LEA Advisory #54—October 26, 1998

1998 Inspection Guide for Solid Waste Landfills—Part 7

Cover

Cover material or native material unsuitable for cover, stockpiled on the site for use or removal, shall be placed so as not to cause problems or interfere with unloading, spreading, compacting, access, safety, drainage, or other operations.

On-site sources of soil must have all-weather access. Stockpiles of cover material created to avoid transport problems during inclement weather must not be located in an area where they cause operational difficulties. In addition, if the stockpiles are located in an intermediate cover area accessing stockpiles should not damage the cover or change drainage patterns significantly.

A sufficient quantity of cover material of a suitable quality to meet the requirements of this Subchapter shall be available. If on-site sources of cover material are insufficient, substantiation must be shown to the EA that an adequate supply of cover material will be provided.

All landfills need to have an adequate supply of cover materials to ensure compliance with the daily cover standard (§20680) and the intermediate cover standard (§20700). The material used for daily cover may be soil or it may be an ADC material, in either case the operator needs to provide, or have access to, an adequate supply on a continual basis in order to ensure that the facility will be fully covered at the end of each operating day.

If the facility is using soil as daily cover the operator should ensure that any on-site borrow source is accessible year round. If the borrow area is, or may be, impacted by winter rains, the operator must create or provide other provisional stockpiles that will allow the facility to adequately cover the working face throughout the rainy season. If all soil is imported for cover the operator must ensure that the persons providing the cover will be able to access the site and deliver adequate soils throughout the year. In addition, any contract regarding the quantities of cover material needed should be written in a manner that will provide adequate deliveries of soil to ensure compliance with §20680.

If the operator is using ADC the same concept(s) would be applicable—the operator must maintain an adequate amount of ADC material, such as chipped green waste or other approved ADC to ensure coverage each operating day. In addition to the ADC stockpile the operator should also have access to an adequate supply of soil to ensure that, in lieu of ADC, the site will always have a cover source.

Finally, the soil material must be suitable for use as cover and able to control vectors, fires, odors, blowing litter, and scavenging, as well as drainage when applied as intermediate cover. In other words, cover material should not be excessively rocky, gravelly, or structurally inconsistent or be too permeable allowing excessive rainwater to infiltrate into waste or create or allow excessive odors or landfill gas to emit into the atmosphere. Common sense can be applied towards determining the adequacy of a particular soil as a cover material. Concerns regarding excessive water or air permeability should be referred to the RWQCB and/or AQMD/APCD as applicable.

Note: Revised regulations regarding ADC are included here, having been incorporated into 27 CCR under the authority of the CIWMB, effective November 5, 1997 and February 3, 1998. These regulations (§20680–Daily Cover, §20690–CIWMB Alternative Daily Cover, §20695–Cover Performance Standards, §20700–Intermediate Cover) are the subject of LEA Advisory #48 (December 10, 1997 and March 2, 1998), which displaces previous CIWMB correspondence and guidance regarding the use of ADC.

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(a) Except as provided in paragraph (b) and §20690, or otherwise specified in 40 CFR Part 258, the owners or operators of all municipal solid waste landfill units must cover disposed solid waste with a minimum of six inches of compacted earthen material at the end of each operating day, or at more frequent intervals if necessary, to control vectors, fires, odors, blowing litter, and scavenging. For the purposes of this section, the operating day shall be defined as the hours of operation specified in the solid waste facility permit, and may extend for more than 24 hours if operations are continuous.

(b) The EA, with concurrence by the CIWMB, may grant a temporary waiver from the requirements of paragraph (a) if the owner or operator demonstrates that there are extreme seasonal climatic conditions that make meeting such requirements impractical.

(c) Earthen material or alternative cover materials of an alternative thickness shall be placed over all surfaces of disposed solid waste for other than municipal solid waste landfill units as required by the EA to control vectors, fires, odors, blowing litter, and scavenging without presenting a threat to human health and the environment. This requirement shall also apply to municipal solid waste landfills which qualify for a delay in the general compliance date or additional flexibility as specified in 40 CFR Part 258.

(d) For the purposes of this section, earthen material shall include contaminated soil as defined in Title 14, California Code of Regulations, §17361(b), and soil with contaminants other than petroleum hydrocarbons which has been approved for use as landfill daily cover by the RWQCB, and any other governmental agencies from which approval is required, such as the Department of Toxic Substances Control and Air Pollution Control District or Air Quality Management District.

(e) For waste classification, composition, and liquid percolation requirements of daily cover, refer to the SWRCB requirements set forth in §20705 of this article.

