TITLE 9. ENVIRONMENT

STATE WATER CONTROL BOARD

Final Regulation

Title of Regulation: 9VAC25-790. Sewage Collection and Treatment Regulations (amending 9VAC25-790-10, 9VAC25-790-30, 9VAC25-790-50, 9VAC25-790-110, 9VAC25-790-460, 9VAC25-790-880).

Statutory Authority: § 62.1-44.15 of the Code of Virginia.

Effective Date: November 23, 2022.

Agency Contact: Andrew Hammond, Department of Environmental Quality, 1111 East Main Street, Suite 1400, P.O. Box 1105, Richmond, VA 23218, telephone (804) 698-4101, FAX (804) 698-4178, or email andrew.hammond@deq.virginia.gov.

Summary:

Pursuant to Chapter 356 of the 2022 Acts of Assembly, the amendments conform the regulation to a statutorily change shifting authority to issue and enforce permits from the State Water Control Board to the Department of Environmental Quality.

9VAC25-790-10. Definitions.

Unless otherwise specified, for the purpose of this chapter the following words and terms shall have the following meanings unless the context clearly indicates otherwise:

"Area engineer" means the licensed professional engineer at the Department of Environmental Quality responsible for review and approval of construction plans and related materials who serves the area where a sewerage system or treatment works is located.

"Biosolids" means a sewage sludge that has received an established treatment for required pathogen control and is treated or managed to reduce vector attraction to a satisfactory level and contains limited levels of pollutants, such that it is acceptable for use by land application, marketing or distribution in accordance with the Virginia Pollution Abatement Permit Regulation (9VAC25-32) and the Virginia Pollutant Discharge Elimination System Permit Regulation (9VAC25-31).

"Biosolids use facility" means a type of treatment works that specifically treats or stores biosolids.

"Board" means the Virginia State Water Control Board. When used outside the context of the promulgation of regulations, including regulations to establish general permits, "board" means the Department of Environmental Quality.

"CTC" means a Certificate to Construct issued in accordance with the provisions of this chapter. This certificate will normally be in the form of a letter granting authorization for construction.

"CTO" means a Certificate to Operate issued in accordance with the provisions of this chapter. This certificate will normally be in the form of a letter granting authorization for operation.

"Critical areas/waters" means areas/waters in proximity to shellfish waters, a public water supply, recreation or other waters where health or water quality concerns are identified by the Virginia Department of Health or the State Water Control Board.

"Conventional design" means the designs for unit operations (treatment system component) or specific equipment that has been in satisfactory operation for a period of one year or more, for which adequate operational information has been submitted to the department to verify that the unit operation or equipment is designed in substantial compliance with this chapter. Equipment or processes not considered to be conventional may be deemed as alternative or nonconventional.

"Department" means the Virginia Department of Environmental Quality.

"Director" means the Director of the Department of Environmental Quality or an authorized representative.

"Discharge" means (when used without qualification) discharge of a pollutant.

"Effluent limitations" means any restrictions imposed by the board or department on quantities, discharge rates, and concentrations of pollutants that are discharged from point sources into surface waters, the waters of the contiguous zone, or the ocean.

"Exceptional quality biosolids" means biosolids that have received an established level of treatment for pathogen control and vector attraction reduction and contain known levels of pollutants, such that they may be marketed or distributed for public use in accordance with this chapter.

"Indirect discharger" means a nondomestic discharger introducing pollutants to a POTW.

"Industrial wastes" means liquid or other wastes resulting from any process of industry, manufacture, trade or business, or from the development of any natural resources.

"Land application" means the distribution of treated wastewater of acceptable quality, referred to as effluent, or supernatant from biosolids use facilities or stabilized sewage sludge of acceptable quality, referred to as biosolids, upon, or insertion into, the land with a uniform application rate for the purpose of assimilation, utilization, or pollutant removal. Bulk disposal of stabilized sludge in a confined area, such as in landfills, is not land application.

"Licensee" means an individual holding a valid license issued by the Board for Waterworks and Wastewater Works Operators.

"Licensed operator" means a licensee in the class of the treatment works who is an operator at the treatment works.

"Local review" means a program for obtaining advance approval by the director of an owner's general local plans and specifications for future connections to, or extensions of, existing sewerage systems and of a plan for implementing them, in lieu of obtaining a CTC and CTO for each project within the scope of the plan.

"Manual" and "Manual of Practice" means Part III (9VAC25-790-310 et seq.) of the Sewage Collection and Treatment Regulations.

"Operate" means the act of making a decision on one's own volition (i) to place into or take out of service a unit process or unit processes or (ii) to make or cause adjustments in the operation of a unit process or unit processes at a treatment works.

"Operating staff" means individuals employed or appointed by any owner to work at a treatment works. Included in this definition are licensees whether or not their license is appropriate for the classification and category of the treatment works.

"Operator" means any individual employed or appointed by any owner, and who is designated by such owner to be the person in responsible charge, such as a supervisor, a shift operator, or a substitute in charge, and whose duties include testing or evaluation to control treatment works operations. Not included in this definition are superintendents or directors of public works, city engineers, or other municipal or industrial officials whose duties do not include the actual operation or direct supervision of a treatment works.

"Owner" means the Commonwealth or any of its political subdivisions, including, but not limited to, sanitation district commissions and authorities, and any public or private institution, corporation, association, firm or company organized or existing under the laws of this or any other state or country, or any officer or agency of the United States, or any person or group of persons acting individually or as a group that owns, operates, charters, rents, or otherwise exercises control over or is responsible for any actual or potential discharge of sewage, industrial wastes, or other wastes to state waters, or any facility or operation that has the capability to alter the physical, chemical, or biological properties of state waters in contravention of § 62.1-44.5 of the State Water Control Law.

"Permit" in the context of this chapter means a CTC or a CTO. Permits issued under 9VAC25-31 or 9VAC25-32 will be identified respectively as VPDES permits or VPA permits.

"Primary sludge" means sewage sludge removed from primary settling tanks designed in accordance with this chapter that is readily thickened by gravity thickeners designed in accordance with this chapter.

"Point source" means any discernible, confined and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, landfill leachate collection system, vessel or other floating craft from which pollutants are or may be discharged. This term does not include return flows from irrigated agriculture or agricultural storm water runoff.

"Pollutant" means dredged spoil, solid waste, incinerator residue, filter backwash, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials (except those regulated under the Atomic Energy Act of 1954, as amended (42 USC 2011 et seq.)), heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal, and agricultural waste discharged into the water. It does not mean:

1. Sewage from vessels; or

2. Water, gas, or other material that is injected into a well to facilitate production of oil or gas, or water derived in association with oil and gas production and disposed of in a well, if the well used either to facilitate production or for disposal purposes is approved by the board department, and if the board department determines that the injection or disposal will not result in the degradation of ground or surface water resources.

