020-12 Wyo. Code R. § 12-12 - Treatment

State Regulations
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(a) 2018 TSS, parts 4.2.1, 4.2.1(b)-(c), clarification, presedimentation; 4.2.2-4.2.2(c), clarification, coagulation; 4.2.4, 4.2.4(b)-4.2.4(d)(3), coagulation, sedimentation; 4.3.1.1, filtration, rapid rate gravity filters, pretreatment; 4.3.1.4-4.3.1.4(o), filtration, rapid rate gravity filters, structural details and hydraulics; 4.3.1.6-4.3.1.6(d)(2)(d), filtration, rapid rate gravity filters, filter material; 4.3.1.6(d)(4), filtration, rapid rate gravity filters, filter material, granular activated carbon (GAC); 4.3.1.6(e)-4.3.1.6(e)(1)(b), filtration, rapid rate gravity filters, filter material, support media; 4.3.3.6-4.3.3.6(b), filtration, diatomaceous earth filtration, pre-coat; 4.3.3.7-4.3.3.7(c), filtration, diatomaceous earth filtration, body feed; 4.3.3.8-4.3.3.8(e), filtration, diatomaceous earth filtration, filtration; 4.3.3.10- 4.3.3.10(a)(4), filtration, diatomaceous earth filtration, appurtenances; 4.3.4.2, filtration, slow sand filters, number; 4.3.4.4, filtration, slow sand filters, rates of filtration; 4.3.4.5, filtration, slow sand filters, underdrains; 4.3.4.6-4.3.4.6(e), filtration, slow sand filters, filter material; 4.3.4.7, filtration, slow sand filters, filter gravel; 4.3.4.8, filtration, slow sand filters, depth of water on filter beds; 4.3.4.9, 4.3.4.9(b), (e) and (f), filtration, slow sand filters, control appurtenances; 4.4.1- 4.4.1(b), disinfection, contact time, CT, and point(s) of application; 4.4.3- 4.4.3(d) and (f), disinfection, testing equipment; 4.4.4.3, disinfection, chlorine, automatic switch-over; 4.4.4.7, disinfection, chlorine, cross-connection protection; 4.4.4.8, disinfection, chlorine, pipe material; 4.4.5, disinfection, chloramines; 4.4.6.1, disinfection, ozone, design considerations; 4.4.6.2- 4.4.6.2(e), disinfection, ozone, feed gas preparation; 4.4.6.3- 4.4.6.3(d), disinfection, ozone, ozone generator; 4.4.6.4-4.4.6.4(b), disinfection, ozone, ozone contactors; 4.4.6.5-4.4.6.5(g), disinfection, ozone, ozone destruction unit; 4.4.6.6, disinfection, ozone, piping materials; 4.4.6.7-4.4.6.7(c), disinfection, ozone, joints and connections; 4.4.6.8-4.4.6.8(h), disinfection, ozone, instrumentation; 4.4.6.9-4.4.6.9(h), disinfection, ozone, alarms; 4.4.6.11-4.4.6.11(c), disinfection, ozone, construction considerations; 4.5.1, softening, lime or lime-soda process; 4.5.1.1, softening, lime or lime-soda process, hydraulics; 4.5.1.3, softening, lime or lime-soda process, chemical feed point; 4.5.1.4, softening, lime or lime-soda process, rapid mix; 4.5.1.5, softening, lime or lime-soda process, stabilization; 4.5.1.6-4.5.1.6(b), softening, lime or lime-soda process, sludge collection; 4.5.1.7, softening, lime or lime-soda process, sludge disposal; 4.5.1.8, softening, lime or lime-soda process, disinfection; 4.5.1.9, softening, lime or lime-soda process, plant start-up; 4.5.2.1, softening, cation exchange process, pre-treatment requirements; 4.5.2.2, softening, cation exchange process, design; 4.5.2.3, softening, cation exchange process, design; 4.5.2.4, softening, cation exchange process, depth of resin; 4.5.2.5, softening, cation exchange process, flow rates; 4.5.2.7, softening, cation exchange process, underdrains and supporting gravel; 4.5.2.8, softening, cation exchange process, brine distribution; 4.5.2.9, softening, cation exchange process, cross-connection control; 4.5.2.10, softening, cation exchange process, bypass piping and equipment; 4.5.2.11, softening, cation exchange process, additional limitations; 4.5.2.12, softening, cation exchange process, sampling taps; 4.5.2.13-4.5.2.13(f), softening, cation exchange process, brine and salt storage tanks; 4.5.2.14, softening, cation exchange process, salt and brine storage capacity; 4.5.2.15, softening, cation exchange process, brine pump or eductor; 4.5.2.18, softening, cation exchange process, construction materials; 4.5.2.19, softening, cation exchange process, housing; 4.5.3, softening, water quality test equipment; 4.6-4.6.14, anion exchange treatment; 4.7-4.7.11, aeration; 4.8, iron and manganese control; 4.8.1-4.8.1.3, iron and manganese control, removal by oxidation, detention and filtration; 4.8.2, iron and manganese control, removal by the lime-soda softening process; 4.8.3-4.8.3(f), iron and manganese control, removal by manganese coated media filtration;-4.8.4, iron and manganese control, removal by ion exchange; 4.8.6-4.8.6(d), iron and manganese control, sequestration by polyphosphates; 4.8.7-4.8.7(e), iron and manganese control, sequestration by sodium silicates; 4.8.8, iron and manganese control, sampling taps; 4.9.3-4.9.3(e), stabilization and corrosion control, carbon dioxide addition; 4.9.5, 4.9.5(c)-4.9.5(c)(9), stabilization and corrosion control, phosphates, design; 4.9.6-4.9.6.1(c)(4), stabilization and corrosion control, pH/alkalinity adjustment; 4.10, taste and odor control; 4.10.1, taste and odor control, flexibility; 4.10.2, taste and odor control, chlorination; 4.10.3, taste and odor control, chlorine dioxide; 4.10.4-4.10.4(f), taste and odor control, powdered activated carbon; 4.10.8, taste and odor control, potassium permanganate; 4.11, membrane technologies for public water supplies; 4.11.1-4.11.1(c), membrane technologies for public water supplies, pilot study/preliminary investigations; 4.11.2-4.11.2(l)(4), membrane technologies for public water supplies, general design considerations; 4.11.3-4.11.3(h), membrane technologies for public water supplies, systems treating surface water or GWUDI; 5.4.7-5.4.7(f), specific chemicals, fluoride; 5.4.8, specific chemicals, activated carbon; 9.3-9.3(a)(2), precipitative softening sludge, lagoons; 9.4.1-9.4.1(h), alum sludge, lagoons; 9.5-9.5.1(k), red water waste, sand filters; 9.5.2-9.5.2(g), red water waste, lagoons; 9.5.3, red water waste, discharge to community sanitary sewer; are herein incorporated by reference.

