Current through September 21, 2024
The construction and operation of solids separators and
liquid animal waste treatment lagoons shall meet the following minimum
standards. Methane generation, composting, and other treatment systems are
encouraged. Permitting of such systems shall be reviewed under provisions of
Section 31 of these regulations. When considering alternate technology, primary
emphasis shall be given to environmental protection, improved odor management,
and pathogen control. The appropriate MidWest Plan Service publications are the
preferred basis for alternative designs.
(a) Solids separation techniques may be used
to remove solids from the animal waste. To be considered separated solid
manure, the solids content must be greater than ten (10) percent by weight and
the resultant mass must pass the paint filter test, i.e., when the mass is
placed in a paint filter no liquid shall drain through the filter.
(i) Separated solids shall be stored on a
water tight paved surface:
(A) The storage
area shall be sloped to a gutter that drains to the liquid animal waste
treatment facility.
(B) The storage
area shall not receive precipitation runoff from other areas of the
facility.
(C) The storage floor or
pavement shall have adequate structural integrity for the equipment used to
load or remove the solids.
(ii) Operation of the solids separator and
solids storage area shall follow the odor, dust, and vector control procedures
required by Sections 40, 41, and 42 of these regulations.
(A) All solids shall be removed from the
storage area and the area cleaned within thirty
(30) days after the spring thaw each
year.
(B) Pesticides and
rodenticides shall be employed as necessary to control rodents or insects
breeding or feeding on the solids. The vector control agents used shall not
leave any residuals in or on the solid animal waste.
(iii) The solids storage area shall be large
enough to hold six (6) months' production of animal wastes unless the
management plan demonstrates the ability to use the animal wastes in a more
timely fashion.
(b)
Wastewater treatment lagoons receiving liquid animal wastes diluted with water
to a solids content of five (5) percent or less by weight shall be sized and
constructed according to this section and one of the following references, USDA
Part 651 Agricultural Waste Management Field Handbook, MWPS-8 Swine Housing and
Equipment Handbook, or MWPS-18 Livestock Waste Facilities Handbook, or later
version as adopted by division policy. The design report shall reflect which
reference is used as the basis of design. Lagoons receiving dilute liquid
wastes as defined in Section 3(m) may be designed as single cell compacted clay
lined structures. Lagoons receiving animal wastes other than dilute liquid
wastes shall be designed with a minimum of two (2) cells with the capability to
continue confined swine feeding operations with one (1) cell removed from
service for maintenance or repair.
(c) Earthwork standards.
(i) Soils used in constructing the lagoon
bottom and dike cores (not including the liner) shall be relatively
incompressible, have low permeability, and be free from organic material or
trash. The soil shall be compacted at a water content that shall ensure
structural stability, reduce hydraulic seepage, and reduce settling. The soil
shall provide an adequate foundation for the liner, if used.
(ii) For lagoons that are not specified to
receive a geomembrane liner, no rocks larger than six (6) inches in length
shall be permitted in any of the designated embankment.
(iii) For lagoons specified to be lined with
a geomembrane liner, rocks larger than six (6) inches in length shall not be
placed within five (5) feet of the interior slope of any lagoon embankment.
Material containing by volume less than 25 percent of rock larger than six (6)
inches and less than 12 inches in length may be placed in the remainder of the
embankment.
(iv) Outer dike slopes
shall not be steeper than one (1) vertical to three (3) horizontal. Flatter
slopes may be required to maintain slope stability. Outer dike slopes shall
prevent surface runoff from entering the lagoons.
(v) Inner dike slopes shall be sloped between
one (1) vertical to four (4) horizontal and one (1) vertical to three (3)
horizontal. Flatter inner slopes may be allowed where vegetation, due to the
shallower slopes, shall not interfere with treatment or the dike's integrity.
Interior slopes surfaced with concrete paving or riprap may be constructed at
slopes of one (1) vertical to two (2) horizontal.
(vi) The minimum top dike width shall be 12
feet to allow access to maintenance vehicles. Top dikes wider than 12 feet
shall be required when necessary to ensure structural stability.
(vii) The minimum freeboard at the maximum
operating level shall be three (3) feet.
(viii) Interior embankments shall be
protected from wave action with riprap, paving, or other erosion resistant
material. The following conditions may be exempted from the riprap
requirements:
(A) Lagoons of one (1) surface
acre or less.
(B) Lagoons with a
geomembrane liner.
(C) Embankments
cut into natural slopes when a soil liner is not provided.
(D) Lagoons sheltered from wind or where wind
velocities are low enough that significant erosion shall not occur.
(ix) Exterior of dikes, top of
dikes, and all interior dike surfaces where riprap or a seal is not provided
shall be covered with topsoil and seeded with suitable dry land grasses to
prevent erosion. A coarse uniform graded gravel may be substituted for the
vegetation requirement.
(x) The
seepage through the lagoon bottom and side walls shall not cause a violation of
the groundwater standards as described in Chapter 8, Quality Standards for
Wyoming Groundwaters, Water Quality Division Rules and Regulations.
(d) The allowable permeability of
a compacted clay liner shall be based on the type of lagoon construction and
the type of liquid animal waste contained in the lagoon.
(i) The specifications for compacted clay
liners shall be based upon the results of a preliminary testing program and
shall contain the type of material, optimum and acceptable range in water
content, acceptable range for compaction, and maximum allowable particle size.
Compacted clay liners used to protect groundwater quality shall meet the
following criteria:
(A) The tests for water
content and density shall be taken during the placement of each lift of the
liner. A total minimum liner thickness of one (1) foot shall be provided and
shall be constructed with maximum lifts of one-half (0.5) foot. Either
permeability testing of undisturbed core samples from the in-place seal, or
detailed tests such as particle size distribution and Atterburg limits shall be
conducted. Detailed tests should confirm that the soil specified was used for
liner construction. One (1) test shall be conducted per acre per lift. For core
sampling of the in-place liner, one (1) core of the completed liner shall be
tested per acre. The permittee shall provide the Division written certification
by a Wyoming registered professional engineer that the soil liner was
constructed according to the permit and that final testing indicated results
within the allowable limits established by the permit.
