Recommended Design Criteria for Disposal of Effluent by Irrigation...
Administrative Considerations...
Effluent for final disposal through irrigation equipment should first be preceded by a secondary treatment works, including disinfection when required. If the effluent, after treatment, cannot meet the requirements of ARSD 74:03:15 of the Ground-water Quality Standards, a Ground- water Discharge Plan may be required. The Department's Ground-water Quality Program staff should be contacted to determine the necessity of a Ground-water Discharge Plan (The Division of Water Rights should be contacted to determine if a Water Permit is required)*. Water Management Board definition of irrigation ARSD 74:02:01:01(2) "Irrigation," the artificial application of water for the purpose of supplying sufficient moisture for plant growth. Disposal of contaminated water is not considered to be irrigation unless other water is used along with the contaminated water. A Water Permit and/or a Ground-water Discharge Plan, if required, must be approved by the South Dakota Board of Water Management prior to initiation of the Step 4 grant. The State Conservation Commission must approve the compatibility of the soil and water for crop irrigation purposes. This approval must be obtained before an application for a Water Permit can be advertised for consideration by the Water Management Board. The following procedure is recommended before considering disposal of wastewater through irrigation equipment as a method of treatment :

1. At least one representative sample of the wastewater should be collected and submitted to the Water Quality Laboratory, Brookings, South Dakota, for analysis and a preliminary interpretation of irrigability. If the wastewater is not suitable for irrigation, alternate methods of treatment should be considered. If the effluent water could be used for irrigation, Step 2 should be followed.

2. If a soil classification study has been completed by the Soil Conservation Service, the soils information should be reviewed to determine if the soil in the proposed area is suitable for irrigation, using waters of the quality as determined in Step 1.

3. If a soils classification study of the proposed irrigation site has not been completed, the applicant should contact the local Conservation District and request that the Soil Conservation Service complete a soils classification for the proposed site. The soils information should then be analyzed to determine if the soil at the proposed site is suitable for irrigation using the waters in question. *Water Management Board definition of irrigation ARSD74:02:01:01(2) "Irrigation," the artificial application of water for the purpose of supplying sufficient moisture for plant growth. Disposal of contaminated water is not considered to be irrigation unless other water is used along with the contaminated water.

4. After the water quality information and the soils information has been obtained, the Cooperative Extension Service, S.D.S.U., Brookings, South Dakota, should be contacted for advice on application rates and irrigation practices. The engineering report must contain pertinent information on location, geology, soil conditions, area for expansion, hydrology and any other factors which may affect the feasibility and acceptability of the proposal. The following specific information is to be submitted prior to initiation of the Step 4 grant or final approval of plans and specifications by the Department staff. The process design manual for Land Treatment of Municipal Wastewater, October, 1981, or latest edition, U.S. EPA, should be used as a reference.
General Information...
1. Legal description of the disposal site.

2. The location of all existing and proposed residences, commercial or industrial development, roads and ground or surface water supplies within one-half mile of the proposed site.

3. Analytical data of the wastewater showing as a minimum: total dissolved solids, electrical conductivity, pH, total suspended solids, 5-day biochemical oxygen demand (BOD5), ammonia nitrogen, total kjeldahl nitrogen, nitrates, phosphorus, chlorides, sulfates, carbonates, bicarbonates, calcium, magnesium, sodium, fecal coliform, adjusted sodium adsorption ratio and percent sodium. When industrial wastes are involved, analytical data showing the following should also be included : aluminum, arsenic, beryllium, boron, cadmium, chromium, cobalt, copper, fluoride, iron, lead, lithium, manganese, molybdenum, mercury, nickel, selenium, silver and zinc.

4. Representative percolation and infiltration data of the top soil and the subsoil layers between the surface and the ground-water table.

5. Representative data on the chemical and bacteriological quality of the ground-water as well as its elevation and the rate and direction of flow under existing and proposed conditions of use.