"Pollution" means such alteration of the physical, chemical or biological properties of any state waters as will, or is likely to, create a nuisance or render such waters (i) harmful or detrimental or injurious to the public health, safety or welfare, or to the health of animals, fish or aquatic life; (ii) unsuitable with reasonable treatment for use as present or possible future sources of public water supply; or (iii) unsuitable for recreational, commercial, industrial, agricultural or for other reasonable uses; provided that: (a) an alteration of the physical, chemical or biological property of state waters, or either a discharge, or a deposit, of sewage, industrial wastes, or other wastes to state waters by any owner, which by itself is not sufficient to cause pollution, but which, in combination with such alteration of, or discharge, or deposit to state waters by other owners is sufficient to cause pollution; (b) the discharge of untreated sewage by any owner into state waters; and (c) contributing to the contravention of standards of water quality duly established by the State Water Control Board are "pollution" for the terms and purposes of this chapter.

"Reliability" means a measure of the ability of a component or system to perform its designated function without failure or interruption of service.

"Responsible charge" means designation by the owner of any individual to have the duty and authority to operate a treatment works.

"Settled sewage" is effluent from a basin in which sewage is held or remains in quiescent conditions for 12 hours or more and the residual sewage sludge is not reintroduced to the effluent following the holding period. Sewage flows not in conformance with these conditions providing settled sewage shall be defined as nonsettled sewage.

"Sewage" means the water-carried and nonwater-carried human excrement, kitchen, laundry, shower, bath or lavatory wastes, separately or together with such underground, surface, storm and other water and liquid industrial wastes as may be present from residences, buildings, vehicles, industrial establishments or other places.

"Sewage sludge" or "sludge" means any solid, semisolid, or liquid residues which contain materials removed from municipal or domestic wastewater during treatment including primary and secondary residues. Other residuals or solid wastes consisting of materials collected and removed by sewage treatment, septage and portable toilet wastes are so included in this definition. Liquid sludge contains less than 15% dry residue by weight. Dewatered sludge contains 15% or more dry residue by weight.

"Sewerage system" or "sewage collection system" means a sewage collection system consisting of pipelines or conduits, pumping stations and force mains and all other construction, devices and appliances appurtenant thereto, used for the collection and conveyance of sewage to a treatment works or point of ultimate disposal.

"Shall" or "will" means a mandatory requirement.

"Should" means a recommendation.

"Sludge management" means the treatment, handling, transportation, use, distribution or disposal of sewage sludge.

"State waters" means all water, on the surface and under the ground, wholly or partially within, or bordering the state or within its jurisdiction.

"Substantial compliance" means designs that do not exactly conform to the guidelines set forth in Part III as contained in documents submitted pursuant to this chapter but whose construction will not substantially affect health considerations or performance of the sewerage system or treatment works.

"Subsurface disposal" means a sewerage system involving the controlled distribution of treated sewage effluent below the ground surface in a manner that may provide additional treatment and assimilation of the effluent within the soil so as not to create a point source discharge or result in pollution of surface waters.

"Surface waters" means all state waters that are not ground water as defined in § 62.1-255 of the Code of Virginia.

"Toxic pollutant" means any pollutant listed as toxic under § 307(a)(1) or, in the case of sludge use or disposal practices, any pollutant identified in regulations implementing § 405(d) of the Clean Water Act.

"Treatment works" means any device or system used in the storage, treatment, disposal or reclamation of sewage, sewage sludge or combinations of sewage and industrial wastes, including but not limited to pumping, power and other equipment and their appurtenances, septic tanks and any works, including land, that are or will be (i) an integral part of the treatment process or (ii) used for ultimate disposal of residues or effluents resulting from such treatment. Treatment works does not mean land application of biosolids on private land, as permitted under the Virginia Pollution Abatement Permit Regulation (9VAC25-32) and the Virginia Pollutant Discharge Elimination System Permit Regulation (9VAC25-31).

"Virginia Pollution Abatement (VPA) permit" means a document issued by the board, department pursuant to 9VAC25-32 or a general permit issued as a regulation adopted by the board in accordance with 9VAC25-32-260, authorizing pollutant management activities under prescribed conditions.

"Virginia Pollutant Discharge Elimination System (VPDES) Permit" means a document issued by the board, department pursuant to 9VAC25-31 or a general permit issued as a regulation adopted by the board in accordance with 9VAC25-31-170, authorizing, under prescribed conditions, the potential or actual discharge of pollutants from a point source to surface waters and the use or disposal of sewage sludge. Under the approved state program, a VPDES permit is equivalent to an NPDES permit.

"Water quality standards" means the narrative statements for general requirements and numeric limits for specific requirements, that describe the water quality necessary to meet and maintain reasonable and beneficial uses.

Such standards are established by the State Water Control Board under § 62.l-44.15(3a) of the Code of Virginia as the State Water Quality Standards (9VAC25-260).

9VAC25-790-30. Extent.

A. Powers and procedures. The board department reserves the right to utilize any lawful procedure for the enforcement of this chapter and standards contained in this chapter.

B. Establishment. Authority for the regulations and standards contained in this chapter for the operation, construction, or modification of sewerage systems or treatment works are established, pursuant to § 62.1-44.19 of the Code of Virginia.

C. Delegation. The director, or an authorized representative, may perform any act of the board provided under this regulation, except as limited by 62.1-44.14 of the Code of Virginia.

9VAC25-790-50. CTCs and CTOs.

A. No owner shall cause or allow the construction, expansion or modification (change of 25% or more in capacity or performance capability or 20% for a biosolids use facility) of a sewerage system or treatment works except in compliance with a CTC from the director unless as otherwise provided for by this chapter and standards contained in this chapter. Furthermore, no owner shall cause or allow any sewerage systems or treatment works to be operated except in compliance with a CTO issued by the director which authorizes the operation of the sewerage systems treatment works including biosolids use facilities unless otherwise provided for by this chapter and standards contained in this chapter. Conditions may be imposed on the issuance of any CTC or CTO, and no sewerage systems or treatment works may be constructed, modified, or operated in violation of these conditions.

B. Discharges of 1,000 gpd or less. On-site (located within owners property) residential sewage treatment works having a design capacity of 1,000 gallons per day or less may not be governed by this chapter and standards contained in this chapter if the performance reliability of such technology has been established by an approved testing program (9VAC25-790-210). These treatment works are regulated by other applicable regulations of the board (9VAC25-110) and of the Virginia Department of Health (12VAC5-610 and 12VAC5-640). Owners of such treatment works shall make application in accordance with and obtain the necessary permits from the board, department, or the Virginia Department of Health as appropriate via the application procedures established for such treatment works.