(b) The capacity of the water treatment or water production system shall be designed for the maximum daily demand at the design year.

(c) Presedimentation shall be required for raw waters that have episodes of turbidity in excess of 1,000 Nephelometric turbidity units (NTU) for a period of one week or longer.

(d) Basins shall meet the following requirements:

(i) Basins without mechanical sludge collection equipment shall have a minimum detention time of three days;

(ii) Basins with mechanical sludge collection equipment shall have a minimum detention time of three hours;

(iii) Basins shall have a bottom slope to drain of ¼ inch per foot without mechanical sludge collection equipment and two inches per foot with mechanical sludge collection equipment; and

(iv) Basins shall have a minimum of one, eight-inch drain line to completely dewater the facility.

(e) Rapid dispersal of chemicals throughout the water shall be accomplished by mechanical mixers, jet mixers, static mixers, or hydraulic jump and shall meet the following requirements:

(i) For mechanical mixers, the minimum Gt (velocity gradient (sec-1) x t (sec)) provided at maximum daily flow shall be 27,000;

(ii) The detention time in a flash mixing chamber shall not exceed 30 seconds at maximum daily flow conditions; and

(iii) The basin shall have a drain.

(f) Flocculation shall comply with the following requirements:

(i) Mechanical flocculators shall be used for low-velocity agitation of chemically treated water.

(ii) The minimum detention time of 10 minutes shall be provided.

(iii) Basins shall have a minimum of one drain line to dewater the facility.

(iv) The velocity gradient (G value) shall be adjustable through the use of variable speed drives. The velocity gradient for single basin systems shall be 30 sec-1, 20 sec-1 in the final basin of a two-stage system, and 10 sec-1 in the final basin of a three-stage system.

(v) The tip speed for a single-speed drive system shall not exceed 3 feet per second (ft/sec). Variable speed drives shall provide tip speeds between 0.5 and 3.0 ft/sec.

(vi) The velocity of flocculated water through pipes or conduits to settling basins shall not be less than 0.5 ft/sec or greater than 1.5 ft/sec.

(g) Sedimentation basins shall comply with the following requirements:

(i) The maximum diameter in circular basins shall be 80 feet.

(ii) The minimum basin side water depth shall be eight feet if mechanical sludge collection equipment is provided or basin sludge hopper segments are less than 100 square feet in surface area and 15 feet if basins are manually cleaned.

