Stormwater Management Facility Inspections

Planter boxes are a subtype of bioretention entirely enclosed in a waterproof box. Runoff is directed into the planter box, infiltrating into an optimized soil blend. The soil and ponding layer store water, allowing it to evaporate or be transpired by plants. An underdrain and overflow system maintain rapid drainage. Pollutants are removed by plants or chemical reactions with the soil.

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Examining the inflow. Check that the splash rocks are present and there is no erosion. The downspout should flow into the planter box.
2. Examining the health of the plants. Dead or missing plants should be replaced. Invasive plants (aggressive species not naturally found in Virginia) or excessive weeds should be removed. Trees should be removed (except in facilities built with them).
3. Examining the facility’s structural stability.
4. Examining the overflow. There should be sufficient ponding depth to capture water. Excessive depth can also detrimental. The intended ponding depth is listed for each facility on the inspection notice. 

Take the three photos below: 

Some facilities include pretreatment. Pretreatment filters sediment before it reaches the facility, slowing soil clogging. The online inspection form will ask for a photo if pretreatment is present. 

Maintenance: 

• Replace plants as necessary. Please use the plant list(PDF, 324KB) for approved bioretention plants and planting guidance. If you want to install native plants not on the list, contact us for approval.
• Projects with landscape plans must plant per the plan.
• Do not plant invasive species, fruits and vegetables, or trees (unless replacing an existing tree). Remove volunteer trees.
• Adjust the ponding depth with shredded hardwood mulch for adjustments less than 3 inches. Do not use pine mulch, gravel, or dyed mulch. Use approved bioretention media for adjustments greater than 3 inches. Contact us for guidance on approved bioretention media. Do not use garden soil, potting soil, or topsoil. Free shredded hardwood mulch is available from Arlington’s Earth Products Yard while supplies last, do not use leaf mulch.
• Replace or reset the splash rocks as necessary. Use large rocks or a splash pad. Gravel will wash away. 
• Repair erosion and remove excess sediment as necessary. Remove dirt, leaves, and debris from pretreatment (if present).
• If you observe standing water more than 72 hours after rain stops, please contact us for guidance.
• Do not alter the drainage area, inflow/outflow, or run electrical wiring through a planter box.
• Do not add fertilizer.

Bioretention Plant List(PDF, 324KB)

Planter Box Maintenance Fact Sheet(PDF, 2MB)

How-To Videos

Bioretention delays and treats runoff by directing stormwater into a vegetated depression. The depression infiltrates runoff through a soil blend optimized for treatment. The soil and ponding layer store water, allowing it to evaporate or percolate into deep soil. An underdrain and overflow system maintain rapid drainage. Pollutants are removed by plants or chemical reactions with the soil.

Inspection:

Follow the instructions on the inspection form. Inspections are generally the same for planter boxes and rain gardens. Inspections include: 

1. Examining the inflow. Check that the splash rocks are present and there is no erosion. Water should be able to flow into the bioretention.
2. Examining the health of the plants. Dead or missing plants should be replaced. Invasive plants (aggressive species not naturally found in Virginia) or excessive weeds should be removed. Trees should be removed (except in facilities built with them).
3. Examining the facility’s general stability.
4. Examining the overflow. There should be sufficient ponding depth to capture water. Excessive depth can also detrimental. The intended ponding depth is listed for each facility on the inspection notice. 

Take the three photos below:

Some facilities include pretreatment. Pretreatment filters sediment before it reaches the facility, slowing soil clogging. The online inspection form will ask for a photo if pretreatment is present. 

Maintenance: 

• Replace plants as necessary. Please use the plant list(PDF, 324KB) for approved bioretention plants and planting guidance. If you want to install native plants not on the list, contact us for approval.
• Projects with landscape plans must plant per the plan.
• Do not plant invasive species, fruits and vegetables, or trees (unless replacing an existing tree). Remove volunteer trees.
• Adjust the ponding depth with shredded hardwood mulch for adjustments less than 3 inches. Do not use pine mulch, gravel, or dyed mulch. Use approved bioretention media for adjustments greater than 3 inches. Contact us for guidance on approved bioretention media. Do not use garden soil, potting soil, or topsoil. Free shredded hardwood mulch is available from Arlington’s Earth Products Yard while supplies last, do not use leaf mulch.
• Replace, reset, or clean the splash rocks as necessary. Use large rocks or a splash pad. Gravel will wash away.
• Repair erosion and remove excess sediment as necessary. Remove dirt, leaves, and debris from pretreatment (if present).
• If you observe standing water more than 72 hours after rain stops, please contact the stormwater team for guidance.
• Do not alter the drainage area or run electrical wiring through a bioretention.
• Do not add fertilizer.

