dewatering & coastal issues h 2 0 & erosion control workshop ucf stormwater management...

Dewatering & Coastal Issues”H20 & Erosion Control Workshop”

UCF Stormwater Management Academy

March 15-16, 2007

Jim Smoot, PhD, PE

Molly Wood, PE

U.S. Department of InteriorU.S. Geological Survey

Dewatering OperationsDewatering OperationsINTRODUCTIONINTRODUCTION

• Overview of Dewatering TechnologiesOverview of Dewatering Technologies• Selection, Design, and Operational ConsiderationsSelection, Design, and Operational Considerations

CONTROL TECHNOLOGIESCONTROL TECHNOLOGIES• Sediment TrapsSediment Traps• Sediment BasinsSediment Basins• Weir TanksWeir Tanks• Dewatering TanksDewatering Tanks• Gravity Bag FiltersGravity Bag Filters• Sand Media FiltersSand Media Filters• Pressurized Bag and Cartridge FiltersPressurized Bag and Cartridge Filters• Chemical Treatment - ContinuousChemical Treatment - Continuous• Chemical Treatment - BatchChemical Treatment - Batch

Control Control Technology Technology SelectionSelection

Does water have quality problems

other than sediment (e.g. odor, sheen,

foam, discoloration)?

Is it feasible to manage water

without discharge to stormwater

system or receiving waters?

Additional approaches and technologies beyond the scope of this manual may be needed –

consider consulting a water quality treatment expert

Retain water on-site

(infiltrate)

Discharge by agreement to

sanitary sewer

Transport for off-site disposal

Start

Will sediment settle in a reasonable time

and produce low enough turbidity?

Design Weir Tank or Dewatering Tank System

Design Sediment Trap or Sediment

Basin

Design Gravity-Bag, Pressurized-Bag, Cartridge, or

Media Filter-System

Consider chemical treatment

alternatives

Select and test chemicals and

dosages

Design Chemical Treatment System

No

No

Yes

No

Select Appropriate

BMP

Yes

Yes

Comparison of Dewatering TechnologiesComparison of Dewatering TechnologiesTreatment

Technology Group

Treatment Technology

Pollutant Treated Design Flow (gpm)

Footprint(sq. ft.)

Sediment Traps & Sediment Basins

Sediment Traps Sediment 25 to 500 Varies

Sediment Basins Sediment 25 to 500 Varies

Weir Tanks & Dewatering Tanks

Weir Tanks Sediment, Metals, Oil & Grease

60 to 100 1,800

Dewatering Tanks Sediment, Metals, Oil & Grease

Varies 1,200 to 1,500

Filters Gravity Bag Filter Sediment and Metals 300 to 800 100 to 400

Sand Media Filter Sediment, Metals, BOD 80 to 1,000 17 to 450

Pressurized Bag and Cartridge Filter

Sediment, Metals, BOD, and Hydrocarbons

50 to 1,000 200 to 320

Chemical Treatment

Continuous Chemical Treatment

Sediment Varies Varies

Batch Chemical Treatment

Sediment Varies Varies

SEDIMENT TRAPSSEDIMENT TRAPS

A A sediment trapsediment trap is a temporary basin formed by excavation and/or construction of an earthen is a temporary basin formed by excavation and/or construction of an earthen embankment or low drainage area to detain sediment-laden runoff and allow sediment to embankment or low drainage area to detain sediment-laden runoff and allow sediment to settle out before discharging. Sediment traps are generally smaller than sediment basins. settle out before discharging. Sediment traps are generally smaller than sediment basins.

SEDIMENT BASINSSEDIMENT BASINS

A A sediment basinsediment basin is a temporary basin with a controlled release structure that is formed by is a temporary basin with a controlled release structure that is formed by excavation or construction of an embankment to detain sediment-laden runoff and allow excavation or construction of an embankment to detain sediment-laden runoff and allow sediment to settle out before discharging. Sediment basins are generally larger than sediment to settle out before discharging. Sediment basins are generally larger than sediment traps.sediment traps.

WEIR TANKS AND DEWATERING TANKSWEIR TANKS AND DEWATERING TANKS

A A weir tankweir tank separates water and waste by using weirs. The configuration of the weirs (over separates water and waste by using weirs. The configuration of the weirs (over and under weirs) maximizes the residence time in the tank and determines the waste to be and under weirs) maximizes the residence time in the tank and determines the waste to be removed from the water, such as oil, grease, and sediments. removed from the water, such as oil, grease, and sediments.

A A dewatering tankdewatering tank removes debris and sediment. Flow enters the tank through the top, removes debris and sediment. Flow enters the tank through the top, passes through a fabric filter, and is discharged through the bottom of the tank. The filter passes through a fabric filter, and is discharged through the bottom of the tank. The filter separates the solids from the liquids. separates the solids from the liquids.

Weir TankWeir TankDewatering TankDewatering Tank

FILTERSFILTERS

A A gravity bag filtergravity bag filter is a square or rectangular bag made of non-woven geotextile fabric that is a square or rectangular bag made of non-woven geotextile fabric that collects sand, silt, and fines. collects sand, silt, and fines.

