5 CCR 1002-81
Materials incorporated by reference in this regulation are available for public inspection during regular business hours at the Colorado Department of Public Health and Environment, Water Quality Control Division, 4300 Cherry Creek Drive South, Denver, Colorado. The regulation incorporates the materials as they exist at the date of the promulgation of this regulation and does not include later amendments to or editions of the incorporated materials. All material incorporated by reference may be examined at any state publications depository library.
81.0 AUTHORITY
Section 25-8-205, C.R.S. as amended.
81.1 PURPOSE
The purposes of this control regulation are:
81.2 DEFINITIONS
(1) “ANIMAL FEEDING OPERATION”
An “animal feeding operation” is a confined animal or poultry growing operation (facility) for meat, milk or egg production or stabling wherein livestock are fed at the place of confinement for 45 days or longer in any 12 month period and crop or forage growth is not maintained in the area of confinement, and the facility does not meet one of the criteria for a concentrated animal feeding operation.
(2) “ANIMAL UNIT”
“Animal Unit” means a unit of measurement used to determine the animal capacity of an animal-feeding operation containing two or more species of animals. The animal unit capacity of an operation is determined by multiplying the number of animals of each species by the appropriate equivalency factor from Table 1, and summing the resulting totals for all animal species contained in the operation. TABLE I Animal Unit Equivalency Factors Animal Species Equivalency Factor Slaughter and feed cattle 1.00 Mature dairy cattle 1.43 (milked or day)
Sheep or lambs 0.10 Horses 2.00 Turkeys 0.018 Chickens broiler or layer 0.01 (if the facility has continuous overflow watering)
Chickens broiler or layer 0.033 (if the facility has a liquid manure system)
Ducks 0.20
(3) “AVERAGE WORKING CAPACITY”
“Average working capacity” is the average occupancy of the animal feeding operation on a year-round basis defined as the sum of the end-of-month occupancy rates divided by the number of months during a calendar year the facility conducts animal feeding operations.
(4) “CONCENTRATED ANIMAL FEEDING OPERATIONS”
“Concentrated Animal Feeding Operation”, means a concentrated, confined animal or poultry growing operation (facility) for meat, milk or egg production or stabling, in pens or houses wherein the animals or poultry are fed at the place of confinement for 45 days or longer in any 12 month period and crop or forage growth or production is not sustained in the area of confinement. Two or more animal-feeding operations under common ownership or management are deemed to be a single animal-feeding operation if they are adjacent or utilize a common area or system for manure disposal. “Concentrated Animal Feeding Operations” meet one or more of the following criteria:
(5) “DIRECTOR”
(6) “EXPANDED FACILITY”
An “Expanded Facility” is a concentrated animal feeding operation which is increased in physical area or average working capacity by one third of the existing capacity on or after the effective date of this amendment.
(7) “HOUSED ANIMAL FEEDING OPERATION”
“Housed animal feeding operation” is an operation with totally roofed buildings with open or enclosed sides wherein livestock or poultry are housed on solid concrete or dirt floors, slotted (partially open) floors over pits or manure collection areas in pens, stalls or cages, with or without bedding materials and mechanical ventilation. For the purposes of this subchapter, the term housed lot includes the terms slotted floor building, barn, stable, or house, for livestock or poultry, as these terms are commonly used in the agriculture industry.
(8) “HYDROLOGICALLY SENSITIVE AREA”
“Hydrologically Sensitive Area” includes: Areas where significant groundwater recharge occurs or where contamination from animal feeding operations could impact existing drinking waiter withdrawals, classified uses, or reasonably likely future public drinking water system withdrawals; areas where animal feeding operations could impair water bodies subject to antidegradation review or classified for Class 1 Recreation or Class 1 Aquatic Life.
(9) “MAN-MADE DRAINAGE SYSTEM”
“Man-made drainage system” means a drainage ditch, flushing system, or other drainage device which was constructed by man and is used for the purpose of transporting wastes.
(10) “MANURE”
“Manure” is defined as feces, urine, litter, bedding, or feed waste from animal feeding operations.
(11) “NEW FACILITY”
A “new facility” is an operation which was constructed on or after August 30, 1992.
(12) “NO DISCHARGE”
The term “no-discharge” shall be defined as no-discharge of manure or process wastewater to waters of the state except in the event of an applicable design storm event specified in section in 81.3(b).
(13) “OPEN ANIMAL FEEDING OPERATION”
“Open animal feeding operation” consists of pens or similar confinement areas with dirt, concrete, or other paved or hard surfaces wherein animals or poultry are substantially or entirely exposed to the outside environment except for small portions of the total confinement area affording protection by windbreaks or small shed-type shade areas. For the purposes of this regulation, the form open animal feeding operation is synonymous with the terms yard, pasture lot, dirt lot, and dry lot, for livestock or poultry, as these terms are commonly used in the agricultural industry.
(14) “OPERATOR”
“Operator” means any individual, partnership or corporation, or association doing business in this state.
(15) “PROCESS WASTEWATER”
“Process wastewater” means any process-generated wastewater and any precipitation (rain or snow) which comes into contact with any manure or any other raw material or intermediate or final material or product used in or resulting from the production of animals or poultry or their direct products (e.g., milk, eggs).
(16) “PUBLIC DRINKING WATER SYSTEM”
“Public Drinking Water System” means a system for the provision to the public of piped water for human consumption, if such system has at least 15 service connections or serves an average of at least 25 persons daily at least 60 days out of the year. A public drinking system includes both community and non- community systems.
(17) “REACTIVATED FACILITY”
A “Reactivated Facility” is a concentrated animal feeding operation which has been in a non-operating status for three consecutive years and is reactivated on or after August 30, 1992.
(18) “RECONSTRUCTED FACILITY”
A “Reconstructed Facility” is a concentrated animal feeding operation which is reconstructed on or after August 30, 1992, due to damage from a flood, fire, dilapidation or reconfiguration of the facility.
(19) “SIGNIFICANT GROUNDWATER RECHARGE”
“Significant groundwater recharge” is defined as high or very high seepage rates as determined using the methods described in SCS NENTC-Engineering Geology Technical Note No. 5 attached as Appendix A or other authoritative document as approved by the Division.
(20) “TEN YEAR TWENTY-FOUR HOUR STORM” AND “TWENTY FIVE-YEAR TWENTY-FOUR HOUR STORM”
“Ten year twenty-four-hour storm” and “twenty-five year twenty-four-hour storm” mean a storm of a 24- hour duration which yields a total precipitation of a magnitude which has a probability of recurring once every ten or twenty-five years, respectively, as shown in Appendix B.
(21) “VADOSE ZONE”
“VADOSE ZONE” means the zone between the land surface and the water table. It includes the area beneath the root zone, intermediate zone, and capillary fringe. Saturated bodies, such as perched ground water, may exist in the vadose zone, also called zone of aeration and unsaturated zone.
(22) “WATERS OF THE STATE”
“Waters of the State” means any and all surface and subsurface waters which are contained in or flow in or through this state, except waters in sewage systems, waters in treatment works of disposal systems, waters in potable water distribution systems, and all water withdrawn for use until use and treatment have been completed.
81.3 SURFACE WATER PROTECTION REQUIREMENTS-Concentrated Animal Feeding Operations (A) General Performance Requirements Concentrated animal feeding operations are required to be operated as no-discharge facilities. Compliance with the no-discharge provision can only be achieved by installation and operation of adequate manure and process wastewater collection, storage and land application facilities.
(B) Design Criteria (1) An operator of an existing concentrated animal feeding operation shall not discharge manure, process wastewater or stormwater runoff from the facility to state waters except as the result of a storm in excess of a 25-year, 24-hour storm. The 25-year, 24-hour storm event design criterion applies to all stormwater diversion structures (e.g. dikes, berms, ditches) as well as manure and process wastewater retention and control structures.
(2) Runoff volume from the concentrated animal feeding operation surface shall be determined from soil cover complex curve number 90 for unpaved lots, or soil cover complex curve number 97 for paved lots, as defined by the United States Department of Agriculture (U.S.D.A.) Soil Conservation Service and as depicted in Appendix C. The director may approve the use of a different soil cover complex curve number on a case-by-case basis.
(C) Operation and Maintenance Requirements
81.4 GROUND WATER PROTECTION REQUIREMENTS - CONCENTRATED ANIMAL FINDING
(A) Manure and Process Wastewater Retention Structures Except as provided in subsection 81.4(8) and (C), below, all process wastewater retention structures shall be constructed of compacted or in-situ earthen materials or other very low permeability materials, and shall be maintained, so as not to exceed a seepage rate of 1/32"/day (1 X 10-6 cm/sec.). The operator shall have available suitable evidence that a completed lining meeting the requirements of this subsection 81.4(A) was constructed.
(B) Retention structures which collect storm water runoff from open animal feeding operations and no other waters except, if any, water which has not come into contact with manure or process wastewater, such as boiler cooling water or flow-through livestock drinking water, shall be constructed of a material and maintained so as not to exceed a seepage rate of 1/4" per day (1 X 10-5 cm/sec.), provided that the retention structure is dewatered so that the full runoff storage capacity is restored within 15 days of the storm event, consistent with the provisions of Section 81.5.
(C) Earthen retention structures in existence as of August 30, 1992, shall be exempt from the requirement to have available suitable evidence that a completed lining meeting the requirements of subsection 81.4(A) has been constructed. Whenever the Director makes a determination that seepage of nutrients or other pollutants from manure or process wastewater into ground water occurs at a rate greater than allowed in this section, the Director may require compliance with the provisions of subsections (A)(1), (2), or (3) of this section.
