Wastewater Treatment Plant Closure - PUB2568

Facilities that plan to stop operating a wastewater treatment facility must obtain approval from the Missouri Department of Natural Resources’ through a closure plan. That closure plan addresses wastewater and sludge removal, dewatering activities, removing treatment structures, removing solid waste, or leaving in place as clean fill, site grading and site shaping so that ponding does not occur. Submit closure plans to the department for review no later than 90 days after stopping operations. Permittees are required to retain their operating permit until the facility is properly closed, per 10 CSR 20-6.010(12) and 10 CSR 20-6.015, and all outstanding issues and concerns have been resolved.

If a facility is required to undergo closure as a result of enforcement actions, the Facility Closure Request Form MO 780-2512 and Closure Plan should be submitted according to the agreement or order with the department's Water Protection Program, Compliance and Enforcement section. Follow the timeframes established in the enforcement agreement in submitting documents and closing the treatment plant.

If the State Revolving Funds (SRF) are being used for closing an existing facility, the Closure Plan is approved by the engineers in the department's Financial Assistance Center. For SRF projects, closure often occurs with the building of a new treatment plant or through regionalization by extending interceptors and often part of the loan or grant is to pay for the treatment plant closure.

Once the department approves a closure plan, the facility may start closing the treatment plant. A land disturbance permit is required if disturbing more than one acre throughout the course of the closure process. This permit can be obtained through the department’s ePermitting process.

Once the closure process is complete according to the approved closure plan, the facility must submit a Request for Termination of Operating Permit MO 780-2814 to the department’s central office in Jefferson City. 

Submittal Process Summary

1. Submit Closure Plan, along with the Facility Closure Request Form to the regional office for approval. Work with the department reviewer on questions and comments on the submitted plan.
2. If closure involves more than one acre of disturbed area, apply for a land disturbance permit.
3. Complete closure according to the submitted plan and approval letter.
4. Once closure is complete, submit request for termination of operating permit to the central office in Jefferson City and the Missouri State Operating Permit will be terminated.

Closure Plans and Process

The following sections provide the minimum information the department expects in the closure plan, along with the general steps that closure for each treatment type would require. While the following information should be used to guide a permittee during the closure process, there may be alternative solutions available. More detailed requirements concerning solids evaluation and disposal requirements are included in Standard Conditions Part III of the facility’s operating permit. Closure plans are site-specific and need to address site-specific concerns and activities.

Lagoons

This category includes aerated lagoons, storage basins, flow equalization basins, earthen basins and retrofits to lagoons. The off-site discharge of lagoon effluent to ground or surface waters is prohibited without a discharge permit.

1. Wastewater may be land-applied at the appropriate agronomic rates, or pumped into the treatment facility or receiving system replacing the lagoons, provided the rate is such that hydraulic and/or organic overloading and surging of the replacement system is prevented and provided permission is obtained from the owner of the replacement system.
2. If the above method is not possible, the lagoon may be drained into the receiving stream at a rate not exceeding the maximum design flow of the lagoon, provided that before draining, the lagoon is allowed to stabilize without additional inflowing wastewater for a period not less than the design detention time of the lagoon.  It should not violate water quality standards and must comply with applicable permitted effluent limits.
3. After the treated wastewater has drained from the lagoon, allow the solid accumulation on the bottom of the lagoon to dry.
4. A disinfectant suitable for control of odors and vectors shall be applied to all remaining solids when necessary. After drying the solids should be mixed with soil and left on the bottom of the lagoon, be removed for disposal in an approved landfill, or disposed in by another approved method.
5. The lagoon may be filled with soil or may be allowed to remain bowl shaped, so as to be utilized for purposes other than waste handling, i.e., fish ponds, irrigation ponds, etc., provided this practice does not violate local health and vector control regulations and approval is obtained prior to any alternative use of the facility. All wastewater and biosolids must be removed from the lagoon before use as a pond.
6. The influent sewer shall be plugged or capped. All wastewater shall be drained from the piping and disposed of in an approved manner.
7. All mechanical equipment, piping, valves and liner materials (e.g., plastic and clay liners) shall be removed from the lagoons and disposed of in an approved manner.
8. A backfill and grading plan shall be instituted to reclaim the empty basins to the original site topography. Otherwise, any abandoned basin shall require an engineered plan of surface runoff and groundwater interception control to avoid standing, stagnant water.
9. Disturbed areas should be properly stabilized and vegetated. Disturbed areas will be considered stabilized when perennial vegetation, pavement or structures using permanent materials cover all areas that have been disturbed.