9VAC25-790-110. Preliminary engineering proposal.

A. Objective. The objective is to facilitate a determination by the department that the proposed design selected by the owner either requires, or does not require, submission of design documents for a formal technical evaluation to establish that the following standards will be reliably met by operation of the facility or system: (i) compliance with effluent limitations and treatment requirements established by the board or department; and (ii) conformance with applicable minimum requirements established by this chapter and standards contained in this chapter, in order that a CTC be issued.

B. Content. The preliminary engineering proposal when submitted for evaluation shall consist of an engineering report and preliminary plans which shall contain the necessary data to portray the sewerage system or treatment works problems and solutions. The requirement for a complete preliminary engineering proposal for small flow or minor projects (design flow less than one million gallons per day (mgd)) can be waived by the department in accordance with the letter from the owner's engineer summarizing the agreements reached at the preliminary engineering conference. For all proposals involving sewerage systems or treatment works, whether new or upgraded, the engineer shall make an evaluation of the l00-year flood elevation at the proposed site or sites, using available data and sound hydrologic principles. If a flood potential is indicated, the flood plain boundaries shall be delineated on a site map, showing its relation to the proposed facility or facilities and actions proposed to comply with this chapter shall be included in the preliminary engineering proposal or with the letter summarizing the agreements reached at the preliminary engineering conference. A conceptual plan for closure of the treatment works shall be discussed prior to final design to anticipate such an occurrence. On major projects (design flow of 1 mgd or more) excluding sewerage systems that are exempted from technical evaluation, the preliminary engineering proposal can include as a minimum the following information as applicable:

1. Mapping of present site location and evaluation of site constraints.

2. Data supporting predicted service population.

3. Identification of specific service area for immediate consideration and possible extensions.

4. Data, including reliable measurements or predictions of design flow and analyses of sewage constituents as a basis of process design.

5. Description of treatment process and flow plans identifying the proposed arrangement of basins, piping and related equipment with unit operation design parameters and sizes.

6. Description of sludge management method.

7. Plan for imposed operations requirements, i.e., certain unit operations may be required to operate independently of others in accordance with the reliability classification, while achieving the treatment performance necessary to meet permit limits under average design conditions.

8. Demonstration of compliance with state and local laws and regulations.

9. Summary of findings, conclusions and recommendations.

10. Description of existing institutional constraints or other unresolved problems that influence selection of alternative solutions.

11. Estimate of capital and operating costs of all alternatives presented if available as public information.

12. For those projects for which a Virginia Revolving Loan will be requested, the ways in which the special requirements contained in Title II of P.L. 92-500 will be met (infiltration, cost effectiveness, etc.).

13. Staffing and operating requirements for facility.

14. Identification consistent with all applicable area wide plans, of drainage basin, service area, and metropolitan area plans.

15. Designation of owner's representative for design purposes.

16. For land application proposals, the information required by Part III (9VAC25-790-310 et seq.) of this chapter, as appropriate.

The format for the Preliminary Engineering Proposal is listed in Part IV (9VAC25-790-940 et seq.) of this chapter.

C. Approval. The department will approve or disapprove the preliminary engineering proposal and notify the owner in accordance with 9VAC25-790-80 C.

9VAC25-790-460. Standards.

A. The minimum degree of treatment to be provided shall be adequate in design to produce an effluent in accordance with this chapter, that will comply with the provisions of the State Water Control Law and federal law, and any water quality standards adopted by the State Water Control Board or effluent limitations adopted by the State Water Control Board or Department of Environmental Quality or orders issued by the State Water Control Board or Department of Environmental Quality. The expected performance levels of conventional treatment processes are described in subsection F of this section.

B. Industrial flows. Treatment works receiving industrial wastewater flows at a rate or volume exceeding 90% of the combined average daily influent flow can be designed and operated through the applicable requirements imposed by the State Water Control Board/Department Board or Department of Environmental Quality, provided that public health and welfare protection issues are resolved. Otherwise, consideration shall be given to the character of industrial wastes in the design of the treatment works. In such cases, the treatability characteristics of the combined (sewage and industrial) wastewater shall be provided and addressed in the treatment process design. Pilot-scale testing as described in this chapter may be required to predict the full-scale treatment works operations.

C. Design loadings. Design loading refers to the established capacity of a unit operation or treatment process to reliably achieve a target performance level under projected operating conditions. Component parts and unit operations of the treatment works shall be arranged for greatest operating convenience, flexibility, economy, and to facilitate installation of future units.

1. Treatment works to serve existing sewerage systems shall be designed on the basis of established average sewage characteristics with sufficient capacity to process peak loadings. Excessive inflow/infiltration is an indication of deficiencies in the sewerage system and the design engineer shall provide an acceptable plan for eliminating or handling these excessive flows so that there will be no discharge of inadequately treated wastewaters or impairment of the treatment process.

2. A new treatment works must be designed in accordance with anticipated loadings. Table 3, found in this section, presents generally accepted minimum design flows and loadings. Deviations from Table 3 shall be based on sound engineering knowledge, experience and acceptable data substantiated in the design consultant's report. Numbers of persons per dwelling shall be based upon planning projections derived from an official source.

3. The design of treatment process unit operations or equipment shall be based on the average rate of sewage flow per 24 hours except where significant deviation from the normal daily or diurnal flow pattern is noted. The design flow for industrial wastewater flow contributions shall be determined from the observed rate of flow during periods of significant discharge or, in the case of proposed or new contributions, the industrial owner shall provide flow projections based on existing facilities of a similar nature. The following factors shall be included in determining design flows:

a. Peak rates of flow delivered through conduits as influent to the treatment process unit operations.

b. Data from similar municipalities, if applicable.

c. Wet weather flows.

4. The design organic loading should be based on the results of acceptable analytical testing of the wastewater or similar wastewater and shall be computed in the same manner used in determining design flow.

5. All piping and channels shall be designed to carry the maximum expected flow. If possible, the influent interceptor or sewer shall be designed for open channel flow at atmospheric pressure. If a force main is used to transmit the influent to the treatment works, a surge or equalization basin should be provided upstream of biological unit operations to provide a more uniform loading. Bottom corners of flow channels shall be filled and any recessed areas or corners where solids can accumulate shall be eliminated. Suitable gates and valves shall be placed in channels to seal off unused sections which might accumulate solids and to provide for maintenance.

