Landfill Closure Guidance - PUB0187

The Missouri Department of Natural Resources’ Solid Waste Management Program (SWMP) developed this technical bulletin to provide assistance to owners of sanitary, demolition and utility waste landfills and their consultants in obtaining closure approval from the department. This bulletin is intended to address closure of landfills under the current Missouri Solid Waste Management law and rules.

The closure requirements for older facilities vary widely, depending on the regulations applicable to closure of the specific facility. The department asks owners of older facilities contact the SWMP prior to beginning closure. Contact information is provided at the end of this.

All owners or operators applying for closure approval must have a department-approved closure/post-closure plan. For further information regarding the preparation of closure/post-closure plans, see SWMP’s technical bulletin titled Guidance For Preparing Solid Waste Disposal Area Closure and Post-Closure Plans or contact the SWMP for assistance. 

Regulatory Requirements

Most of the specific regulatory requirements for closure can be found in the Missouri Solid Waste Management Regulations. 

• The requirements for closure and post-closure plans and financial assurance for all landfills are addressed in subsections 10 CSR 80-2.030(4)(A) and (B).
• Cover requirements are addressed in section 10 CSR 80-3.010(17) for sanitary landfills, section 10 CSR 80-4.010(17) for demolition landfills, and section 10 CSR 80-11.010(14) for utility waste landfills. 
• Quality assurance/quality control requirements for final cover system construction are addressed in section (6) of each chapter (3.010, 4.010, and 11.010).
• Both chapters address the timeframes for closure. 

Closure Timelines

The regulatory timeframes for landfill closure can be summarized as follows:

• Notify the SWMP in writing at least 180 days prior to the anticipated date of last receipt of waste.
• Implement closure within 30 days of last receipt of waste.
• Establish vegetation within 180 days of applying or regrading final cover soil.
• Complete closure within 180 days of initiating closure activities.

Time extensions may be granted by the SWMP. To request an extension the owner or operator must submit a written request to the SWMP within at least 30 days of the closure deadline and include a proposed schedule for completing closure. Extensions will be granted on a case-by-case basis, and only when the owner or operator has made a considerable effort to close the landfill.

Final Closure Guidance

As each phase of the landfill is completed, final cover must be applied. A good final cover will help minimize surface water infiltration and subsequent leachate production, and landfill gas production for sanitary and demolition landfills. The following are descriptions of the various components of a final cover system, listed from the bottom up in all cases:

Sanitary and Demolition Landfills Without Composite Liners

• Two feet of compacted soil classified as CH, CL, ML, SC or MH as per ASTM method D-2487.
• One foot of vegetative soil

Sanitary and Demolition Landfills With Composite Liners 

• One foot of compacted soil classified as CH, CL, ML, SC or MH as per ASTM method D-2487
• Geomembrane, thickness equal to that of the membrane in the bottom liner system (at least 30 mil thick or 60 mil for HDPE)
• Lateral drainage layer atop the geomembrane
• Two feet of vegetative soil

Utility Waste Landfills

• One foot of compacted soil classified as CH, CL, ML, SC or MH as per ASTM method D-2487.
• One foot of vegetative soil

Note: All borrow area soil used for cover construction must be tested so the soil meets the approved standards per the applicable regulations. 

Construction and Grading

The following concepts apply to all final cover construction:

• Final contours must not exceed the originally approved permitted final contours unless written approval is granted by the department prior to closure.
• The compacted soil layer must be constructed in 6- to 8-inch lifts until the desired thickness is achieved.
• The compacted soil must be covered so as to prevent damage from desiccation.
• Side slopes must not exceed permitted final grade or 3:1 (horizontal: vertical), whichever is less.
• Those areas that require the placement of a geomembrane as a component of final cover must be smooth and free of any deleterious material, ruts, ridges or other protrusions, and shall not be allowed to erode prior to the installation of the membrane.
• Surface water control structures shall be constructed promptly to prevent erosion and to control stormwater runoff.

Vegetation

Once the cover has been applied, the top surface of the landfill must be vegetated (within 180 days). Considerations for establishing a good stand of vegetation should include:

• Species of grasses/legumes
• Soil testing to determine and plant nutritional requirements (fertilizer, soil amendments)
• Seeding rate
• Seedbed preparation
• Planting Methods
• Seeding windows (season)
• Mulching or other erosion control measures

In the past, the department has not encouraged the establishment of native warm season-grasses on landfills because most types of native grasses require periodic burning, as opposed to mowing, to control invasive species and maintain a healthy stand of grass. Maintenance burning of final cover vegetation on landfills is not allowed.  However, native warm-season grasses may be approved as final cover vegetation if the landfill owner can provide adequate maintenance procedures.