(B) For compacted clay liners, a method of
maintaining the seal at or above optimum moisture conditions is
required.
(ii) Unlined
lagoons or lagoons using compacted clay liners as the primary liner shall
require a subsurface investigation and monitoring plan according to the
provisions of Chapter 3, Section 17(b), (c), and (d).
(A) Lagoons receiving dilute liquid wastes
may be designed as a single cell system. Dilute liquid waste systems shall not
have a combined evaporation and exfiltration rate that exceeds 25 percent of
the minimum daily inflow from operations.
(B) Multiple cell lagoons shall not have a
combined evaporation and exfiltration rate that interferes with the treatment
processes occurring in the lagoons.
(iii) Control of the exfiltration from
lagoons may be provided by a cone of depression. The cone of depression created
by the withdrawal of groundwater to provide water for the operation must be
adequate to intercept all leachate from the lagoon. Water rights for the
pumping necessary to create the cone of depression must be adjudicated before
the issuance of a permit for a confined swine feeding operation using this
method of animal waste treatment.
(e) Geosynthetic clay liners installed
according to the manufacturer's instructions are acceptable. Geosynthetic clay
liners shall have a maximum hydraulic conductivity of 1 X 10-8
cm/sec. The liner manufacturer shall have more than ten million
square feet of its product installed. The liner installation contractor shall
be approved by the manufacturer. Geosynthetic clay liners used as primary
liners require:
(i) Surface erosion and
abrasion protection provided shall be acceptable to the liner manufacturer. The
factor of safety for slope failure of the composite liner shall be shown to be
at least 1.5:1. Primary geosynthetic clay liners shall be installed over a
compacted clay liner. The compacted clay liner shall have a minimum thickness
of one (1) foot and a maximum permeability of 1 X
10-5 cm/sec. Compacted clay liners shall be
constructed, tested, and certified in accordance with the provision of Section
35(d)(i)(A). This type of construction shall satisfy the requirements for a
subsurface investigation as required by the provisions of Chapter 3, Section
17(b). A monitoring system installed according to the provisions of Chapter 3,
Section 17(b) shall be required.
(ii) Geosynthetic clay liners may be used as
secondary liners. Overlying leachate collections systems shall be sand blankets
at least four (4) inches in thickness. Synthetic drainage media shall not be
used with geosynthetic clay liners.
(f) Geomembrane liners constructed of
polyvinyl chloride or polypropylene shall be at least 30 mils in thickness.
High density polyethylene liners shall be at least 60 mils in thickness. The
liner manufacturer shall have more than ten million square feet of its product
installed. Geomembrane liners installed and operated according to this section
shall satisfy the requirements for a subsurface investigation and monitoring as
required by the provisions of Chapter 3, Section 17(b).
(i) Secondary containment shall be required
for all geomembrane liners. The secondary containment shall be one of the
following:
(A) A compacted clay liner with a
maximum permeability of 1 X 10-6 cm/sec.
(B) A geosynthetic clay liner.
(C) A geomembrane liner with a minimum
thickness of 20 mils backed by a compacted clay liner one (1) foot thick with a
maximum permeability of 1 X 10-5 cm/sec.
(D) Compacted clay liners shall be
constructed, tested, and certified in accordance with the provision of Section
35(d)(i)(A).
(ii)
Geomembrane liners require a secondary containment system.
(A) The drainage layer between the primary
and secondary liners shall have a minimum hydraulic transmissivity of one (1)
gpm/foot. Synthetic drainage media may be used when the secondary liner is a
geomembrane. All other construction shall require a durable granular filter
blanket with a minimum thickness of four (4) inches. The drainage layer shall
have a minimum grade of 0.4 percent.
(B) Perforated or slotted collection lines
shall be installed in the drainage layer arranged to create sub-cells with a
maximum area of two (2) acres or less. A means of monitoring the collection
system to isolate a leak to an individual sub-cell shall be provided. No
portion of the drainage layer should be more than 100 feet from a collection
line.
(C) The collection lines
shall drain to a sump enclosed by the secondary liner. The sump shall be
designed so that the maximum high liquid level during operating conditions is
below the invert of any collection line discharging to the sump. The sump shall
be large enough to allow the pump installed to operate with a minimum pumping
time of two (2) minutes between the automatic start and stop levels. A high
level alarm shall be installed.
(D)
The recovery pump in the sump shall be self-priming and capable of pumping a
volume at least four (4) times the failure rate of flow designated in the
permit for the lagoon. The pump shall have a totalizing hour meter that records
total time of operation.
(E)
Monitoring requirements are as follows:
(I)
High level alarms shall be continuously monitored.
(II) The totalizing hour meters shall be read
at least weekly. If the calculated recovery rate exceeds the allowable for the
smallest sub-cell, the inflow from each sub-cell must be measured to determine
individual sub-cell compliance.
(F) Reporting and required repair actions are
as follows:
(I) If the recovery rate exceeds
400 gpd/acre for any sub-cell as delineated by the recovery system, the
permittee shall notify the Division within seven (7) days. Repair of the
primary liner must be scheduled within twelve (12) months.
(II) If the recovery rate exceeds 800
gpd/acre for any sub-cell as delineated by the recovery system, the Division
shall be notified within 48 hours. Repair of the primary liner must be
scheduled within sixty (60) days.
(III) If the high alarm level is reached, the
Division must be notified immediately. Repairs must be initiated
immediately.
