Code of Maine Rules › 01 - DEPARTMENT OF AGRICULTURE, CONSERVATION AND FORESTRY › 001 - AGRICULTURE - GENERAL › Chapter 565 - Nutrient Management Rules › ATTACHMENTS › Attachment C - NRCS Code 313

Current through 2024-29, July 17, 2024
Natural Resources Conservation Service
CONSERVATION PRACTICE STANDARD
WASTE STORAGE FACILITY
Code 313
(No)
November 2017
DEFINITION
An agricultural waste storage impoundment or containment
					 made by constructing an embankment, excavating a pit or dugout, or by
					 fabricating a structure.
Purpose
To store manure, agricultural by-products, wastewater, and
					 contaminated runoff to provide the agricultural operation management
					 flexibility for waste utilization.
Conditions Where Practice Applies
Use where regular storage is needed for wastes generated by
					 agricultural production or processing and where soils, geology, and topography
					 are suitable for construction of the facility. For reception pits, use the NRCS
					 Conservation Practice Standard (CPS) Waste Transfer (Code 634).
For liquid waste storage facilities implemented with an
					 embankment, this practice applies only to low hazard structures as defined in
					 the NRCS National Engineering Manual (NEM), Part 520.23.
This practice does not apply to the storage of human waste
					 or routine animal mortality.
General Criteria Applicable to All Waste Storage
					 Facilities.
Laws and Regulations
. Plan, design, and
					 construct the waste storage facility to meet all Federal, State, and local laws
					 and regulations.
Location
. Locate and design the waste storage
					 facility such that it is outside the 100-year floodplain unless site
					 restrictions require locating it within the floodplain. If located in the
					 floodplain, protect the facility from inundation or damage from a 25-year flood
					 event. Additionally, follow the policy found in the NRCS General Manual (GM)
					 190, Part 410.25, Floodplain Management, which may require providing additional
					 protection for storage structures located within the floodplain.
Locate waste storage structures at least 100 feet from
					 wells.
Waste storage facilities, other than field stacking
					 facilities shall have a bottom elevation that is a minimum of 2 feet above the
					 seasonal high water table. The storage shall have bottom elevation that is a
					 minimum of 18 inches to bedrock. If the bedrock separation is less than 24
					 inches, then 6 inches of the separation profile must contain an impermeable
					 layer. These separation distances and soils criteria are shown in Figure 1. The
					 bottom elevation is defined as the lowest elevation manure is stored, for
					 example, the top of the concrete floor.
Click
					 here to view Image
Soils that do not meet the criteria in Figure 1 can
					 be modified. Modifications to the site in order to meet seasonal high water
					 table separation distance criteria shall address buoyant forces, pond seepage
					 rate, and non-encroachment of the water table by contaminants. These
					 modifications may include lowering the water table by the use of perimeter
					 drains, building up the soil profile to increase the separation distance, or
					 increasing setback distances from resource concerns. Any impermeable layers
					 used to meet bedrock separation distance criteria shall use material such as
					 clay. Material must be reviewed and approved by Soil Resource Specialist. If a
					 site cannot be modified a synthetic liner may be used meeting the requirements
					 found under Liners within
Additional Criteria for Liquid Waste
					 Storage
Consult with a Soil Resource Specialist to locate
					 proposed waste storage facility and determine any modification needed to meet
					 separation distances and soils criteria. Comply with all local, state, and
					 federal laws and regulations on separation distances from resource concerns
					 such as wells, property lines, water bodies, and aquifers.
Storage Period
. The storage period is the
					 maximum length of time anticipated between emptying events. Base the minimum
					 storage period on the timing required for environmentally safe waste
					 utilization considering the climate, crops, soil, equipment, and local, State,
					 and Federal regulations.
Design Storage Volume
. Size the facility to
					 store the following volumes as appropriate.
Operational Volume
Manure, wastewater, bedding, and other wastes
						accumulated during the storage period.
										For liquid or slurry storage facilities, include
						normal precipitation (omit diverted roof runoff) less evaporation during the
						storage period.
										Normal runoff from the facility's drainage area
						during the storage period.
										Planned maximum residual solids. Provide a minimum of
						6 inches for tanks unless a sump, ramp, or other device allows for complete
						emptying.
