Wisconsin Administrative Code
Department of Natural Resources
NR 200-299 - Environmental Protection - Wisconsin Pollutant Discharge Elimination System
Chapter NR 204 - Domestic sewage sludge management
Section NR 204.07 - Land application of sludge

Universal Citation: WI Admin Code ยง NR 204.07

Current through August 26, 2024

(1) GENERAL. No person may land apply sludge in a manner which does not comply with the requirements of a WPDES permit and this chapter.

(2) APPROVED SITES. The permittee shall obtain written or computer generated approval from the department for each site on which sludge is applied in bulk prior to land application, unless the permittee is authorized to inspect and approve their own sites under s. NR 204.06(6). The department shall review and issue either approval, conditional approval or denial within 60 business days following receipt of the site's complete application, unless weather conditions preclude adequate site evaluation. Each site shall be reviewed based on information contained in the report required by s. NR 204.06(6). Failure to comply with the conditions of the site approval may result in the revocation of the approval and be considered a violation of the permit. Reapproval shall be contingent on submittal of an operations report for the site which shall specify how further violations will be avoided. When a permittee contracts with another party to land apply sludge and the land applier is not required to hold its own WPDES permit under s. NR 204.05, the permittee maintains responsibility, as well as the land applier, for compliance with the WPDES permit and this chapter. The permittee shall supply the land applier with all information necessary to ensure compliance. The land applier shall also make reasonable attempts to obtain all information needed to ensure compliance with this chapter.

(3) OPERATIONAL AND SITE OR FIELD REQUIREMENTS.

(a) Bulk sludge may not be applied to the land if it is likely to adversely affect a threatened or endangered species or its designated critical habitat, or a designated historical site.

(b) Bulk sludge may only be applied to sites that meet the requirements in Table B. Other sites, as specified in s. NR 204.09, may be approved by the department in writing on a case-by-case basis.

(c) Bulk sludge may not be applied to soils with a high groundwater level or bedrock at a depth of less than 3 feet. Exceptions may be granted by the department on a case-by-case basis. Parameters which may be considered for exceptions include: demonstration that the soil has an available water holding capacity that is greater than 5 inches, above the high groundwater level or bedrock; whether the high groundwater is a seasonal condition; depth of saturation at the proposed time of application to determine whether a seasonal use approval may be granted and other relevant site specific conditions.

(d) Bulk sludge may not be applied on sites with soils which have a rapid permeability of greater than 6 inches per hour unless, through consideration of the sludge characteristics, loading rate, cropping practices and other soil characteristics, department approval is obtained.

(e) The pH of the soil shall be 5.5 or greater at the time the bulk sludge is applied, unless after consideration of the sludge quality, cropping practices and soil characteristics of the site, the department determines that the pH should be higher to protect the environment or public health.

(f) If the soil at a site or field is classified as highly erodible on the United States department of agriculture's county by county soil conservation service soil survey, the department may impose additional management practices, such as soil conservation practices, to minimize erosion from the site.

(g) Class B sludge, as specified in sub. (6) (b), that is land applied to sites shall have restricted public access for a period of 30 days for low exposure sites such as a farm field, and one year for high exposure sites such as a city park, following sludge application. Access may be restricted by the location of the site on private property, fencing or posting the application site, or other department approved methods that minimize human contact with the sludge.

(h) Bulk sludge shall be applied in a manner to minimize soil compaction, to prevent surface runoff and to control objectionable odors. Sludge may not be applied on saturated soils, during significant rainfall events or in areas with ponded water or to areas which are subject to ponding.

(i) Bulk sludge land application vehicles or equipment shall be moving at all times while sludge is being applied to ensure uniform application. Uniform application shall be accomplished for surface application vehicles by the use of a splash plate, spreader bar, beaters, expellers or other department approved methods.

(j) Bulk sludge transporting vehicles and equipment may not leak sludge during use, transport, operation or storage. Vehicles utilized for the land application of liquid sludge shall have cab actuated discharge valves.

(k) Sludge which has a PCB concentration greater than 50 mg/kg (dry weight) may not be applied unless a management plan is approved by the U.S. EPA region V administrator pursuant to 40 CFR 761.60(a) (5) (iii). Sludge with a PCB concentration greater than 10 mg/kg (dry weight) shall be injected or incorporated into the soil.

(l) Application of bulk sludge, by any person, on frozen or snow covered ground is prohibited unless it is demonstrated, to the satisfaction of the department, that there are no other reasonable disposal methods available and there is absolutely no likelihood that the sludge will enter the waters of the state, or except as provided in par. (m).