D. Pilot plant studies. Pilot plants are defined as small scale performance models of full size equipment or unit operation design. The physical size of pilot plants varies from laboratory bench-scale reactors, with volumetric capacities of one or more liters up to several gallons, up to larger capacity arrangements of pumps, channels, pipes and tankage capable of processing thousands of gallons per day of wastewater.

Pilot scale studies are to include detailed monitoring of treatment performance under operating conditions similar to design sizes, including the proper loading factors. A sampling and analytical testing program is to be developed by the owner and evaluated by the department in order that the results of pilot plant studies can be utilized to verify full size designs.

E. Grease management. An interceptor basin or basins shall be provided to separate oil and grease from wastewater flows discharged to sewage collection systems whenever such contributions will detrimentally affect the capacity of the collection system or treatment works such that permit violations will actually or potentially occur, or such contributions will result in an actual or a potential threat to the safety of the operational staff. Interceptor basins shall be located in compliance with the Statewide Building Code as close to the source of oil and grease as practical. Interceptor basins shall be sized in accordance with the applicable building codes and local standards but shall be designed as a minimum to retain the volume of flow containing the oil or grease for each continuous discharge occurrence. But interceptor basins shall also provide a minimum volume in accordance with the following:

1. Provide two gallons of volume for each pound of grease received; or

2. Provide a minimum retention period of three hours for the average daily volume of flow received.

Interceptor basins shall be routinely maintained, including the periodic, scheduled removal of accumulations of oil and grease, within a portion of the basin volume as necessary, to prevent detrimental effects on system operation. The oil and grease shall be handled and managed in accordance with state and federal laws and regulations.

F. Expected performance. Conventionally designed sewage treatment unit operations and processes should result in an expected performance level when processing design loadings in accordance with this chapter (see Table 4 of this section). A conventional arrangement of unit operations would include primary and secondary phases. The primary phase involves the use of suspended solids setting basins called primary clarifiers. The secondary phase typically includes a biological reactor and secondary clarifier to maintain a population of microorganisms (biomass) capable of achieving a significant reduction of organic matter (Biochemical Oxygen Demand) contained in the sewage. Advanced treatment processes will include primary, secondary and tertiary phases, typically involving filtration unit operations. Conventional processes can be modified to provide for reduced levels of nutrients in the treated effluent as described in Article 9 (9VAC25-790-870 et seq.) of this part. The use of nonconventional processes to achieve required performance levels shall be considered in accordance with the provisions of Article 2 (9VAC25-790-380 et seq.) of this part.

TABLE 2. BUFFER ZONE REQUIREMENTS FOR PRIMARY AND SECONDARY SEWAGE TREATMENT UNIT OPERATIONS*.
A. Unit Operations That Are Totally Enclosed(1)
DESIGN FLOW, gpd	BUFFER ZONE(4)
1. <1,000	None
2. >1,000 to <500,000	50 feet
3. Greater than 500,000	100 feet
B. Unit Operations Using Low Intensity Mixing or Quiescent System(2)
DESIGN FLOW, gpd	BUFFER ZONE(4)
1. <40,000	200 feet
2. >40,000 to <500,000	300 feet
3. Greater than 500,000	400 feet
C. Unit Operations Using Turbulent High Intensity Aeration or Mixing(3)
DESIGN FLOW, gpd	BUFFER ZONE(4)
1. <40,000	300 feet
2. >40,000 to <500,000	400 feet
3. Greater than 500,000	600 feet
*Notes: (1)For example, package plant with units totally enclosed as an integral part of its design and manufacture. A package plant treatment works is defined by these regulations as a preengineered and prefabricated structural arrangement of tankage and channels with all necessary components for onsite assembly and installation. The design flow of package plants should be less than 0.1 mgd. Also frequent agricultural use of Class I treated sludge. (2)For example, covered basins, bottom tube aerated facultative lagoons or ponds, or surface flow application of treated effluent. Also, frequent agricultural use of Class II treated sludge. (3)For example, uncovered surface mixed basins or trajectory spray irrigation for land application of treated effluent. Also frequent agricultural use of Class III treated sludge. (4)Discharge locations shall be located no closer than 100 feet and up to 200 feet from any private or public water supply source.

TABLE 3. CONTRIBUTING SEWAGE FLOW ESTIMATES TO BE USED AS A DESIGN BASIS FOR NEW SEWAGE WORKS.
Discharge facility(1)	Contributing Design Units	Flow gpd	BOD5 #day(3)	S.S. #day	Flow duration, hours
Dwellings	Per person	100(2)	0.2	0.2	24
Schools w/showers and cafeteria	Per person	16	0.04	0.04	8
Schools w/o showers w/cafeteria	Per person	10	0.025	0.025	8
Boarding Schools	Per person	75	0.2	0.2	16
Motels @ 65 gal. per person (rooms only)	Per room	130	0.26	0.26	24
Trailer courts @ 3 persons/trailer	Per trailer	300	0.6	0.6	24
Restaurants	Per seat	50	0.2	0.2	16
Interstate or through highway restaurants	Per seat	180	0.7	0.7	16
Interstate rest areas	Per person	5	0.01	0.01	24
Service Stations	Per vehicle serviced	10	0.01	0.01	16
Factories	Per person/per 8-hr. shift	15–35	0.03–0.07	0.03–0.07	Oper. Per.
Shopping centers	Per 1,000 square foot of ultimate floor space	200–300	0.1	0.1	12
Hospitals	Per bed	300	0.6	0.6	24
Nursing Homes	Per bed	200	0.3	0.3	24
Doctor's offices in medical centers	Per 1000 square foot	500	0.1	0.1	12
Laundromats, 9–12 machines	Per machine	500	0.3	0.3	16
Community colleges	Per student & faculty	15	0.03	0.03	12
Swimming pools	Per swimmer	10	0.001	0.001	12
Theaters (drive-in type)	Per car	5	0.01	0.01	4
Theaters (auditorium type)	Per seat	5	0.01	0.01	12
Picnic areas	Per person	5	0.01	0.01	12
Camps, resort day & night w/limited plumbing	Per camp site	50	0.05	0.05	24
Luxury camps w/flush toilets	Per camp site	100	0.1	0.1	24
Notes: (1)Colleges, universities and boarding institutions of special nature to be determined in accordance with subdivision B 2 of this section. (2)Includes minimal infiltrations/inflow (I/I) allowance and minor contributions from small commercial/industrial establishments. (3)#/Day - Denotes pounds per day.

