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Minnesota Stormwater Manual

Difference between revisions of "Operation and maintenance of filtration"

(Created page with " ===Operation and Maintenance=== ====Overview==== <p>The most frequently cited maintenance concern for filters is surface and under-drain clogging caused by org...")
 
 
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The most frequently cited maintenance concern for filters is surface and [[Glossary#U|underdrain]] clogging caused by organic matter, fine silts, hydrocarbons, and algal matter. Common operational problems include:
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*standing water;
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*clogged filter surface; and
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*clogged, inlet, outlet or under-drains
  
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===Operation and Maintenance===
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==Design phase maintenance considerations==
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====Overview====
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Implicit in the design guidance in the previous sections is the fact that many design elements of filtering systems can minimize the maintenance burden and maintain pollutant removal efficiency. Key examples include limiting drainage area, providing easy site access (''REQUIRED''), and providing adequate pre-treatment (''REQUIRED'').
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<p>The most frequently cited maintenance concern for filters is surface and [[Glossary@U|under-drain]] clogging caused by organic matter, fine silts, hydrocarbons, and algal matter. Common operational problems include:</p>
 
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*Standing water
 
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*Clogged filter surface
 
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*Clogged, inlet, outlet or under-drains
 
  
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====Design Phase Maintenance Considerations====
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==Construction phase maintenance==
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<p>Implicit in the design guidance in the previous sections is the fact that many design elements of filtering systems can minimize the maintenance burden and maintain pollutant removal efficiency. Key examples include: limiting drainage area, providing easy site access (''REQUIRED''), and providing adequate pre-treatment (''REQUIRED'').</p>
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Proper construction methods and sequencing play a significant role in reducing problems with operation and maintenance (O&M). In particular, with filter construction the most important action for preventing operation and maintenance difficulties is to ensure that the contributing drainage area has been fully stabilized prior to bringing the practice on line (this is a ''REQUIRED'' practice).
 +
<p>Inspections during construction are needed to ensure the filter practice is built in accordance with the approved design and standards and specifications. Detailed inspection checklists should be used that include sign-offs by qualified individuals at critical stages of construction, to verify the contractor’s interpretation of the plan is acceptable with the designer. Example construction phase inspection checklists exist for [[Bioretention - construction inspection checklist|bioretention]], [[Media filter system - construction inspection checklist|media filter systems]], and [[Vegetative filter system - construction inspection checklist|vegetative filter systems]].</p>
  
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====Construction Phase Maintenance====
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==Post-construction operation and maintenance==
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<p>Proper construction methods and sequencing play a significant role in reducing problems with operation and maintenance (O&M). In particular, with filter construction the most important action for preventing operation and maintenance difficulties is to ensure that the contributing drainage area has been fully stabilized prior to bringing the practice on line (this is a ''REQUIRED'' practice).</p>
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Proper maintenance is critical to the successful operation of a filtration practice. Without regular maintenance, filtration system media can become clogged, losing its ability to conduct water at the designed rate. This can lead to stagnant water, mosquito breeding habitat, and reduction or elimination of pollutant removal capacity.
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<p>Inspections during construction are needed to ensure the filter practice is built in accordance with the approved design and standards and specifications. Detailed inspection checklists should be used that include sign-offs by qualified individuals at critical stages of construction, to verify the contractor’s interpretation of the plan is acceptable with the designer. An example construction phase inspection checklist is [[Stormwater pond/ wetland - construction inspection checklist|here]].</p>
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{{alert|A maintenance plan clarifying maintenance responsibility is ''REQUIRED''.|alert-danger}}
  
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Effective long-term operation of filtration practices necessitates a dedicated and routine maintenance schedule with clear guidelines and schedules. Some important post-construction considerations are provided below.
  
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===Post-construction Operation and Maintenance===
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*A site specific operation and maintenance (O&M) plan that includes the following considerations should be prepared by the designer prior to putting the stormwater filtration practice into operation:
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<p>Proper maintenance is critical to the successful operation of a filtration practice. Without regular maintenance, filtration system media can become clogged, losing its ability to conduct water at the designed rate. This can lead to stagnant water, mosquito breeding habitat, and reduction or elimination of pollutant removal capacity.</p>
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**operating instructions for drawdown valves, gates and removable weirs (surface filters only);
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{{alert|A maintenance plan clarifying maintenance responsibility is ''REQUIRED''.|alert-danger}}
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**vegetation maintenance schedule;
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**inspection checklists; and
 +
**routine maintenance checklists
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*A legally binding and enforceable maintenance agreement should be executed between the facility owner and the local review authority to ensure the following:
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**sediment should be cleaned out of the sedimentation chamber when it accumulates to a depth equal to ½ the total depth to the outlet, or when greater than 1.5 feet, whichever is less. The sediment chamber outlet devices should be cleaned/repaired when drawdown times exceed 36 hours. Trash and debris should be removed as necessary; and
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**silt/sediment should be removed from the filter bed when the accumulation exceeds one inch. When the filtering capacity of the filter diminishes substantially (i.e., when water ponds on the surface of the filter bed for more than 48 hours), the top few inches of discolored material should be removed and replaced with fresh material. The removed sediments should be disposed in an acceptable manner (i.e., landfill).
 +
*Media filters that have a grass cover should be mowed as needed during the growing season to maintain maximum grass heights less than 12 inches.
  