(m) Application of bulk sludge on frozen or snow covered soils may be approved by the department on a case-by-case basis until storage is available, as required in s. NR 204.10. Department approvals for application on frozen or snow covered soils shall require the following restrictions at a minimum:
1. Sites or fields used shall have slopes less than or equal to 2%.

2. An application rate of less than 10,000 gal/acre.

3. Application is not allowed within 750 feet of any surface water, wetland or floodplain.

(n) When a WPDES permit requires testing for radium-226 and the sludge is subsequently found to contain radium-226, the land application of the sludge shall be terminated when the soil level of radium-226 equals or exceeds 2 picocuries per gram of soil on a dry weight basis in the top 12 inches of soil. In addition to other criteria in this section, the following conditions shall be adhered to when land applying sludge containing radium-226:
1. The soil pH shall be at least 6.0 prior to the application of sludge containing radium-226. This pH shall be maintained during the period the site is used for the land application of sludge containing radium-226.

2. The soil shall have at minimum a 6 inch layer with a clay content of at least 18% within the top 5 feet of the soil profile and be above the seasonal high groundwater level and bedrock. This determination shall be based primarily on the detailed county soil survey books.

3. The soil shall have at minimum a 6 inch layer with an organic matter content of at least 12 tons/acre within the top 5 feet of soil and be above seasonal high groundwater or bedrock. This determination shall be based primarily on the on-site soil test.

4. The department may on a case-by-case basis conditionally approve fields that do not meet all criteria established in subds. 1. to 3., where evaluation of sludge characteristics, soil features and management practices indicate no adverse impacts to the environment or public health would result.

5. Sludge containing radium-226 may not be applied to fields used for the production of tobacco.

6. Application of radium-226 sludge shall be terminated when the calculated site loading reaches 1640 microcuries per acre. To continue site use, the permittee shall sample soils according to a plan approved by department, and show that soil radium-226 activity is below 2 pCi/g in the top foot of soil.

Note: 1 microcurie = 10-6 curies, 1 picocurie = 10-12 curies

7. If plant tissue sampling for radium-226 is required by the department in the permit, it shall be done in accordance with a department approved method. The number of plant tissue samples obtained shall be identical to the number of subsamples needed to constitute a composite soil sample and shall yield a wet weight of approximately 4 pounds. The entire above ground plant shall be obtained as near as possible to the soil subsample site. Plant samples shall then be segregated between the above ground tissue, such as stems, stalks, petioles or leaves, and the "edible" portion, such as fruit, grain or seed.

(o) Table B site restrictions apply to all sludges that are applied to land in bulk unless prior department approval has been received. The distances stated in Table B are minimums. Table C applies to all bulk sludge designated as Class B with respect to pathogens that is applied to land. The intervals of time listed in Table C refer to the time period between the sludge application and harvesting. The permittee or land applier shall supply the farmer with the information in Table C, in a timely manner, to ensure compliance with these requirements.

Table B

Sludge Applied to the Land in Bulk

Site Criteria

Surface

Incorporation

Injection

Depth to bedrock

3 ft.

3 ft.

3 ft.

Depth to high groundwater

3 ft.

3 ft.

3 ft.

Allowable slopes

0-6%

0-12%

0-12%

Distance to wells

-Community water supply or school

1000 ft.

1000 ft.

1000 ft.

-Other*

250 ft.

250 ft.*

250 ft.*

Minimum distance to residence, business or recreation area

500 ft.

200 ft.

200 ft.

Minimum distance to residence or business w/permission

250 ft.

100 ft.

100 ft.

Distance to rural schools and health care facilities

1000 ft.

1000 ft.

500 ft.

Distance to property line

50 ft.**

25 ft.**

25 ft.**

Minimum distance to streams, lakes, ponds, wetlands or channelized waterways connected to a stream, lake, pond or wetland.

-Slope 0 to < 6

200 ft.

150 ft.

100 ft.

-Slope 6 to <12

Not allowed

200 ft.

150 ft.

Minimum distance to grass waterways, or dry run with a 50 foot range grass strip. ***

-Slope 0 to <6

100 ft.

50 ft.

25 ft.

-Slope 6 to <12

Not allowed

100 ft.

50 ft.

Soil permeability range (in/hr)

0.2-6.0

0-6.0

0-6.0

* Separation distances to non-potable wells used for irrigation or monitoring may be reduced to 50 ft. if the sludge is incorporated or injected and the department does not determine that a greater distance to the wells is required to protect the groundwater.