(D) Manure and Process Wastewater Conveyance Structures:
81.5 BENEFICIAL USE AND DISPOSAL OF MANURE AND PROCESS WASTEWATER -
If land application is utilized for disposal of manure or process wastewater, the following requirements shall apply:
(B) Treatment and Discharge:
If treatment other than land application is utilized prior to discharge to state waters a CDPS permit shall be required for the operation.
81.6 ANIMAL FEEDING OPERATIONS - BEST MANAGEMENT PRACTICES
The following Best Management Practices (BMPs) shall be utilized by animal feeding operations, as appropriate based upon existing physical conditions, and site constraints. Best management practices means, for purposes of this regulation, activities, procedures, or practices necessary for the reduction of impacts from animal feeding operations, as described in 81.6. The following practices to decrease runoff volume from animal feeding operations are BMPs within the meaning of this regulation:
81.7 MANURE AND PROCESS WASTEWATER MANAGEMENT PLANS
All new, reactivated, reconstructed or expanded concentrated animal feeding operations and existing concentrated animal feeding operations which have been determined by the Director to be in significant noncompliance with these regulations shall submit a manure and process wastewater management plan to the Division. The Division will provide comments on the adequacy of the plan within 45 days of receipt of such submittal, except for the land application plan portion, if required, the review of which is governed by subsection 81.5(A) (5)(c). This plan, shall include details demonstrating the facilities' adequacy to comply with these regulations. The plan, at a minimum, shall include the following: legal owner, local contact, legal description of the site, surface area of the site along with a drainage schematic, the design animal unit capacity, storm water and wastewater conveyance facilities, manure and process wastewater containment and treatment facilities, and information on the manure and process wastewater disposal sites. The Division may require additional information characterizing the manure and process wastewater if deemed necessary to insure protection of state waters. Process wastewater retention structures or manure stockpiles shall not be located within a mapped 100-year floodplain as designated and approved by CWCB unless proper flood proofing measures (structures) are designed and constructed. Facility designs as required under this section shall be prepared by a registered professional engineer, the USDASoil Conservation Service or qualified Agricultural Extension Service Agent or other individual with demonstrated expertise in the design of such facilities.
81.8 MONITORING
Existing concentrated animal feeding operations which are in compliance with the provisions of sections 81.3, 81.4, and 81.5 shall not be required to conduct water quality monitoring except as provided under_ subsection 81.5(A)(5)(c). The Division may request the Commission to require an operator of a concentrated animal feeding operation to perform site-specific water quality monitoring whenever the Division determines that the facility poses a significant potential risk to beneficial uses of state waters. In making a determination of whether monitoring should be required pursuant to this control regulation, the Commission may consider factors which include but are not limited to: the size of the operation, the economic impact of the proposed monitoring activities, whether there is suspected contamination of state waters attributable to the facility, whether early detection of groundwater contamination is essential to protect valuable drinking water sources, and whether there has been a significant failure on the part of the operator to comply with this regulation and such significant noncompliance indicates there is a high probability that applicable water quality standards or numerical protection levels may be violated.
81.9 EXCLUSIONS
The provisions of this control regulation are not applicable to housed commercial swine feeding operations permitted under section 61.13 of the Colorado Discharge Permit System Regulations, Regulation #61, as defined under section 61.2 of that regulation. APPENDIX A SEEPPAGE: A SYSTEM FOR EARLY EVALUATION OF THE POLLUTION POTENTIAL OF AGRICULTURAL GROUNDWATER ENVIRONMENTS CONTENTS Page Background and Scope 2 Purposes 3 Discussion of 3 Methcdoloqy Limitations of the System 7 Instructions Step 1. Distance 9 Between Site of Practice and Point of Water Use Step 2. Land Slope 10 Step 3. Depth to Water 11 Table Step 4. Vadose Zone 12 Material Step 5. Aquifer Material 13 step 6. Soil Depth 11 Step 7. Attenuation 15 Potential of Soil Step 8. Determination of 18 Site Index Number and Pollution Potential Category References Cited 20 Worksheet 1: 21 Computation of Site Index Number Worksheet 2: 22 Computation of Step 7, Factor Levels for Characteristics Affecting Attenuation Potential of Soil Illustrations Figure 1: Typical Setting 5 for Steps in SEEPAGE Method List of Tables Table 1: Ratings for 9 Distance Between Site and Point of Water Use Table 2: Ratings for 10 Land Slope Table 3: Ratings for 11 Depth to Water Table Table 4: Ratings for 12 Vadose Zone Material Table 5: Ratings for 13 Aquifer Material Table 6: Ratings for Soil 14 Depth Table 7: Ratings for 17 Factors Affecting Attenuation Potential of Soil Table 7a: Ratings for 18 Attenuation Potential of Soil Table 8: Pollution 18 Potential Categories of Site Index Numbers Table 9: Summary of 19 Score Ranges for Each Step Background The importance of our nation's ground water resource cannot be overstated. Over 50 percent of the U.S. population (1980 Census) is served by ground water; 97 percent of the rural population depends upon it for domestic supplies (U.S. Geological Survey, 1985). Our reliance upon the ground water resource has been steadily growing. Ground water withdrawals have increased 159 percent between 1950 and 1980 while surface water withdrawals have risen only 107 percent (Solley, et. al., 1983). Currently, less than one percent of the resource is estimated to be polluted (Lehr, 1982). The most frequently cited sources of contamination of ground water are deficient septic systems, leaking underground storage tanks, and agricultural activities, such as fertilizer and pesticide applications. The most common contaminanants affecting the nation's ground water are sewage, nitrates (such as fertilizers), and synthetic organic chemicals, such as those used in the manufacture of pesticides, as well as petroleum hydrocarbons used in gasoline (US EPA, 1987). More than 99 percent of all contamination problems are in the shallow aquifers (LeGrand, 1983).
The problems of air and surface water pollution are being worked on through the legislative process to restrict or discontinue the release of contaminants. However, the problem of ground ‘water degradation is far more difficult to overcome. Ground water contamination is hard to detect because it is hidden from view; it is almost always discovered by detection in someone's well. _Moreover, it typically takes a long time for ground water pollution to show itself, and it takes a very long time for an aquifer to flush itself of the pollutant. Since flushing periods are typically in the range of tens, hundreds, or even thousands of years, the result is often a permanently damaged aquifer (Freeze and Cherry, 1979). Defining the extent of aquifer contamination is extremely costly and technically, challenging. Restoring polluted ground water to its original quality is nearly impossible.
Scope The protection of ground water quality is probably best accomplished by prevention of contamination. The U.S. Department of Agriculture (1987) encourages private landowners to use agricultural practices that prevent, minimize, or avoid harmful levels of contamination in ground water. Although the Soil Conservation Service provides technical assistance on many types of activities that may affect ground water, there is little guidance provided in SCS technical references concerning ground water quality. Technical Note- 5 has been developed to provide guidance on the evaluation of hydrogeologic conditions at proposed, sites for such elements of resource management systems that could have the potential to adversely influence ground water quality.
The procedure is based on three recently developed systems (Aller, 1987; LeGrand, 1983; and Wisconsin Geological and Natural History Survey, 1985) and uses quantitative ranking of some of the most important factors affecting a site's susceptibility to ground water contamination. The method makes a systematic evaluation of proposed conservation practice sites. Information used is generally available in field offices: Soil Survey Reports, topographic maps, State and US Geological Survey reports, and simple, on-site observations. The system can be used by those with diverse backgrounds and a basic understanding of ground-water hydrology;
Purposes * The system serves as a screening tool early in the conservation planning process when sites for practices are being ● selected. Potential problems that previously nay have gone unrecognized are identified early in planning. Sites that have very high pollution potential can be avoided or afforded appropriate defensive design measures.
* The system allows the user to compare the relative risks of ground water contamination among various sites and to select the most favorable site.
* The system identifies when a specialist is needed, or when a more detailed, site-specific evaluation is necessary.
* The system provides insight on how either the site or the practice may need to be modified to provide for protection of ground water.
Discussion of Methodology The system focuses on two main subsurface zones: the vadose zone where water and leachable contaminants move vertically downward, and the uppermost saturated zone where ground water moves essentially laterally. The system is best suited for situations where the contaminant is assumed to be introduced at the ground surface, dissolved in water, and has the mobility of water. The system is designed to apply only to the uppermost ground water system (the water table aquifer), and not to deeper, confined aquifers.
There are many hydrogeologic factors which influence the behavior and movement of contaminants in the ground. This system addresses seven of the most important ones that can be evaluated with readily available information. The seven factors include:
Each factor is divided into numerical ranges with values; which vary between one and tan. The ratings for aquifer and vadose zone materials may vary; a rating value can be interpolated and selected according to specific available information, or in the absence thereof, the typical rating can be selected. Scores for each factor are obtained by multiplying the weight by the rating. Once the scores for the seven factors have been determined, they are summed. The sum of the scores is the Site Index Number (SIN). Site Index Numbers can be used to compare various sites for a proposed conservation practice. The site with the lowest SIN is the least sensitive to ground water contamination. TheSite Index Numbers are ranked into Pollution Potential Categoies of LOW, MODERATE, HIGH, and VERY HIGH for both concentrated and dispersed sources of contamination (Table 8). A HIGH or VERY HIGH Pollution Potential Category is a good indication that the site has significant constraints and should be reviewed by a qualified specialist. A ranking of LOW is not necessarily a guarantee that the site will be trouble-free since the procedure addresses only some of the factors that influence ground water contamination. Generally speaking, a site with a ranking of LOW or MODERATE will be superior to one of HIGH or VERY HIGH and is, consequently, more preferable. Keys to Symbols Surface Soil (As mapped by U.S.D.A.)