TABLE 4. EXPECTED PERFORMANCE FOR VARIOUS CONVENTIONAL TREATMENT PROCESSES. Effluent Value Range(1) (mg/l)
A. Primary/secondary treatment process.
		BOD5(2)	TSS(2)
1. Primary		100–180	100–150
2. Facultative Aerated Lagoon		24–45	24–30
	a. With Clarification
	b. Without Clarification
3. Biological contactors		24–50	24–50
4. Activated Sludge		24–30	24–30
5. Biological Plus Filtration(3)		10–20	5–15
6. Primary plus constructed wetlands(4)		24–40	24–40
7. Primary plus Aquatic Ponds(5)		20–30	20–30

B. Advanced treatment process.
			BOD5	TSS	PO4-P	NH3-N
1. Physical chemical(6) and			45–95	20–70	1–10	20–30
	a. F		20–70	1–20	1–10	20–30
	b. F & AC		5–10	0.1–10	1–10	20–30
2. Biological(7) and
	a. C & S		12–20	12–24	0.5–10	5–30
	b. C, S, & F		6–11	0.5–15	0.5–10	5–30
	c. C, S, F & AC		1–5	0.1–5	0.1–10	5–30
	d. Microscreening
		(1) 21 microns @ 5 GPM/sq. ft.	2–14	1–14	20–30	5–30
		(2) 35 microns @ 8 GPM/sq. ft.	5–20	3–17	20–30	5–30
3. BNR(8)			20–30	20–30	2–4	1–3
4. Other biological and natural treatment processes evaluated on a case-by-case basis.
NOTES: (1)Ranges reflect normal expected upper and lower values for process, performance, considering design and operations variability. Upper range value reflects performance expected for conventional loadings. (2)Effluent values for soluble phosphorus and ammonia nitrogen are not given for conventional primary and biological processes since these are not designed as nutrient removal processes. However, phosphorus is removed in biological sludge and ammonia is oxidized to nitrate in biological effluents. Typical effluent values range from 4 to 5 mg/l of total phosphorus and from nearly 0 to more than 30 mg/l ammonia, for fully nitrified to unnitrified effluent. (3)Coagulant and polymer addition prior to filter to be provided. (4)Subsurface flow microbial-plant filter system with a minimum detention of three days, or surface flow system with a minimum retention of six days. (5)Aquatic pond providing one acre of surface area (5-foot depth) per 200 population equivalent or less. (6)Physical - Chemical: means coagulation by aluminum, iron or other metal salts or, precipitation by lime, followed by clarification and may include filtration. Unit processes include, as a minimum, flash mix, flocculation, and sedimentation. Filtration operations will be necessary to achieve effluent TSS levels of 15 mg/l or less. (7)Biological: means any of the biological treatment processes including activated sludge and its process variations, attached growth systems including various filters, and facultative and fully aerated lagoons which are capable of producing a secondary effluent containing 30 mg/l BOD5 and TSS or less. (8)Biological Nutrient Removal performance will be a function of influent levels of nutrients with typical influent values of 4 to 6 mg/l of PO4-P and 20 to 40 mg/l of NH3-N. Additional nitrification operations would be necessary to achieve TKN levels of less than 10 mg/l. Denitrification may produce effluent total nitrogen levels of 5 to 10 mg/l. LEGEND: C = Coagulation S = Sedimentation F = Filtration and AC = Activated Carbon BNR = Biological Nutrient Removal

9VAC25-790-880. Land treatment.

A. Site specific information shall be submitted with the preliminary proposal in accordance with this chapter and standards contained in this chapter.

Land treatment systems shall have adequate land for pretreatment facilities, storage reservoirs, administrative and laboratory buildings, and buffer zones, as well as the application sites (field area). The availability of this land should be determined prior to any detailed site evaluation. Site availability information should be obtained concerning:

1. Availability for acquisition or acceptable control.

2. Present and future land use.

3. Public acceptance.

B. Site design. Conformance to local land use zoning and planning should be resolved between the local government and the owner. Adjacent owners should be contacted by the applicant to establish whether significant opposition to the proposed location, or locations, exists. Concerns of adjacent landowners will be considered in the evaluation of site suitability. Public meetings may be scheduled either during or after the evaluation of final design documents so that the department can discuss the technical issues concerning the system design through public participation procedures. Public hearings may be held as part of the certificate/permit issuance procedures.

1. The estimated established site size should be calculated using a typical maximum annual loading depth of 36 inches for slow rate systems and a maximum depth of 72 inches per year for high rate systems to compute the field area size. In addition, the buffer zone area should be estimated using a typical distance of 200 feet from the extremities of the field areas to adjacent property lines. This total estimated site area should be available and permission obtained to gain access to the site for field investigations.

2. When investigating a potential site for application of wastewater, there are some limiting factors, including topography, soils, and vegetative growth (crop), which shall be evaluated early to determine site suitability for a land treatment system. This evaluation should be made in two phases: a preliminary phase and a field investigation phase.

3. The preliminary phase of site evaluations should include the identification of the proposed location of the land treatment system on a recent U.S.G.S. topographic map (7.5 minute quadrangle) or acceptable reproduction or facsimile thereof. A property line survey map should also be available for use in identifying the site location or locations.

4. The 100-year flood elevation should be identified and the proposed pretreatment unit processes should be roughly located in relation to elevation.

5. Preliminary soils information should include a soil site suitability map and include information to identify soil textures, grades, drainage, erosion potential, suitability for certain crops, etc. Information on soil characteristics may be available from either the National Resources Conservation Service (NRS) Office, the local Cooperative Extension Service Agent, or the Soil and Water Conservation Nutrient Management Specialist.

6. The field area available for effluent application may be estimated using typical criteria based on topography and soil characteristics. Field areas should be delineated on topographic maps of the proposed land treatment site.

7. The land treatment system design consultant should arrange a Preliminary Engineering Conference (PEC), as described in this chapter, as a final step in the preliminary phase of the site evaluation. The requirements for soil borings and backhoe pits as needed to study soils should be established at the PEC. A site visit should be scheduled at the PEC that involves the appropriate regulatory personnel and the owner and design consultant.

8. The land treatment system design consultant may not wish to conduct detailed field investigations of site topography, hydrology and soil characteristics prior to the site visit by regulatory personnel and their advisors. However, the proposed locations of field areas and pretreatment units should be established and identified during the site visit. The location of any existing soil borings, backhoe pits, springs, wells, etc., should also be identified during the site visit. Soil borings and backhoe pits may be excavated prior to, during and following the site visit as required. The requirements for soil permeability and hydraulic conductivity testing should be developed either during or shortly after the site visit.

9. Applicants for development of all land treatment systems shall be required to submit at least the minimum required information as required for the appropriate certificate/permit to be issued.

