The design and construction of animal waste storage facilities for confined swine feeding operations shall meet the following minimum standards:
(a) Animal waste storage structures shall be required to have secondary containment and liquid recovery systems incorporated because they are subject to a constant hydraulic head.
(b) A total minimum animal waste storage capacity equal to nine (9) months waste production shall be provided to allow for the limited periods when manure slurries may be land applied.
(c) The design of the operational unit shall permit any animal waste storage structure to be removed completely from service for repair without significant impact to the feeding operation.
(d) Concrete construction shall conform to recommendations of the "Concrete Manure Storage Handbook," MWPS-36 dated 1994, or later version as adopted by division policy, published by the MidWest Plan Service and available from the land grant universities of the North Central Region.
(e) Structures interior to or beneath swine housing facilities constructed of concrete, shall meet the following requirements: (Construction of other materials shall be addressed pursuant to Section 31 of these regulations.) - (i) Construction shall be of air entrained concrete with a 28-day compressive strength of 4000 psi or better. All joints shall be keyed construction and sealed with a high quality elastomeric caulk. All expansion joints shall have bulb type water stops.
- (ii) The secondary containment shall consist of a geomembrane liner at least 30 mils thick installed according to the manufacturer's recommendations, a geosynthetic clay liner, or a compacted clay liner at least one (1) foot thick with a permeability of 1 X 10-6 cm/sec or less. Compacted clay liners shall be constructed, tested, and certified in accordance with the provision of Section 35(d)(i)(A). The secondary containment shall be graded to the recovery system with a minimum grade of 0.4 percent.
- (A) The secondary containment surfaces shall drain by gravity into the recovery system. The recovery pump shall have a totalizing hour meter and a high level alarm.
- (B) The amount of the liquids being recovered from the secondary containment surface shall be determined and recorded on a weekly basis. If the calculation of liquids recovered exceeds sixty (60) gallons/week/thousand square feet of confinement building, repair of the storage tank or pit must be completed within six (6) months. The permittee shall report any rate greater than this to the Division within seven (7) days.
- (C) If the recovery rate exceeds 120 gallons/week/thousand square feet of confinement building, the storage facility must be emptied within sixty (60) days and repairs made. The permittee shall report any rate greater than this to the Division within 48 hours.
- (D) If the high alarm level is reached, the Division must be notified immediately. The storage tank must be emptied immediately.
- (iii) Animal waste shall not be allowed to accumulate to within one (1) foot of the bottom of the floor slats.
- (iv) Interior or under floor animal waste storage facilities shall be mechanically ventilated. If the exhaust gas from this mechanical ventilation is determined to be a source of problem odors, treatment of the exhaust gas shall be required. A positive odor control technology resulting in either the adsorption or destruction of the odor causing gases shall be installed.
(f) Above grade structures are subject to the following requirements: - (i) Above grade structures shall be surrounded with a containment dike designed to hold a minimum of 1.5 times the tank volume.
- (ii) Secondary containment shall be designed and operated pursuant to Section 34(e)(ii) of these regulations.
- (iii) A floating cover shall be maintained on uncovered above ground structures. Other BAT may be employed or required instead of a floating cover.
(g) Below grade external structures shall be either concrete or lined earthen storage basins. - (i) Concrete structures and secondary containment systems shall be designed according to this section.
- (ii) Lined earthen storage basins shall be designed according to Section 35(c) and (d) of these regulations.
- (A) Only earthen basins with geomembrane liners and secondary containment shall be allowed. The geomembrane liner shall be a minimum of 60 mils thick and installed according to the manufacturer's instructions.
- (B) The engineering design report must show the animal waste removal operations shall not damage the integrity of the liner.
- (iii) A floating cover shall be maintained on uncovered below grade external structures. Other BAT may be employed or required instead of a floating cover.
020-20 Wyo. Code R. § 20-34