STEP Systems

Septic Tank Effluent Pumped (STEP) systems are used throughout the state, often in conjunction with recycling media filters or POD systems. Residential septic system owners should contact the local health department for decommissioning guidance. In all cases, tanks used for storing septage, sewage sludge or grease cannot be reclaimed for potable water use.

1. The influent sewer shall be plugged or capped.
2. All septage, sewage sludge, grease and sediment (e.g., grit) should be pumped and removed from the tanks and disposed off-site, to a permitted wastewater treatment plant or landfill. The septic tank should be pumped so effluent will not seep into the environment and so human contact is minimized.
3. The tank should then be removed and disposed of properly. Dosing tanks and/or distribution boxes shall be filled or removed. Outlets to the leach fields shall be plugged or capped. All pumps, piping and valves associated with the treatment plant should be removed and disposed of properly.
4. The hole should be completely backfilled with compacted earth, sand, gravel or other approved material.

Recycling Media Filters

Recycling Media Filters include recirculating sand filters, gravel filters and other types of media.

1. Sever and cap the influent line entering the wastewater treatment plant.
2. Remove all wastewater/sludge from the plant. Wastewater/sludge must be disposed of at a permitted treatment plant or land applied under the proper permit and conditions.
3. Dismantle and remove all piping, mechanical and electrical equipment from the site. Some of these items can be recycled, salvaged or reused. Items that can’t be recycled, salvaged or reused must be removed and disposed of at a permitted landfill.
4. Basins can be demolished and the concrete treated as clean fill or left on-site. If a basin is left on-site, the floor must be cracked so it cannot hold water and filled completely with clean fill material. Acceptable clean fill materials are discussed in the Construction and Demolition Wastes Section below.
5. The media can be disposed of at a permitted landfill.
   • The fine sand and gravel material can also be land applied under the proper permit and conditions; however the larger sand and gravel material is not suitable for land application.
   • The larger rock can be used as clean fill but it must be washed first. 
   • The department recommends removing the top layer of smaller/finer material and land applying, leaving the larger rock in the basin. 
   • Then with a pressure washer clean the larger rock. The wash water must be allowed to drain to the recirculation tank and not allow it to be discharged. Once the larger rocks are washed they can be treated as clean fill. 
   • The wash water must also be removed from the site and disposed of at a permitted treatment plant. 
   • The bottom of the sand filter basin must be cracked so it cannot hold water and filled completely with clean fill.

Pod Systems

Pod Systems include systems such as Advantex and EcoPod.

1. Sever and cap the influent line entering the wastewater treatment plant.
2. Remove all wastewater/sludge from the plant. Wastewater and sludge must be disposed of at a permitted treatment plant or land applied under the proper permit and conditions.
3. Dismantle and remove all pods from the site. Pods and filters must be disposed of at a permitted landfill or recycled, salvaged or reused.
4. Dismantle and remove all piping, mechanical and electrical equipment from the site. Some of these items can be recycled, salvaged or reused. Items that can’t be recycled, salvaged or reused must be removed and disposed of at a permitted landfill.

Package Plant Systems

Package plant shall include prefabricated factory assembled units and other modular type units designed for the treatment of wastewater through activated sludge processes and modifications thereof.

1. Sever and cap the influent line entering the wastewater treatment plant.
2. Remove all wastewater/sludge from the plant. 
   • Wastewater/sludge must be disposed of at a permitted treatment plant or land applied under the proper permit and conditions.
3. Dismantle and remove all piping, mechanical and electrical equipment from the site. Some of these items can be recycled, salvaged or reused.  Items that can’t be recycled, salvaged or reused must be removed and disposed of at a permitted landfill.
4. Basins can be demolished and the concrete treated as clean fill or left on-site.
   • If a basin is left on-site, the floor must be cracked so it cannot hold water and filled completely with clean fill material. 
   • Materials that are considered as clean fill are discussed in the Construction and Demolition Wastes Section below.
5. Dismantle and remove all piping, mechanical and electrical equipment from the site. Some of these items can be recycled, salvaged or reused. Items that can’t be recycled, salvaged or reused must be removed and disposed of at a permitted landfill.