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<p>Effective long-term operation of filtration practices necessitates a dedicated and routine maintenance schedule with clear guidelines and schedules. Some important post-construction considerations are provided below along with ''RECOMMENDED'' maintenance standards in the table below. A more detailed checklist of maintenance activities and associated schedules is provided in the table below.</p>
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Example operation and maintenance checklists exist for [[Bioretention - operation and maintenance checklist|bioretention]], [[Media filter system - operation and maintenance checklist|media filter systems]], and [[Vegetative filter system - operation and maintenance checklist|vegetative filter systems]].
 +
The following table provides a more detailed checklist of maintenance activities and associated schedule along with ''RECOMMENDED'' maintenance standards.
  
 
{{:Recommended maintenance activities for media filters}}
 
{{:Recommended maintenance activities for media filters}}
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*A site specific O&M plan that includes the following considerations should be prepared by the designer prior to putting the stormwater filtration practice into operation:
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{{alert|The filter media should consist of an 18-inch layer of clean washed medium sand (meeting ASTM C-33 concrete sand) on top of the underdrain system.|alert-warning}}
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*Operating instructions for drawdown valves, gates and removable weirs (surface filters only).
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*Vegetation maintenance schedule.
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<noinclude>
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*Inspection checklists
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==Related pages==
−
*Routine maintenance checklists
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*[[Overview for sand (media) filters]]
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*A legally binding and enforceable maintenance agreement should be executed between the facility owner and the local review authority to ensure the following:
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*[[Types of sand (media) filters]]
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*Sediment should be cleaned out of the sedimentation chamber when it accumulates to a depth equal to ½ the total depth to the outlet, or when greater than 1.5 feet, whichever is less. The sediment chamber outlet devices should be cleaned/repaired when drawdown times exceed 36 hours. Trash and debris should be removed as necessary.
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*Design criteria for sand (media) filters
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*Silt/sediment should be removed from the filter bed when the accumulation exceeds one inch. When the filtering capacity of the filter diminishes substantially (i.e., when water ponds on the surface of the filter bed for more than 48 hours), the top few inches of discolored material should be removed and replaced with fresh material. The removed sediments should be disposed in an acceptable manner (i.e., landfill).
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**See [[Design criteria for filtration]]
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*Media filters that have a grass cover should be mowed as needed during the growing season to maintain maximum grass heights less than 12 inches.
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*[[Construction specifications for sand (media) filters]]
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*[[Assessing the performance of sand (media) filters]]
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*Operation and maintenance of sand (media) filters
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**See [[Operation and maintenance of filtration]]
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*Calculating credits
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**[[Calculating credits for sand (media) filters]]
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**[[Calculating credits for iron enhanced sand filter]]
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*[[Cost-benefit considerations for sand (media) filters]]
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*[https://stormwater.pca.state.mn.us/index.php?title=References_for_filtration References for sand (media) filters]
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*[[Requirements, recommendations and information for using sand filter as a BMP in the MIDS calculator]]
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*[[CADD images for individual best management practices|Links to detail images]]
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**Perimiter sand filter details: [[File:Perimeter Sand Filter PERIMETER SAND FILTER DETAILS (1).pdf]]
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**Surface sand filter: [[File:SURFACE Sand Filter3 Surface sand filter (1).pdf]]
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**Underground sand filter: [[File:UNDERGROUND SAND FILTER Layout2 (1).pdf]]
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*[[Calculating credits for dry swale (grass swale)]]
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*[[Calculating credits for dry swale (grass swale)|Step-pool]]
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*[[Calculating credits for wet swale (wetland channel)]]
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*[https://stormwater.pca.state.mn.us/index.php?title=Category:Level_3_-_General_information,_reference,_tables,_images,_and_archives/Images/Sand_filter,_iron_enhanced_sand_filter,_media_filter_photos Sand filter and iron enhanced sand filter photos]
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*[https://stormwater.pca.state.mn.us/index.php?title=Category:Level_3_-_General_information,_reference,_tables,_images,_and_archives/Tables/Sand_filter,_iron_enhanced_sand_filter,_media_filter Sand filter and iron enhanced sand filter tables]
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*[[Fact sheet for filtration|'''Fact sheet for filtration''']] (Includes vegetated filters)
  
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{{alert|The filter media should consist of an 18-inch layer of clean washed medium sand (meeting ASTM C-33 concrete sand) on top of the underdrain system.|alert-caution}}
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[[Category:Level 3 - Best management practices/Specifications and details/Operation and maintenance]]
 +
</noinclude>

Latest revision as of 13:51, 29 December 2022

The most frequently cited maintenance concern for filters is surface and underdrain clogging caused by organic matter, fine silts, hydrocarbons, and algal matter. Common operational problems include:

  • standing water;
  • clogged filter surface; and
  • clogged, inlet, outlet or under-drains

Design phase maintenance considerations

Implicit in the design guidance in the previous sections is the fact that many design elements of filtering systems can minimize the maintenance burden and maintain pollutant removal efficiency. Key examples include limiting drainage area, providing easy site access (REQUIRED), and providing adequate pre-treatment (REQUIRED).

