7 Del. Admin. Code § 7103-138.0

Current through Register Vol. 28, No. 4, October 1, 2024

Section 7103-138.0 - Agricultural Utilization of Sludge and Septage

138.1 This section applies to the land application of sewage sludges, sludge products, and septage which meet the minimum quality criteria specified in Subsection 117.0 and pathogen reduction requirements of Section 131.0, but do not meet the Exceptional Quality standards for general distribution and marketing.

138.1.1 Agronomic Rate:

138.1.1.1 Sewage sludge application rates must be calculated based on the following:

138.1.1.1.1 The nitrogen required by the crop to be grown according to University of Delaware Cooperative Extension Service crop fertility recommendations. Crop demand must be based on realistic yield goals determined either through the average of the three highest yields from the previous five years for each field for each specific crop, or Extension recommendations.

138.1.1.1.2 The total crop nitrogen requirement less any nitrogen that will be available from mineralization of previous manure or sludge applications, legumes, or expected manure applications.

Table 702-1. Estimated Percentages and Amounts of Organic N Mineralized After Sludge of Various Types are Applied to Soils

Time After sludge Applic. (years)	Unstabilized Primary and Waste Activated	Aerobically Digested	Anaerobically Digested	Composted
	F % No*	KmHI kg/mt/%No	F % No	Km kg/mt/%No	F % No	Km kg/mt/%No	F % No	Km kg/mt/%No
0-1	40	4.00	30	3.00	20	2.00	10	1.00
1-2	20	1.20	15	1.05	10	0.80	5	0.45
2-3	10	0.48	8	0.45	5	0.36	3	0.25
3-4	5	0.22	4	0.21	3	0.21	3	0.25
4-5	3	0.12	3	0.16	3	0.20	3	0.24
5-6	3	0.12	3	0.15	3	0.19	3	0.23
6-7	3	0.12	3	0.15	3	0.19	3	0.23
7-8	3	0.11	3	0.15	3	0.18	3	0.22
8-9	3	0.11	3	0.15	3	0.18	3	0.21
9-10	3	0.11	3	0.15	3	0.17	3	0.21
10-yr steady state	93		75		56		39

^*Percentage of organic N (N_o) present mineralized during time interval shown.

^Hkg N released per metric ton of sludge applied per % organic N in the sludge. For example, application of an anaerobically digested sludge containing 3% organic N at 10 mt/ha would result in the following amounts of N mineralization: year 0, 3% N_o x 10 mt/ha x 2.0 = 60 kg N/ha; year 1 3% N_o x 10 mt/ha x 0.80 = 24 kg N/ha; year 2, 3% N_o x 10 mt/ha x 0.36 = 10.8 kg N/ha.

^I Multiply kg/mt by 2 to obtain lbs./ton.

138.1.2 For domestic septage - the annual application rate for domestic septage applied to agricultural land, forest, or a reclamation site shall not exceed the annual application rate calculated using equation (138.1.2.1)

N

138.1.2.1 Equation: AAR = ----------

0.0026

Where:

AAR = Annual application rate in gallons per acre per 365 day period.

N = Amount of nitrogen in pounds per acre per 365 day period needed by the crop or vegetation grown on the land.

138.1.3 The Plant Available Nitrogen (N_p) of the sewage sludge or sludge product shall be calculated at the summation of the ammonia, nitrate and % inorganic Nitrogen mineralized in the first year, bases on a recent rolling average analyses for the sludge source.

Equation (1): N_p = S [No₃^-) + Kv (NH₄⁺) + F (No)](10)

Where:

N_p = Plant available N from the current year's sludge application only.

S = Sludge application rate (dry mt tons/ha).

No₃^- = Percent nitrate-N in sludge (as percent, e.g. 1% = 1.0).

Kv =Volatilization factor = 0.5 for surface applied liquid sludge, or 1.0 for incorporated liquid sludge and dewatered sludge applied in any manner.

NH₄⁺ = Percent ammonia-N in the sludge, as percent (e.g. 3% = 3.0).

F = Organic Nitrogen mineralization factor (year 0-1) from Table 702.1 (percentage expressed as a fraction e.g. 20% = .20).

N_o = Percent organic nitrogen in the sludge (as percent e.g. 3% = 3.0).

138.1.1.1.4 If sludge has been applied in previous years the nitrogen available in the current year from each previous application can be calculated as follows:

Equation (2): N_m = (K_m)(N_o)(s)

Where:

N_m = The quantity of N mineralized in the year under consideration, in kg/ha.

K_m = Mineralization factor for the year under consideration from Table 702.1 (in kg/mt/%N_o).

N_o = Percent organic N originally present in the sludge (as percent e.g. 3% = 3.0).

S = Sludge Application rate (mt/ha) in the year under consideration.