1002_81_2'As mapped by U.S.D.A.jpg Vadose Zone Material (Unsaturated zone above aquifer and below surface soils; may be soil or rock materials.)
1002_81_3'Unsaturated zone above aquifer and below surface soils; may be soil or rock materials.jpg Aquifer Material (Saturated zone capable of yielding useful supplies of water; may be soil or rock materials.)
1002_81_4'Saturated zone capable of yielding useful supplies of water; may be soil or rock materials.jpg Unfractured Rock (Non-waterbearing; defines lower limit of aquifer in this case.) 1002_81_5'Non-waterbearing; defines lower limit of aquifer in this case.jpg Contaminant Plume (Assumes contaminant has same density and solubility as water, and is dissolved in water.) Arrows denote direction of flow of plume.
1002_81_6'Assumes contaminant has same density and solubility as water, and is dissolved in water.jpg An assessment of the scores of the individual factors can provide insight on how the site or the practice may need to be modified to provide for the protection of the ground water. A summary of the score ranges for the seven parameters is given in Table 9. For example, in the case of an animal waste storage pond, high scores in Soil Depth and Aquifer Material (such as thin soil over karst limestone) are indications that the site will need defensive design measures to protect against ground water contamination. Measures may include the use of some type of liner (such as compacted clay, concrete, or plastic) or abandonment of the site for a more favorable location. If all factors are low except Horizontal Distance, then relocating the site further from the water supply well (or point of concern) would be advisable, in addition to lining. LIMITATIONS OF THE SYSTEM The ground water pollution potential of a site is a function of many interrelated hydrogeologic, environmental, and cultural factors, and contaminant, characteristics. Only a few important hydrogeologic factors are considered in this system. The overriding concern in the development of this system is ease of use. Some information is not readily available or easily developed so such information was excluded. Although the system is simple in concept, it is logical and systematic in its approach, and will achieve the intended purposes.
While recharge is an important climate-related factor, it is not addressed by this system. Recharge is water derived mainly from precipitation or irrigation. It percolates from the ground surface, through the soil and vadose zones to an aquifer. Recharge water that originates directly above a source of contamination is responsible for the leaching and movement of pollutants. Generally speaking, the potential for pollution at a. site with increases with increasing recharge. Recharge outside the boundaries of a contamination source is generally considered beneficial to the aquifer. The general lack of readily available data and the complexities in its evaluation preclude considering it in this system. It is important to know whether a contaminant is moving toward or away from a water supply. In humid areas, the frequency of precipitation is usually sufficient to provide recharge to maintain a permanent water table that generally reflects surface topography. Land slope can often be used to ascertain the direction of flow. -● Unfortunately, radial flow paths, unusual geology, and peculiar contaminant characteristics can too often invalidate this assumption. Hence, the system does not address direction of flow.
The system does' not take into account the size and proximity of the population at risk, nor the importance of the aquifer itself to that population.
The system is not designed to apply to specific types of contamination; it does not address contaminant severity (which includes contaminant toxicity, volume, mobility, and persistence), contaminant magnitude (which includes concentration of contaminant, number of contaminants, and plume size), or how the contaminant is released into the environment (as a slug, intermittently, or continuously). Another point to remember is that some conditions that may be beneficial for ground water protection car. be harmful to surface water quality. Consider for example, a large field on steep slopes with freshly applied chemicals. If a heavy rain occurs., the steep slopes promote high erosion rates and rapid runoff of contaminated surface water. Steep slopes are rated favorably in Table 2 (Land Slope) for ground water protection, but of course they are detrimental to erosion rates and surface water quality. Conversely, the installation of terraces on the slopes would reduce soil erosion and runoff while causing greater infiltration of chemical-laden water into the ground. Conservationists must carefully consider these potentially conflicting effects.
The Pollution Potential Category does not reflect the site's suitability for a particular conservation practice. The suitability of a site depends upon many criteria, including hydrogeologic, environmental, engineering, economic, political, and regulatory. The Category is an indication of the ground-water pollution potential of an area.
This system is intended to be used as a screening tool in the conservation planning process. It must not be utilized as a substitute for a professionally conducted, detailed investigation for design purposes. Instructions Use the Worksheets in the back of this Technical Note (pp. 21 and 22) for recording data and calculating the Site Index Number (SIN) and the Pollution Potential Category for each site under consideration. Follow the instructions for each step carefully.
Step 1. DISTANCE BETWEEN SITE AND POINT OF WATER USE A. Determine whether the potential source of pollution at the site classifies as Concentrated or Dispersed, then select the appropriate weight given at the bottom of Table 1.
B. Measure the horizontal distance between the site and the point of water use (such as a well) or some designated point of concern (such as a property line).
C. Determine rating for distance using Table 1.
D. Multiply rating times weight to obtain score for Step 1.
E. Record the weight, rating, and score for Step 1 on the Worksheet for Site Index Number, p. 21. Table 1: Ratings for Distance Between Site and Point of Water Use Distance (Feet) Rating 0 - 30 10 30 - 60 9 60 - 100 8 100 - 160 7 160 - 250 6 250 - 500 5 50O - 1000 4 1000 - 3200 3 3200 - 6400 2 > 6400 1 Concentrated Source, Dispersed Source Weight:
STEP 2. LAND SLOPE A. Measure the slope of the land surface at the site.
B. Determine rating value for slope using Table 2.
C. Select weight for appropriate source given at bottom of Table 2.
D. Multiply rating times weight to obtain score for Step 2.
E. Record the weight, rating, and score for Step 2 on the Worksheet for Site Index Number, p. 21. Table 2: Ratings for Land Slope Percent Slope Rating 0-2 10 2-6 9 6-12 5 12 - 18 3 > 18 1 Concentrated Source, Dispersed Source, Weight: 3 Weight: 1 Significance of Factor: The slope of the land surface at the site influences runoff/infiltration relationships. The flatter the slope, the greater will be infiltration of water (and any dissolved pollutants) into the soil, and therefore, the greater will be the ground-water pollution potential. Steeper slopes tend to induce greater surface water runoff, a condition which can be detrimental from the standpoint of erosion and surface water quality.
Steeper slopes can often indicate higher ground water velocities. Summary: The flatter the slope of the land surface, the greater the ground-water pollution potential. The steeper the slope, the greater the potential for erosion and surface water pollution. STEP 3. DEPTH TO WATER TABLE A. Estimate the shallowest depth to the water table that is below the elevation of the base (or proposed base) of the site more than 5 percent of the year. Use Soil Survey Reports, well logs, or hand auger observations for shallow depths.
B. Determine rating value for depth using Table 3.
C. Select weight for appropriate source given. at bottom of Table 3.
D. Multiply rating times weight to obtain score for Step 3.
E. Record the weight, rating, and score for Step 3 on the Worksheet for Sita Index Number, p. 21. Table 3: Ratings for Depth to Water Table Depth to Water (Feet) Rating 0 10 0-2 9 2-5 8 5-15 7 15-25 6 25-35 5 35-60 4 60-90 3 90 - 200 2 200 1 Concentrated Source, Dispersed Source, Weight: 5 Weight: 5 Significance of Factor: The water table can be defined as the boundary between the unsaturated zone and underlying zone of saturation. The depth to the water table determines the vertical distance through which a pollutant must move to reach the top of an aquifer. The greater the depth, the greater the time of travel. The greater the time that the pollutant is in contact with the surrounding material, the greater will be the opportunity for attenuation of the pollutant by processes such as oxidation, decay, and sorption. Summary: The shallower the water table, the greater the groundwater pollution potential. STEP 4. VADOSE ZONE MATERIAL A. Determine type of material in vadose zone (between surface soils and aquifer).
B. Select rating for type of materials in the vadose zone using Table 4.
C. Select weight for appropriate source given at the bottom of Table 4.
D. Multiply the rating times weight to obtain score for Step 4.
E. Record the weight, rating, and score for Step 4 on the Worksheet for Site Index Number, p. 21. Table 4: Ratings for Type of Material in Vadose zone Vadose Zone Material Rating* Typical Rating Silt or Clay 1 - 2 1 Shale, Claystone 2 - 5 3 Limestone 2 - 7 6 Sandstone 4 - 8 6 Limestone, Sandstone, 4 - 8 6 and Shale Sequences “Dirty” Sand and Gravel 4 - 8 6 (having > 12% silt and clay)
Basalt 2 - 10 9 Karst Limestone 8 - 10 10 Concentrated Source, Dispersed Source, Weight Weight: 5 4 * Note: Use higher ratings if there are open fractures or other macro-pores in any of deposits. Base adjustment on spacing and of openings.
Significance of Factor: The vadose zone can be defined as the unsaturated (or discontinuously unsaturated) material that is above the water table and below the surface soil. The type of material in the vadose zone determines the flow path and rate of flow of the water (and pollutants) percolating downward through it. The rate of flow is a function of the permeability of the vadose zone material; permeability rates are greatly increased by the presence of fractures in the material. Thus the 'time available for attenuation processes (such as sorption, oxidation, dispersion, mechanical filtration, etc.) to take place is inversely related to permeability. Permeability rates can be inferred from the type of materials. Summary: The greater the permeability of a material, the lower will be its attenuation capacity, and therefore the higher will be the ground-water pollution potential. STEP 5. AQUITER MATERIAL A. Determine aquifer material using geologic maps of-area and on-site inspection.