Bioretention Plant List(PDF, 324KB)

Microbioretention Maintenance Fact Sheet(PDF, 4MB)

How-To Videos

The steps for inspecting rain garden style bioretention are the same as planter boxes. If no overflow pipe is present, suspend a string from one side of the depression to the other and measure the height from the bottom. 

Permeable pavements reduce runoff by allowing rain to pass through gaps in the surface. Water is stored in a gravel reservoir under the pavement, where it infiltrates into the soil. Most pavements use pavers, while some use porous concrete or asphalt.

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Examining the surface of the pavement. Weeds/vegetation and debris between pavers should be removed.
2. Checking for surface ponding after rain. This indicates clogging, which needs to be repaired.
3. Examining the structural integrity of the pavement. Pavers should not slump or crack.
4. Examining the surrounding area for sediment or unstable soil. This could flow onto the pavement, clogging the surface.
5. Opening the observation well (if present) to check for standing water. Most permeable pavements have observation wells. Observation wells appear as metal caps set in PVC pipe or metal. Significant standing water indicates water is not draining into the underlying soil. You may need a countersunk plug wrench to open the cap. If you can’t find the cap or it is stuck, contact the stormwater team.

Take the two photos below:

Some facilities include pretreatment. Pretreatment filters sediment before it reaches the facility, slowing clogging. The online inspection form will ask for a photo if pretreatment is present. 

Maintenance: 

• Remove vegetation growing from the pavement surface. Water from permeable pavements enters the groundwater table, so please do not spray herbicide. Alternative methods include manually pulling weeds, pouring boiling water over weeds, using vinegar, or using hydrogen peroxide. 
• Remove leaves and debris from the surface. Remove debris caught in between pavers.
• Add #8 or #9 stone if gravel level between pavers is low.
• Do not add sand or polymeric sand.
• Remove dirt, leaves, and debris from pretreatment (if present).
• Stabilize the soil around the pavement by maintaining healthy grass or plants. Soil eroding onto the pavement should be immediately addressed.

Permeable Pavement – How to clean clogged permeable pavers

Permeable Pavement Maintenance Fact Sheet(PDF, 2MB)

How-To Videos

Concentrated runoff is directed into a buried gravel reservoir. The reservoir stores water, allowing it to infiltrate into the surrounding soil. A pop-up emitter provides overflow capacity. Dry wells are like infiltration trenches, but much smaller. 

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Examining the downspout connection where it goes underground. The downspout should be fully connected to the underground pipe.
2. Examine the pop-up emitter. The emitter should not be blocked or broken.
3. Removing the pop-up emitter (it will lift off). Leaves and debris should be removed. Lifting the cleanout rod (if present) enables easy debris removal.
4. Inspecting the gutters for clogs or debris. Homeowners should regularly clean their gutters to prevent overflows and foundation/siding damage.

Take the two photos below:

Gutter guards are installed alongside dry wells to prevent pipe clogging. Photos are not required. Gutters should still be inspected and cleaned regularly.

Dry wells are frequently installed along with planter boxes. Water exiting the planter box through the underdrain is directed into the dry well. Inspections are not required for dry wells connected only to a planter box. Inspections are only required for dry wells which receive water directly from a downspout.

Maintenance: 

• Clean gutters to prevent clogs.
• Clean the observation well to prevent clogs.
• Replace the pop-up emitter if damaged. A broken pop-up emitter may create a trip hazard or allow debris into the observation well.
• Repair erosion or settling as necessary. We recommend maintaining healthy grass around the pop-up emitter to prevent erosion. Trees are not ideal due to long-term clogging by roots.
• Reconnect the downspout and ground pipe as necessary. Settling can sometimes lead to disconnection. If water is not routed toward the dry well, this can lead to erosion around the foundation. 