6. A description including maps showing elevation and contours of the site and adjacent areas which may be suitable for expansion.

7. Climatoligical data for the area.

8. Location, depth and outlet of underdrains on the site.

9. Representative soil boring data to a depth of at least 25 feet, to ground-water, or to bedrock. Information, including a detailed description of the properties of the major soil types present and any soil survey information, available from the Soil Conservation Service of the U.S. Department of Agriculture.
Storage...
1. An effluent storage pond system shall have a minimum of 210 days capacity without consideration for evaporation.

2. The pond shall be designed and constructed in accordance with the applicable criteria for wastewater stabilization ponds found in Chapters IV and V.
Location of Disposal Site...
1. The disposal site should be at least one mile from any municipal water supply and one-fourth mile from any private domestic water supply, except that in limestone or other unusual geological areas, a greater distance may be required.

2. The disposal site should be at least one- fourth mile from any human habitation or area which is likely to be developed for the same within the proposed use period of the project.

3. The disposal site should be at least one- fourth mile from state parks or recreation areas, unless disinfection is provided.

4. The disposal site shall be at least 100 feet from neighboring property lines or road right-of-ways.

5. The disposal site should be at least one- fourth mile from lakes.

6. Conditions 1-5 may be disregarded when the wastewater has undergone extensive treatment and could be considered reclaimed water suitable for human consumption.

7. A statement from the local planning agency on the planned uses of the disposal site and adjacent land and compatibility with other uses.

8. Wastewater used for the irrigation of golf courses, parks, playgrounds, lawns, and in other areas where the public has access shall be provided with disinfection sufficient to ensure that a geometric mean number of total coliform organisms does not exceed 200 organisms per 100 milliliters which should be adequate to protect human health. It should be realized, however, that this level probably will not eliminate all pathogenic viruses.
Design of Disposal Area...
1. The vertical distance between the surface of the disposal fields and the maximum height of the ground- water table should be a minimum of six feet, or more if possible, except where it is necessary that the site be provided with underdrains to intercept the percolate for discharge to surface waters, in which case the distance between the surface of the disposal field and the underdrains should be a minimum of four feet.

2. Separation of underdrains will be dependent on soil types and flow gradients. The process design manual for Land Treatment of Municipal Wastewater, October, 1981, or latest edition, U.S. EPA, may be used as a reference.

3. Flow measuring devices shall be provided for disposal sites when underdrains are utilized to intercept and collect percolate for discharge to surface waters.

4. The disposal period for design purposes should be a maximum of 18 weeks. This time may be exceeded during operation of the facility if weather conditions permit.

5. The effluent shall be applied at a rate not to exceed the following :



6. or in accordance with the maximum application rate for the soil type and method of application as given in the South Dakota Soil Conservation Irrigation Guide.

7. For the purpose of determining land requirements, a maximum application of wastewater shall be limited to 2 inches/acre/week or a total of 24 inches/acre/year. To prevent ground saturation and runoff, no applications are permitted during periods of heavy or prolonged rainfall, snow cover or when the ground is frozen.

8. A nitrogen mass balance shall be performed. The total annual load should be determined by using the process design manual for Land Treatment of Municipal Wastewater, October 1981, U.S. EPA, as a reference.

9. To the extent possible, a buffer zone around the land disposal site shall be provided through purchase of additional land and/or control of the land use through zoning ordinances. To protect downwind, adjacent land usage from mist and/or aerosol contamination, provisions should be made for a wind break or an increase in the buffer zone, or increased disinfection.

10. The effluent shall be applied so as not to have an adverse effect on vegetation. In the absence of suitable natural vegetation, provisions shall be made for establishing and maintaining an acceptable vegetative cover on the site. The Conservation District, Soil Conservation Service or Cooperative Extension Service, S.D.S.U., should be consulted for this information.

11. Computation of the area required for disposal shall be based upon soil types, representative percolation and infiltration data, evapotranspiration data, available rainfall data, the maximum disposal period and application rates plus an allowance for system maintenance and for drying and harvesting cover crops where applicable.