138.1.1.1.5 If the sludge is only applied one time, the N_o available in subsequent years is the amount calculated in eq (2). Sites which have received multiple sludge applications must include the summation of currently available N_p from N_o mineralization calculations for each previous sludge application.

138.2 Buffer Zones.

138.2.1 Unless treated by PFRP, sewage sludge may not be land applied within the following buffer zones:

SurfaceApplication	Surface Injection
Occupied off-site dwelling	200 feet	100 feet
Occupied on-site dwelling	100 feet	50 feet
Potable wells	100 feet	100 feet
Non-potable wells	25 feet	25 feet
Public roads	25 feet	15 feet
Property lines	50 feet	25feet
Bedrock outcrops	50 feet	25 feet
Streams, tidal waters, or other water bodies	50 feet	25 feet
Drainage ditches	25 feet	25 feet

138.2.2 The Department may require increased buffer distances or may reduce buffer distances, and may set buffer zones between sludge boundaries and other land uses such as wetlands. In making these determinations, the Department may consider adjacent land use, type of sludge, sludge application method, sludge application rate, sludge quality and level of treatment, land slopes, vegetative cover used, the nature of any surrounding bodies of water, and any other factors considered relevant by the Department.

138.3 Pathogen Control.

138.3.1 Sewage sludge and septage treated by a PSRP process as described in Subsection 86.0 may be land applied in the State with the following restrictions:

138.3.1.1 Food crops with harvested parts that touch the sewage sludge/soil mixture and are totally above the land surface shall not be harvested for 14 months after application of sewage sludge.

138.3.1.2 Food crops with harvested parts below the surface of the land shall not be harvested for 20 months after application of sewage sludge when the sewage sludge remains on the land surface for four months or longer prior to incorporation into the soil.

138.3.1.3 Food crops with harvested parts below the surface of the land shall not be harvested for 38 months after application of sewage sludge when the sewage sludge remains on the land surface for less than four months prior to incorporation into the soil.

138.3.1.4 Food crops, feed crops, and fiber crops shall not be harvested for 30 days after application of sewage sludge.

138.3.1.5 Animals shall not be allowed to graze on the land for 30 days after application of sewage sludge.

138.3.1.6 Turf grown on land where sewage sludge is applied shall not be harvested for one year after application of the sewage sludge when the harvested turf is placed on either land with a high potential for public exposure or a lawn, unless otherwise specified by the permitting authority.

138.3.1.7 Public access to land with a high potential for public exposure shall be restricted for one year after application of sewage sludge.

138.3.1.8 Public access to land with a low potential for public exposure shall be restricted for 30 days after application of sewage sludge.

138.3.1.9 Bulk sewage sludge shall not be applied to a public contact site unless the sludge meets exceptional quality standards.

138.3.1.10 Tobacco is grown or will be grown.

138.3.2 No person shall use spray irrigation equipment to apply sludge unless such person has demonstrated to the Department in his permit application the specific means by which pathogens will be controlled so as not to present a public health hazard. At a minimum, the report shall include the design effectiveness of the proposed bactericidal and viricidal equipment, the means by which aerosol-borne bacteria and viruses will be contained and the impact of wind velocity on the latter's transport offsite or that appropriate buffer zones have been included, and the Department has approved such equipment or areas as part of the permit.

138.4 In no case shall the pollutant loading rate to a field exceed the levels set forth in Section 115.0 Table 402.4 and Table 402.5.

138.5 The Department may deny an application to apply lime stabilized sludge or high lime content sludge on a specific site if the Department determines that the application will result in the average soil pH on the site exceeding the optimum pH range for the crop to be grown.

138.6 Site characteristics. No person shall apply sludge to a site unless the site complies with all of the following:

138.6.1 The soils shall have a minimum depth from surface to impermeable strata of 20 inches.

138.6.2 The site shall have a minimum depth from surface to seasonal high water table of 20 inches. The operator may establish this minimum depth through the use of a tile drain system. An NPDES permit will be required for the discharge from the tile drain. Sites where the minimum depth from surface to seasonal high water table is less than 20 inches but no less than 12 inches may be considered if application to the soil is restricted to:

138.6.2.1 May, June, July or August and appropriate vegetation is established and harvested as practicable, and

138.6.2.2 Those periods when actual water table depth is at least 20 inches below the maximum depth of tillage to be used for the vegetation.

138.6.3 Slopes to be utilized for sludge application may not exceed 15 percent, except that the Department may allow slopes of up to 30 percent for forest systems in the permit.

138.6.4 Soil pH is to be adjusted to values of 6.2 or above unless the natural climatic conditions and soil chemistry preclude such values. In these cases, lime additions suitable to the vegetation used are to be applied in conjunction with annual metal monitoring of that vegetation.