C. Site features. The soil at a potential site should be identified in terms of its absorption capacity and crop production classification, which is a function of physical and chemical characteristics. Important physical characteristics include texture, structure and soil depth. Chemical characteristics that may be important include pH, ion exchange capacity, nutrient levels, and organic fraction. The absorption capacity of a soil may be directly related to soil texture and structure. Soil color may provide an indication of the movement of moisture through soil. Hydraulic conductivity may be estimated from in-field tests using acceptable infiltrometer devices. In addition, the absorption characteristics of a soil may be related to its hydraulic conductivity as measured by both in situ and laboratory tests using acceptable procedures (Table 9). The conductivity tests should be conducted in the most restrictive layer within the depth affected by the land application system. Soil productivity and nutrient management characteristics are discussed in the Virginia Pollution Abatement Permit Regulation (9VAC25-32).

1. Soil evaluation for a land treatment system should follow a systematic approach of selecting proper locations for borings or excavations based on topographic position, slopes and drainage. The physical characteristics of site soils should then be verified by an acceptable number of recorded observations that include soil depth to horizon changes, restrictive layers and parent material, color, texture and structure, for borings or excavations to a minimum depth of five feet.

2. If the soil characteristics differ substantially between borings or excavations, without a logical technical reason for the variation, then additional boring and excavation locations should be studied to identify the nature and extent of the changes in soil patterns throughout the proposed site.

3. The soil characteristics of the proposed site should be described by a qualified technical specialist knowledgeable in the principles of soil science, agronomy, and nutrient management. The long-term impact of land application of the treated effluent on site soils and vegetation or crops must be evaluated by the land treatment system design consultant. Certain minimum soil depths are required for approval of a land application site. The minimum required depth for field areas will depend on the type of land application system as well as the soil characteristics.

4. Representative soil samples shall be collected for each major soil type identified by the field investigation and analyzed for certain parameters in accordance with this chapter.

5. Detailed information on the geologic conditions of the proposed site shall be provided by a geologist or other technical specialist, or specialists, knowledgeable in geohydrologic principles.

a. Detailed information on the site hydrology and groundwater shall be provided by a geologist, hydrologist or other technical specialist, or specialists, knowledgeable in hydrologic principles and ground water hydrology.

b. The depth to the permanent ground water table below the site shall be determined. The location, depth and extent of perched water tables as well as the estimated seasonal fluctuations shall be established. The effect of the permanent and seasonal water tables on performance of the particular land treatment system shall be evaluated by the design consultant.

c. The characteristics of ground water movement under the proposed site should be established and evaluated using piezometer installations or other acceptable methods. The potential impact of the land treatment system on aquifer hydraulics and water quality shall be predicted through the use of modeling and appropriate monitoring devices.

d. The present and planned uses of the aquifer(s) identified as affected by the land treatment system should be determined by the consultant.

D. Land treatment methods. The following methods, or combinations thereof, as regulated by the appropriate permit or certificate, are considered conventional technology in accordance with this chapter:

1. Irrigation - slow rate. Wastewater may be applied by spraying, flooding, or ridge and furrow methods. Irrigation methods are designed not to discharge to surface waters.

2. Rapid infiltration. Wastewater may be applied by spreading and spraying. The system shall be designed to meet all certificate/permit requirements and groundwater standards.

3. Overland flow. This method of wastewater renovation is best suited for soils with low permeability. Generally, a permit or certificate for a discharge to surface waters must be issued.

E. Other alternatives. Natural treatment systems such as aquatic ponds, constructed wetlands and biological/plant filters and other aquatic plant systems are somewhat related to land treatment technology. Natural treatment involves the use of plants in a constructed but relatively natural environment for the purpose of achieving treatment objectives. The major difference between nonconventional natural and conventional treatment systems is that conventional systems typically use a highly managed and controlled environment for the rapid treatment of the wastewater. In contrast, nonconventional natural systems use a comparatively unmanaged environment in which treatment occurs at a slower rate.

1. The use of natural treatment as a part of a land treatment system may take several forms including ponds called "Aquatic Processing Units" (APU). Floating plants such as water hyacinths and duckweed are often used in APU treatment.

2. Constructed wetlands are defined as areas where the wastewater surface is controlled near (subsurface flow) or above (free water surface) a soil or media surface for long enough each year to maintain saturated conditions and the growth of related vegetation such as cattails, rushes, and reeds.

3. Constructed wetlands must provide for groundwater protection and may be used to provide additional treatment to primary, secondary, or highly treated effluents prior to final discharge.

4. Natural (existing) wetlands are considered as state waters and any discharge to them shall be regulated in accordance with an issued discharge permit or certificate.

F. Features. Biological treatment that will produce an effluent either with a maximum BOD₅ of 60 mg/l or less, or be of such quality that can be adequately disinfected, if necessary, shall be provided prior to natural treatment, including use of conventional unit operations prior to the land application of treated effluent and advanced treatment prior to reuse.

Disinfection may be required following or prior to land application and other natural treatment. If spray irrigation equipment is utilized, adequate aerosol management including pre-disinfection shall be provided.

Buffer zones around field areas shall be provided in accordance with the monitored maximum microbiological content of the applied effluent as follows, with no reduction in required minimum distances to water sources and channels:

Fecal Coliform Count(1) (No./100 mls)	Minimum Buffer Distance, Feet
200 or less	200(2)
23 or less	50(3)
2.2 or less	None, but no application during occupation of field area(3)
Notes:
(1)Exceeded by no more than 10% or less of samples tested.
(2)No public use of field areas.
(3)Transient public use may occur after a three-hour drying period following application.

1. The owner shall provide sufficient holding time to store all flow during periods either when crop nutrient uptake is limited or nonexistent, the ground is frozen, surface saturation occurs during wet weather, the ground is covered with snow, or the irrigation site or field areas cannot otherwise be operated. The total volume of holding required shall be based on the storage necessary to provide for climatic conditions and the nutrient management requirements of the field area crop. Operational storage necessary for system maintenance shall be provided. Climatic holding periods shall be based on the most adverse conditions of freezing and precipitation, as taken from accurate recorded historical data that are available for the local area (in no case less than 25 years). The storage volume shall be sufficient to prevent any unpermitted discharges to state waters.

2. A minimum holding period of 120 days shall be required when climatic data is not available. System backup storage shall be determined by the complexity of the entire treatment system. An increase or reduction of minimum storage may be considered on a case-by-case basis based on adequate documentation of agronomic crop production and nutrient utilization.

3. The depth of the volume containment for total storage requirements shall be measured above any minimum depth requirements for maintenance.

4. The owner shall provide a minimum reserve area equivalent in size to 25% of the design field area. Additional reserve area may be required as evaluated by the division, if the general conditions of the field area are deemed marginal or in proximity of critical areas or waters. The reserve area shall be capable of being used as a functional area within 30 days of notice.