B. Select the rating for aquifer material from Table 5; use the typical rating unless more specific knowledge justifies modifying it within the given ranges.
C. Select the weight for appropriate source given at the bottom of Table 5.
D. Multiply the rating times the weight to obtain score for Step 5.
E. Record the. weight, rating, and score for Step 4 on the Worksheet for Site Index Number, p. 21. Table 5: Ratings for Aquifer Material Aquifer Material Rating* TypicalRating Shale, Claystone 1 - 3 2 Unweathered 2 - 5 3 Metamorphic/Igneous Rock Weathered/Fractured 3 - 5 4 Metamorphic/Igneous Rock Glacial Till 3 - 5 4 Sandstone, Limestone, and Shale Sequences (rate higher if fractured) 5-9 6 Massive Sandstone 4 - 9 6 Massive 4 - 9 6 Limestone/Dolomite Sand and Gravel 6 - 9 8 Basalt (rate higher if 2 - 10 9 fractured/vesicular)
Concentrated Source, Dispersed Source, Weight: 3 Weight: 3 * Note: Use higher ratings if there are any open joints, fractures, or other macro-pores in any of these materials. Base adjustment on the spacing and size, of the openings. Significance of Factor: An aquifer can be defined as a saturated geologic material which will yield useable quantities of water. Ground water can be transmitted through an aquifer two ways: (1) through the pore spaces between the particles that make up the material (called primary porosity) and, (2) through the fractures and cavities that developed after the material was formed (called secondary porosity). The type of aquifer material controls the flow path and path length which a pollutant must follow; it also influences its permeability, the aquifer's ability to transmit water. Generally speaking, permeability is lower in fine- grained materials (such as clays or shales) and in materials lacking interconnecting fractures (such as unweathered rocks); permeability tends to be higher in coarse-grained materials, such as clean sands and gravels. The occurrence of secondary fractures in a geologic material greatly increases the paths available foreground water flow and, hence, greatly increases the permeability. Permeability can be inferred from the type of aquifer material. The aquifer materials listed in Table 5 are arranged by increasing permeabilities.
Summary: The greater the permeability of aquifer material, the greater the rate at which a pollutant can spread through the aquifer. The greater the permeability, the less time for attenuation processes to occur. Thus, aquifers comprised of materials with high permeabilities will have high ground-water pollution potential.
STEP 6. SOIL DEPTH A. Determine depth of soil using information from the local Soil Survey Report or by on-site inspection.
B. Select rating for soil depth using Table 6.
C. Select weight for appropriate source given at bottom of Table 6.
D. Multiply the rating times the weight to obtain score for Step 6.
E. Record the weight, rating, and score for Step 6 on the Worksheet for Site Index Number, p. 21. Table 6: Ratings for Soil Depth.
A. Select a factor level for each of the six physical/chemical soil characteristics given in Table 7 using information from the local Soil Survey Report. Use the Step 7 Worksheet, (p. 22) to record the selected values.
B. Sum values of the six factor levels.
C. Use this sum to determine the rating for the attenuation potential of the soil from Table 7a.
D. Select the weight for the appropriate source given at the bottom of Table 7a.
E. Multiply the rating for attenuation potential of the soil times the weight to obtain score for Step 7.
F. Record the weight, rating, and score for Step 7 on the worksheet for Site Index Number, p. 21. Significance of Factor: In the surface soil zone, a great variety of biological, physical, and chemical processes act on a pollutant and tend to lessen its potency or reduce its volume. These processes, collectively referred to as attenuation, prevent or retard the movement of pollutants into deeper subsurface zones. The degree of attenuation depends on the time a pollutant is in contact with the material through which it passes, and the amount of surface area of the particles making up the material. Both the time and the surface area are functions of the grain size of the material and the distance through which the pollutant must pass. Thus, the finer the grain size of the material and the thicker the deposit, the greater will be the attenuation of the pollutant. The eventual fate of most pollutants and the resulting quality of ground water will thus depend on the degree of attenuation that takes place. The attenuation potential of a soil can be estimated from six physical/chemical characteristics listed in Soil Survey Reports:
In Table 7 below, the following abbreviations are used for Soil Texture Classes (USDA Classification) : 1 = loam, sil = silt loam, scl = sandy clay loam, si = silt, c = clay, sic = silty clay, cl = clay loam, sicl = silty clay loam, sc = sandy clay, lvfs = loamy very fine sand, vfsl = very fine sandy loam, lfs = loamy fine sand, fsl = fine sandy loan, s = sand, ls = loamy sand, s1 = sandy loam. Table 7: Factor Levels for Characteristics Affecting Attenuation Potential of Soil Physical/Chemical Classes Factor Level Characteristics Texture of Surface 1, sil, scl, si 9
scl, 1, sil, cl, sicl (if clay 7 fraction is a shrinking or or aggregated type, subtract 3 points)
lvfs, vfsl, lfs, fsl 4 s, ls, sl, > 15 % wood 1 fragments > 3/4 in.
(below the A) 0.6 - 2.0 (moderate) 6
> 20.0 (very rapid) 1 Soil Drainage Class well drained 10 somewhat excessively 7 drained moderately well drained 4 somewhat poorly, poorly, 1 and very poorly drained;
and excessively drained Table 7a Ratings for Attenuation Potential of Soils Range of the -Sum of 6 Rating for Attenuation Verbal Rating Factor Ratings for Potential Characteristics in Table 8a.
5-10 10 Least Potential 11 - 15 9 Least Potential 16 - 20 8 Least Potential 21 - 25 7 Marginal 26-30 6 Marginal 31 - 34 5 Good 35 - 40 4 Good 41 - 44 3 Best 45 - 48 2 Best 49 - 53 _1 Best Concentrated Source Dispersed Source, Weight: 2 Weight: 5 STEP 8. DETERMINATION OF SITE INDEX NUMBER AHD POLLUTION POTENTIAL CATEGORY
A. After determining the 7 scores in Steps 1 through 7 above, add them up. The sum is the Site Index Number (SIN). The SIN can vary between 23 and 230 for Concentrated Sources, and between 27 and 270 for Dispersed Sources.
3. Use Table 8 to determine the Pollution Potential Category of the SIN. Table 8: Pollution Potential Categories of Site Index Numbers Source of Pollution Pollution Potential Category of 1 Site Index Numbers LOW MODERATE HIGH VERY HIGH Concentrated 23 - 63 64 - 136 137 - 138 189 - 230 Dispersed 27 - 65 66 - 158 159 - 223 229 - 270 Significance of Site Index Number (SIN): The larger the SIN, the greater the pollution potential of the ground water at the site. The number itself has no intrinsic value. Concentrated Source SINs can only be compared to other Concentrated Source SINs (and Dispersed Source SINs only with Dispersed Source SINs) ; Concentrated Source SINs cannot be compared to Dispersed Source SINs. Significance of Pollution Potential Category: The Pollution Potential Category provides a basis for ranking the relative magnitude of the SIN. It also provides a rationale for requesting a specialist if the site is not rejected. If the category is HIGH or VERY HIGH, or if the investigator is not confident in some of the values selected in the analysis, a specialist should be requested to provide detailed technical assistance. See “Discussion of Methodology” (p. 3), and “Limitations of System” (p. 7), for additional information. Table 9: Summary of Scare Ranges for Each Step CONC. WEIGHT DISP. WEIGHT SUMMERY OF OF SCORE RANGES FOR EACH FARAMETER LOW MODERATE HIGH V.HIGH STEP 1 DISTANCE 5 2 STEP 2 LAXO SLOPE 1 3 STEP 3 WATER DEPTH 5 5 STEP 4 ADOSE ZONE 5 4 STEP 5 AQUIFER 3 3 STEP 6 SOIL OEPTH 2 3 STEP 7 ATTENIATION 2 5 REFERENCES CITED 1. Aller, L., Bennett, T., Lehr, J. H., and Petty, R. J., May, 1987, DRASTIC: A standardized system for evaluating ground water pollution potential using hydrogeologic settings: U.S. Environmental Protection Agency, EPA/600/2-87/035, 455 pp.
2. Freeze, R. Alien, and Cherry, John A., 1979, Groundwater: Prentice-Hall, Inc., Englewood Cliffs, N.J., 604 pp.
3. LeGrand, Harry E., 1983, A standardized system for evaluating waste-disposal sites: 2nd. Ed., National Water Well Association, Worthington, OH, 49 pp.
4. Lehr, Jay H., Winter, 1982, How much ground water have we really polluted?: Ground Water Monitoring Review, Vol. 2, No. 1, pp. 4-5.
5. Solley, Wayne B., Chase, E. B.,. Mann. W. B.- IV, 1983, Estimated use of water in the United States in 1980: U. S. Geological Survey Circular 1001, 56 pp.
6. U.S. Department: of Agriculture, November 9, 1987, USDA Policy for Ground Water Quality: Departmental Regulation No. 95CO-8, Washington, D.C., 20250, 3 pp.
7. U.S. Environmental Protection Agency, USDI, November 10, 1987. ”EPA gives Congress status of Nation's Water Quality: Environmental News Release, Office of Public Affairs (A-107), Washington, D.C. 20460, 3 pp.
