Tipo de Instalaciones y Equipos

There are several advantages and disadvantages to choosing a specific or multiple combinations of BMPs. In order to select the most beneficial options for reducing phosphorus, the following structural BMPs options have been investigated.60

Sediment Fore bays Advantages:

 Provides pretreatment of runoff before delivery to other BMPs

 Slows velocities of incoming stormwater

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 Easily accessed for sediment removal

 Longevity is high with proper maintenance

 Relatively inexpensive compared to other BMPs

 Greater detention time than proprietary separators Disadvantages:

 Removes only coarse sediment fractions

 No removal of soluble pollutants

 Provides no recharge to groundwater

 No control of the volume of runoff  Frequent maintenance is essential

Vegetated Filter Strips Advantages:

 Reduces runoff volumes and peak flows

 Slows runoff velocities and removes sediment

 Low maintenance requirements

 Serves as an effective pretreatment for Bioretention cells

 Can mimic natural hydrology

 Small filter strips may be used in certain urban settings

 Ideal for residential settings to treat runoff from small parking lots and roads

 Can be used as part of runoff conveyance system in combination with other BMPs

32 Disadvantages:

 Variability in removal efficiencies, depending on design

 Little or no treatment is provided if the filter strip is short-circuited by concentrated flows

 Often a poor retrofit option due to large land requirements

 Effective only on drainage areas with gentle slopes (less than 6 percent).

 Improper grading can greatly diminish pollutant removal

Bioretention Areas (Rain Gardens) Advantages:

 Can be designed to provide groundwater recharge and preserves the natural water balance of the site

 Can be designed to prevent recharge where appropriate

 Supplies shade, absorbs noise, and provides windbreaks

 Can remove other pollutants besides TSS including phosphorus, nitrogen and metals

 Can be used as a stormwater retrofit by modifying existing landscape or if a parking lot is being resurfaced

 Can be used on small lots with space constraints

 Small rain gardens are mosquito death traps

 Little or no hazard for amphibians or other small animals

Disadvantages:

 Requires careful landscaping and maintenance  Not suitable for large drainage areas

33 Constructed Stormwater Wetland

Advantages:

 Relatively low maintenance costs

 High pollutant removal efficiencies for soluble pollutants and particulates.

 Removes nitrogen, phosphorus, oil and grease

 Enhances the aesthetics of a site and provides recreational benefits  Provides wildlife habitat

 Depending upon design, more land requirements than other BMPs Disadvantages:

 Until vegetation is well established, pollutant removal efficiencies may be lower than anticipated

 Relatively high construction costs compared to other BMPs

 May be difficult to maintain during extended dry periods

 Does not provide recharge

 Creates potential breeding habitat for mosquitoes

 May present a safety issue for nearby pedestrians

 Can serve as decoy wetlands, intercepting breeding amphibians moving toward vernal pools

Wet basin Advantages:

 Capable of removing both solid and soluble pollutants

 Capable of removing nutrients and metals

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 Can increase adjacent property values when properly planned and sited

 Sediment generally needs to be removed less frequently than for other BMPs  Can be used in retrofits

Disadvantages:

 Capable of removing both solid and soluble pollutants

 Capable of removing nutrients and metals

 Aesthetically pleasing BMP

 Can increase adjacent property values when properly planned and sited

 Sediment generally needs to be removed less frequently than for other BMPs  Can be used in retrofits

Drainage Channels Advantages:

 Conveys stormwater

 Generally less expensive than curb and gutter systems

 Accents natural landscape

 Roadside channels reduce driving hazards by keeping stormwater flows away from street surfaces during storms

Disadvantages:

 Higher degree of maintenance required than for curb and gutter systems

 Roadside channels are subject to damage from off-street parking and snow removal

 Provides limited pollutant removal compared

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 May be impractical in areas with flat grades, steep topography or poorly drained soils

 Large area requirements for highly impervious sites

Grassed Channel Advantages:

 Provides pretreatment if used as the first part of a treatment train

 Open drainage system aids maintenance

 Accepts sheet or pipe flow

 Little or no entrapment hazard for amphibians or other small animals

Disadvantages:

 Short retention time does not allow for full gravity separation

 Limited bio-filtration provided by grass lining

 Cannot alone achieve 80% TSS removal

 Must be designed carefully to achieve low flow rates for Water Quality Volume purposes

 Mosquito control considerations

Water Quality Swale Advantages:

 May be used to replace more expensive curb and gutter systems

 Roadside swales provide water quality and quantity control benefits, while reducing driving hazards by keeping stormwater flows away from street surfaces

 Accents natural landscape

 Can be used to retrofit drainage channels and grass channels

36 Disadvantages:

 Higher degree of maintenance required than for curb and gutter systems

 Roadside swales are subject to damage from off-street parking, snow removal, and winter deicing

 Subject to erosion during large storms

 Individual dry swales treat a relatively small area

 Impractical in areas with very flat grades, steep topography or poorly rain soils

 Wet swales can produce mosquito breeding habitat

 Should be set back from shellfish growing areas and bathing beaches

Dredging Advantages:

 Will release and remove nutrients from water

Disadvantages:

 Releases toxic substances into Pond

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