(iii) The outer walls of the settling basin shall extend at least 12 inches above the surrounding ground and provide at least 12 inches of freeboard to the water surface. Where the basin walls are less than four feet above the surrounding ground, a fence or other debris barrier shall be provided on the wall.

(iv) Basin bottoms shall slope toward the drain at not less than one inch per foot where mechanical sludge collection equipment is provided and ¼ inch per foot where no mechanical sludge collection equipment is provided.

(v) The basin overflow rate shall not exceed 1,000 gpd/ft² at design conditions.

(vi) Mechanical sludge collection shall be provided if settleable organics are present in the water or the source water exceeds secondary maximum contaminant levels identified at 40 CFR 143.3.

(vii) Pipes for removing sludge shall not be less than six inches in diameter and arranged to facilitate cleaning. Valves on sludge lines shall be located outside the tank.

(h) Facilities with softening sedimentation or clarification for softened groundwater sources shall meet the following requirements:

(i) The basin overflow rate shall not exceed 21,000 gpd/ft² at the design flow; and

(ii) Mechanical sludge removal shall be provided and shall be designed to handle a load of 40 lbs/ft of collector scraper arm length.

(i) Solids contact units are acceptable for combined softening and clarification of well water where water quality characteristics are not variable and flow rates are uniform and consistent. Solids contact units shall meet the requirements of paragraphs (c) and (e) of this Section and may be considered under the following circumstances:

(i) Solids contact units may be considered for use as clarifiers without softening when they are designed as conventional sedimentation units; and

(ii) Solids contact units may be used for other treatment processes such as rapid mixing or flocculation when the individual components of the units are designed for that specific treatment process.

(j) Tube clarifiers that are horizontal or steeply inclined may be used when designed as follows:

(i) The maximum flow rate shall be less than 2.0 gpm/ft² based on the surface area of the basin covered by the tubes;

(ii) The top of the tubes shall be more than 12 inches from the underside of the launder and more than 18 inches from the water surface and the spacing of the effluent launder shall not be more than three times the distance from the water surface to the top of the tube modules;

(iii) Sludge shall be removed using 45-degree or steeper hoppered bottoms, mechanical devices that move the sludge to hoppers, or devices that remove settled sludge from the basin floor using differential hydraulic level; and

(iv) A method of tube cleaning shall be provided that may include provisions for a rapid reduction in clarifier water surface elevation, a water jet spray system, or an air scour system. If cleaning is automatic, controls shall cease clarifier operation during tube cleaning and a 20-minute rest period.

(k) Filtration systems shall comply with the following requirements:

(i) Vertical or horizontal pressure filters shall not be used on surface waters. Pressure filters may be used for groundwater filtration, including iron and manganese removal;

(A) Slow rate sand filters may be used when maximum turbidity is less than 50 NTU and the turbidity present is not caused by colloidal clay; and

(B) Maximum color shall not exceed 30 units.

(ii) Washwater troughs shall comply with the following requirements:

(A) Washwater troughs shall not cover more than 25 percent of the filter area;

(B) The minimum distance between the bottom of the trough and the top of the unexpanded media shall be 12 inches;

(D) There shall be no more than six feet clear distance between troughs;

(E) The trough and wastewater line shall be sized for a filter backwash rate of 20 gpm/ft² plus a surface wash rate of 2 gpm/ft²;

(F) The backwash system shall be sized to provide a minimum backwash flowrate of 20 gpm/ft² or a rate necessary to provide a 50 percent expansion of the filter bed;

(G) The system and wash water storage shall be designed to provide two, 20-minute washes in rapid succession and shall meet the following requirements:

(I) If only one filter is provided, the backwash system needs to provide only one 20-minute backwash; and

(II) If pumps are used to convey water to the filter(s) or to the wash water tank, two equivalent pumps shall be provided.

(H) Washwater shall be filtered and disinfected;

(I) The washwater rate shall be controlled on the main wash water line and the flowrates shall be metered and indicated;

(J) Air-assisted backwash systems may be used when the design precludes disturbing the gravel support and the minimum flowrate for air-assisted backwash shall be 12 gpm/ft²;

(K) A surface wash system shall be provided and shall meet the following requirements:

(I) The system shall be capable of supplying 0.5 gpm/ft² for a system with rotating arms and 2 gpm/ft² for fixed nozzles, at a minimum pressure of 50 psi; and

(II) The surface wash can be air-assisted.