3. U.S. Geological Survey, USDI, 1985, National Water Summary-1984, Hydrologic Events, Selected Water Quality Trends, and Ground-Water Resources: Water-Supply Paper 2275, 468 pp.
9. Wisconsin Geological and Natural History Survey, September, 1985, Groundwater protection principles and alternatives for Rock County, Wisconsin: Special Report 8, 73 pp. WORKSHEET FOR STEP 7 -FACTOR LEVELS FOR CHARACTERISTICS AFFECTING ATTENUATION POTENTIAL OF SOIL- This worksheet must be filled out to obtain a value for STEP 7 on the Site Index Number Worksheet (p. 21). Select. factor levels from Table 7 (p. 17).
APPENDIX C RUNOFF FOR INCHES OF RAINFALL Tenths 0.0 0.1 0.2 1 0.32 C.39 .0.46 2 1.09 1.18 1.27 3 1.98 2.08 2.17 4 2.92 3.02 3.11 5 3.88 3.97 4.07 6 4.85 4.94 5.04 7 5.82 5.92 6.02 8 6.61 6.91 7.00 9 7.79 7.89 7.99 10 8.78 8.88 8.98 11 9.77 9.87 9.97 12 10.76 10.86 10.96 13 11.76 11.86 11.96 14 12.75 12.85 12.95 15 13.75 13.85 13.94 16 14.74 14.84 14.94 17 15.74 15.84 15.94 18 16.73 16.83 16.93 19 17.73 17.83 17.93 20 18.73 18.83 18.93 NOTE: Runoff value determined by equation 1002_81_81_81.9_APPCinline1.jpg REFERENCE: National Engineering Handbook, Section 4, HYDROLOGY RUNOFF FOR INCHES OF RAINFALL Tents 0.0 0.1 0.2 0 .00 0.04 1 0.71 0.80 0.90 2 1.67 1.77 1.87 3 2.66 2.76 2.86 4 3.65 3.75 3.85 5 4.65 4.75 4.85 6 5.64 5.74 5.84 7 6.64 6.74 6,84 8 7.64 7.74 7.84 9 8.64 8.74 8.84 10 9.64 9.74 9.84 11 10.64 10.74 10.84 12 11.64 11.74 11.84 13 12.64 12.74 12.84 14 13.64 13.74 13.84 15 14.64 14.74 144.84 16 15.64 15.74 15.83 17 16.63 16.73 16.83 18 17.63 17.73 17.83 19 16.63 18.73 18.83 20 19.63 19.73 19.83 Note: Runoff value determined by equation 1002_81_81_81.9_APPCinline2.jpg REFERENCE: National Engineering Handbook, Section 4, HYDROLOGY APPENDIX D Agriculture Waste Management Field Manual o.6 Nutrient uptake calculation Table 6-3 can be used to calculate the approximate nutrient uptake by agricultural crops. Typical crop yields are given only as default values and should be selected according to local information.
1. Select the crop or crops that are to be grown in the cropping sequence.
2. Determine the plant nutrient uptake as a percentage of dry weight from table 8-3.
3. Determine the crop yield in pounds per acre.
4. Multiple the crop yield by the percentage of nutrient contained in the crop. The solution is pounds per acre of nutrients removed in the harvested crop.
6.7 Nutrient uptake calculation example
Corn and alfalfa are grown in rotation and harvested as high moisture corn and forage. To calculate the nutrient uptake harvested in pounds per acre, follow the above steps.
1. Corn and alfalfa 2. From table 6-3:
3. Yields are taken from local data base:
4. Multiplying percent nutrients by dry matter yield:
Dry wt. Typical ------Average concentration of nutrients (percent) lbs/bu yield/acre N P plant pan Grain crops of the dry harvested material Barl 48 50 1.82 0.34 0.43 0.05 0.10 0.16 0.0 0.0 0.00 ey bu. 016 016 31
stra w Co 56 120 1.61 0.28 0.40 0.02 0.10 0.12 0.0 0.0 0.00 m bu. 007 011 18
5 T.
stra w Oil 22, 1.13 0.25 0.16 0.19 0.09 0.0 0.0 pal 000 043 225 m lbs.
6 T.
fron ds, ste 1.07 0.49 1.69 0.36 ms Pea 22- 2,8 3.60 0.17 0.50 0.04 0.12 0.24 0.0 0.0 nuts 30 00 008 040 lbs.
d 3 T. 4.48 0.43 3.37 1.47 0.06 0.68 0.0 0.0 stra 001 008 w Soy 60 35 6.25 0.64 1.90 0.29 0.29 0.17 0.0 0.0 0.00 bea bu. 017 021 17 ns 2 T. 235 032 1.04 1.00 0.45 025 0.0 0.01 0.00 stov 010 15 38 er Sun 25 1,1 3.57 1.71 1.11 0.18 0.34 0.17 0.0 flo 00 022 wer lbs.
Grapes 12 tons 0.28 0.10 Oranges 54,000 lbs. 0.002 0.02 Peaches 15 tons 0.12 0.03 Pineapple 17 tons 0.43 0.35 Silage crops % of the dry harvested material-- Alfalfa haylage (50% dm) 10 wet/5 dry 2.79 0.33 Com silage (35% dm) 20 wet/7 dry 1.10 0.25 Forage sorghum (30% 1.44 0.19 1.02 dm) 20 wet/6 dry Oat haylage (40% dm) 10 wet/4 dry 1.60 0.28 Sorghum-sudan (50% 10 wet/5 dry 1.36 0.16 dm)
Sugar crops %of the fresh harvested material Sugarcane 37 tons 0.16 0.04 Sugar beets 20 tons 0.20 0.03 tops 0.43 0.04 Tobacco % of the dry harvested material All types 2,100 lbs. 3.75 0.33 Turf grass % of the dry harvested material ----------------- Bluegrass 2tons 2.91 0.43 Bentgrass 23 tons 3.10 0.41 Bermudagrass 4 tons 1.88 0.19 Plant nutrient uptake by specified crop and removed in the harvested pan of the crop- Continued plant pan ble crops % of the fresh harvested material \ill\ppere 9 tons 0.40 0.12 \ill\dry 0.5 ton 3.13 0.45 \ill\ge 20 tons 0.33 0.04 \ill\ts 13 tons 0.19 0.04 \ill\va 7 tons 0.40 0.13 \ill\y 27 tons 0.17 0.09 \ill\mbers 10 tons 0.20 0.07 \ill\ace (heads) 14 tons 0.23 0.08 \ill\ons 18 tons 0.30 0.06 \ill\s 1.5 tons 3.5S 0.40 \ill\ 14.5 tons 0.33 0.05 \ill\bers 3 tons 0.88 0.26 \ill\corn 5.5 tons 0.89 0.24 \ill\potatoes 7 tons 0.30 C.04 \ill\ets 15 tons 0.26 0.04 \ill\ 22 tons 0.30 0.04 Wetland plants ----% of the dry harvested material---- Cattails 8 tons 1.02 0.18 Rushes 1 ton 1.67 Salt 1 1.44 0.27 0.62 gras ton s Sedges 0.8 ton 1.79 0.26 Water hyacinth 3.65 0.87 Duckweed 3.36 1.00 Arrowweed 2.74 Phragmites 1.83 0.10
651.67 References
Adam, R, R Lagace, and M. Vallieres, 1986. Evaluation of beef feedlot runoff treatment by a vegetative filter. ASAE paper 86-208, St.Joseph MI 49085-9659.
Bernstein, L. 1964. Salt tolerance of plants. U.S. Dep. Agric Inf. Bull 283,24 pp. \ill\ Production, mineral accumulation, and pigment concentration in Typha latifolia and Scirpus americanus_Ecology 5O:285-290.
Burns, J.C., P.W. Westerman, LD. King, G.A. Cummings, MR Overcash, and L. Goode 1985. Swine Lagoon effluent applied to coastal bermudagrass: L Forage yield, quality, and element removal J. Environ. Qual 14:9-14.
Dillaha T.A., J.H. Sherrard, D.Lee, S. Mostaghimi and V.O. Shanholtz 1989. Evaluation of vegetative filter strips as a best management practice for feed lots. Journal WPCF 6O:1231-1238. Doyle. R.C., and G.S. Stanton, 1977. Effectiveness of forest and grass buffer strips in improving the water quality of manure polluted runoff. ASAE paper 77-2501. St. Joseph, MI 49085. Firestone, M.K. 1982. Biological denitrifiction. In F.J. Stevenson (ed), Nitrogen in agricultural soils Agronomy 22:289-326.
Hanaway, J.J. 1962. Corn growth and composition in relation to soil fertility. II. Uptake of N, P,and K and their distribution in different plant parts during the growing season. Agron J. 64:217-222. Hensler, R.F, R.J. Olson, and O.J. Attoe, 1970. Effects of soil pH and application rates of dairy cattle manure on yield and recovery of twelve plant nutrients by corn Agron J. 62:828-830. Hornbeck, J.W., and W. Kropelin 1982. Nutrient removal and leaching from a whole-tree harvest of northern hardwoods. J. Environ. Qual. 11:309-316.
Jenny, H. 1941. Factors of soil formation pp. 224-225. McGraw-Hill Book Company, lnc New York. Kabata-Pendias, A, and H. Pendias, 1984. Trace elements in soils and plants CRC Press Boca Ratan, FL.
Keeney, D.R 1980. Prediction of soil nitrogen availability in forest ecosystem: A literature review. Forest Sci. 26:159-171.