5. Some allowance for a reduced reserve shall be allowed if additional storage is provided or if there is an alternate treatment mode (e.g., discharge) that can be utilized by the facility.

6. Design criteria for treatment or storage ponds shall be in accordance with this chapter and standards contained in this chapter. In addition, the following requirements shall be met:

a. A minimum operational water depth shall be maintained.

b. Provisions shall be made to allow complete drainage of the pond for maintenance.

c. Duplicate pumps shall be provided if necessary to transport pond flows, with the capacity of each pump sized to handle the maximum rate of flow plus an allowance to deplete stored volumes.

d. Disinfection may be provided either upstream from ponds, or the pond effluent may require disinfection.

e. When chlorination is utilized to disinfect pumped flows, the detention time of the holding pond chlorination facilities shall provide a minimum of 30 minutes of contact time, based on the maximum design pumping rate in accordance with this chapter and standards contained in this chapter.

G. Design loadings. Loading rates shall be based on the most critical value as determined by the liquid and nutrient application rates, or total application amounts for other constituents (such as boron, salts, pH-alkalinity, copper or sodium, etc.), present in such concentrations as could produce pollution of either the soil, cover crop, or water quality. Total weekly application (precipitation plus liquid loading rate) shall not exceed two times the design loading rate. This higher than conventional loading rate shall be used only to balance seasonal water deficits, and groundwater quality standards shall not be exceeded unless a variance to the violated standard has been approved by the State Water Control Board department.

1. An overall water balance shall be investigated in accordance with one of the following equations based on design criteria:

a. Irrigation or infiltration

design precipitation + effluent applied = evapotranspiration + hydraulic conductivity.

b. Overland flow

design precipitation + effluent applied = evapotranspiration + hydraulic conductivity + runoff.

2. Design precipitation shall be the wettest year for a 10-year period (return frequency of one year in 10). Minimum time period for this analysis should be 25 years. Average monthly distribution (average percentage of the total annual precipitation that occurs in each month) shall be assumed.

3. Design evapotranspiration (monthly) shall be 75% of average monthly pan evaporation values collected at official weather stations within or contiguous to the Commonwealth of Virginia and should be representative (similar geographically and climatological) of the proposed site.

4. Design hydraulic conductivity shall be a given percentage (see Table 9) of respective laboratory and field measurements that yield the rate at which water passes through the soil under presoaked conditions.

The test methodology should be in accordance with current published procedures made available to the department.

TABLE 9. DESIGN HYDRAULIC CONDUCTIVITY
Type of Test	Percent of minimum measured value to be used in design
i. Saturated Vertical Hydraulic Conductivity	7
ii. Basin Infiltration	12.5
iii. Cylinder Infiltrometers	3
iv. Air Entry Permeameter	3
v. (Other--to be evaluated by the department)

5. During periods of application, the applied nitrogen shall be accounted for through (i) crop uptake and harvest; (ii) denitrification; (iii) addition to surface water and ground water, or storage in soil. In winter, site loadings for slow rate systems shall not exceed the hydraulic design for those particular months. Winter application of treated effluent may be provided only (i) to cool season grasses (ii) following three consecutive days of minimum daily temperatures in excess of 25°F and maximum in excess of 40°F.

6. The annual liquid loading depth for plant nitrogen requirements shall be determined by the following equation:

L = N/2.7C

Where:

N = Crop nitrogen uptake, lb/acre/yr.

C = Total nitrogen concentration, mg/l

C = TKN + NO2-N + NO3-N

L = Annual liquid loadings depth, ft/yr.

TKN = Total KJELDAHL nitrogen = organic N + NH₃ - N

7. The monthly nitrogen loading rate design should be distributed over the growth cycle of the particular crop, as much as practicable.

8. If other nutrients, organics, or trace elements are present in concentrations critical to either crops, soil, or water quality, then a total mass balance similar to that for nitrogen shall be investigated for each critical element or compound.

9. The land application design average rate shall be determined by the climatic conditions, selected crops, and soil characteristics. However, the maximum application rates in terms of depth of effluent applied to the field area shall be as follows:

a. One-fourth inch per hour.

b. One inch per day.

c. Two inches per week (one inch per week in forest field areas used for year round application).

H. Field area design. Field area is defined as the area of land where renovation of wastewater takes place (area under actual spray or distribution pattern). The field area shall be designed to satisfy the most critical loading parameter (i.e., annual liquid loading depth) according to the following equation:

Field Area (acres) = Q/D*365/(365-S)

Where:

Q = Wastewater flow in (acre-inches/week)

D = Applied depth in inches/week

S = Minimum required storage capacity + annual resting periods during the application season when no waste can be land applied.

1. The minimum storage capacity shall be the average design volume of flow accumulated over a period of 60 days, unless other storage periods are justified by climatic data. It should be noted that the field area equation does not take into consideration the area needed for reserve capacity or future expansion (no less than 25% of design field area).

2. The field area shall be divided into smaller sections for application to allow for rotational use of these sections. Rotational operation shall be designed to provide the maximum resting periods for field areas. The distribution system shall be designed to meet the requirement for alternating application to the field area sections. Minimum resting periods shall be two days, one day and two weeks for irrigation, overland flow and infiltration-percolation, respectively. Maximum wetting period shall not exceed five days, one week, and one day respectively for irrigation, infiltration-percolation, and overland flow, respectively. Resting and wetting periods depend on soil types, climatic conditions, harvesting requirements, etc.

3. The field area or areas shall be adequately enclosed with suitable fencing to prevent access to livestock and the public where necessary. Signs shall be posted at sufficient intervals (100 to 300 feet) around the entire perimeter of field areas to identify the land treatment operation and specify access precautions.

4. A groundwater monitoring system shall be provided in accordance with the permit or certificate requirements. A minimum of one upgradient and two downgradient monitoring wells shall be provided. The well locations, along with typical well construction specifications, shall be submitted with the proposal. Upon installation, the driller's log shall be submitted. Additional monitoring well locations may be required if deemed necessary upon evaluation of monitoring data. The results of any required sampling and testing of groundwater shall be submitted to the department for evaluation in accordance with the operating permit.

5. Representative agriculturally related soil tests are required on crop dependent systems to ensure adequate vegetative cover. The growing and maintaining of a vegetative cover on application sites is a very integral part of the system. The plants prevent soil erosion and utilize nutrients and water. The system design should provide for a proper balance between applied amounts of water and nutrients. The designer may wish to consult with both agronomic and nutrient management specialists on these matters. The design shall address crop and nutrient management.