(L) Both backwash and surface wash supply systems shall be provided with adequate backflow prevention;

(iii) Single media beds shall use either clean crushed anthracite or a sand and anthracite mixture, the media shall have an effective size of 0.45 - 0.55 mm and a uniformity coefficient not greater than 1.65, and shall meet the following requirements:

(A) When gravel is used as supporting media, it shall consist of coarse aggregate in which most of it is round and of similar size and shape;

(B) Gravel as supporting media shall have sufficient strength and hardness to resist degradation during handling and use, be free of harmful materials and exceed the minimum density requirements; and

(iv) Dual media coal sand filters shall consist of a coarse layer of coal not less than 15 inches deep above a layer of fine sand not less than eight inches deep on a torpedo sand or garnet layer of support not less than three inches on gravel support.

(v) Filter bottoms and strainer systems shall be limited to pipe, perforated pipe laterals, tile block, and perforated tile block. Perforated plate bottoms or plastic nozzles shall not be used.

(vi) Every filter shall have:

(A) Influent and effluent taps;

(B) A head loss gauge;

(D) A waste drain for draining the filter component to waste;

(E) A filter rate flow meter;

(F) Polymer feed facilities including polymer mixing, storage tank and at least one feed pump for each filter compartment; and

(G) Recorders on the turbidimeters.

(vii) Filter rate control shall be such that the filter is not surged. The filter rate of flow shall not change more than 0.3gpm/ft² per minute. A filter that stops and restarts during a cycle shall have a filter-to-waste system installed. Declining flow rate filters shall not be used unless the flow rate for each filter is controlled to a rate less than allowed in paragraph (j)(iii) of this Section and there are four more individual filters.

(viii) A filter to waste cycle shall be provided after the filter backwash operation. The filter to waste cycle shall be at least 10 minutes.

(ix) Multi-media filter beds shall contain a depth of fine media made up of anthracite (specific gravity 1.5), silica sand (specific gravity 2.6), and garnet sand or ilmenite (specific gravity 4.2-4.5). The bed depths and distribution shall be determined by the water quality and shall meet the following requirements:

(A) There shall not be less than 10 inches of fine sand and 24 inches of anthracite;

(B) The relative size of the media shall be such that the hydraulic grading of the material during backwash will result in a pore space that progressively goes from coarse to fine in the direction of flow;

(C) The multi-media shall be supported on two layers of special high-density gravel placed above the conventional silica gravel supporting bed;

(D) The special gravel shall have a specific gravity not less than 4.2;

(E) The bottom layer shall consist of particles passing U.S. Standard 5 mesh sieves and retained in U.S. Standard 12 mesh sieves and shall be 1 ½ inches thick; and

(F) The top layer shall consist of particles passing U.S. Standard 12 mesh sieves and retained in U.S. Standard 20 mesh sieves and shall be 1 ½ inches thick.

(x) Diatomaceous earth filtration shall comply with the following requirements:

(A) Diatomaceous earth filters may be used under the following circumstances:

(I) To remove turbidity from surface waters where turbidities entering the filters do not exceed 10 NTU and where total raw water coliforms do not exceed 100 organisms/100 mL;

(II) Where the raw water quality exceeds the previously mentioned limits when flocculation and sedimentation are used preceding the filters; and

(III) To remove iron from groundwaters.

(B) The proposed diatomaceous earth filtration shall include pressure or vacuum type units; and

(D) The proposed diatomaceous earth filtration shall include a continuous monitoring turbidimeter with recorder on each filter effluent for plants treating surface water.

(l) All designs that propose supplies of surface water, groundwater under the direct influence of surface water, and groundwater that does not meet 40 CFR Part 141 or where other treatment is provided, shall include disinfection via one of the following methods:

(i) Chlorine;

(ii) Chloramines, recommended only for secondary disinfection;

(iii) Chlorine dioxide;

(iv) Ozone;

(v) Ultraviolet light; or

(vi) Other disinfecting agents that demonstrate reliable application equipment is available and that include testing procedures for a residual that is recognized in Standard Methods for the Examination of Water and Wastewater 2018.

(m) All designs that require disinfection shall demonstrate that:

(i) The system will maintain a detectable residual throughout the distribution system; and

(ii) The applicant has considered the formation of disinfection byproducts when selecting the disinfection.