										Additional storage when required to meet management
						goals or regulatory requirements.
Emergency Volume (liquid storages
					 only)
25-year, 24-hour precipitation on the surface of the
						liquid or slurry storage facility at the maximum level of the required design
						storage.
										25-year, 24-hour runoff from the facility's drainage
						area.
Freeboard Volume
(for liquid or
					 slurry waste storage exposed to precipitation)
Minimum of 6" for vertical walled tanks.
										Minimum of 12" for all other facilities.
Exclude nonpolluted runoff from the structure to the
					 fullest extent practical except where including the runoff is advantageous to
					 the operation of the agricultural waste management system.
Inlet.
Design inlet to resist corrosion,
					 plugging, freeze damage, and ultraviolet deterioration. Incorporate erosion
					 protection as necessary.
Waste Removal.
Provide components for removing
					 waste such as gates, pipes, docks, wet wells, pumping platforms, retaining
					 walls, or ramps. Incorporate features to protect against erosion, tampering,
					 and accidental release of stored waste as necessary. Design ramp slopes to
					 accommodate anticipated equipment and traction available. Use NRCS CPS Nutrient
					 Management (Code 590) for land application of stored material or follow other
					 disposal options outlined in a Comprehensive Nutrient Management Plan
					 (CNMP).
Accumulated Solids Removal.
To preserve
					 storage volume, make provision for periodic removal of accumulated solids. The
					 anticipated method for solids removal must be accommodated in design,
					 particularly in determining the configuration of impoundments and the type of
					 liner to be used.
Maximum Operating Level.
The maximum operating
					 level for liquid storage structures is the level that provides the operational
					 volume.
Staff Gauge.
For earthen waste storage
					 structures place a staff gauge or other permanent marker in the liquid storage
					 facility to clearly indicate the following elevations:
Maximum operating level (top of the operational
						volume).
										Emergency level (top of the design storage
						volume).
For storages where the contents are not visible and a staff
					 gauge would not be visible, such as below a slatted floor, identify the method
					 for the operator to measure the depth of accumulated waste in the Operation and
					 Maintenance Plan.
Safety.
Include appropriate safety features to
					 minimize the hazards of the facility (refer to American Society of Agricultural
					 and Biological Engineers (ASABE) Standard EP470, Manure Storage Safety for
					 guidance, as needed).
Provide warning signs, fences, ladders, ropes, bars, rails,
					 and other devices as appropriate, to ensure the safety of humans and livestock.
					 Provide ventilation and warning signs for covered waste holding structures, as
					 necessary, to prevent explosion, poisoning, or asphyxiation.
Design covers and grating over openings such that livestock
					 or humans cannot accidentally displace them and fall into the facility.
Design pipelines with a water-sealed trap and vent, or
					 similar device, if there is a potential for gases from the pipe to accumulate
					 in confined spaces.
Place a fence around impoundments and uncovered tanks which
					 have exposed walls less than 5 feet above ground surface. Use the NRCS CPS
					 Fence (Code 382) for design of a fence that will prevent accidental entry by
					 people or animals likely to be onsite. Except at pushoff and unloading
					 locations, fencing around waste storage facilities shall be one of the
					 following:
Woven Wire, 6" grid, See typical drawing
						ME-FNC-WWF
										Chain Link, See typical drawing ME-FNC-CLF
At all pushoffs, pumping pads, and agitation locations,
					 install safety features to prevent equipment, people, and livestock from
					 accidentally falling into storage. Gate panels are to be used at pumping and
					 agitation locations. Rail or bars are to be used at push-off locations.
					 Position bar or rail so that the bucket or scarper can pass underneath.
Post universal warning signs, if needed, to prevent
					 children and others from entering liquid waste storage structures.
Roofs and Covers.
Use NRCS CPS Roofs and
					 Covers (Code 367) for design of waste storage facility covers or roofs, as
					 needed.
Treated Wood.
Use criteria from NRCS CPS Roof
					 and Covers (Code 367) for treated wood and fasteners.
Additional Criteria for Liquid Waste
					 Storage
A liquid waste storage impoundment is a facility where the
					 stored material does not consistently stack and is either a natural topographic
					 depression, manmade excavation, or diked area formed primarily of earthen
					 materials, such as soil (although the unit may be lined with manmade materials)
					 .