Assistance with establishing vegetation may be obtained from the United States Department of Agriculture, Natural Resource Conservation Service (NRCS). The NRCS has many available publications which may prove useful, particularly the Field Office Technical Guide (FOTG) for the county in which the landfill is located. For example, Section IV of each FOTG contains useful information on critical area planting (Code 342) and establishing grassed waterways (Code 412). Contact information for the NRCS office in your area is available online.

The department must perform a final closure inspection following construction of the final cover system to determine whether the vegetation is adequate to control erosion. The department considers a good stand of healthy vegetation to be one that provides dense vegetative cover over the majority of the landfill surface. A landfill with a large area, or a large percentage of the overall surface area, that is either completely devoid of vegetation or has very sparse vegetation, is not adequately vegetated. It is difficult, if not impossible, to establish an exact, measurable standard.  However, if the deficiencies in the final cover vegetation are no more severe than what can be expected during normal post-closure maintenance, it is generally acceptable as final cover.

Quality Assurance/Quality Control

When constructing the final cover the approved Quality Assurance/ Quality Control (QA/QC) plan must be followed to ensure the cover system is properly constructed.  Proper QA/QC procedures include:

• Periodic conformance testing and continuous visual classification of the soil used to construct the compacted soil cap
• Continuous observation during construction of the compacted soil cap
• Testing the moisture and density of each lift of the compacted soil cap (usually with a nuclear moisture/density gauge) once every 10,000 square feet (i.e. on 100 foot centers)
• Surveying the elevations of the top of waste, the top of the compacted clay cap, and the final surface (including surface water control structures) on 100 foot centers and along breaks in grade
• For composite final covers, observation of the geomembrane welding techniques, destructive and non-destructive testing of the geomembrane, and manufacturer’s quality control testing and certification
• Continuous observation during application of the seed, fertilizer, and mulch on the final cover system

The procedures specified in the approved QA/QC plan will be much more detailed that what is described above.  This is intended only to address the major aspects of QA/QC.

Submittals for Closure Approval

Before closure can be approved, three copies of the following documentation must be submitted. 

• A letter, signed by the owner of the landfill, transmitting the final closure documentation and requesting that the department approve final closure of the landfill and release the closure financial assurance.
• A final closure certification report prepared by a professional engineer registered in the state of Missouri which includes a certification that final closure has been completed in accordance with the approved closure plan, a narrative describing the construction and QA/QC process and other information necessary to support the certification, such as laboratory and field testing results, final contour and other as-built drawings, survey control data, field logs, photographs, etc.
• A survey plat prepared by a Missouri registered land surveyor meeting the Minimum Standards for Property Boundary Survey specified in 10 CSR 30-2 and containing the information required by the recordkeeping requirements of 10 CSR 80-3.010(20)(C)2.A, 10 CSR 80-4.010(20)(C)2.A, or 10 CSR 80-11.010(17)(C)2.A, as applicable. The plat should be sealed by the registered land surveyor at the time of submittal.
• A certified copy of the property deed
• For landfills permitted prior to Jan. 1, 1987 which close after Jan. 1, 1989, a draft easement granting the department access to the property during the post-closure period. The department’s standard form titled Agreement for Easement, Notice and Covenant Running With Land must be used. The draft must be signed and dated by an appropriate representative of the landfill owner and the signature must be notarized.
• An affidavit from the record owner/grantor that affirms the entity holds the title, that the property is able to be encumbered with this easement, and that there are no other encumbrances that would impair this easement

A Note Concerning Survey Plats

The federal solid waste regulations do not include a requirement for landfill owners to submit survey plats upon closure. Those regulations [40 CFR 258.60(i)(1) and (2) ] only require the owner record a notation on the landfill property deed, or some other instrument that is normally examined during title search. The notation must in perpetuity notify any potential purchaser of the property that:

• The land has been used as a landfill.
• Its use is restricted.

Missouri’s regulations require a survey plat showing the detailed property description and the general location of any waste material, and indicating the general type and depth of wastes on the property. Per the regulations, the plat must also show the location of any leachate control, gas control and monitoring, and/or groundwater monitoring systems at the site that must be maintained during the post-closure period, and indicate the length of time the systems must be maintained. These regulatory requirements go a bit further than the federal requirements. In fact, the easement required under Missouri regulations, as mentioned above, satisfies the minimum federal requirement. Also, the Missouri Solid Waste Management Law [section 260.213 RSMo ] prohibits any person from selling, conveying or transferring title to any property that contains a permitted or unpermitted solid waste disposal site without disclosing to the buyer early in the negotiation process the existence and location of the site. These combined requirements far exceed the minimum federal standards for closure documentation.