12. The disposal area shall be diked to prevent any surface runoff of effluent and/or provisions made for its recapture by a system of ditches, storage and pumping facilities or other acceptable means.

13. Extraneous surface water shall be prevented from entering the disposal area.

14. The distribution pressure and devices for the sprinkler or big gun type equipment shall, to the extent feasible, be installed in such a manner as to minimize wind drift of effluent and formation of aerosols.
Safeguards and Monitoring...
1. The site shall be enclosed with a fence capable of discouraging the entrance of unauthorized persons.

2. Appropriate warning signs shall be provided on the fence around the site to inform the public of the nature of the facility and advise against trespassing. At least one sign shall be provided on each side of the site and one for every 500 feet of its perimeter.

3. Shallow observation wells shall be placed in all directions of major ground-water flow from the site. The wells shall not be more than 200 feet outside of the site perimeter, spaced not more than 500 feet apart, and extending into the ground-water table. The shallow wells shall be no deeper than 5 feet below the seasonal low water table and will be screened to intercept the water table. The spacing and depth of the wells may be varied in any particular situation, depending upon circumstances. Shallow wells within the disposal site are also recommended. The wells shall be constructed in accordance with the South Dakota well drilling regulations.

4. Provisions shall be made for measurement of the quantity and quality of the effluent discharging to the disposal area and measurement of the static water level and quality of the water in the observation wells.

5. The application operation should cease during strong winds if the spray is carried toward nearby human habitations, pastures used for dairy grazing, public access areas, or food crops such as produced in gardens, orchards or vineyards.

6. If disinfection is required, chlorine residuals shall be at levels non-toxic to the grasses, plants, fisheries, or aquatic life. Most grasses can tolerate a 2.0 mg/l total residual chlorine level.
Operation and Reporting...
1. NPDES and ground-water permit conditions may require any or all of the following tests every month on samples from all observation wells and the flow from field underdrain outlets: conductivity, chlorides, dissolved solids, nitrates, nitrites, ammonia, fecal coliform, sulfates, BOD5, phosphorus, suspended solids, and pH.

2. Other tests or samples from observation wells or underdrain outlets also may be required as recommended by the Department staff, such tests to be made and reported to the Department before, during and after periods of use of the site.

3. Pertinent operation information shall be submitted monthly to the Department.
Miscellaneous...
1. The quality of the treated wastewater effluent discharged to ground-water must conform with the current recommended State and Federal Drinking Water Standards pursuant to the Federal Safe Drinking Water Act, and the Ground-water Quality Standards, whichever is the better water quality. Discharges to the surface waters shall conform to the South Dakota Surface Water Quality Standards. Any expected departure shall be noted in the engineering report, together with proposed means for conforming, or justification if remedial measures are not proposed.

2. No detrimental change in the ground-water quality shall be allowed without obtaining a Ground-water Discharge Plan. Unpermitted degradation of the ground-water shall require remediation.

3. Adequate pre-operational baseline data on the ground-water quality and other environmental aspects as may be requested, shall be obtained and submitted for review before the site is placed in operation.

4. Leases of farm land for disposal of effluent by irrigation should be for the design life of the project. It is recommended that the design life of the project be at least 20 years.

5. If disinfection is required, the following features should be provided : ( a ) Alarm device for malfunction of disinfection system. ( b ) Automatic switch-over devices for chlorine cylinders. ( c ) Automatic shut-off of irrigation unit if chlorination system malfunctions.
Deviations from Design Criteria...
The Department may consider and allow deviations where adequate documentation is provided to prove the need for such deviation. Water Management Board definition of irrigation ARSD 74:02:01:01(2) "Irrigation," the artificial application of water for the purpose of supplying sufficient moisture for plant growth. Disposal of contaminated water is not considered to be irrigation unless other water is used along with the contaminated water.