(n) Disinfection equipment shall comply with the following requirements:

(i) Chlorination equipment shall comply with NSF/ANSI/CAN 61-2020/NSF/ANSI/CAN 600-2021 and the following requirements:

(A) Positive displacement pumps shall be provided for solution feed gas chlorinators or hypochlorite feeders;

(B) The chlorine solution injector/diffuser shall provide a rapid and thorough mix with all the water being treated;

(C) If the application point is to a pipeline discharging to a clearwell, the chlorine shall be added to the center of the pipe at least 10 pipe diameters upstream of the discharge into the clearwell;

(D) Gas chlorinators shall comply with the following requirements:

(I) The injector/eductor shall be selected based on solution pressure, injector water flowrate, feed point backpressure, and chlorine solution line length and size;

(II) The maximum feed point backpressure shall not exceed 110 psi unless a chlorine solution pump is used; and

(III) Gauges shall be provided for chlorine solution pressure, feed water pressure, and chlorine gas pressure or vacuum.

(E) Standby equipment of sufficient capacity shall be available to replace the largest chlorinator unit. Well systems providing no treatment other than disinfection are exempt from the requirements of this paragraph (E) and are not required to provide standby chlorination equipment.

(ii) Points of application and contact time shall comply with the following requirements:

(A) Filtration types shall comply with the contact time and minimum chlorine residuals required in Table 3 of this Section after the appropriate baffling factor has been applied to the reactor. Contact times assume a baffling factor of 0.1 unless documentation justifying the use of a higher baffling factor is provided. Contact time requirements are based on worst-case operating conditions of water temperature of 32.9 degrees Fahrenheit and pH of 9.

Table 3. Required Contact Time and Residual by Filtration Type

Filtration Type	Required Contact Time (minutes), 0.4 mg/L minimum chlorine residual	Required Contact Time (minutes), 1.0 mg/L minimum chlorine residual
Conventional Filtration	162.5	73
Direct Filtration, Bag or Cartridge Filtration, Slow Sand Filtration, Diatomaceous Earth Filtration	325	146
Membrane Filtration (MF or UF)	30	12

(B) When chlorine is applied to a groundwater source to maintain a residual, a 4-log inactivation shall be achieved prior to the first customer.

(o) Systems that propose disinfection via ultraviolet light shall comply with the following requirements:

(i) Proposed designs for ultraviolet light shall include the following information in the ultraviolet reactor influent water quality analysis:

(A) Influent temperature (degrees Fahrenheit);

(B) UV transmittance (UVT) at a reported wavelength of 254 nm and a pathlength of 1 cm;

(D) Total hardness (mg/L as CaCO₃);

(E) pH;

(F) Alkalinity (mg/L as CaCO₃);

(G) Total iron (mg/L) influent < 0.3mg/L;

(H) Calcium (mg/L); and

(I) Total manganese (mg/L) influent <0.03 mg/L

(ii) Proposed designs for ultraviolet disinfection systems shall include the following information:

(A) The maximum, average, and minimum flowrates;

(B) A matrix that identifies paired flow and ultraviolet treatment values;

(D) Log inactivation requirements;

(E) Operating approach (UV intensity vs. calculated dose);

(F) Maximum and minimum operating pressures;

(G) Maximum pressure at the UV reactor;

(H) UV system redundancy;

(I) Lamp cleaning strategy;

(J) Mercury trap for broken UV lamps;

(K) Maximum headloss through the UV reactor;

(L) A demonstration that the UV reactor(s) shall be hydrostatically tested to 1.5 times the rated operating pressure;

(M) A demonstration that the UV reactor(s) shall be designed to ensure that plant personnel can change lamps and the UV intensity meter without draining the reactor; and

(N) A demonstration that the units shall meet NSF/ANSI/CAN Standard 61.

(iii) Ultraviolet treatment systems shall be designed to comply with the Ultraviolet Disinfection Guidance Manual for the Final LT2ESWTR and the following dose requirements:

(A) The UV disinfection system shall deliver a validated dose that meets or exceeds the required dose at the end of lamp life, with fouled sleeves.

(B) The minimum required validated dose used for system design shall incorporate a Combined Age and Fouling Factor (CAF), calculated as:

CAF = EOLL x FF.

EOLL is the ratio of the lamp output at the end of life relative to the new lamp output

FF is the fouling factor.

(D) The FF shall be:

(I) 0.5 for UV systems with no sleeve wiping system;

(II) 0.75 for UV systems with mechanical wiping only; or

(III) 0.95 for UV systems with a combined online chemical and mechanical cleaning.

(E) The validated dose that meets or exceeds the required dose shall be delivered under maximum flow and design (UVT) condition, when the larger UV unit is out of service.

