R315-303-3. Standards for Design

  (1) Minimizing Liquids. An owner or operator of a landfill shall minimize liquids admitted to active areas by:

  (a) covering according to Subsection R315-303-4(4);

  (b) prohibiting the disposal of containerized liquids larger than household size, noncontainerized liquids, sludge containing free liquids, or any waste containing free liquids in containers larger than household size;

  (c) designing the landfill to prevent run-on of all surface waters resulting from a maximum flow of a 25-year storm into the active area of the landfill; and

  (d) designing the landfill to collect and treat the run-off of surface waters and other liquids resulting from a 25-year storm from the active area of the landfill.

  (e) If the owner or operator of a landfill has received a storm water permit as issued by the Utah Division of Water Quality and is meeting the requirements of the permit, the landfill may be exempt, upon approval of the Director, from the run-on and run-off control requirements of Subsections R315-303-3(1)(c) and (d).

  (2) Leachate Collection Systems.

  (a) An owner or operator of a landfill required to install liners shall:

  (i) install a leachate collection system sized according to water balance calculations or using other accepted engineering methods, either of which shall be approved by the Director;

  (ii) install a leachate collection system so as to prevent no more than one foot depth of leachate developing at any point in the bottom of the landfill unit; and

  (iii) install a leachate treatment system or a pretreatment system, if necessary, in the case of discharge to a municipal water treatment plant.

  (b) The returning of leachate to the landfill or the recirculation of leachate in the landfill may be done only in landfills that have a composite liner system or an approved equivalent liner system.

  (3) Liner Designs. An owner or operator of a landfill shall use liners of one of the following designs:

  (a) Standard Design. The design shall have a composite liner system consisting of two liners and the associated liner protection layers and a drainage system for leachate collection:

  (i) an upper liner made of synthetic material with a thickness of a least 60 mils; and

  (ii) a lower liner of at least two feet thickness of recompacted clay or other soil material with a permeability of no more than 1 x 10^-7 cm/sec having the bottom liner sloped no less than 2% and the side liners sloped no more than 33%, except where construction and operational integrity can be demonstrated at steeper slopes, with the synthetic liner installed in direct and uniform contact with the compacted soil component; or

  (b) Equivalent Design.

  (i) The Director may approve an alternative liner design, on a site specific basis, if it can be documented that, under the conditions of location and hydrogeology, the equivalent design will minimize the migration of solid waste constituents or leachate into the ground or surface water at least as effectively as the liner design required in Subsection R315-303-3(3)(a).

  (ii) When approving an equivalent liner design, the Director shall consider the following factors:

  (A) the hydrogeologic characteristics of the facility and surrounding land;

  (B) the climatic factors of the area; and

  (C) the volume and physical and chemical characteristics of the leachate; or

  (c) Alternative Design.

  (i) The owner or operator may use, as approved by the Director, an alternative design.

  (ii) The owner or operator must demonstrate that the ground water quality protection standard of Subsection R315-303-2(1) can be met. The demonstration must be approved by the Director, and must be based upon:

  (A) the hydrogeologic characteristics of the facility and the surrounding land;

  (B) the climatic factors of the area;

  (C) the volume and physical and chemical characteristics of the leachate;

  (D) predictions of contaminate fate and transport in the subsurface that maximize contaminant migration and consider impacts on human health and the environment; and

  (E) predictions of leachate flow from the base of the waste to the uppermost aquifer; or

  (d) Stringent Design. When conditions of location, hydrogeology, or waste stream justify, the Director may require that the liner of a landfill be constructed to meet standards more stringent than the liner designs of Subsection R315-303-3(3)(a).

  (e) Small Landfill Design.

  (i) The small landfill design applies only to a Class II Landfill.

  (ii) Each new Class II Landfill and any existing Class II Landfill seeking facility expansion shall meet the location standards of Section R315-302-1.

  (iii) Each new and existing Class II Landfill shall meet the performance standards of Section R315-303-2.

  (iv) A Class II Landfill, which meets the requirements of Subsection R315-303-3(3)(e)(v), is exempt from the liner, leachate collection system, and ground water monitoring requirements of Rule R315-303.

  (v) A Class II Landfill will be approved only if:

  (A) there is no evidence of existing ground water contamination;

  (B) the landfill serves a community that has no practicable waste management alternative as determined by the Director;

  (C) the landfill is located in an area which receives less than 25 inches of annual precipitation;

  (D) the landfill receives, on a yearly average, no more than 20 tons of waste per day, or if a tonnage cannot be determined, serves a population of no more than 8,900; and

  (E) the landfill meets all the requirements in Rules R315-301 through 320 applicable to Class II landfills.

  (vi) A Class II Landfill may lose the exemptions of the small landfill design if at any time the landfill receives more than 20 tons of solid waste per day, based on an annual average, or has caused ground water contamination.

  (4) Closure. At closure, an owner or operator of a Class I, II, IIIa, IVa, and V Landfill shall use one of the following designs for the final cover.

  (a) Standard Design. The standard design of the final cover shall consist of two layers:

  (i) a layer to minimize infiltration, consisting of at least 18 inches of compacted soil, or equivalent, with a permeability of 1 x 10^-5 cm/sec or less, or equivalent, shall be placed upon the final lifts;

  (A) in no case shall the cover of the final lifts be more permeable than the bottom liner system or natural subsoils present in the unit; and

  (B) the grade of surface slopes shall not be less than 2%, nor the grade of side slopes more than 33%, except where construction integrity and the integrity of erosion control can be demonstrated at steeper slopes; and

  (ii) a layer to minimize erosion, consisting of:

  (A) at least 6 inches of soil capable of sustaining vegetative growth placed over the compacted soil cover and seeded with grass, other shallow rooted vegetation or other native vegetation; or

  (B) other suitable material, approved by the Director.