To reiterate, the purpose of the survey plat is to record the existence of the landfill in the chain of title to alert any potential purchaser of the property. It is not necessarily intended to make the potential purchaser aware of particular design details (e.g., the contours of the landfill footprint, the layout of the gas collection system or the location of the groundwater monitoring wells). Those details are available in the department’s files. In fact, those files should be the source of detailed information for any potential purchaser, not the survey plat.

In addition, when a land surveyor certifies a survey meets the Minimum Standards for Property Boundary Survey, they are certifying a property boundary survey, not necessarily the accuracy of the locations of the various environmental control and monitoring systems. It is also redundant to include this type of information on the survey plat when it is available on the engineering (as-built) drawings. As such, the SWMP has on occasion allowed owners to submit a separate engineering drawing to be recorded in the chain of title along with the survey plat, showing the location and layout of the environmental control and monitoring systems that are in place at the landfill. In fact, while either approach is acceptable, the SWMP prefers landfill owners take the latter approach rather than cluttering a survey plat with too much information. If a survey plat and an engineering drawing are submitted as part of the closure documentation, both documents must be submitted to the SWMP for review along with the other closure documentation, prior to being recorded. 

A Note Concerning Easements

For landfill permitted after Jan. 1, 1987, the easement was required to be executed following issuance of the permit, but prior to beginning waste disposal operations, so it should have been taken care of prior to closure. If your landfill was permitted prior to Jan. 1, 1987 and no easement has been executed with the department, you should contact the SWMP and discuss the matter. The SWMP will require you to begin the process of developing the easement so it may be executed as soon as possible. 

Note: Filing of Survey Plat:

1. Within 30 days of department approval of the plat, the owner or operator shall file the plat with the county recorder of deeds.
2. Two copies of the recorded plat shall be submitted to the department within 30 days of the filing.
3. Owners or operators of solid waste disposal areas permitted prior to Jan. 1, 1987 and which close after Jan. 1, 1989 as part of closure must
   1. Execute an easement with the department or its agents to enter the site to monitor, maintain or take remedial action during the 30 year post-closure period.
   2. Submit evidence to the department that a notice and covenant running with land has been filed with the county recorder of deeds. The notice and covenant shall specify the following:
      1. The property has been permitted as a sanitary landfill.
      2. That use of the land which interferes with the closure/post-closure plan is prohibited.
4. SWMP has created a standard form which must be submitted upon completion of closure. This form should be completed concurrently with the survey plat.

Final Closure Approval/Denial

Once the final closure documentation described above has been submitted, the SWMP will review the certification report, survey plat and easement, and determine whether the final closure documentation is approvable. The SWMP will also conduct a final closure inspection to verify that vegetation has been adequately established and the final cover is free of excessive erosion. Based on its review of the final closure documentation and inspection of the landfill, the SWMP will either approve or deny the request for final closure. If final closure is approved, the owner will be notified in writing and the SWMP will initiate release of the closure financial assurance.

If final closure is denied, the owner will be notified in writing and the deficiencies will be explained. A reasonable timeframe for correcting the deficiencies and demonstrating compliance will be given to the landfill owner.

In some situations, the SWMP may approve the survey plat, the engineering drawing if one is submitted, the easement, and/or the engineering certification report in advance of issuing final closure approval. The SWMP might also provide comments on any or all of the documents, which will need to be addressed before the SWMP can approve them. The point is the review and approval of these documents sometimes run separate courses. Approval of final closure will only be issued after the SWMP approves all of the documentation and finds the landfill to be in satisfactory condition upon inspection.

Recording of Survey Plat and Easement

Following the SWMP’s review and approval of the survey plat (and engineering drawing if one is submitted), the easement, notice and covenant running with the land, and the affidavit, the owner will be required to file the documents with the Recorder of Deeds in the county where the landfill is located. The regulations require the plat be recorded within 30 days of the SWMP’s approval of the document, so this is the general timeframe we will follow for recording of the documents. Once the documents have been recorded, one notarized original and one notarized copy of each recorded document, showing the recorder’s seal or stamp, and the book and page number, must be submitted to the SWMP for our records.

Other Recommended Guidance

• University of Missouri Extension Services document Soil Sampling Hayfields and Row Crops (G9217)
• University of Missouri Extension Services document Interpreting Missouri Soil Test Reports (G9112)