Dry Well Maintenance Fact Sheet(PDF, 13MB)

Concentrated runoff is directed into a plastic or concrete tank. A regulated outflow slowly drains the tank. An overflow pipe provides capacity for large storms.

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Inspecting the gutters. Clean if necessary.
2. Inspecting the inflow screen. Clean if necessary.
3. Inspecting pipe connections for leaks.
4. Inspecting the tank for debris accumulation. 
5. Inspecting the outflow for erosion or clogging.
6. Having the tank’s structural integrity and pipework inspected by a professional (once every 5 years).

Take the three photos below:

Gutter guards are sometimes installed alongside detention tanks to reduce debris in the downspout. Photos are not required. Gutters should still be inspected and cleaned regularly. 

Maintenance: 

• Cleaning the gutters 1-2 times a year.
• Cleaning the inflow screen regularly.
• Repairing leaks, clogs, or pipes as needed.
• Removing sediment and debris from the tank as needed (most tanks include a drain plug for this purpose).
• Repairing erosion as needed.
• Do not use detention tanks for rainwater harvesting. Tanks should be allowed to drain freely so that they can detain water in every storm. You may add a rain barrel to a downspout with an existing detention tank. Added rain barrels should not impact the function of the tank. 

Detention Tank Maintenance Fact Sheet(PDF, 1MB)

How-To Videos

Concentrated runoff is directed into a large, buried gravel reservoir. The reservoir stores water, allowing it to infiltrate into the surrounding soil. A layer of sand under the gravel filters the water. Infiltration trenches are like dry wells, but much larger, and with extra features. Newer designs use underground pipes, as shown above. Older designs use gravel at the surface, capturing overland flows. 

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Examining the contributing area for erosion. Erosion should be repaired and stabilized.
2. Examining pre-treatment devices (gutter guards and sump pits) for debris and sediment. Remove debris and sediment.
3. If the facility inflows are underground: examining the downspouts. The downspouts should be fully connected to the underground pipes.
4. If the facility receives surface drainage: examining the surface gravel. Clear debris or replace gravel if necessary.
5. Examining the observation well for standing water within 3 days of a storm in which at least 0.5 inches of rain falls. Standing water in the observation well indicates water is not infiltrating. 

You will need to inspect the infiltration trench three days after a storm with 0.5 inches or more of rain. This is not currently required for any other facility type. We recommend using any of the three rain gauges below to check recent rainfall:

• USGS Gauge 385309077102101 – Falls Church City Hall
• USGS Gauge 385334077112801 – Falls Church Maintenance Yard
• USGS Gauge 01652500 – Four Mile Run and Shirlington Road

Use the displayed graphs to determine the quantity of recent rainfall. Use your mouse wheel to zoom in and your cursor to determine the precipitation at a particular time. By default, these links will provide graphs set correctly. The correct settings are "continuous data," "precipitation, total, inches," and a 3-day interval. 

These three gauges provide an option to subscribe to email notifications for precipitation events. If interested:

1. Create a WaterAlert account
2. Open the website for your desired gauge and click “Subscribe to WaterAlert”
3. Check that the gauge ID is correct and that the alert is set to "Precipitation, total, inches"
4. Set the alert to "Accumulated over period - 24 hours"
5. Set the value to "Greater than 0.5 inches"
6. Set the alert to "Once per day"
7. Click "Create alert"

Please note that the precipitation must fall as rain for the trench to be inspected (not snow). These gauges do not distinguish between precipitation types.  

Take the two photos below:

Some facilities include pretreatment. Pretreatment filters sediment before it reaches the facility, slowing clogging. The online inspection form will ask for a photo if pretreatment is present. Many facilities include gutter guards, but these do not require photos or inspection. Have your gutters inspected and cleaned regularly to prevent clogs or overflows. 

Maintenance:

• Repair erosion as necessary. Maintain healthy grass around and over the trench. To avoid clogging by roots, do not plant trees over the trench.
• Clean pretreatment devices (sump pits, gutter guards) as necessary.
• If the facility inflows are underground: reconnect downspouts as necessary. Disconnection can occur as soil settles and results in erosion around the foundation.
• If the facility receives surface drainage: clear debris from the surface gravel. Replace the inflow gravel if clogging occurs. 