Liners.
Select a liner material that will meet
					 the requirements of the management, waste consistency, loading method, and
					 unloading method. Use liners which meet or exceed NRCS CPS Pond Sealing or
					 Lining (Codes: 520 - Compacted Soil Treatment, 521 - Geomembrane or
					 Geosynthetic, or 522 -Concrete). Design concrete liners for reduced seepage.
					 For concrete liners use 3500 psi concrete, 5" thick, with #4 rebar spaced 12"
					 each direction. No cut joints are needed or allowed. Water stops are required
					 at any cold joint.
Foundation.
Locate the impoundment in soils
					 with a permeability that meets all applicable regulations or line the
					 impoundment with suitable material.
Perform subsurface investigations for all waste storage
					 impoundments sufficient in detail and analysis to support the design in
					 accordance with NRCS NEM, Part 531, Geology. Describe the soil material
					 encountered, location of any seeps, depth-to-high-water table, depth to
					 bedrock, and presence of sink holes in karst topography.
For the design of a liner on a site located in a floodplain
					 and other locations where there is potential for uplift, include an evaluation
					 of all potential buoyant uplift forces on the liner. Limit projected uplift
					 head under clay liners to a gradient of less than 0.5 ft/ft in the clay liner.
					 The gradient is determined as the difference in total head between the top and
					 the bottom of a clay liner when buoyant forces exist (such as when the
					 floodplain is flooded) divided by the thickness of the clay liner.
Outlet.
An outlet that can automatically
					 release stored material is not permitted except for septic tanks that feed a
					 treatment system such as a waste treatment strip or leaching field or outlets
					 leading to another storage facility with adequate capacity. Design a permanent
					 outlet that will resist corrosion and plugging. Provide a backflow prevention
					 measure for an outlet that pumps wastewater to secondary storage located at a
					 higher elevations.
Embankments
. For an impoundment with greater
					 than one acre of surface area and where wave action is a concern, increase the
					 embankment height to account for calculated wave height. In all cases, increase
					 the constructed embankment height by at least 5 percent to allow for
					 settlement. Stabilize all embankments to prevent erosion or
					 deterioration.
Minimum embankment top widths are shown in table 1. Design
					 the combined side slopes of the settled embankment to be equal to or flatter
					 than 5 horizontal to 1 vertical, with neither slope steeper than 2 horizontal
					 to 1 vertical unless provisions are made for stability. The total embankment
					 height (effective height) is the difference in elevation between the auxiliary
					 (emergency) spillway crest or the settled top of the embankment if there is no
					 auxiliary spillway and the lowest point in the cross section taken along the
					 centerline of the embankment.
Table 1. Minimum Top Widths
Total embankment height (ft)
Top width (ft)
Less than 15
8
15-19.9
10
20-24.9
12
25-30
14
30-35
15
Spillway or Equivalent Protection.
For a
					 facility having a total embankment height greater than 20 feet, construct an
					 auxiliary (emergency) spillway or route through the spillway or store below the
					 spillway another volume equivalent to the emergency volume.
Excavations.
Design excavated side slopes to
					 meet the requirements of the liner used, see NRCS CPS Pond Sealing or Lining,
					 Compacted Soil Treatment (Code 520), Pond Sealing or Lining, Geomembrane or
					 Geosynthetic (Code 521) or Pond Sealing or Lining, Concrete (Code 522).
Additional Criteria for Fabricated
					 Structures
Definition. Fabricated structures include steel
					 prefabricated tanks and waste storage structures constructed from precast or
					 cast in place concrete walls with a concrete floor.
Foundation.
Based on subsurface investigation,
					 provide a foundation for fabricated waste storage structures to safely support
					 all superimposed loads without excessive movement or settlement. Perform
					 subsurface investigations for all fabricated structures sufficient in detail
					 and analysis to support the design in accordance with NRCS NEM, Part 531,
					 Geology. Describe the soil material encountered, location of any seeps, depth
					 to high water table, depth to bedrock, and presence of sink holes in karst
					 topography.