Kilmer, V.J. I982. Handbook of soils and climate in agriculture pp. 225-226, 288-290. CRC Press, Boca Raton-FL.
Kirkham M.B. 1985. Agricultural use of phosphorus in sewage sludge. Adv. Agron 35:129-161. Klausner, S.D., and R.W. Guest. 1981. Influence of NH conversions from dairy cattle manure on the yield of corn. Agron. J. 73:720-723.
Lowrance, R.R. Leonard, and J. Sheridan, 1985. Managing riparian ecosystems to control nonpoint pollution. J. Soll and Water Cons. 40L:87-91.
Martin J.H, and W.H. Leonard 1949. Principles of field crop production. Macmillan Company, New York Morrison F.B. 1959. Feeds and feeding. Morrison Publishing Company. Clinton IA. Sanchez P.A. 1976. Properties and management of soils in the tropics. pp-200-203. John Wiley & Sons, New York.
Sawyer, J.E, and R.G. Hoeft, 1990. Greenhouse evaluation of simulated injected Liquid beef manure. Agron J. 82:613-618.
Schertz, D.L, and D.A Miller, 1972. Nitrate-N accumulation in the soil profile under alfalfa. Agron J. 64:660-664.
Schuman, B.A and L.F. Elliott 1978. Cropping an abandoned feedlot to prevent deep percolation of nitrate nitrogen. Science 126(4)237-243.
\ill\schwer, C.B. and J.C Clausen 1989. Vegetative Filter treatment of dairy milkhouse wastewater. J. Environ, Qual, 18:446-451.
\ill\mpson K 1986. Fertilizers and manures p. 85. Longman Group Limited, London and New York. \ill\ewart B.A 1974. Selected materials relating to role of plants in waste management. USDA Southwest Great Plains Research Center, Bushland, TX.
\ill\utton, A.L, D.W. Nelson, J.D. Hoff, and V.B Mayrose. 1982. Effects of injection and surface application of liquid swine manure on crop yield and soil composition. J. Environ Qual 11:468-472. Tisdale, S.L, W.L Nelson, and J.D. Beaton. 1985. Soil fertility and fertilizers. Macmillan, New York. United States Department of Agriculture, Agricultural Research Service. 1985. The impact of wetlands on the movement of water and nonpoint pollutants from agricultura! watersheds. ARS Water Quality and Watershed Research laboratory. Durant, OK.
United States Department of Agriculture, Agricultural Research Service 1986. Utilization of sewage sludge compost as a soil conditioner and fertilizer for plant growth. AIB 464, U.S. Govt Printing Office, Washington, DC.
United States Environmental Protection Agency. 1983. Land application of municipal sludge process design manual. MunicipaI Environmental Research Laboratory, Cincinnati, OH. U.S Govt Printing Office, Washington, DC.
United States Environmental Protection Agency. 1979. Animal waste utilization on cropland and pastureland. EPA-600/2-79-059. U.S. Govt Printing Office, Washington, DC. Walsh, L.M, and J.D. Beaton 1973. Soil testing and plant analysis. Soil Sci. Soc. Amer \ill\ Wild, A 1988. Russell's soil conditions and plant growth. Longman Scientific & Technical John Wiley & Sons, Inc, New York.
Young, R.A, T. Huntrods, and W. Anderson, 1980. Effectiveness of vegetated buffer strips in controlling pollution from feedlot runoff. J. Environ. Qual. 9:483-487. APPENDIX E Often receive rates of manure far in excess of maximum-yield requirements. These excessive applications, in some cases, result in an accumuation of nutrients approaching toxic levels and he leaching of nitrate into the groundwater. Manure management is a major problem that faces agriculture. The estimated annual manure production by various types of animals is presented in Table 1. Manure Composition The nutrient composition of farm manure varies widely even for the same species of animal. In the past, animal wastes were considered to be largely solids. Disposal was a problem because it required handling a large tonnage of low-analysis material. Today, an increasing amount of the waste is a fluid and the analysis is even lower because of the higher water content. The approximate fertilizer value for various manure handling systems is listed in Tables 2 and 3. These values are not absolute but serve as an aid indicating the amounts of plant nutrients that may be present. Animal wastes should be analyzed prior to land application if reliable local data are not available.
Moisture Content Manure contains 10 percent to 80 percent water, depending whether the material is stockpiled or taken directly from the feedlot. A simple method to determine water content is to weigh wet manure and then spread it on a sheet of plastic to air dry. When it dries, weigh it again and calculate its former moisture percentage as follows:
Table 1: Annual manure production by various animals (wet weight). Raw manure production per Animal 1,000 pounds animal weight ___________________to gal/yr ns/yr Dairy cow 15.0 3.614 Beef feeder 11.0 2.738 Beef cow 11.5 2.884 Swine feeder 18.0 4.380 Swine breeding herd 6.5 1.533 Sheep 7.5 1.679 Poultry layer 10.0 2.336 Poultry broiler 13.0 3.139 Turkey 11.0 2.592 Horse 8.5 2.044 NOTE: Raw manure includes feces and urine. The wet weight of animal manures ranges between 8 and 9 pounds per gallon.
SOURCE: Vitosh. et al., 1988.
Table 2: Composition of various solid manures.
Source of Mature Bedding or litter Dry matter Ammonium N % - lb/ton raw waste- Swine No 18 6 Yes 18 5 Beef No 52 7 Yes 50 8 Dairy No 18 4 Yes 21 5 Sheep No 28 5 Yes 28 5 Poultry No 45 26 Yes 75 36 Turkey No 22 17 Yes 29 13 Horse Yes 46 4 NOTE: The nutrient value of manure varies with different feed and management systems. For the actual nutrient value of manure on your farm an analysis is necessary. SOURCE: Vitosh. et at, 1988.
Table 3: Composition of various liquid manures.
SOURCE: Vitosh. et. al.1988 81.15 STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY, AND PURPOSE (1992 Confined Animal Feeding Operation Control Regulation Revisions)
The provisions of sections 25-8-202(7), 25-8-205, 25-8-206, and 25-8-308, C.R.S. 1973, as amended provide the specific statutory authority for adoption of this regulation. The Commission also adopted, in accordance with section 24-4-103(4), C.R.S. the following Statement of Basis and Purpose. Overview The original Feedlot Control Regulation, 5 C.C.R. 1002-5 et. seq. was adopted by the Commission in 1974. The format of the regulation was changed in 1976 and there have been no further changes to it since then. Several recent developments have indicated the need for the Commission to modify the regulation both in terms of substance and format. Such developments include the establishment of the Basic Standards for Groundwater and the adoption of the groundwater discharge amendments to the Permit Regulations.
A strict interpretation of the previously adopted Feedlot Control Regulation would indicate that discharges of process wastewater from any operation that meets the definition of a feedlot are prohibited That definition encompasses a wide variety of operations of all sizes. The Commission has determined that it is desirable to improve the focus of the regulation upon water quality in terms of protecting beneficial uses and insuring applicable standards are not violated, while maintaining consistency with federal regulations. Therefore the regulation presently being adopted addresses two different categories of confined animal feeding operations: concentrated animal feeding operations and other animal feeding operations. Purpose of the Regulation Based upon the information received into the record during this rulemaking hearing, the Commission has determined that the purposes of this control regulation are to prevent the discharge of manure; or process wastewater from concentrated animal feeding operations into waters of the state and to encourage that these materials be retained and utilized beneficially on agricultural land. The Commission recognizes that livestock produce manure and process wastewater which when properly used, supply nutrients and organic matter to soils. The mere presence of livestock manure and process wastewater in a given location does not denote pollution, but may, when improperly stored, transported or disposed of, create adverse impacts upon public health and the environment. A primary concern of the Commission is to ensure that manure and process wastewater associated with confined animal feeding operations is handled in a manner which does not cause exceedances of applicable standards or harm to existing or classified uses of state waters. While the Commission has drawn a distinction between the regulatory requirements pertaining to concentrated animal feeding operations and other animal feeding operations, it intends that the latter types of operations nevertheless protect surface water, ground water and soil resources, through proper application of “best management practices“ based upon existing physical conditions and constraints at the facility site.
The Commission, in adopting this regulation does not intend to address public health nuisance conditions or land use controls such as zoning requirements or policies. Concentrated Animal Feeding Operations The Commission has defined concentrated animal feeding operations as those facilities with a larger capacity or which are located in areas where the potential adverse impacts associated with a discharge are particularly severe. For these facilities, the adopted rule establishes specific manure and process wastewater retention and disposal requirements which focus on proper design, construction and operation as the primary means to prevent discharges of pollutants into surface and ground waters. Concentrated animal feeding operations are confined operations that fall under one of three specific criteria. The first criterion is based on the number and type of animals confined. The second criterion is a case-by-case designation based on certain discharges to surface waters. The last criterion is based on the facility's location in a hydrologically sensitive area. In the noticed proposal, these sensitive areas were described as sensitive environmental areas. The rule adopted by the Commission renames these areas to more accurately reflect the types of potential impacts the regulation addresses (i.e., water quality and human health impacts).
