stormwater pond and wetland maintenance concerns and solutions · stormwater pond and wetland...

Center for Watershed Protection

Stormwater Pond and WetlandStormwater Pond and WetlandMaintenance Concerns and SolutionsMaintenance Concerns and Solutions

Sally Hoyt Ted Brown



Presentation OverviewPresentation Overview

•• Guidebook Contents and ObjectivesGuidebook Contents and Objectives•• Eight Maintenance ConcernsEight Maintenance Concerns•• Two specific concernsTwo specific concerns•• ConclusionConclusion


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


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


Maintenance Activity ProfilesMaintenance Activity Profiles

Permanent Pool Dredging and Muck Removal

Clogging Access

Pipe Repairs Mechanical Components

Vegetation Management Nuisance Issues


Permanent PoolPermanent Pool


CloggingClogging


Pipe RepairsPipe Repairs


VegetationVegetationManagementManagement


Dredging Dredging and Muckingand Mucking


Access Access


Mechanical ComponentsMechanical Components


Nuisance IssuesNuisance Issues

AnimalsAnimals MonocultureMonoculture vegetationvegetation


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)


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


Permanent Permanent PoolPoolDesignDesign

LowLow--flow Orificeflow OrificeDesignDesign


Permanent PoolPermanent PoolDesignDesign

Riser Riser LocationLocation


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


Permanent Permanent PoolPool

Construction Construction InspectionInspection


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


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


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).


CloggingCloggingDesignDesign

Design Category Clogging

Selecting the Right STP Site Layout/Grading Plan Pre-treatment Access Embankments/ Dams Conveyance Riser Miscellaneous Landscaping ESC Plans


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


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:


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

stormwater pond and wetland maintenance concerns and solutions · stormwater pond and wetland...

Documents