Where a nonuniform foundation cannot be avoided or where
					 applied loads may create highly variable foundation loads, calculate settlement
					 based upon site-specific soil test data. Index tests of site soil may allow
					 correlation with similar soils for which test data is available. If no test
					 data are available, use presumptive bearing strength values for assessing
					 actual bearing pressures obtained from table 2 or another nationally recognized
					 building code. In using presumptive bearing values, provide adequate detailing
					 and articulation to avoid distressing movements in the structure.
Table 2. Presumptive Allowable Foundation and Lateral
					 Pressure1
Class of materials
Allowable foundation pressure (psf)
Lateral bearing (psf/ft) below natural grade
Coefficient of friction
Cohesion (psf)
Crystalline bedrock
12,000
1,200
0.70
-
Sedimentary and foliated rock
4,000
400
0.35
-
Sandy gravel or gravel (GW and GP)
3,000
200
0.35
-
Sand, silty sand, clayey sand, silty gravel, clayey
								gravel (SW, SP, SM, SC, GM and GC)
2,000
150
0.25
-
Clay, sandy clay, silty clay, clayey silt, silt and
								sandy silt (CL, ML, MH and CH)
1,500
100
-
130
1 International Building Code
					 (IBC), 2015, International Code Council (ICC)
Structural Loadings.
Design the waste storage
					 structure to withstand all anticipated loads in accordance with the
					 requirements in NRCS NEM, Part 536, Structural Design. Such loads should
					 include internal and external loads, hydrostatic uplift pressure, concentrated
					 surface and impact loads, and water pressure due to seasonal high water table,
					 frost or ice.
Calculate loading from lateral earth pressures using soil
					 strength values determined from the results of appropriate soil tests and
					 procedures described in Technical Release 210-74, Lateral Earth Pressures.
					 Table 3 provides minimum lateral earth pressure values when soil strength tests
					 are not available. If heavy equipment will operate near the wall, use an
					 additional soil surcharge or an additional internal lateral pressure in the
					 wall analysis as appropriate.
For the lateral load from stored waste not protected from
					 precipitation, use a minimum 65 lb/ft2/ft of depth
					 as the design internal lateral pressure. Use a minimum value of 60
					 lb/ft2/ft of depth for the lateral load from stored
					 waste protected from precipitation and not likely to become saturated. Use a
					 minimum internal lateral pressure of 72 lb/ft2/ft of
					 depth for sand-laden manure storage if the percentage of sand exceeds 20%.
					 Designers may use lesser values if supported by measurement of actual pressures
					 of the waste to be stored.
Table 3. Minimum Lateral Earth Pressure
					 Values1
Description of backfill material 
								c
Unified soil classification
Design lateral soil load
								(lb/ft2/ft of depth) 
								a
Active pressure
At-rest pressure
Well-graded, clean gravels; gravel-sand
								mixes
GW
30
60
Poorly graded clean gravels; gravel-sand
								mixes
GP
30
60
Silty gravels, poorly graded gravel-sand
								mixes
GM
40
60
Clayey gravels, poorly graded gravel-sand
								mixes
GC
45
60
Well-graded, clean sands; gravely sand mixes
SW
30
60
Sand-silt clay mix with plastic fines
SP
30
60
Silty sands, poorly graded sand-silt mixes
SM
45
60
Sand-silt clay mix with plastic fines
SM-SC
45
100
Clayey sands, poorly graded sand-clay mixes
SC
60
100
Inorganic silts and clayey silts
ML
45
100
Mixture of inorganic silt and clay
CL-ML
60
100
Inorganic clays of low to medium plasticity
CL
60
100
Organic silts and silt clays, low plasticity
OL
Note 
								b
Note 
								b
Inorganic clayey silts, elastic silts
MH
Note 
								b
Note 
								b
Inorganic clays of high plasticity
CH
Note 
								b
Note 
								b
Organic clays and silty clays
OH
Note 
								b
Note 
								b
1 Table 1610.1, Lateral Soil
					 Load, International Building Code (IBC), 2015, International Code Council
					 (ICC).
a Design loads based on moist
					 conditions for the specified soils at optimum density. Include the weight of
					 the buoyant soil plus hydrostatic pressure for submerged or saturated
					 soil.
b Unsuitable as backfill
					 material.
c Base the definition and
					 classification of soil in accordance with ASTM D 2487.
Structural Design.