The Commission finds that prevention of process wastewater and manure discharges is particularly important when such discharges may impact areas of significant groundwater recharge, waters which are currently used for drinking water purposes or which could be used for drinking water purposes in the future, and waters subject to antidegradation review. Therefore, operations located within these hydrologically sensitive areas are considered to be concentrated animal feeding operations. Some parties have expressed concern with the inclusion of facilities in the Concentrated Animal Feeding Operation category, based on their potential impacts on reasonably likely future drinking water supplies. It is the Commission's intent, through this regulation, to protect classified as well as existing but unclassified drinking water uses from the potential impacts of animal feeding operations. In addition, the Commission intends this regulation to preserve existing drinking water supplies which are not currently used but which may be used for public consumption in the future. For that reason, the rule adopted by the Commission includes within the definition of hydrologically sensitive areas, areas where contamination from animal feeding operations could impact reasonably likely future public drinking water system withdrawals. In order to determine whether these future withdrawals are reasonably likely, the Division must take into account the background quality as well as the decreed or permitted use of the water. A definition of public drinking water systems, consistent with the definition found in the state's safe drinking water regulations, is adopted by the Commission as part of this regulation. Animal Feeding Operations For those confined animal feeding operations not included in the concentrated animal feeding operations category the Commission has prescribed best management practices (BMPs) which are aimed at reducing the water quality impacts from these operations. The BMPs provide guidance to the small operations for solids removal, runoff and process water reduction and groundwater protection. The goal of these requirements is the same as that for concentrated animal feeding operations-i.e., preventing discharge of pollutants to ground and surface water. However, considering the lesser likelihood of adverse impacts from these facilities, and the goal of economic reasonableness, the Commission has determined that the establishment of BMPs is the most appropriate control mechanism for these facilities at this time. Surface and Ground Water Protection Requirements for Concentrated Animal Feeding Operations The adopted rule preserves the general performance, design, and operation requirements for the protection of surface waters established in the feedlot regulation which it amends. Facilities are required to operate as no-discharge operations by designing and constructing structures to retain contaminated storm and wastewater within an applicable storm event. The adopted rule adds specificity to these requirements.
While the existing feedlot regulation requires no discharge to state waters, including groundwater, from confined animal feeding operations, it provides no direction regarding what is expected from a facility in order to achieve the no discharge to groundwater requirement. The amendment adopted by the Commission fills that void by specifying design and construction requirements for manure and process wastewater retention and conveyance structures. The Commission recognizes that existing facilities may find it difficult to demonstrate that retention structures which have been constructed prior to the effective date of this rule are in compliance with these specific design and construction requirements. It is not the Commission's intent in adopting this rule to cause operators to be automatically in noncompliance. For this reason, the adopted rule does not require operators to demonstrate that manure and process wastewater retention structures in existence at the time the rule becomes effective meet design and construction requirements. If, however, the Division determines that seepage at a rate greater than allowed is occurring, the operator may be required to redesign and reconstruct existing structures in order to meet the seepage rates required.
The evidence presented at the hearing indicates that process-generated wastewater from animal feeding operations may contain levels of nitrates and other pollutants equivalent to those contained in domestic wastewater treatment facilities. The Commission finds that, in order to comply with the no discharge requirement, structures which retain process-generated wastewater, whether in combination with stormwater or not, must be lined so as not to exceed a seepage rate of 1/32" per day. This approach is consistent with the approach adopted by the Commission in the groundwater amendments to the Regulations for the State Discharge Permit System, (5 CCR 1002-2, Section 6.10). The Commission recognizes that structures which retain runoff from open animal feeding operations for a short term, which runoff is not combined with process-generated wastewater, do not pose the same potential impacts to groundwater as full-time process-generated wastewater retention structures. The runoff retained in the former type of structures comes into contact with manure or raw, intermediate, or final products of operation and is, therefore, process wastewater. However, given the dilute nature of the waste retained and the short retention time allowed (i.e., they must kept in a dewatered status as defined in subsection 4(B)), these structures are subject to a more lenient maximum seepage rate requirement. The rule adopted by the Commission requires that these structures be designed, constructed, and maintained, so as not to exceed a seepage rate of 1/4" per day. The Commission also understands that these runoff retention structures often retain, in addition to runoff sources of process wastewater, raw water, such as boiler cooling water and flow-through livestock drinking water. These raw water sources are isolated from areas where manure or raw, intermediate or final products are found. Therefore, while not considered process wastewaters while diverted, they become process wastewaters when commingled with the runoff contained in the retention structures. Structures which retain commingled process wastewater runoff and these raw water sources are subject to the 1/4" per day maximum seepage rate requirement.
Beneficial Use and Disposal of Manure and Process Wastewater Two primary means of disposal of manure and process wastewater are addressed in the adopted rule: land application and treatment and discharge. Innovative methods of disposal are encouraged and require the Division's approval. Treatment and discharge of manure and process wastewater into state waters requires a CDPS permit.
The Commission recognizes that proper land application of manure and process wastewater from animal feeding operations may be quite beneficial to agricultural land. The Commission also recognizes, however, that improper land application or land application at a rate greater than that which plants can utilize, may result in adverse impacts to the state's waters. In order to ensure that the maximum benefits of land application are obtained, without impacting the quality of ground and surface waters, the rule adopted specifies land application practices requirements and a tiered approach to maximum land application rates to be allowed.
The adopted rule specifies three alternative methods of calculation of appropriate land application rates. The first two methods contemplate the use of manure and/or process wastewater to supply pant nutrients. Accordingly, land application rates under either method is limited to the amount of nutrients which are plant available at any given time. The first method contemplates a text-book approach to rate calculation, based on a number of preestablished conditions. Because they are preestablished, these conditions are conservative and may result in application rates which are more restrictive than necessary to ensure that all nutrients are plant available at any given site. Operators who want to avoid the cost of site-specific conditions analysis may use this first method, provided that commercial fertilizers are not used in addition to manure and or process wastewater at the land application site. Operators who want to land apply at a rate that takes into account site-specific conditions may do so after performing site-specific agronomic analyses as specified under the second method provided in the adopted rule. The Commission finds that all the elements specified under the second method are necessary to derive an appropriate site-specific application rate. Operators who rely on either method need not obtain the Division's prior approval, but an operator relying on the second method must keep copies of all agronomic analyses and make them available for inspection.
The second method of calculating manure and/or process wastewater application rates requires an agronomic analysis comparable to that which is performed by farmers and ranchers in order to determine appropriate levels of nutrients which must be added to growing crops in a given growing season. This analysis requires a determination of the residual nutrient content of the soil in order to determine the amount of nutrients that can be added through land application or any other nutrient sources, including commercial fertilizers, in order to supply the necessary crop requirements. An operator who utilizes this method may also rely on commonly accepted mineralization rates, i.e., the rates at which organic nitrogen in manure and process wastewater converts to inorganic forms, such as nitrates, which are available to plants, but which pose a risk of ground water contamination. The third land application rate calculation method provided in the adopted rule contemplates not only the supply of plant nutrients, but also the disposal of excess manure and process wastewater beyond that which is available for plant uptake. For example, other potential mechanisms for nutrient losses, such as volatilization and denitrification, may be considered. The Commission finds that the combination of plant uptake and land treatment techniques could be an adequate method to remove pollutants in the context of concentrated animal feeding operations. The Commission also finds, however, that reliance on the third method of land application rates calculation poses a significantly increased risk of adverse impacts to state waters. Therefore, an operator who wishes to land apply manure and/or process wastewater at rates allowed under the third calculation method must incur the expense of comprehensive studies and, if deemed necessary by the Division, of monitoring, to ensure that applicable water quality standards and protection levels are not exceeded. In addition, operators relying on the third rate calculation method must obtain interim and/or final approval from the Division prior to land application. Operators who choose to exceed the rates of application allowed under the second method of calculating application rates must perform a comprehensive analyses required under Section 5(A)(5)(c). Operators who land apply manure and/or process wastewater on a “continuous or near continuous basis” must also comply with those provisions. The phrase “on a continuous or near continuous basis” is designed to include those facilities which, due to their size and intensity, land apply waste on a regular, year-round basis, rather than on a seasonal or sporadic basis utilized in more common farming operations. Manure and Process Wastewater Management Plans The Commission intends this regulation, including the amendment hereby adopted, to be a self- implementing control regulation which requires no permit as a condition for operation of a confined animal feeding facility, whether concentrated or not The Commission finds, however, that planning is necessary in order to ensure that concentrated animal feeding facilities meet the regulation's requirements. Such planning is necessary whenever an improvement to an existing facility or the construction of a new facility will take place. Planning is also crucial when an existing facility is not performing in accordance with the no discharge parameters established in the regulation, and may be in need of improvement. The Commission further finds that in order to better monitor compliance with this self-implementing regulation, and in order to be more responsive to public inquiries, the Division needs to be informed of the existence and operation of concentrated animal feeding operations. Therefore, the adopted rule requires new, reactivated, reconstructed, and expanded concentrated animal feeding operations, as well as existing operations which are in significant noncompliance, to submit to the Division a Manure and Process Wastewater Management Plan.
Such plan need not be approved by the Division unless it includes the land application plan which may be required pursuant to section 5. If a land application plan is included, only the land application plan must be approved. However, the Division will review the plan submitted and may provide comments to the operator within 45 days of receipt. The Commission does not intend the Division's comments to be binding on the operator, nor does the Commission intend the Division's comments or lack thereof to be relied upon as an approval or a denial of the matters addressed in the plan. The Commission finds, however, that the Division's input early in the planning process may help to prevent noncompliance after construction has taken place.
