Wet pond treating from a shopping center Maintaining an Maintaining an underground BMP

Urban Stormwater Best Management Practices (BMPs) Inspection Program of Alexandria, VirginiaCity runoff from developed areas. developed runoff from http://www.alexandriava.gov/tes/DEQ/ the City’s inspection program. the City’s individuals and property owners owners property individuals and overflow riser are, their BMPs what understand

Trash inside an Trash inside Services, Division of Environmental Quality This brochure was developed to help to help was developed This brochure Department of Transportation and Environmental the water impacts of stormwater the quality City’s stormwater management program program management City’s stormwater on local water resources. resources. on local water pollution water BMPs are an important component of the important component are an BMPs maintenance requirements, and the role of and the role requirements, maintenance A stormwater “Best Management Practice” (BMP) is a facility or structure that reduces or structure is a facility (BMP) which aims to reduce the impacts of storm- the which aims to reduce

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I ERVICE S City of Alexandria of City Alexandria

Phone: 703-838-4334 Alexandria, VA 22314Alexandria, VA Environmental Services Services Environmental management facilities. stormwater BMPs, contact: DDITIONAL 301 King Street, Room 3900 service your particular needs. needs. particular your service

A Division of Environmental Quality Quality Environmental of Division Department of Transportation and and of Transportation Department http://www.alexandriava.gov/tes/DEQ/ http://www.alexandriava.gov/tes/DEQ/ AINTENANCE M non-inclusion on this list constitute any such any on this list constitute non-inclusion For more information about this brochure and and brochure this about information For more have experience in maintaining stormwater have representation or warranty. You should retain a You should or warranty. representation provide BMP owners with a list of vendors whowith a list of vendors BMP owners provide Alexandria Supplement to the Northern Virginia to the Northern Supplement Alexandria BMP Handbook Agreement City of Alexandria BMP Maintenance City of Alexandria Management Environmental Ordinance Quality City of Alexandria Plan Water Master Supplement Management brochure Management” Pollution and “Stormwater maintenance company only after making a thorough a thorough after making only company maintenance The City’s Division of Environmental Quality can Quality of Environmental Division The City’s Please note that the City makes no representation or or representation no makes that the City Please note warranties regarding the qualif warranties regarding any particular vendor, nor does a vendor's inclusion or or inclusion a vendor's does nor vendor, any particular review of that company's qualifications and its ability to its ability to and qualifications company's of that review found at: can be resources Links to the following http://alexandriava.gov/tes/DEQ/deqpublications.html • • • • •

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Regular , W OES ? D HY HEM W T ECESSARY (Article XIII, Section XIII, (Article AND , NPSECT I HEM T BMPS N ITY C wet and dry ponds, bioretention wet and dry ponds, ARE