Activated Sludge

Activated Sludge facilities include sequencing batch reactors, oxidation ditches and extended aeration plants.

1. The influent sewer shall be capped or plugged.
2. All sewage, sludge and sediment shall be removed. All tanks shall be removed or completely backfilled with compacted sand, earth, gravel or other approved material.
3. All piping, buildings, equipment, chemicals, other liquids, spare parts, etc. shall be removed.
4. Tanks and buildings may remain in place for other uses if they are properly cleaned and retrofitted so they are not a safety or environmental hazard.
5. All biosolids and waste materials shall be removed from the site; see the Biosolids and Construction and Demolition Sections below.
6. The effluent line shall be cleaned and removed or plugged.
7. Disturbed areas should be properly stabilized and vegetated. Disturbed areas will be considered stabilized when perennial vegetation, pavement or structures using permanent materials cover all areas that have been disturbed.

Industrial Facilities

As industrial facilities have often been in place longer and may have been used for a variety of industrial activities, closure at these facilities may be more complex than the closure of a municipal or private domestic treatment plant.

1. When closing an industrial facility or a portion of the facility, contact the permit writer and the regional office to coordinate the information required for closure of the wastewater treatment facilities, including domestic and process wastewater.
2. If the facility is required to have a stormwater permit under 10 CSR 20-6.200, then all industrial activities must cease and all industrial materials must be removed or protected with best management practices to be utilized during closure geared toward minimizing the discharge of contaminants via stormwater, removal of items exposed to precipitation events and qualify for no-exposure standards.
3. Disturbed areas should be properly stabilized and vegetated. Disturbed areas will be considered stabilized when perennial vegetation, pavement or structures using permanent materials cover all areas that have been disturbed.

The Toxicity Characteristic Leaching Procedure (TCLP) is the legal standard established by the U.S. Environmental Protection Agency to determine whether a waste contains hazardous levels of toxins. It measures the leachability of toxic substances under conditions that simulate the environment of a solid waste landfill. Most commercial environmental labs can perform this test.

The owner or contractor must arrange to provide a lab with a representative sample of the waste generated by the removal. A representative sample reflects the true makeup of the waste that will be generated or removed on average throughout the entire project. Paint removal, characterization of coal ash, coal ash removal, biosolids and industrial sludge removal are all items that TCLP testing should be completed for. Depending on the nature of the waste and the final disposition, other testing may be required.

Biosolids Removal

Biosolids (sludge) removal at the treatment plant must also be completed as part of closure and be addressed in the closure plan. The closure plan needs to include a detailed operation plan on how the biosolids will be removed. The operation plan needs to include:

1. Methods for biosolids removal from the lagoon or thickening processes to maintain a uniform and consistent percent solids.
2. Set up of equipment or processes for the treatment of wastewater sludge as warranted.
3. Wastewater biosolids sampling procedures, including the equipment used for sampling, testing and quality control measures.
4. Odor control procedures.
5. Contingency plans for potential equipment breakdown during the cleanup operation, and for wastewater biosolids found not to meet Standard Conditions Part III standards.

Additionally, the closure plan needs to include the following information to characterize the biosolids:

