system, unless underdrains or pumped recovery wells are employed for lowering
				  the water table. The applicant should refer to Part A, Section 5 for innovative
				  technology permit requirements.
(d)
				  Runoff and erosion. All land treatment sites will be protected from upslope
				  runoff by diversion ditches capable of intercepting the overland flow from a
				  10-year 24-hour storm event, unless it is otherwise demonstrated that a storm
				  of this size will not have an impact on the site. A runoff collection ditch is
				  required at the base of overland flow slopes or on sloping irrigation sites
				  where site conditions are such that over application of wastewater and/or
				  seasonal precipitation events may threaten to pollute Surface Waters of the
				  State. Provisions for storage, return and reapplication are required where a
				  runoff collection ditch is required.