HY AINTAINS W M The City of Alexandria Environmental Management Ordinance implements the City’s stormwater management program in with the Virginia Stormwater compliance Management Act and Chesapeake Bay Preservation Act. These regulations of City to control the level require the waterways such as the pollutants entering Potomac River and the Chesapeake Bay. pollutants BMPs are designed to reduce and sediments, oil, grease such as nutrients. Examples of urban stormwater BMPs are as the City of Ultra urban areas such Alexandria are densely developed areas and pervious open space with scarce stormwater storage surfaces. Underground sand such as and treatment practices filters and hydrodynamic separators are they require very little well suited because surface space. of development As a requirement approval, the City requires BMP owners to maintain their facilities vary according to Maintenance needs will drainage area the type of facility and inspect to it. Owners should contributing every few their facilities months and after events. significant rainfall areas, sand and storm filters, and filters, and and storm areas, sand devices. hydrodynamic separator for proper maintenance is necessary long-term viability.function and 13-109).This is stated in their maintenance in 13-109).This is stated agreement. The agreement conveys to successive landowners. City staff conducts of BMPs to ensure facilities are inspections properly. being maintained and functioning SAND FILTERS WET PONDS BMP INSPECTION AND MAINTENANCE NEEDS Urban sand filters are located in underground BMP INSPECTION AND MAINTENANCE NEEDS Wet detention ponds concrete vaults that have multiple chambers. The are constructed basins first chamber is for settling, the second chamber has that have a permanent BIORETENTION AREAS the filter and under lying drainage system, and the pool of water through- Bioretention areas, often referred to as rain gardens, are third is a discharge chamber or clear well. As storm- out the year, or at landscape features that store and treat stormwater runoff. water flows into the first chamber, large particles least during periods of is directed into shallow, vegetated settle out, finer particles and other pollutants are normal rainfall. depressions with removed as stormwater flows through the filter me- Pollutant removal Wet Pond underlying layers of dium. Pollutants are removed by physical filtration, occurs through soil, sand, and gravel. adsorption, and bacterial uptake. settling, as stormwater runoff is stored in the pond. These areas are Additional pollutant uptake of nutrients also occurs There are several design variations of sand filters designed to mimic through biological activity (i.e. algal uptake). Wet including: Delaware, DC, Austin, Alexandria natural ecosystems ponds are among the most cost-effective and Compound, and Dry Vault filters. where pollutant widely used BMP when space is available. removal occurs Access to sand filter Inside vault of sand filter through soil infiltration Recently installed Maintenance: and plant uptake. They bioretention area • Conduct routine mowing are commonly located • Keep embankments stable / fill animal burrows in parking lot islands or in residential open spaces. • Remove sediment from pond when necessary

• Manage vegetation / seed and stabilize bare Maintenance: spots • Maintain vegetation and replace mulch as needed • Inspect and clean any mechanical components • Remove trash and sediment STORM FILTERS • Keep free of debris / remove trash • Watch for water standing > 72 hours which can indicate These BMPs are comprised of an underground • Keep risers, spillways and outlets clear clogging of subsurface layers and under-drain system concrete vault that houses media-filled filter cartridges. Pollution removal occurs through DRY PONDS mechanical filtration, ion exchange, and adsorption Dry detention ponds to the filter media. The vault has an under-drain sys- HYDRODYNAMIC SEPARATOR DEVICES are basins with out- tem to release treated stormwater. Examples of this Hydrodynamic separators are flow-through structures lets that have been type of BMP are StormFilter™ and VortFilter™. that have an insert chamber to trap sediments, oil and designed to store other pollutants. Water enters the vault insert and drops stormwater runoff for Inside StormFilter™ vault through a weir / pipe into a settling chamber where large a specified period of particles settle out. Examples of these devices are Dry Pond time, usually 48 Stormceptor™, Vortechnics™, AquaShield™, hours, to allow BaySaver™, and Downstream Defender™. particles and pollutants to settle. Unlike wet ponds, these facilities do not have a large permanent pool. Maintenance: ™ View inside Stormceptor Dry ponds can be planted with wetland vegetation • Check oil and sediment to provide additional nutrient and pollutant uptake. levels Maintenance for Sand and Storm Filters: • Clean out chamber when Maintenance: • Remove trash and sediment from chambers unit has reached capacity • Conduct routine mowing • Remove oil layer from permanent pool (this is performed with a • Keep embankments and slopes stable • Remove and replace top layer of sand filter and sump vac or vacuum underlying filter fabric • Remove sediment as necessary Filtertruck, Cartridge depending on type Manage vegetation, seed and stabilize bare spots • Keep inlets and outlets clear of debris • of unit). See device’s • Fill animal burrows • Maintain wiring and pumps (if applicable) operation manual • Keep trenches / basin free of debris and trash • Replace media-filled filter cartridges • Remove trash and keep access • Keep risers, spillways and outlets clear • Maintain access areas (doors, grates, covers) areas clear of debris Access manhole cover • Watch for water standing > 72 hours