1. General information about the lagoon, storage basin or mechanical treatment plant such as:
   • Wastewater biosolids source(s).
   • Volume.
   • Age.
   • Estimated quantity of the wastewater biosolids.
2. Description of the operational status of the lagoon. For example, if currently out of service, provide the length of time since each lagoon has been in service.
3. A sampling plan proposal describing how and where representative biosolids samples will be collected must be provided (must include a layout plan). The sampling locations must be specified on the facility schematic layout that is included in the closure plan for approval by the department.
   • The sampling protocol will depend on the lagoon size and the amount of biosolids in the lagoon, along with physical properties, such as volume, thickness, etc.
   •  Representative sampling locations shall be selected and identified on the lagoon layout plan. For larger lagoons, additional samples and sampling locations may be required;
   • Composite samples shall be analyzed for (at a minimum) percent solids, pH and the dry weight concentration of total Kjeldahl nitrogen, ammonium nitrogen, nitrate nitrogen, total phosphorous and total potassium.
   • For fecal coliform testing, representative biosolids samples must be collected from various locations throughout the lagoon.
   • For wastewater treatment plants that have received industrial wastewater, the soil in the area of the sludge treatment or storage area (e.g., sludge drying beds) may require testing for hazardous materials including heavy metals. The specific testing parameters need established with consideration of the types of industries that have discharged to the treatment plant, past discharge monitoring reports and other relevant information.
   • The department may require the analysis of other parameters if considered necessary to protect public health and the environment.
4. Sampling procedures shall also address any abnormalities and sampling details that may be associated with this process.
5. Sampling of the biosolids for pathogens, metals, nitrogen and moisture content is required prior to discharge to a permitted land application site for forage crop (animal feed) propagation. Sampling parameters for the landfill disposal of dewatered biosolids shall be made in accordance with the landfill’s waste acceptance criteria.
6. The sampling, sample handling and analyses of analytical constituents required by the department shall be performed in accordance with 40 CFR Part 503, which requires testing for inorganic constituents be done in accordance with the most recent edition of the “Test Methods for Evaluating Solid Waste, Physical/ Chemical Methods,” EPA Publication SW-846. This publication lists procedures for sample handling and preservation.

Chemical Removal

Chemicals used and stored at the facility must be disposed of according to the Material Data Safety Sheet or relocated for use elsewhere. Material Data Safety Sheets can be found online, but should be stored with the chemicals.

Monitoring Wells

If the facility previously installed monitoring wells, plug, abandon and seal all monitoring wells in conformance with Missouri geological regulations, 10 CSR 23-4.080.

Asbestos Requirements for Demolition or Renovation Projects

The department’s Air Pollution Control Section regulates demolition and renovation projects involving public buildings and appurtenances. For more information on state and federal asbestos requirements, please contact the Air Pollution Control Program at 573-751-4817 or visit the department's  Asbestos webpage.

1. Specific to wastewater treatment facilities, asbestos containing materials can be found in items such as pipe or vessel insulation, gaskets, valve packings, mastics, trickling filter media, lab fume hoods and countertops, ceiling and wall materials, flooring products and roofing.  Asbestos cement pipe has also been used in both water distribution and wastewater collection systems. 
2. An inspection for the presence of asbestos containing materials must be conducted prior to the start of any demolition or renovation activities. Only state-certified asbestos inspectors can be used.  
3. There are two types of notifications required by the department in regard to demolition and renovation projects.
   • Asbestos abatement project notifications and demolition notifications must be submitted to the department at least 10 working days prior to the start of a regulated asbestos abatement or demolition project.
   • A copy of the asbestos inspection report and laboratory analytical results must accompany the notification.
   • The notification period allows the department time to inspect the projects and ensure they are being performed in compliance with all of the applicable requirements.
4. Additional information is available in How to Handle Asbestos Containing Debris - PUB2121.

Construction and Demolition Waste Regulations

The department’s Waste Management Program regulates all construction, demolition and renovation wastes for institutional, commercial, public and industrial structures. For more information about clean fill, recovered materials or regulated wastes, contact the Waste Management Program at 573-751-5401.

1. All construction, renovation and demolition waste that cannot be recycled/ salvaged/ reused and that does not meet the definition of clean fill must be properly disposed of at a permitted transfer station or landfill.  
2. Additional information regarding construction and demolition waste is available in Managing Construction and Demolition Waste - PUB2045.
3. Demolition or renovation operations can create several different kinds of waste:
   • Clean fill includes uncontaminated soil, rock, sand, gravel, asphaltic concrete, blocks and bricks, and minimal amounts of wood, metal and inert solids.
     • Minimal means the smallest amount possible.
     • These can be used to fill in excavated holes from demolition or construction projects.
   • Recovered materials include doors and windows, which can be removed for reuse, or scrap metal and asphalt shingles, which can be taken to a recycling center.
   • Regulated wastes are wastes that cannot be used as clean fill and cannot be recovered for reuse or recycling. These wastes must be taken to a permitted landfill or transfer station for proper disposal.
   • Hazardous waste and asbestos containing material - The most common hazardous materials encountered during demolition and renovation projects are lead paint and objects contaminated by lead paint.