138.6.5 For silvicultural application the soil may remain at ambient pH provided sufficient litter exist on the forest tract floor as determined by the Department.

138.6.6 If the site is planted with nursery crops that require a pH of less than 6.2, the Department may approve a soil pH of 5.8 or greater in the permit.

138.7 Application to soil.

138.7.1 Sludge shall be spread evenly over the site using conventional agronomic equipment such as manure spreaders, spray equipment, or other applicators, or by commercial equipment specifically designed for sludge application on agricultural land.

138.7.2 Sludge or products derived from sewage sludge shall be applied to the soil surface or incorporated in a manner that prevents unreasonable nuisance or odor conditions.

138.7.3 The sludge applied shall be incorporated into the soil as required in Section 600 or by the end of each working day except under the following circumstances when:

138.7.3.1 Liquid sludge is surface sprayed, odors and nuisances are controlled, and the Department determines that there will be no adverse impact on the environment or public health; or

138.7.3.2 Site management plans such as no till farming or the presence of an established crop precludes sludge incorporation, adequate site features exist to preclude sludge migration from the site, odors and nuisances are controlled, and the Department determines that there will be no adverse impact on the environment or public health.

138.7.4 For the surface application of sludge for top or side dressing on hayfields, for pastures, for cover crops, in forests or for no-till crops when the previous no-till crop was harvested for grain in a manner that left adequate crop residue, the Department may either:

138.7.4.1 Approve a greater than 24 hour time period for incorporating sludge into the soil as part of the permit, or

138.7.4.2 Not require incorporation as part of the permit.

138.7.5 The areas to receive sludge application shall be clearly marked with stakes or contain other markers before the sludge application.

138.7.6 Trucks shall be reasonably cleaned on the site to prevent drag-out of soil or sludge onto public roads.

138.8 Weather.

138.8.1 No person may apply sludge when the ground surface is saturated or covered with snow, or during periods of rain or runoff.

138.8.2 No person may apply sludge when the ground is frozen, unless the Department has approved such application in the permit and all of the following conditions exist:

138.8.2.1 The slopes at the site do not exceed three percent.

138.8.2.2 The site contains sufficient vegetation or a well-established cover crop to prevent runoff of sludge.

138.8.2.3 No sludge storage capacity or other means of storage or disposal exists at the generating facility.

138.8.2.4 No run-off.

138.9 Daily Record Keeping and Reporting Requirements.

138.9.1 Permit applicants must provide the landowner and operator or the proposed site with a copy of the Project Development Report and permit application and information as specified in Section 1100.

138.9.2 Any person that land applies sludge shall make and maintain an operational record for each day that sludge is applied and when any other management activities are conducted at the land application site. The daily operational record shall be recorded on a form supplied by the Department and include the following:

138.9.2.1 The date, type, and wet and dry weights of the sludge applied.

138.9.2.2 The facility from which the sludge originated.

138.9.2.3 The transporters of the sludge.

138.9.2.4 The particular map location of the area currently being used for land application of sludge, and the areas where sewage sludge was previously applied within 5 years.

138.9.2.5 A record of any major deviations from the operating plan.

138.9.2.6 General daily weather conditions.

138.9.2.7 The application rate for sludge.

138.9.2.8 A record of all actions taken to correct violations of the Delaware Environmental Protection Act and the Department's regulations.

138.9.2.9 Management undertaken, such as planting and harvesting of crops, fertilizers and chemicals added, tillage practices, etc.

138.9.3 When sludge is being stored at the site, the operator shall maintain accurate operational records sufficient to determine whether the sludge is being stored in accordance with the Department's requirements for such operations.

138.10 Annual Record Keeping and Reporting Requirements.

138.10.1 Any person that utilizes sludge by land application shall submit to the Department and landowner an annual operation report on or before February 1 of each year.

138.10.2 The annual operation report, which shall be submitted in a format specified by the Department, shall include the following:

138.10.2.1 The weight or volume of each type of sludge received.

138.10.2.2 The type, weight, and volume of sludge received from each generator location where the sludge originated.

138.10.2.3 A copy of the applier's current public liability insurance policy.

138.10.2.4 Any changes in ownership of the land where the operation is conducted or any change in any lease agreement for the use of such land that may affect or alter the applier's rights upon such land.

138.10.2.5 The annual ground water monitoring evaluation if ground water monitoring is required by the Department.

138.10.2.6 A chemical analysis of soil for each field at the facility for those constituents identified in the sludge, unless otherwise specified by the Department in the permit. The procedure for soil analysis shall be consistent with the Department guidance.

138.10.2.7 Any other information required by the Department.

138.10.3 The annual operation report shall also contain a topographic map of the same scale and contour interval as the map required for the initial permit application, showing the field boundaries where sludge has been applied.

7 Del. Admin. Code § 7103-138.0