6. The wastewater application schedule should be worked around the plans for harvesting. A minimum of 30 days shall be required between the last day of application and utilization of all crops. Crops that will be consumed raw by man shall not be grown in land application field areas.

7. Information on the proposed crops and their intended use may be forwarded to the Virginia Department of Agriculture and Consumer Services for evaluation.

I. Low intensity design. The low intensity application or irrigation field area should be as flat as possible with maximum slopes of 5.0% or less. The design of low intensity irrigation of treated effluent shall provide for nutrient management control. When it is necessary to locate field areas on slopes of eight to 12%, special precautions shall be taken to prevent seepage or runoff of sewage effluent to nearby streams. Dikes or terraces can be provided for field areas, together with runoff collection and return pumping equipment. The maximum field area slope should be 12%. The irrigation field area shall be located a minimum distance of 50 feet from all surface waters.

1. Five feet of well-drained loamy soils are preferred. The minimum soil depth to unconsolidated rock should be three feet. The hydraulic conductivity should be between 0.2-6 inches/hour.

2. The minimum depth to the permanent water table should be five feet. The minimum depth to the seasonal water table should be three feet. Where the permanent water table is less than five feet and the seasonal water table is less than three feet, the field area application rate shall be designed to prevent surface saturation. In addition, underdrain and groundwater pumping equipment may be required.

3. The method of applying the liquid to the field shall be designed to best suit prevailing topographic, climatic, and soil conditions. Two methods of application are:

a. Sprinkler systems with low trajectory nozzles or sprinkler heads to uniformly distribute the applied effluent across a specified portion of the field area. Application is to be restricted in high winds that adversely affect the efficiency of distribution and spread aerosol mists beyond the field areas.

b. Ditch irrigation systems that utilize gravity flow of effluent through ditches or furrows, from which effluent percolates into the soil. For uniformity of distribution, the slope of the field area is to be uniform and constant.

4. The height of spray nozzles, pressure at the spray nozzles and spacing of the laterals shall be adequate to provide uniform distribution of the effluent over the field area. The design height and pressure of the spray nozzles shall avoid damage to vegetation and soil.

5. Adequate provisions shall be made to prevent freezing and corrosion of spray nozzles and distribution lines when the system or a section of the system is not in operation.

6. Appropriate vegetation shall be maintained uniformly on all field areas. Usually water tolerant grasses with high nitrogen uptakes are used. Over seeding with cool season grasses may be necessary during the fall season, prior to October 15 of each year. Silviculture sites and reuse irrigation sites may also be used with this type of land treatment.

J. Rapid infiltration. This form of treatment requires the least amount of land. Renovation is achieved by natural, physical, chemical, and biological processes as the applied effluent moves through the soil. Effluent is allowed to infiltrate the soil at a relatively high rate, requiring a field area with coarse grained soils. This system is designed for three main purposes (i) ground water recharge; (ii) recovery of renovated water using wells or underdrains with subsequent reuse, or (iii) discharge and recharge of surface streams by interception of ground water.

1. Five feet of sand or loamy sand is preferred. Soil grain size should be greater than.05 mm in size. The hydraulic conductivity should be greater than two inches/hour.

2. The permanent ground water table shall be a minimum of 15 feet below the land surface. With this method, a recharge mound is not uncommon and shall be properly evaluated by the consultant. A minimum distance of 10 feet should be maintained between the land surface and the apex of the recharge mound (during a worse-case situation). Lesser depths may be acceptable where under drainage is provided.

3. Spreading and spraying are the two main application techniques that are suitable for infiltration-percolation.

4. Design application rates will vary according to the site area, soil, geology, and hydrology characteristics.

5. The buffer distances from extremities of field areas to private wells should be at least 400 feet.

K. Overland flow. Renovation of wastewater is accomplished by physical, chemical, and biological means as applied effluent flows through vegetation on a relatively impermeable sloped surface. Wastewater is sprayed or flooded over the upper reaches of the slope and a percentage of the treated water is collected as runoff at the bottom of the slope, with the remainder lost to evapotranspiration and percolation. Overland systems should be capable of producing effluent at or below secondary level; however, additional treatment units may be needed to achieve the permitted effluent limitations.

1. Soils should have minimal infiltration capacity, such as heavy clays, clay loams or soils underlain by impermeable lenses. The restrictive layers in the soil should be between one to two feet from the surface to maintain adequate vegetation. The hydraulic conductivity should be less than 0.2 inches/hour. Field area slopes shall be less than 8.0%. Monitoring wells shall be provided.

2. Renovated water shall be collected at the toe of the slope in cut off ditches or by similar means and channeled to a monitoring point and disinfected as required.

3. The effluent application method should achieve a sheet flow pattern that will produce maximum contact between the applied wastewater and the soil medium. This can be accomplished by lateral distribution methods, low pressure sprays and moderate to high pressure impact sprinklers discharging onto porous pads or aprons designed to distribute the applied flow while preventing erosion. Maximum application rates in terms of depth of effluent should be less than 10 inches per week.

4. Perennial field area vegetation shall be required. Hydrophilic or water tolerant grasses are usually grown with this type of system.

L. Alternative design. Information submitted for approval of other natural treatment systems and reuse alternatives shall include performance data obtained from either full-scale systems similar to the proposed design, or pilot studies conducted over a testing period exceeding one year, to a period of two years, based on test results.

Special consideration should be given to the following factors in planning and design of natural systems:

1. Many aquatic plants are sensitive to cold temperatures and may require the use of a protected environment or operation on a seasonal basis. Some plants may be considered unacceptable for use and their growth must be controlled.

2. Control of insects, particularly mosquitoes, is normally required for constructed wetlands and aquatic plant systems. The use of mosquito-eating fish and water depth adjustments are recommended.

3. Some constituents which may be present in wastewaters, particularly those having high industrial loads, are toxic to many aquatic plants. Therefore, tests should be conducted to identify possible toxics prior to selection of the aquatic plant species.

4. Natural systems utilize a higher life form of less diversity than found in more conventional biological treatment systems. This lack of biological diversity may reduce treatment performance. Constructed wetland and aquatic plant systems could be more susceptible to long term process upsets. Therefore, the effects of fluctuations in climate and wastewater characteristics is extremely important in the design of natural systems.

5. Some aquatic plant and animal species have the potential to create a nuisance condition if inadvertently released to natural waterways. Federal, state and local restrictions on the use of certain aquatic plants and animals shall be considered.

6. Harvesting and the use or disposal of aquatic plants should result in removal of organics, solids and nutrients such as nitrogen and phosphorous from the APU effluent. Management of residual matter shall be in accordance with this chapter and standards contained in this chapter.