Monitoring The Commission, in its notice for this rulemaking hearing, specifically requested input from the public regarding the need for water quality monitoring at concentrated animal feeding operations. There was a great deal of concern expressed by the regulated community about the possible imposition of monitoring requirements on top of the mandatory management practices set forth in this regulation. Some parties expressed the view that monitoring is appropriate and should be required by the Division. The Commission recognizes that this regulation consists, for the most part, of stringent technology-based requirements aimed at achieving no discharge of manure and process wastewater to waters; of the state. Where these are complied with, further monitoring is not required. The Commission feels, however, that there are circumstances where the potential risk to beneficial uses of state waters, as reflected, for example, by potential violations of water quality standards and numerical protection levels, posed by a concentrated animal feeding operation may warrant monitoring. Such circumstances and some of the factors which must be considered prior to requiring a facility to monitor are outlined in the adopted rule. Because there is a potentially significant cost associated with groundwater monitoring, the Commission has decided that it should be involved in each decision to require monitoring from a concentrated animal feeding operation, except as provided in subsection 5(A)(5)(c) of the regulation. Therefore, except as provided in subsection 5(A)(5)(c), the Division will be required to bring cases to the Commission where it feels monitoring is needed. Then, upon the request of the Commission, the Division may require monitoring to be conducted by an operator.
An exception to the stringent no discharge requirements set forth in this regulation is the manure and process wastewater land application rate allowed under subsection 5(A)(5)(c). Given the potential risk of groundwater contamination associated with such practices, the Commission has determined that monitoring may be required directly by the Division when such practices are proposed by the operator. Statutory Considerations In adopting this amendment the Commission has considered several additional statutory provisions beyond the authorities underlying this regulation. Section 25-3-205(5) restricts the Commission from adopting control regulations which require agricultural “nonpoint source dischargers” to utilize treatment techniques which require additional consumptive or evaporative use which would cause material injury to water rights. This section also provides that control regulations related to agricultural practices shall be promulgated only if incentive, grant and cooperative programs are determined by the Commission to be inadequate and such regulations are necessary to meet state law or the federal act The Commission has determined, that discharges from Confined Animal Feeding Operations are point sources under federal and state law. Moreover, no grant or incentive programs are currently in place to address the water quality impacts which may be associated with confined animal feeding operations. The Commission heard testimony from the Colorado Cattle Feeders Association, to the effect that efforts are under way to develop a program which would offer technical assistance to its membership. The Commission feels that while such program, if developed may proved to be of valuable assistance to the Division in furtherance of the purposes of the amended regulation, such program alone would be inadequate to achieve the regulation's purposes. Given the limited scope of the program and the nature of the regulation and sources affected, the Commission has determined that the self-implementing regulations, as adopted, is the appropriate means to address potential impacts from confined animal feeding operations. Section 25-8-504(2) restricts the Division from issuing a permit for animal or agricultural waste on farms and ranches except as may be required by the federal act or regulations. The Commission has chosen to regulate the discharge of process wastewater and manure through a control regulation which is “self implementing” rather than through a permit mechanism. The Commission has not made any findings with respect to the question of whether the discharges of pollutants associated with confined animal feeding operations may be subject to permitting requirements.
Section 25-8-202(8) provides that the Commission may promulgate rules more stringent than corresponding enforceable federal requirements only if based on sound scientific evidence in the record and the Commission determines that such rules are necessary to protect the public health, beneficial use of water, or the environment of the state. The Commission recognizes that certain elements of this regulation go beyond corresponding enforceable federal requirements. For example, the class of facilities which belong to the concentrated animal feeding operation category under this regulation is somewhat broader than would meet the federal criteria for determining a concentrated animal feeding operation. Evidence in the record demonstrates that significant quantities of nitrogenous wastes and oxygen demanding wastes are potentially associated with animal feeding operations which are smaller than 1,000 animal units. Unless proper measures such as best management practices are implemented, these operations may have significant impacts on the quality of ground waters. These potential impacts to the state's groundwater are not addressed by the federal regulations; therefore, there are no corresponding enforceable federal requirements with respect to ground water. The Commission has included facilities located in significant groundwater recharge areas, or where drinking water withdrawals are currently taking place, or where public drinking water system withdrawals are reasonably likely, within the definition of concentrated animal feeding operations, in order to provide such protection. The Commission adopted requirements affecting animal feeding operations which do not meet the definition of concentrated animal feeding operations. While these requirements also go beyond corresponding enforceable federal requirements for surface water protection, the Commission was persuaded by the written and oral testimony which indicated that given the runoff associated with thunderstorms and large snowmelt events which occur in Colorado and the significant quantities of nitrogen compounds and biochemical oxygen demanding compounds which can accumulate at animal feeding operations, even small facilities should be controlled with accepted best management practices. Given the tendency of most streams in the state to exhibit extremely low flows from late summer to early spring each year, the Commission determined that the mandatory application of best management practices was necessary to protect the beneficial uses of state waters from runoff containing animal wastes. The Commission was also concerned with the need to prevent groundwater pollution, especially where existing or reasonably likely withdrawals for drinking water may occur. As indicated above, there are no corresponding enforceable federal ground water requirements.
81.16 STATEMENT OF BASIS SPECIFIC STATUTORY AUTHORITY AND PURPOSE: JULY, 1997
81.17 FINDINGS REGARDING BASIS FOR EMERGENCY RULE AMENDMENTS ADOPTED ON
81.18 STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE: FEBRUARY,
These changes add incorporation by reference language to assure compliance with the requirements of the State Administrative Procedure Act, 24-4-103(12.5) C.R.S.
81.19 FINDINGS REGARDING BASIS FOR EMERGENCY RULE FOR AMENDMENTS ADOPTED ON
14. In order to provide continuous regulatory coverage so that the implementation can begin promptly, an emergency rule is necessary to cover the period until April 30, 1999. Accordingly, the Commission finds that immediate adoption of the temporary rule is imperatively necessary in order to comply with the mandates and deadlines of Amendment 14. Adoption of the permanent rule implementing Amendment 14 complied with the requirements of section 24-4-103, C.R.S. (1998). The permanent and temporary rules are substantively identical. The Commission therefore further concludes that compliance with the provisions of section 24-4-103, C.R.S. (1998) in adoption of a rule for the period March 30, 1999 to April 30, 1999 would be contrary to the public interest. The Commission designates the effective period for this emergency rule as March 30, 1999 through April 30, 1999.
81.20 STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE: MARCH, 1999
BASIS AND PURPOSE:
Amendment 14, approved by the Colorado voters on November 3, 1998, adds a new section 25-8-501.1 to the Colorado Water Quality Control Act. These provisions establish a new requirement that an individual discharge permit be obtained by any person who operates, constructs, or expands a “housed commercial swine feeding operation.” In this rulemaking hearing, the Commission adopted revisions to the Colorado Discharge Permit System Regulations to implement these new requirements. Regulation #61 (5 CCR1002-61). addition, corresponding revisions were adopted for the Confined Animal Feeding Operations Control Regulation, Regulation #81 (5 CCR 1002-81) to avoid regulatory overlap. In particular, the Commission has added a new section 81.9 to this regulation, to clarify that housed commercial swine feeding operations that obtain a permit under new section 61.13 of the discharge permit regulations are excluded from coverage under this control regulation.
81.21 STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE: AUGUST, 2002 RULEMAKING The provisions of sections 25-8-202(1)(c) and (2), 25-8-205, 25-8-401, 25-8-501.1, and 25-8-504, C.R.S. provide the specific statutory authority for the amendments to this regulation adopted by the Commission. The Commission has also adopted, in compliance with section 24-4-103(4), C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE:
The provisions of sections 25-8-202(1)(c) and (2), 25-8-205, 25-8-401, 25-8-501.1, and 25-8-504, C.R.S. provide the specific statutory authority for the amendments to this regulation adopted by the Commission. The Commission has also adopted, in compliance with section 24-4-103(4), C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE:
Federal regulation 40 CFR 123.26 requires states that have been designated to administer federal regulations to adopt regulations that are at least as stringent as the corresponding federal regulations. Colorado has administered the federal Concentrated Animal Feeding Operations (CAFOs) under Regulation #81 since 1974. However, certain provisions of Regulation #81 are not as stringent us the federal CAFO regulations. The existence of these provisions has resulted in confusion among CAFO operators regarding what regulatory standards should be followed. In addition, some CAFOs may be in compliance with the state regulation but not with the federal regulations, which are still fully enforceable. The Commission has determined that it is appropriate to modify the regulation by making certain provisions of the regulation equivalent to the federal CAFO regulatory requirements. Therefore, the regulation presently being adopted includes revisions to four (4) different sections. Section 81.2(2) was revised to reflect animal unit equivalency factors for animal species that are as stringent as those reflected in the federal regulations.
Sections 81.3(B) and 81.3(C)(2) were revised to reflect the federal requirement that all CAFO facilities be designed, constructed, and operated to contain all process generated wastewaters plus the runoff from a 25-year, 24-hour rainfall event for the location of the CAFO. Section 81.3(C)(5) was modified to delete Section 81.3(C)(5)(1) since it was inconsistent with this federal requirement. The effect of the revisions to Sections 81.3(6), 81.3(C)(2), and 81.3(C)(5)(1) is that the regulation now consistently indicates that CAFOs can only discharge as the result of receiving within a 24-hour period rainfall that is in excess of a 25-year, 24-hour rainfall event. In contrast, CAFOs that do not have sufficient storage capacity in their retention structures to retain all process wastewater plus the runoff resulting from any series of rainfall events occurring over a short period of time (days or weeks) (also known as chronic storm events) cannot discharge as the result of such a series of events unless covered as point sources under a discharge permit, per Section 61.3 of the Colorado Discharge Permit System regulations.