** The distances to property lines may be reduced with the written permission of both property owners.

*** Separation distances not required if grass waterway or dry run with grass strip is contained within a site or field for the purpose of erosion control.

(4) SLUDGE QUALITY (STANDARDS AND PROCESSES).

(a) In addition to other requirements in this chapter, there are 3 categories of requirements of sludge quality which must be satisfied before the sludge may be applied to land. The categories are listed in subs. (5), (6) and (7). They are metal concentrations, pathogen densities and treatment processes, and vector attraction reduction. Each category is divided into 2 levels which determine a higher or lower quality of sludge. They are: for metals-pollutant concentrations and ceiling concentrations, specified in sub. (5); for pathogens-class A and class B, specified in sub. (6); and for vector attraction reduction-treatment processes and physical barriers, specified in sub. (7). A sludge shall meet the minimum, or lower quality, requirements for each category in order to be land applied. When a sludge meets the higher quality level in all 3 categories, it is considered exceptional quality sludge. When a sludge meets the higher level in the metals category it is considered high quality and exempt from tracking cumulative metal loadings to the application sites.

(b) When a sludge is exceptional quality or when it is bagged and satisfies the requirements in sub. (5) (c) or (d), it may be used on lawns or home gardens. Sludge not meeting those requirements may not be used on lawns or home gardens.

(c) Sludge that will be sold or given away in a bag shall, at a minimum, satisfy the class A pathogen requirements in sub. (6) (a), one of the vector attraction reduction process requirements in sub. (7) (a) to (i) and either the high quality pollutant concentration limits in Table 3 or the ceiling concentration limits in Table 1. Bagged sludge that does not meet the high quality limits in Table 3 is subject to the requirements in sub. (5) (d).

Table C

Minimum Duration Between Application and Harvest\grazing\access for Class B Sludge Applied to the Land

Criteria

Surface

Incorporation

Injection

Food crops whose harvested part may touch the soil/sludge mixture (beans, melons, squash, etc.)

14

months

14 months

14

months

Food crops whose harvested parts grow in the soil (potatoes, carrots, etc.)

20/38 months*

20/38 months*

38 months

Feed or other food crops (field corn, hay, sweet corn, etc.)

30 days

30 days

30 days

Grazing of animals

30 days

30 days

30 days

Public access restriction

-High potential**

1 year

1 year

1 year

-Low potential

30 days

30 days

30 days

*The 20 month duration between application and harvesting applies when the sludge that is surface applied stays on the surface for 4 months or longer prior to incorporation into the soil. The 38 month duration is in effect when the sludge remains on the surface for less than 4 months prior to incorporation.

**This includes application to turf farms which place turf on land with a high potential for public exposure.

(5) METAL CONCENTRATIONS.

(a) Table 1 lists the ceiling concentrations of metal pollutants for sludge that is land applied. Sludge may not be applied to land if the concentration of pollutants in the sludge exceeds any of the ceiling concentration limits established in Table 1. Options available if a ceiling concentration in sludge is exceeded include: retesting, mixing with another sludge or other material and demonstration of compliance with Table 1, landfilling or incinerating.

(b) Table 2 lists the cumulative metal pollutant loading limits for sites on which bulk sludge is applied. If bulk sludge is applied to land and the sludge does not meet the pollutant concentration limits in Table 3, then the limits in Table 2 shall apply to all land application sites. Bulk sludge that does not meet the Table 3 concentration limits may not be applied to sites where the cumulative pollutant loading limits in Table 2 have been reached. When bulk sludge that does not meet Table 3 limits is applied to land, the permittee shall monitor and retain cumulative pollutant loadings records to each site, and shall notify the department, in their annual report, when any site reaches 90% of the allowable cumulative loading for any metal established in Table 2.

(c) Sludge shall meet all the pollutant concentration limits established in Table 3, to be considered high quality. High quality sludge is exempt from the cumulative loading limits specified in par. (b).

Table 1

Ceiling Concentrations

Pollutant

Ceiling concentrations (milligrams per kilogram-ppm) (dry weight)

Arsenic

75

Cadmium

85

Copper

4300

Lead

840

Mercury

57

Molybdenum

75

Nickel

420

Selenium

100

Zinc

7500

Table 2

Lifetime Cumulative Metal Loadings

Pollutant

Kg/ha

lbs/ac

Arsenic

41

36

Cadmium

39

34

Copper

1500

1339

Lead

300

268

Mercury

17

15

Molybdenum

Deleted Until EPA

Revises

Nickel

420

375

Selenium

100

89

Note: The department strongly encourages permittees to produce sludge which meets the high quality pollutant concentration limits set in Table 3.