At all MSWLFs all waste must be covered daily with a minimum of 6 inches of compacted earthen material or soil, regardless of the amount of waste received, except for facilities where:

• ADC is used pursuant to §20690.
• A temporary cover waiver has been granted by the EA, and concurred with by the CIWMB.
• The site qualifies for small landfill flexibility regarding frequency of cover application (please refer back to page 2 and review the U.S. EPA final ruling for small landfill flexibility regarding daily cover requirements).

For non-MSWLFs, or for those MSWLFs that qualify for small landfill cover frequency flexibility, 6 inches of earthen material, or alternative cover materials of an alternative thickness, pursuant to §20690, shall be placed over waste at a frequency approved by the EA (please also refer to Page 2 for U.S. EPA cover frequency flexibility). At all landfills the purpose of daily cover is to control, prevent, and/or mitigate vectors, fires, odors, blowing litter, and scavenging. If the cover is not adequately performing these functions compliance with this standard is not plausible.

The most effective way to check daily cover at a disposal site is to arrive early in the morning and observe the active face prior to the start of operations. An alternative method is to observe the operator place cover as disposal operations cease for the day. This will provide two possible checks of compliance with cover frequency and will also help reveal possible unpermitted nighttime operations. For landfills that cover at a frequency, which is not daily (every 24 hours), the inspector should make an effort to schedule the inspection on the day after cover is applied or on the day it is going to be applied to more accurately determine compliance with this standard.

The inspector should look for waste that is completely uncovered, exposed, or protruding through cover (daylighting). A violation should be noted for uncovered wastes or excessive daylighting. Excessive daylighting is where waste is protruding through the cover material in multiple and/or relatively large areas of the most recently covered cells.

The inspector should ascertain that there are at least 6 inches of soil over the entire active area and may reconsider assessments of cover based on any daylighting observed. It is not realistic to measure all daily cover manually to see if there is, indeed, 6 inches over the entire working face. It should be possible to make assessments on the depth of cover material by walking the site and using visual observations from several angles. If those efforts are insufficient to assess cover depth, and the inspector has reason to believe that there definitely is not 6 inches of cover, spot measurements could be taken of the cover as part of the inspection.

Inadequate daily cover has the potential to cause other problems both on and off site and may lead to other violations being observed such as litter migrating off site, nuisances in the form of odors, or the creation of safety hazards. Repeat violations or areas of concern should be discussed with the operator, as applying adequate daily cover is one of the most important functions of a sanitary landfill. If daily cover was adequately applied the day before but was subsequently disturbed by vectors, such as bears or birds, it is not necessarily a violation of this standard. In other words, the effort to cover by the operator was adequate but the problem is vectors and the damage they cause (see 27 CCR §20810).

When assessing daily cover, the inspector should also take into account climatic conditions both before and during the inspection. In other words, did harsh weather affect the operator’s ability to place cover adequately? If daily cover operations are inadequate another aspect to consider is the adequacy of equipment available on site.

Finally, to facilitate communication between the inspector and the operator regarding daily cover at an operation the inspector should convey his/her expectations regarding the adequacy of cover to the operator during the inspection or at the exit interview, or even during any site visit, to ensure that both parties agree as to what constitutes compliance with this standard. General agreement between the operator and the inspector regarding what constitutes adequate daily cover is the best way to ensure that the operator has clear expectations of what is expected by the inspector.

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27 CCR §20690 CIWMB Alternative Daily Cover

The use of any material other than soil as an ADC must be approved by the EA on a case-by-case basis. The use of ADC is now widespread throughout the state and the inspector should be prepared to assess the performance of any ADC as a daily cover material. In general, the basic guidance for daily cover (§20680) applies to ADC also.

The text of this standard is not included as it only applies if a disposal site is using a cover material other than soil for the purpose of demonstrating its appropriateness as an ADC. This section should be reviewed with respect to the specific alternative cover to be to be used. Sites are evaluated by the EA weekly inspection or in accordance with an EA approved ADC project. See LEA Advisory #48 for the full text of this 27 CCR regulation and associated CIWMB ADC policies.

27 CCR §20695 CIWMB Cover Performance Standards

The text of this standard is not included as it only applies if a disposal site is using a cover material other than soil for the purpose of demonstrating its appropriateness as an ADC. This section should be reviewed with respect to the specific alternative cover to be to be used. Sites are evaluated by the EA weekly inspections or in accordance with an EA approved ADC project. See LEA Advisory #48 for the full text of this 27 CCR regulation and related CIWMB ADC guidance.