Construction phase maintenance

Proper construction methods and sequencing play a significant role in reducing problems with operation and maintenance (O&M). In particular, with filter construction the most important action for preventing operation and maintenance difficulties is to ensure that the contributing drainage area has been fully stabilized prior to bringing the practice on line (this is a REQUIRED practice).

Inspections during construction are needed to ensure the filter practice is built in accordance with the approved design and standards and specifications. Detailed inspection checklists should be used that include sign-offs by qualified individuals at critical stages of construction, to verify the contractor’s interpretation of the plan is acceptable with the designer. Example construction phase inspection checklists exist for bioretention, media filter systems, and vegetative filter systems.

Post-construction operation and maintenance

Proper maintenance is critical to the successful operation of a filtration practice. Without regular maintenance, filtration system media can become clogged, losing its ability to conduct water at the designed rate. This can lead to stagnant water, mosquito breeding habitat, and reduction or elimination of pollutant removal capacity.

Warning: A maintenance plan clarifying maintenance responsibility is REQUIRED.

Effective long-term operation of filtration practices necessitates a dedicated and routine maintenance schedule with clear guidelines and schedules. Some important post-construction considerations are provided below.

  • A site specific operation and maintenance (O&M) plan that includes the following considerations should be prepared by the designer prior to putting the stormwater filtration practice into operation:
    • operating instructions for drawdown valves, gates and removable weirs (surface filters only);
    • vegetation maintenance schedule;
    • inspection checklists; and
    • routine maintenance checklists
  • A legally binding and enforceable maintenance agreement should be executed between the facility owner and the local review authority to ensure the following:
    • sediment should be cleaned out of the sedimentation chamber when it accumulates to a depth equal to ½ the total depth to the outlet, or when greater than 1.5 feet, whichever is less. The sediment chamber outlet devices should be cleaned/repaired when drawdown times exceed 36 hours. Trash and debris should be removed as necessary; and
    • silt/sediment should be removed from the filter bed when the accumulation exceeds one inch. When the filtering capacity of the filter diminishes substantially (i.e., when water ponds on the surface of the filter bed for more than 48 hours), the top few inches of discolored material should be removed and replaced with fresh material. The removed sediments should be disposed in an acceptable manner (i.e., landfill).
  • Media filters that have a grass cover should be mowed as needed during the growing season to maintain maximum grass heights less than 12 inches.

Example operation and maintenance checklists exist for bioretention, media filter systems, and vegetative filter systems. The following table provides a more detailed checklist of maintenance activities and associated schedule along with RECOMMENDED maintenance standards.

Recommended maintenance activities for media filters (Sources: WMI, 1997; Pitt, 1997).
Link to this table

Activity Schedule
  • If filter bed is clogged or partially clogged, manual manipulation of the surface layer of sand may be required. Remove the top few inches of media, roto-till or otherwise cultivate the surface, and replace media with like material meeting the design specifications.
  • Replace any filter fabric that has become clogged.
 As needed
  • Ensure that contributing area, facility, inlets and outlets are clear of debris.
  • Ensure that the contributing area is stabilized and mowed, with clippings removed.
  • Remove trash and debris.
  • Check to ensure that the filter surface is not clogging (also check after storms greater than about 1”).
  • Ensure that activities in the drainage area minimize oil/grease and sediment entry to the system.
  • If permanent water level is present in pre-treatment chamber (e.g., perimeter sand filter), ensure that the chamber does not leak, and normal pool level is retained.
 Monthly
  • Check to see that the filter bed is clean of sediment and the sediment chamber is not more than 6 inches of sediment. Remove sediment as necessary.
  • Make sure that there is no evidence of deterioration, spalling or cracking of concrete.
  • Inspect grates (perimeter sand filter).
  • Inspect inlets, outlets and overflow spillway to ensure good condition and no evidence of erosion.
  • Repair or replace any damaged structural parts.
  • Stabilize any eroded areas.
  • Ensure that flow is not bypassing the facility.
  • Ensure that no noticeable odors are detected outside the facility.
 Annually
  • Remove and replace the top 2-5 inches of media every 3 to 5 years for low sediment applications, more often for areas of high sediment yield or high oil and grease
3 to 5 years


Caution: The filter media should consist of an 18-inch layer of clean washed medium sand (meeting ASTM C-33 concrete sand) on top of the underdrain system.


Related pages

Retrieved from "https://stormwater.pca.state.mn.us/index.php?title=Operation_and_maintenance_of_filtration&oldid=65211"

This page was last edited on 29 December 2022, at 13:51.