Table 3

Pollutant Concentrations

Pollutant

Monthly average concentrations (milligrams per kilogram-ppm) (dry weight)

Arsenic

41

Cadmium

39

Copper

1500

Lead

300

Mercury

17

Molybdenum

Deleted Until EPA Revises

Nickel

420

Selenium

100

Zinc

2800

(d)
1. Table 4 lists the maximum annual pollutant loading rates for sites where bagged sludge that is not high quality is land applied. If bagged sludge does not meet all of the pollutant concentrations in Table 3, the pollutant loading requirements in Table 4 apply to all land application sites utilized, including lawns and home gardens. To ensure that the annual pollutant loading rates in Table 4 are not exceeded, the amount of sludge applied annually shall be less than the annual sludge application rate calculated as follows:

ASAR = (APLR) / (C X 0.001)

Where:

ASAR = Annual sludge application rate in metric tons per hectare per 365 day period calculated on a dry weight basis.

APLR = Annual pollutant loading rate for a pollutant in kilograms per hectare per 365 day period, as stated in Table 4.

C = Pollutant concentration in milligrams, per kilogram of total solids calculated on a dry weight basis.

0.001 = A conversion factor.

2. When distributing bagged sludge that is subject to the Table 4 loading rates, the permittee shall provide an information sheet to each person receiving the bagged sludge or shall print instructions on the bag or container or label. The label instructions or information sheet shall contain the following information, at a minimum:
a. The name and address of the permittee who generated the sludge.

b. A statement that prohibits the use of the sludge except in accordance with the instructions on the label or information sheet.

c. An annual sludge application rate as calculated in this subsection that will ensure that the annual pollutant loading rate limits, established in Table 4, are not exceeded.

d. The percentage content of nitrogen, phosphorus and potassium present in the sludge.

Table 4

Annual Pollutant Loading Rate

Pollutant

Kg/ha

lbs/ac

Arsenic

2.0

1.78

Cadmium

1.9

1.69

Copper

75

66.9

Lead

15

13.4

Mercury

0.85

0.76

Molybdenum

Deleted Until EPA

Revises

Nickel

21

18.7

Selenium

5

4.4

Zinc

140

125

(6) PATHOGEN DENSITIES AND TREATMENT PROCESSES. Sludge may not be land applied unless the Class A pathogen requirements in par. (a) or the Class B pathogen requirements in par. (b) are satisfied. These requirements are summarized in Tables 5 and 6. Bagged sludge and exceptional quality sludge shall satisfy the Class A requirements in par. (a).

(a) One of the requirements in each subds. 1. and 2. shall be met for sludge to be classified as Class A. Class A requirements shall be met prior to or at the time of meeting the vector attraction reduction requirements specified in sub. (7), unless the process used to meet the vector requirements is one of either sub. (7) (f), (g) or (h). Class A requirements are summarized in Table 5:

Table 5

Class A

Parameter

Unit

Limit

Fecal Coliform

MPN/g TS

1000

or

Salmonella

MPN/4g TS

3

AND, ONE OF THE FOLLOWING PROCESS OPTIONS

Temp/Time based on % Solids

Alkaline Treatment

Prior test for Enteric Virus/Viable Helminth Ova

Post test for Enteric Virus/Viable Helminth Ova

Composting

Heat Drying

Heat Treatment

Thermophilic Aerobic Digestion

Beta Ray Irradiation

Gamma Ray Irradiation

Pasteurization

PFRP Equivalent Process
1. Pathogen or indicator organism densities. The required fecal coliform density or salmonella density shall be satisfied immediately after the treatment process in subd. 2. is completed. If the material is bagged or distributed at that time, no re-testing is required. If the material is bagged, distributed or land applied at a later time, the sludge shall be retested and the requirements of subd. 1. a. or b. satisfied at that time also, to ensure that regrowth of the organisms has not occurred.
a. The sludge shall have a fecal coliform density equal to or less than 1,000 most probable number (MPN) per gram of total solids on a dry weight basis. Compliance with this requirement shall be demonstrated by calculating the geometric mean of at least 7 separate samples; or

b. The sludge shall have a salmonella density equal to or less than 3 MPN per 4 grams of total solids on a dry weight basis; and