(a) Compacted earthen material of at least twelve (12) inches shall be placed on all surfaces of the fill where no additional waste will be deposited within 180 days to control vectors, fires, odors, blowing litter and scavenging.

(b) Alternative materials of an alternative thickness (other than at least 12 inches of earthen material) for intermediate cover may be approved by the EA with concurrence by the CIWMB if the owner or operator demonstrates that the alternative material and thickness control vectors, fires, odors, blowing litter, and scavenging without presenting a threat to human health and the environment.

(c) For waste classification, composition, and liquid percolation requirements of intermediate cover and alternative intermediate cover, refer to the SWRCB requirements set forth in §20705 of this article.

(d) Proposed use of alternative intermediate cover shall be subject to site specific demonstration to establish suitability as intermediate cover. Demonstration projects shall be approved by the EA with concurrence by the CIWMB.

Assessment of the intermediate cover standard is similar to that of daily cover in terms of evaluating the condition of the earthen material used for cover purposes. Additionally, the operator may propose using an alternative intermediate cover (AIC). The use of AIC requires a site specific demonstration project approved by the EA with concurrence by the CIWMB (see LEA Advisory #48). Intermediate cover areas are defined as those that are not expected to be used for the placement of waste for at least 180 days. Therefore, the soil or AIC in these areas need to retain its structural integrity for much longer against the forces of wind, erosion, and settlement. The inspector should evaluate as many of these areas at each site as time allows during the day.

Landfills often have large areas of intermediate cover that have been laid down months, if not years, ago. Erosion of intermediate cover is accelerated by water and wind, as well as by differential settlement of both the waste pile and the earthen cover material. Good compaction of the cover material reduces these effects. These erosional forces also contribute to the possible exposure of waste materials, also known as daylighting. One of the prime functions of intermediate cover is to reduce and minimize daylighting over time. As in the evaluation of daily cover, observation of multiple areas of daylighting may be a fairly clear indication of a violation, i.e., that the cover was laid down in insufficient quantities or has been eroded and is in need of repair. Again, it is a good practice for the inspector to have a detailed conversation with the operator regarding what constitutes adequate intermediate cover and what the operator’s responsibilities are should the cover become eroded or otherwise compromised. This is especially true prior to and during the rainy season.

The inspector should make enough observations of the intermediate cover throughout the site to ensure that the cover has been adequately compacted. Evidence of erosion should be investigated to see if waste has been exposed. Heavy erosion should be brought to the operator's attention immediately so that repair of the intermediate cover can be initiated. Also, if heavy erosion occurs, excessive water infiltration into the waste pile may be occurring. Referral to the RWQCB regarding water infiltration issues is appropriate in this situation. Erosion of intermediate cover may also lead to excessive siltation over the facility drainage system.

Using visual observation of the intermediate cover emphasizing possible daylighting and evidence of compaction, the following guidelines would normally apply:

• If there is no daylighting and there is evidence of compaction (i.e., visible compactor or dozer tracks and/or firm material) the standard could be presumed to be in compliance.
• If there is exposed waste or little evidence of compaction (i.e., poor grading, areas of ponding, and loose/soft cover material) the EA should consider the following, in order of importance, when determining whether the standard is in compliance, is an area of concern, or is in violation:

1. Amount of exposed waste, type of waste exposed (i.e., putrescible, easily blown, inert), length of time waste has been exposed and uncovered.
2. History of facility compliance and efforts to stay in compliance, operator's general planning in addressing this standard and maintenance response time.
3. Consideration of site conditions, including cover material properties and weather/climate.
4. Do the conditions observed fail to control one of the following: vectors, fires, odors, blowing litter, scavenging, and drainage?

Observations of recent weather conditions should also be factored into how a facility might look on a given day. Obviously, if it has been raining heavily prior to, or during the inspection, the inspector should consider that the operator is functioning under adverse conditions. Poor preparation by the operator for inclement weather can lead to heavy damage to the intermediate cover. Poor grading practices, inferior compaction, or misplacement of benches and downdrains and other drainage structures can accelerate cover damage. The inspector should also be able to assess whether poor site development or bad cell sequencing may have exacerbated the normal problems expected at a landfill during precipitation events. For example, the operator might create unnecessary depressions or bowls that retain rather than shed water, might construct multiple working faces, or build winter disposal pads that are not designed to merge together. Movement of surface water from, or over, the large areas of intermediate cover common at landfills should not be contributing to damage to the intermediate cover or negatively affecting the function of the drainage system. This would imply that the site has been adequately graded to promote good drainage that is addressed more specifically under the grading of fill surfaces standard §20650.

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