(iv) Ultraviolet disinfection shall comply with the following validation requirements:

(A) The applicant shall submit the manufacturer's bioassay validation report for the proposed UV reactor with the permit application;

(B) The bioassay testing and results shall demonstrate validation by an independent third party in full compliance with the Ultraviolet Disinfection Guidance Manual for the Final LT2ESWTR;

(C) The owner and engineer shall submit a certification to the Administrator if validation requirements are adjusted and identify each of the equipment and system modifications required to ensure that the appropriate dosage is provided for the inactivation requirements;

(D) Bioassay testing shall evaluate reactor performance over the range of:

(I) Flowrates (maximum, average, and minimum);

(II) UVT from 70 percent to 98 percent (measured at 254 nm, 1 cm path length); and

(III) RED at maximum flowrate and design UVT conditions.

(E) The bioassay testing shall incorporate the range of design and operating conditions described in paragraph (o)(i) of this Section for UV Light;

(F) Extrapolations to flowrates, UV transmittance values, or UV doses outside the range actually tested, are not permitted; and

(G) Bioassay testing shall also verify that the head loss generated by the proposed reactor is less than or equal to the specified limits.

(v) Ultraviolet disinfection hydraulics shall comply with the following requirements:

(A) The inlet and outlet piping configuration to the UV reactor shall result in a UV dose delivery that is equal to or greater than the dose delivered when the UV reactor was validated;

(B) If the UV reactor validation is performed off-site, the applicant shall refer to the validation report to determine the validated inlet and outlet conditions that apply to the site-specific requirements; and

(I) The piping configuration shall consist of a minimum of 10 pipe diameters of straight pipe upstream and five pipe diameters of straight pipe downstream of the UV reactors, with additional pipe diameters above the minimum if required by the manufacturer's guidelines for electromagnetic or other flowmeter installation;

(II) The inlet and outlet piping configurations shall be identical to those constructed for the UV reactor validation; or

(III) If on-site validation or custom off-site validation is planned, the inlet and outlet piping hydraulics must be designed according to the manufacturer's recommendations and to accommodate any site-specific constraints.

(vi) Ultraviolet control and measurement instrumentation for each reactor shall comply with the following requirements:

(A) Each reactor shall be capable of measuring UV intensity and lamp status (on/off);

(B) For systems that use the calculated dose monitoring strategy, each reactor shall be capable of measuring or calculating the UV transmittance;

(C) Piping for each UV reactor shall be sized and configured in accordance with the validated operating conditions and maintain equal head loss through each reactor over the range of validated flowrates. Each UV reactor shall not be by-passed;

(D) Each UV reactor train shall have a dedicated flow meter to confirm the validated operating conditions;

(E) UV lamps in the UV reactor shall be submerged at all times during operation;

(F) The specific configuration of the UV reactor(s) within a facility will dictate the use of air release, air/vacuum, or combination air valves to prevent air pockets and negative pressure conditions and the design shall verify that the UV manufacturer was consulted to determine any equipment-specific air release and pressure control valve requirements;

(G) Each UV reactor shall have the piping configured so that it can be isolated and removed from service while the other UV reactor(s) remain in service; and

(H) A booster pump shall be used if the head loss constraints indicate that a pump is necessary. The UV reactor shall be sized accordingly.

(vii) The applicant shall describe the dose monitoring strategy and the operational approach for the UV reactor that complies with the approaches described in Ultraviolet Disinfection Guidance Manual for the Final LT2ESWTR, part 3.5.2.

(viii) The cleaning system for each UV reactor shall comply with the following requirements:

(A) Each UV reactor shall be equipped with an automatic online mechanical lamp sleeve cleaning system and may include optional chemical cleaning;

(B) The UV sensor shall include mechanical cleaning capabilities with an automatically initiated and controlled cleaning cycle; and

(ix) The minimum spare parts kept at a facility shall include the following:

(A) 20 percent of the UV Lamps;

(B) Five percent of the lamp sleeves; and

(p) Facilities that propose disinfection via fluoridation and defluoridation shall comply with the following requirements:

(i) Fluoride storage designs shall demonstrate that:

(A) Fluoride storage tanks shall be covered;

(B) All other storage shall be inside a building; and

(ii) Fluoride feed equipment shall meet the following requirements:

(A) There shall be scales or weight loss recorders for dry chemical feeds and the feeders shall be accurate to within five percent of any desired feed rate;

(B) The application of hydrofluorosilicic acid, if into a horizontal pipe, shall be in the lower half of the pipe;

(D) A fluoride solution shall be applied by a positive displacement pump;

(E) The solution shall not be injected into a point of negative pressure;

(F) All fluoride feed lines and dilution water lines shall be isolated from the potable water supplies by either an air gap above the solution tank or a reduced pressure principal backflow preventer;

(G) Water used for sodium fluoride solution shall have a hardness not exceeding 45 mg/L; and

(H) Flow meters for treated water flow and fluoride solution water shall be provided.

