Center for Watershed Protection
Stormwater Pond and WetlandStormwater Pond and WetlandMaintenance Concerns and SolutionsMaintenance Concerns and Solutions
Sally Hoyt Ted Brown
Center for Watershed Protection
Center for Watershed Protection
Presentation OverviewPresentation Overview
•• Guidebook Contents and ObjectivesGuidebook Contents and Objectives•• Eight Maintenance ConcernsEight Maintenance Concerns•• Two specific concernsTwo specific concerns•• ConclusionConclusion
Center for Watershed Protection
Center for Watershed Protection
Center for Watershed Protection
ThanksThanks
•• Tetra TechTetra Tech•• US EPA Office of Science and TechnologyUS EPA Office of Science and Technology
•• CPJ/EQR Environmental ServicesCPJ/EQR Environmental Services•• Montgomery County (MD) DEPMontgomery County (MD) DEP
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Maintenance GuidanceMaintenance Guidance
•• Top 8 Maintenance ConcernsTop 8 Maintenance Concerns•• Designing for Low Maintenance Ponds and Designing for Low Maintenance Ponds and
WetlandsWetlands•• Construction for Maintenance Problem Construction for Maintenance Problem
PreventionPrevention•• PostPost--Construction Inspection Maintenance Construction Inspection Maintenance
ActivitiesActivities
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Maintenance Activity ProfilesMaintenance Activity Profiles
Permanent Pool Dredging and Muck Removal
Clogging Access
Pipe Repairs Mechanical Components
Vegetation Management Nuisance Issues
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Permanent PoolPermanent Pool
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CloggingClogging
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Pipe RepairsPipe Repairs
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VegetationVegetationManagementManagement
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Dredging Dredging and Muckingand Mucking
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Access Access
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Mechanical ComponentsMechanical Components
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Nuisance IssuesNuisance Issues
AnimalsAnimals MonocultureMonoculture vegetationvegetation
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Maintenance Concerns Maintenance Concerns through STP through STP lifecylelifecyle
•• DesignDesign
•• Construction Construction (Construction Inspection)(Construction Inspection)
•• Inspection Inspection (Ongoing Post(Ongoing Post--Construction Inspection)Construction Inspection)
•• Maintenance Maintenance (Corrective and Preventative Actions)(Corrective and Preventative Actions)
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Permanent PoolPermanent PoolDesignDesign
Design Category Permanent Pool
Selecting the Right STP Site Layout/Grading Plan Pre-treatment Access Embankments/ Dams Conveyance Riser Miscellaneous Landscaping ESC Plans
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Permanent Permanent PoolPoolDesignDesign
LowLow--flow Orificeflow OrificeDesignDesign
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Permanent PoolPermanent PoolDesignDesign
Riser Riser LocationLocation
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Pond/Wetland Feature Key Inspection Points
Core Trench and Embankments
Dimensions/Location Soil Material Backfill and compaction
Principal spillway Watertight joints Backfill and compaction Concrete cradle – dimensions, concrete strength
Riser Orifice sizes and elevations Watertight connections to pipes Trash racks
Storage volumes and grading
Design volumes for pond Microtopography correct for wetland vegetation Permanent pool elevations correct
Vegetative stabilization Stabilization prior to removal of ESC measures
Permanent PoolPermanent PoolConstruction InspectionConstruction Inspection
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Permanent Permanent PoolPool
Construction Construction InspectionInspection
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Permanent PoolPermanent PoolInspectionInspection
Pool Too HighPool Too High: Water : Water levels remain high for levels remain high for more than 2 or 3 days more than 2 or 3 days after a storm; normally after a storm; normally visible pond edges and visible pond edges and plants are submergedplants are submerged
Pool Too Low: Pool Too Low: Stain marks Stain marks visible on riser or control visible on riser or control structure; exposure of structure; exposure of pond bottompond bottom
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Permanent PoolPermanent PoolCorrective ActionsCorrective Actions
Clogged lowClogged low--flow orificeflow orifice
Rodent dams and burrowsRodent dams and burrows
Remove clog; install trash rackRemove clog; install trash rack
Fill burrow; deter rodentsFill burrow; deter rodents
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Permanent PoolPermanent PoolCorrective Actions, continuedCorrective Actions, continued
Leak or seepage in dam Leak or seepage in dam face or pond bottomface or pond bottom
Leak in riser or barrelLeak in riser or barrel
Dye test recommended. Drain pool and Dye test recommended. Drain pool and install pond liner. Repair principal install pond liner. Repair principal spillway or dam.spillway or dam.
Seal leak (See Pipe Repairs).Seal leak (See Pipe Repairs).
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CloggingCloggingDesignDesign
Design Category Clogging
Selecting the Right STP Site Layout/Grading Plan Pre-treatment Access Embankments/ Dams Conveyance Riser Miscellaneous Landscaping ESC Plans
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CloggingCloggingInspectionInspection
•• External clogging detected through visual inspectionExternal clogging detected through visual inspection•• LowLow--flow and internal clogging requires observation of flow and internal clogging requires observation of
the permanent poolthe permanent pool
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CloggingCloggingCorrective ActionsCorrective Actions
•• Manual removalManual removal•• Jetting, back flushing, or Jetting, back flushing, or
routingrouting•• Sediment and muck Sediment and muck
removalremoval•• Dewatering the pondDewatering the pond•• Professional diverProfessional diver
The range of actions to remove a clog:The range of actions to remove a clog:
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CloggingCloggingCorrective Actions Corrective Actions -- PreventionPrevention
•• Frequent debris Frequent debris removalremoval
•• Retrofit to install a Retrofit to install a trash racktrash rack
•• Inspect and repair Inspect and repair the trash rackthe trash rack
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