Generally, Generally, sand filterssand filters provide a final level of treatment. Water is treated by passing it provide a final level of treatment. Water is treated by passing it through canisters filled with sand media.through canisters filled with sand media. They are often used as a secondary or higher They are often used as a secondary or higher level of treatment after a significant amount of sediment and other pollutants have been level of treatment after a significant amount of sediment and other pollutants have been removed using other methods. removed using other methods.

A A pressurized bag filterpressurized bag filter is a unit composed of single filter bags made from polyester felt is a unit composed of single filter bags made from polyester felt material. The water filters through the unit and is discharged through a header. Vendors material. The water filters through the unit and is discharged through a header. Vendors provide bag filters in a variety of configurations. Some units include a combination of bag provide bag filters in a variety of configurations. Some units include a combination of bag filters and cartridge filters for enhanced contaminant removal. filters and cartridge filters for enhanced contaminant removal.

Cartridge filtersCartridge filters provide a high degree of pollutant removal by utilizing a number of individual provide a high degree of pollutant removal by utilizing a number of individual cartridges as part of a larger filtering unit. They are often used as a secondary or higher cartridges as part of a larger filtering unit. They are often used as a secondary or higher (polishing) level of treatment after a significant amount of sediment and other pollutants (polishing) level of treatment after a significant amount of sediment and other pollutants are removed. Units come with various cartridge configurations (for use in series with bag are removed. Units come with various cartridge configurations (for use in series with bag filters) or with a larger single cartridge filtration unit (with multiple filters within). filters) or with a larger single cartridge filtration unit (with multiple filters within).

FILTERSFILTERS

Sand Media FilterSand Media Filter

Gravity Bag FilterGravity Bag Filter

FILTERSFILTERS

Cartridge FilterCartridge Filter

Presurized Bag FilterPresurized Bag Filter

CHEMICAL TREATMENTCHEMICAL TREATMENT

Chemical treatmentChemical treatment includes the application of carefully selected chemicals such as polymers includes the application of carefully selected chemicals such as polymers (e.g. PAM), alum, and other flocculants to waters to aid in the reduction of turbidity by (e.g. PAM), alum, and other flocculants to waters to aid in the reduction of turbidity by more efficient removal of fine suspended sediment. more efficient removal of fine suspended sediment.

BatchBatch

ContinuousContinuous

Coastal IssuesCoastal Issues

INTRODUCTIONINTRODUCTION• Overview of Coastal SettingsOverview of Coastal Settings• Design ConsiderationsDesign Considerations

EROSION CONTROL TECHNOLOGIESEROSION CONTROL TECHNOLOGIES• Temporary ControlsTemporary Controls• Permanent ControlsPermanent Controls

SEDIMENT CONTAINMENT TECHNOLOGIESSEDIMENT CONTAINMENT TECHNOLOGIES• Floating Turbidity BarrierFloating Turbidity Barrier• Sediment Retention BarrierSediment Retention Barrier• Compost Filter BermsCompost Filter Berms

REFERENCESREFERENCES

EROSION CONTROL TECHNOLOGIES -- Temporary ControlsEROSION CONTROL TECHNOLOGIES -- Temporary Controls

Compost/Wood MulchingCompost/Wood Mulching Hydraulic MulchHydraulic Mulch

Soil BindersSoil Binders Temporary HydroseedingTemporary Hydroseeding

EROSION CONTROL TECHNOLOGIES -- Permanent ControlsEROSION CONTROL TECHNOLOGIES -- Permanent Controls

ArmoringArmoring

Establishing Permanent, Establishing Permanent, Salt-Tolerant VegetationSalt-Tolerant Vegetation


Preserving Existing VegetationPreserving Existing Vegetation Construction Site BarrierConstruction Site Barrier

Geotextiles, Mats, and GeogridsGeotextiles, Mats, and Geogrids


Case Study – Polymer-Enhanced ArmoringCase Study – Polymer-Enhanced Armoring

Coastal Storm DamageCoastal Storm Damage



Failure of Traditional Repair ApproachesFailure of Traditional Repair Approaches



Spreading Spreading CompostCompost

Laying MattingLaying Matting



Laying Grass SodLaying Grass Sod



Finished Project After One Year in ServiceFinished Project After One Year in Service

SEDIMENT CONTAINMENT TECHNOLOGIES -- Floating Turbidity BarrierSEDIMENT CONTAINMENT TECHNOLOGIES -- Floating Turbidity Barrier

SEDIMENT CONTAINMENT TECHNOLOGIES -- Sediment Retention BarrierSEDIMENT CONTAINMENT TECHNOLOGIES -- Sediment Retention Barrier

SEDIMENT CONTAINMENT TECHNOLOGIES -- Compost Filter BermsSEDIMENT CONTAINMENT TECHNOLOGIES -- Compost Filter Berms

Soil Erosion and Sediment Control Takes TeamworkSoil Erosion and Sediment Control Takes Teamwork

dewatering & coastal issues h 2 0 & erosion control workshop ucf stormwater management...

Documents

sediment basinssediment25

cartridge filter sediment

sedimentladen runoff

dewatering tankssediment

design weir tank

water quality treatment

weir tank separates

dewatering coastal issues