(iii) Provisions shall be made to allow the transfer of dry fluoride compounds from shipping containers to storage bins or hoppers that minimize the quantity of fluoride dust that enters the room where the equipment is installed and shall meet the following requirements:

(A) The transfer system shall be equipped with an exhaust fan and dust filter that places the hopper or storage bin under negative pressure;

(B) Air exhausted from fluoride handling equipment shall discharge through a dust filter to the atmosphere outside the building and shall not discharge within 50 feet of a fresh air intake for the building; and

(iv) The following methods are acceptable for fluoride removal:

(A) Activated alumina may be used in open gravity filters or pressure filter tanks;

(B) The minimum media depth shall be five feet;

(D) The mesh size for the alumina media shall be between #28 and #48;

(E) Media regeneration facilities shall be provided and shall include both weak caustic and weak acid systems; and

(F) Bone char filtration or lime softening with magnesium addition may be used.

(v) Water that is unstable due either to natural causes or to subsequent treatment shall be stabilized.

(vi) Facilities shall have the capability of feeding both acid and alkalinity.

(vii) Unstable water created by ion exchange softening shall be stabilized by an alkali feed.

(viii) Laboratory equipment shall be provided to determine the effectiveness of stabilization treatment. This shall include testing equipment for hardness, calcium, alkalinity, pH, and magnesium at a minimum.

(q) Taste and odor control equipment shall comply with the following requirements:

(i) Open or closed, granular activated carbon adsorption units may be used to absorb organics for taste and odor control, subject to the following requirements:

(A) The loading rate shall not exceed 10 gpm/ft²;

(B) The minimum empty bed contact time shall be 20 minutes;

(D) There shall be provisions for moving the carbon to and from the contactors;

(E) Contactors may be upflow or downflow design. A single unit is acceptable for countercurrent upflow designs. Downflow designs shall have two or more parallel units;

(F) Contactors shall be designed as open gravity or pressure bed;

(G) Pressure contactors shall have an air-vacuum relief valve fitted with a stainless-steel screen to prevent plugging;

(H) The contactor materials of construction shall be concrete, steel, or fiberglass-reinforced plastic and shall meet the following requirements:

(I) Steel vessels shall be protected against corrosion; and

(II) Inlet and outlet screens shall be made of stainless steel or other suitable materials.

(I) There shall be provisions for flow reversal and bed expansion that meet the following requirements:

(I) Backwashing facilities shall provide up to 50 percent bed expansion; and

(II) Backwashing facilities shall meet the backwash criteria as rapid filters.

(ii) If ozone is used for taste and odor control, there shall be at least 10 minutes of contact time to complete all reactions and the minimum applied feed rate of ozone shall be 1 mg/L, or the design shall identify a contact time and feed rate that demonstrate the application of ozone will not cause an exceedance of the maximum contaminant levels identified at 40 CFR 141.64.

(r) Designs that include the addition of phosphates for stabilization and corrosion control shall demonstrate the evaluation of reactions with aluminum and impacts on wastewater treatment plants to overcome the secondary impacts of phosphates.

(s) Designs that propose anion-exchange treatment shall include a pH/alkalinity feed system unless otherwise approved by the Administrator.

(t) Microscreens shall comply with the following requirements:

(i) A microscreen shall be allowed as a supplement to treatment, but it shall not be used in place of filtration or coagulation;

(ii) The screen shall be capable of removing suspended matter from the water by straining;

(iii) Screens shall be made of corrosion-resistant material;

(iv) Bypass piping around the unit shall be provided;

(v) There shall be protection against back siphonage when potable water is used for washing the screen; and

(vi) Wash water shall be wasted and not recycled to the microscreen.

(u) Membrane technologies shall comply with the following requirements:

(i) Proposed membrane treatment processes shall comply with the requirements of Section 6 of this Chapter. Protocols for pilot plant testing shall incorporate guidance or procedures from the US EPA Membrane Filtration Guidance Manual, Chapter 6.

(ii) All proposed membrane filters shall demonstrate third-party validation for the removal of Giardia or Cryptosporidium. Removal efficiency shall be determined through challenge testing as outlined in the US EPA Membrane Filtration Guidance Manual and one of the following:

(A) Membranes that are used as final compliance filters of a multiple treatment barrier approach shall meet the requirements of 40 CFR Part 141; or

(B) All surface water or groundwater under direct influence (GWUDI) systems using membrane technology shall demonstrate minimum disinfection that meets 4.0-log virus inactivation.