Design
					 structures with reinforced concrete, steel, wood, or masonry materials in
					 accordance with NRCS-NEM, Part 536, Structural Engineering.
Account for all items that will influence the performance
					 of the structure, including loading assumptions, durability,
serviceability, material properties and construction
					 quality. Ensure that the material used for a fabricated structure is compatible
					 with the waste product to be stored. Design structures according the latest
					 versions of the following standards:
Loads: ASCE 7
Reinforced Concrete Structures:
Structural Members: ACI 318
Concrete Slabs for reduced seepage applications: ACI
					 360R
Concrete Slabs for non-water tight applications: ACI
					 330R
Steel Structures: AISC Steel construction
					 Manual
Wood Structures: American Wood Council National
					 Design Specifications for Wood Construction
Masonry Structures: ACI 530
Tanks may be designed with or without a cover. Design
					 openings in a covered tank to accommodate equipment for loading, agitating, and
					 emptying. Equip these openings with fencing, grills or secure covers for
					 safety, and for odor and vector control as necessary.
Sensitive Environmental Settings.
_Where
					 liquid-storage is to be provided in sensitive environmental settings (i.e.,
					 tanks in areas with shallow wells in surface aquifers, high-risk karst
					 topography, or other site-specific concerns), design the storage structure as a
					 reinforced concrete hydraulic or environmental structure according to NRCS NEM,
					 Part 536, Structural Design. Alternatively, use a flexible liner membrane,
					 designed and constructed in accordance with standard engineering and industry
					 practice, to provide secondary liquid containment for structures constructed
					 with other methods described in NRCS NEM, Part 536, Structural Design.
Additional Criteria - Stacking
					 Facilities
A stacking facility may be open, covered, or roofed and is
					 used for wastes which behave primarily as solid. Determine the wall height
					 using the anticipated stacking angle of the waste material. Construct a
					 stacking facility of durable materials such as reinforced concrete, reinforced
					 concrete block, or treated lumber. Design the stacking facility with adequate
					 safety factors to prevent failure due to internal or external pressures,
					 including hydrostatic uplift pressure and imposed surface loads such as
					 equipment which may be used within, on, or adjacent to the structure.
Seepage and Internal Drainage.
_Prevent
					 leachate in amounts that would pollute surface or groundwater with collection
					 and disposal of liquids in a safe manner as necessary. Seepage control may not
					 be necessary on sites that have a roof. Make provisions for drainage of
					 leachate, including rainfall from the stacking area (especially those without a
					 roof). Collect leachate in a tank or waste storage impoundment, or properly
					 treat in a vegetated treatment area.
Field Stacking Facilities
					 Criteria
Design Criteria. Locate field stacking facilities to
					 minimize the risk of surface and ground water contamination. Design
					 considerations shall include the following:
(a) Exclude unpolluted surface and ground
				  water from facilities and loading areas.
(b) Locate stacking facilities a minimum of
				  100 feet away from wells and surface water bodies and a minimum of 300 feet
				  away from Public Water Supplies (these may be wells, lakes, ponds, rivers, or
				  springs). Consider increasing setbacks from resource concerns when they are
				  located downslope from the stacking site.
(c) Locate field stacking facilities on soils
				  that are 18 inches over bedrock and 15 inches to seasonal high water table. The
				  soil shall have a maximum permeability of 2 inches/hour in the C Horizon or a
				  minimum of 18 inches of loamy fine sand or finer material with a permeability
				  of <= 2 inches/hour over the C Horizon. The maximum land slope shall be 8
				  percent. The site needs to be above the 25 year floodplain. These separation
				  distances and soils criteria are also shown in Figure 2. Soils that do not meet
				  the criteria in Figure 2 can be modified. Avoid placing field stacking
				  facilities on soils that are less than 18 inches to bedrock nor soils that are
				  less than 7 inches to the seasonal high water table (hydric soils) or
				  hydraulically restrictive layer. Some possible modifications to field stacking
				  sites include, but are not limited to:
1.
				  Increase setback distances from resource concerns.
2. Dump and spread within 30 days.
3. Berm around edges of the pile with hay
				  bales, silt fence, earth, etc.
4.
				  Create surface runoff diversions.
5. Build the soil up to increase separation
				  distance from bedrock or water table.