2. Pathogen treatment processes.
a. Satisfy the requirements as specified in 40 CFR 503.32(a). 40 CFR 503.32(a) as stated on January 1, 1996 is incorporated by reference; or

Note: Copies of this section are available for inspection in the offices of the department of natural resources, secretary of state, and the legislative reference bureau, Madison, Wisconsin, or may be purchased from the superintendent of documents, U.S. government printing office, Washington DC 20402.

b. Compost the sludge using either within-vessel or static aerated pile composting methods and maintain the temperature of the sludge at 55° C or higher for 3 days, or compost the sludge using windrow composting methods and maintain the temperature of the sewage sludge at 55° C or higher for 15 days or longer. During this period, a minimum of 5 windrow turnings are required; or

c. Dry the sludge by direct or indirect contact with hot gases to reduce the moisture content of the sludge to 10% or lower. Either the temperature of the sewage sludge particles shall exceed 80° C or the wet bulb temperature of the gas in contact with the sludge as the sludge leaves the dryer shall exceed 80° C; or

d. Heat liquid sludge to a temperature of 180° C or higher for 30 minutes; or

e. Agitate liquid sludge with air or oxygen to maintain aerobic conditions. The mean cell residence time for the sludge shall be 10 days at 55° to 60° Celsius; or

f. Irradiate the sludge with beta rays from an accelerator at dosages of at least 1.0 megarad at room temperature; or

g. Sludge is irradiated with gamma rays from certain isotopes, such as Cobalt 60 and Cesium 137, at dosages of at least 1.0 megarad at room temperature; or

h. Maintain the temperature of the sludge at 70° Celsius or higher for 30 minutes or longer; or

i. Treat the sludge in a process that is equivalent to a process to further reduce pathogens, as approved by the department.

(b) Either subd. 1. or one of the requirements in subd. 2. shall be met for the sludge to be classified as Class B. The Class B requirements are summarized in Table 6:

Table 6

Class B

Parameter

Unit

Limit

Fecal Coliform

MPN or CFU/g TS

2,000,000

OR ONE OF THE FOLLOWING PROCESS OPTIONS

Aerobic Digestion

Air Drying

Anaerobic Digestion

Composting

Alkaline Stabilization

PSRP Equivalent
1. Fecal coliform density. The sludge shall have a fecal coliform density of less than or equal to 2,000,000 most probable number (MPN) or colony forming units (CFU) per gram of total solids on a dry weight basis. Compliance with this requirement shall be demonstrated by calculating the geometric mean of at least 7 separate samples; or

2. Pathogen treatment processes.
a. Agitate the sludge with air or oxygen to maintain aerobic conditions for a mean cell residence time and temperature between 40 days at 20° C and 60 days at 15° C; or

b. Dry the sludge on sand beds or on paved or unpaved basins for a minimum of 3 months. During 2 of the 3 months, the ambient average daily temperature shall be above 0° C; or

c. Treat the sludge in the absence of air for a specific mean cell residence time at a specific temperature. Values for the mean cell residence time and temperature shall be between 15 days at 35° to 55° C and 60 days at 20° C; or

d. Compost the sludge using either the within-vessel, static aerated pile, or windrow composting methods and raise the temperature of the sludge to 40° C or higher for 5 days. For 4 hours during the 5 days, the temperature in the compost pile shall exceed 55° C; or

e. Add sufficient lime to the sludge to raise the pH to 12 after 2 hours of contact; or

f. Treat the sludge in a process that is equivalent to a process to significantly reduce pathogens, as approved by the department.

(7) VECTOR ATTRACTION REDUCTION. Sludge may not be land applied unless one of the 11 vector attraction reduction options in pars. (a) to (k) is satisfied. Paragraphs (a) to (i) are processes which treat the sludge to reduce its attraction to vectors. Bagged sludge and exceptional quality sludge shall satisfy one of the requirements in pars. (a) to (i). The options are summarized in Table 7.