  (b) Requirements for any Earthen Final Cover at a Landfill.

  (i) Markers or other benchmarks shall be installed in any final earthen cover to indicate the thickness of the final cover. These markers shall be observed during each quarterly inspection and the earthen cover shall be raised to the appropriate thickness as necessary.

  (ii) Erosion channels deeper than 10% of the total cover thickness shall be repaired as soon as possible following their discovery.

  (c) Alternative Final Cover Design. The Director may approve an alternative final cover design, on a site specific basis, if it can be documented that:

  (i) the alternative final cover achieves an equivalent reduction in infiltration as achieved by the standard design in Subsection R315-303-3(4)(a)(i); and

  (ii) the alternative final cover provides equivalent protection from wind and water erosion as achieved by the standard design in Subsection R315-303-3(4)(a)(ii).

  (d) The expected performance of an alternative final cover design shall be documented by the use of an appropriate mathematical model.

  (i) The input for the modeling shall include the climatic conditions at the specific landfill site and the soil types that will make up the final cover.

  (ii) The model shall:

  (A) be run to show the expected performance of the final cover at normal precipitation for a period of time until stability has been reached; and

  (B) shall be run to show the expected performance of the final cover during the five wettest years on record at the site or the nearest weather station.

  (e) The Director shall use the following criteria as part of the basis for determining if an alternative final cover will be approved:

  (i) If the landfill has a liner design that does not use a synthetic material such as HDPE, the model will compare the infiltration through the standard cover as required in Subsection R315-303-3(4)(a) and shall show that the alternative cover performs as well as the standard cover; or

  (ii) If the landfill has a liner composed in part of a synthetic material such as HDPE, the model must show an infiltration rate of no greater that 3 millimeters of water per year during any year of the model run.

  (f) If a landfill has been constructed using an approved alternative landfill design, the Director may require, on a site-specific basis, the landfill closure design to be more stringent than the standard design specified in Subsection R315-303-3(4)(a) to protect human health or the environment.

  (g) In no case shall any modification be made to the final cover, as placed and approved at closure by the Director, unless that modification:

  (i) is a necessary repair of the approved final cover;

  (ii) maintains or improves the effectiveness of the final cover; and

  (iii) is approved by the Director.

  (5) Gas Control.

  (a) An owner or operator shall design each landfill so that explosive gases are monitored quarterly.

  (b) If the concentration of these gases ever exceed the standard set in Subsection R315-303-2(2)(a), the owner or operator must:

  (i) immediately take all necessary steps to ensure protection of human health and, within 24 hours or the next business day, notify the Director;

  (ii) within seven days of detection, place in the operating record the explosive gas levels detected and a description of the steps taken to protect human health; and

  (iii) within 60 days of detection, implement a remediation plan, that has been approved by the Director, for the explosive gas release, place a copy of the plan in the operating record, and notify the Director that the plan has been implemented.

  (c) Collection and handling of explosive gases shall not be required if it can be shown that the explosive gases will not support combustion.

  (d) The Director may, on a site specific basis, waive the requirement of monitoring explosive gases at a Class II Landfill. The wavier may be granted after:

  (i) considering the characteristics of the landfill and the waste stream accepted;

  (ii) taking into account climatic and hydrogeologic conditions of the site; and

  (iii) completing a public comment period as specified by Section R315-311-3.

  (iv) The Director may revoke any waiver from the requirement of monitoring explosive gases if the lack of monitoring explosive gases at the landfill presents a threat to human health or the environment.

  (v) The requirement to monitor explosive gases inside buildings at a landfill may not be waived.

  (e) A landfill that accepts no municipal waste, or other waste with potential to generate methane during decomposition, is exempt from the gas monitoring requirement of Subsection R315-303-3(5)(a).

  (6) Design Drawings.

  (a) Design drawings and as built drawings of any engineered structure, including landfill liners, leachate collection systems, run-on/run-off control systems, final covers, ground water monitoring systems, and gas collection systems, shall be signed and sealed by a professional engineer registered in the State of Utah.

  (b) As built drawings shall be submitted to the Director on or before 90 days following the completion of the engineered structure at the landfill.

  (7) Other Requirements. An owner or operator shall design each landfill to provide for:

  (a) fencing at the property or unit boundary or the use of other artificial or natural barriers to impede entry by the public and large animals. A lockable gate shall be required at the entry to the landfill;

  (b) monitoring ground water according to Rule R315-308 using a design approved by the Director. The Director may also require monitoring of:

  (i) surface waters, including run-off;

  (ii) leachate; and

  (iii) subsurface landfill gas movement and ambient air;

  (c) weighing or estimating the tonnage of all incoming waste and recording the tonnage in the facility's operation record;

  (d) erecting a sign at the facility entrance that identifies at least the name of the facility, the hours during which the facility is open for public use, unacceptable materials, and an emergency telephone number. Other pertinent information may also be included;

  (e) adequate fire protection to control any fires that may occur at the facility. This may be accomplished by on-site equipment or by arrangement made with the nearest fire department;

  (f) preventing potential harborage in buildings, facilities, and active areas of rat and other vectors, such as insects, birds, and burrowing animals;

  (g) minimizing the size of the unloading area and working face as much as possible, consistent with good traffic patterns and safe operation;

  (h) approach and exit roads of all-weather construction, with traffic separation and traffic control on-site and at the site entrance; and

  (i) communication, such as telephone or radio, between employees working at the landfill and management offices on-site and off-site to handle emergencies.