(v) Facilities that propose bag and cartridge filters shall comply with the procedures identified in Section 6 of this Chapter and the following requirements:

(i) Filter performance will be based on Cryptosporidium oocyst removal;

(ii) The filter shall demonstrate at least a 3-log removal of particle size 1 micron and above with an associated log reduction credit of 2-logs for Giardia and Cryptosporidium;

(iii) Removal efficiency shall be determined through challenge testing as outlined in Toolbox Guidance Manual, Chapter 8 and NSF/ANSI 419-2018;

(iv) The performance demonstration shall be specific to the corresponding housing and type or model of filter. Any other combination of housing and filter that could be used for treatment shall also demonstrate filter efficiency;

(v) Applicants shall include documentation that the proposed bag or cartridge filter has received third-party validation for the removal of Giardia and Cryptosporidium;

(vi) Filter and housing specifications shall include a description of the materials of construction, surface area per filter, and the minimum and maximum operating pressure, and the specifications shall meet the requirements of NSF/ANSI 419-2018 and the Toolbox Guidance Manual, Chapter 8;

(vii) System components such as housing, bags, cartridges, gaskets, and O-rings shall comply with NSF/ANSI/CAN 61 for leaching of contaminants;

(viii) A means for monitoring the performance of the filter shall be provided and shall include at a minimum flow meters and valves, pressure gauges, and sample taps;

(ix) The proposed design shall specify chemical compatibility limitations;

(x) A minimum of two filter housings shall be provided;

(xi) Bag or cartridge filters that are used as final compliance filters of a multiple treatment barrier approach shall meet the requirements of 40 CFR Part 141; and

(xii) All surface water or GWUDI systems using bag or cartridge filter technology shall provide at minimum disinfection that meets 4.0-log virus inactivation and 1.0-log Giardia inactivation or shall demonstrate that combined filtration and disinfection will provide 3-log removal.

(w) Pre-engineered water treatment plants shall comply with the following requirements:

(i) Pre-engineered water treatment plants shall be permitted on a case-by-case basis for specific process applications and flow rates. Multiple units may be installed in parallel to accommodate flow rates;

(ii) Pre-engineered water treatment plant equipment shall be designed in accordance with NSF/ANSI/CAN 61 and NSF/ANSI/CAN 372;

(iv) Pre-engineered water treatment plants shall comply with the procedures in Section 6 of this Chapter to obtain data that demonstrates the treatment effectiveness of the treatment for the source water and the proposed application; and

(v) Each component and process of the pre-engineered water treatment plant shall demonstrate compliance with the applicable design criteria of the respective treatment processes of this Chapter.

(x) Wastes shall be handled and disposed of as follows:

(i) The sanitary and laboratory waste from water treatment plants, pumping stations, or well systems, shall not be recycled to any part of the water plant, and shall be discharged directly into a sanitary sewer when feasible or a permitted on-site disposal system;

(ii) Brine waste from ion exchange plants, demineralization plants, and other similar facilities may not be recycled to the water plant and shall meet the following requirements:

(A) Where discharging to a sanitary sewer, a holding tank shall be provided to prevent the overloading of the sewer and interference with the waste treatment process; and

(B) Where disposal to an off-site waste treatment system is proposed, the sewer and treatment facility shall have the required capacity and dilution capability.

(iii) Acceptable methods of treatment and disposal of lime softening sludge are:

(A) Sludge lagoons, provided that the design of sludge lagoons includes:

(I) The location of the lagoon shall be protected from the 100-year flood;

(II) A means of diverting surface water runoff so that it does not flow into the lagoon;

(III) The freeboard shall be a minimum of three feet;

(IV) An adjustable decanting device for recycling the overflow; and

(V) An accessible effluent sampling point.

(B) Land application of liquid lime softening sludge that demonstrates compliance with Water Quality Rules Chapter 11, Part E;

(D) Mechanical dewatering of sludge may be used;

(E) Recalcination of sludge may be used; and

(F) Lime sludge drying beds shall not be allowed.

(iv) Acceptable methods of treatment and disposal of alum sludge are as follows:

(A) Lagoons may be used as storage and interim disposal. Lagoons used for storage shall have a volume of at least 100,000 gallons for every 1,000,000 gpd of facility water treating capacity.

(B) Alum sludge may be discharged to the sanitary sewer only when the system is capable of handling the waste and with the approval of the owner of the sewer system.

(D) Alum sludge drying beds may be used.

(E) Alum sludge may be acid-treated and recovered.

(F) Disposal at a landfill.

(v) Designs that propose disposal of waste filter wash water from iron and manganese removal plants that include sand filters shall demonstrate the inclusion of a separate structure, unless otherwise approved by the Administrator.

Notes

020-12 Wyo. Code R. § 12-12

Amended, Eff. 7/26/2023.

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