(a) The mass of volatile solids in the sludge shall be reduced by a minimum of 38% between the time the sludge enters the digestion process and the time it either exits the digester or a storage facility; or

(b) The specific oxygen uptake rate SOUR for aerobic sludge shall be equal to or less than 1.5 milligrams of oxygen per hour per gram of total solids on a dry weight basis, corrected to 20° Celsius; or

(c) Demonstrate through additional digestion, in a bench-scale test, that additional volatile solids reduction for anaerobically digested sludge is less than 17%. This shall be demonstrated by digesting a portion of the previously digested sludge anaerobically in the laboratory in a bench-scale unit for 40 additional days at a temperature between 30° and 37° Celsius. This requirement is satisfied when, at the end of the test, volatile solids have been reduced by less than 17%, as measured from the beginning to the end of the test; or

(d) Demonstrate through additional digestion, in a bench scale test, that additional volatile solids reduction for aerobically digested sludge is less than 15%. This shall be demonstrated by digesting a portion of the previously digested sludge, at a concentration of 2% solids or less, aerobically in the laboratory in a bench-scale unit for 30 additional days at a temperature of 20° Celsius. Sludge with higher percent solids shall be diluted with effluent down to 2% at the start of the test. This requirement is satisfied when, at the end of the test, volatile solids have been reduced by less than 15%, as measured from the beginning to the end of the test; or

(e) Sludge shall be treated in an aerobic process for 14 days or longer. During that time, the temperature of the sludge shall be higher than 40°Celsius and the average temperature of the sludge shall be higher than 45°Celsius; or

(f) The pH of the sewage sludge shall be raised to 12 or higher by alkali addition and, without the addition of more alkali, shall remain at 12 or higher for 2 hours and then at 11.5 or higher for an additional 22 hours; or

(g) Dry the sludge to 75% total solids when the sludge contains no unstabilized solids from primary treatment; or

(h) Dry the sludge to 90% total solids when the sludge contains unstabilized solids from primary treatment; or

(i) Treat the sludge in a process which is equivalent to one of the vector attraction reduction requirements specified in pars. (a) to (h), as approved by the department.

Table 7

Vector Attraction Reduction

(One of the following shall be satisfied)

Option

Limit

Where/When Requirements

Must Be Met

Volatile Solids Reduction

>=38%

Across the process

Specific Oxygen Uptake Rate

<=L5 mg O2/hr/g TS

On aerobic stabilized sludge

Anaerobic benchscale test

<17% VS reduction

On anaerobic digested sludge

Aerobic benchscale test

<15% VS reduction

On aerobic digested sludge

Aerobic Process

>14 days, T >40°C and avg T >45°C

On composted sludge

pH adjustment

>12 S.U.

(for 2 hours) and >1L5 (for an additional 22 hours)

When applied or bagged

Drying without primary solids

>75 % TS

When applied or bagged

Drying with primary solids

>90 % TS

When applied or bagged

Equivalent process

Determined by the department

Varies with process

Injection

-

When applied

Incorporation

-

When applied

(j) Injection below the soil surface
1. No significant amount of the sludge shall be present on the land surface within one hour after the sludge is injected.

2. If the injected sludge is Class A, the sludge shall be injected within 8 hours after being discharged from the pathogen treatment process; or

(k) Incorporation
1. Class B sludge shall be incorporated within 6 hours, unless otherwise specified by the department.

2. Class A sludge shall be surface applied within 8 hours after being discharged from a pathogen treatment process. It then shall be incorporated within 6 hours of surface application, unless otherwise specified by the department.

(8) APPLICATION RATES.

(a) The amount of available nitrogen from sludge and other nitrogen sources applied per growing season may not exceed the nitrogen requirement of the crop, as determined by recommendations based on the University of Wisconsin-extension bulletin A-2100, dated April 1991 and incorporated by reference in s. NR 204.06(6) (c). The department may authorize exceptions to this requirement on a case-by-case basis. Review for exceptions will consider proposals such as mine or other site reclamation projects.

(b) Unless specific mineralization rates are determined by the permittee, the following mineralization rates are to be used in calculating the available organic nitrogen from initial sludge application and from carryover of previous years' application: 25%-12%-6% in years 1 through 3.

(c) Bulk sludge may be applied to all leguminous crops, except soybeans, at a volume sufficient to supply 200 pounds per acre of available nitrogen. If sludge is applied to soybeans, the loading shall be limited to 140 pounds per acre of available nitrogen.

(d) Bulk sludge that is land applied and does not meet the pollutant concentrations in Table 3 of sub. (5) (c) may not be applied if the cumulative metals loadings listed in Table 2 of sub. (5) (b) have been reached.

(e) The department shall be notified in writing, by the permittee, when 90% of the lifetime cumulative metal loadings has been reached on any site or field. From that point on, all loading to that site or field shall be individually monitored and reported.

(f) The department may, on a case-by-case basis in the permit, require additional monitoring and limit the land application of sludge containing pollutants that may result in environmental degradation or threaten public health.

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