Northern Virginia Regional Commission also maintains a map of rain gauges.

How-To Videos

Projects that impact the Riparian Buffer Area (RPA) along streams and wetlands may be required to mitigate impacts by planting and maintaining native species or removing invasive (aggressive non-native) species. These activities benefit stream ecosystems, improving their ability to remove pollutants. 

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Documenting the presence of healthy trees and shrubs per the planting plan.
2. Documenting that healthy perennials and groundcovers achieve 80% coverage per the planting plan.
3. Inspecting for weeds in planting areas.
4. Inspecting deer protection on trees (if present).
5. Documenting that 2-3 inches of undyed double-shredded hardwood or leaf mulch is present.
6. Inspecting for invasive vines, groundcovers, perennials, and shrubs.

Take four photos:

1. Two photos showing plants at ground level.
2. Two photos showing tree and shrub canopy/foliage.
3. Before and after maintenance photos (as needed).

Maintenance: 

• Replace plants as necessary. Projects with landscape plans should plant per the plan.
• Do not plant invasive species in the RPA or nearby areas.
• Remove deer protection when trees reach 2 inches in diameter.
• Maintain 2-3 inches of undyed double-shredded hardwood or leaf mulch.
• Plants less than two years old should be watered during periods with less than 1 inch of precipitation per week. Plants more than two years old should be watered during droughts.
• Remove invasive vines, groundcovers, perennials, and shrubs. Examples include English ivy, Japanese/Chinese wisteria, Oriental bittersweet, and Japanese honeysuckle, bamboo, Chinese privet, multiflora rose, vinca, porcelain-berry, bush honeysuckle, and Japanese barberry. For a full list of target species, contact stormwaterinspection@arlingtonva.us. 

Vegetated (green) roofs absorb rainfall. Some water is stored in the soil and evaporates or transpires between storms. Some filters through the soil and drains off the roof. The soil and plants remove contaminants. “Extensive” vegetated roofs have thin soil and shallow-rooted plants such as sedums. “Intensive” vegetated roofs use a thick soil profile landscaped with deeper rooted perennials and shrubs. 

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Inspecting for weeds and organic debris. Weeds and debris should be removed.
2. Examining the health of the plants. There should be at least 80% plant coverage. Plants should be replaced as needed.
3. Checking the roof drains, scuppers, and gutters for debris. They should be cleaned if needed.
4. Inspecting the surface for exposed waterproof membranes. Media should be replenished and membranes repaired if needed.
5. Inspecting for leaks. These should be repaired promptly if present.

Take the two photos below:

Maintenance: 

• Replace plants as necessary to achieve 80% coverage. Buildings with landscape plans must plant per the plan.
• Remove weeds and debris from the media and drains.
• Replenish media as needed. Use only approved green roof media.
• Mulch as needed (for intensive green roofs only).
• Repair the waterproof membrane as needed. 

These three uncommon facilities focus on conveying water. Grass channels are shallow turfgrass ditches through which water travels. They sometimes include check dams to slow water. Dry swales combine grass channels and bioretention into a single facility. They use a ditch, check dams, bioretention filter media, underdrains, and tall plants to slow and filter water. Level spreaders convert concentrated runoff into diffuse sheet flow. This reduces erosion. Design of all three facilities varies. 

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Examining the inlets or level spreader for signs of erosion.
2. Examining the inlets or level spreader for signs of water bypassing the facility.
3. Examining the inlets or level spreader for sediment and debris accumulation.
4. Checking that level spreaders are level.
5. Inspecting grass channel and dry swale interiors for erosion or gullying.
6. Inspecting grass channel and dry swale surfaces for ponding or slow-draining water.
7. Inspecting grass channel and dry swale check dams for erosion and sediment accumulation.
8. Inspecting grass channel and dry swale vegetation for 95% cover and good health.

Take two photos:

1. An overall photo showing the entire facility.
2. A close-up photo of one part of the facility. 

Maintenance: 

• Clean out accumulated sediment, organic debris, and trash.
• Repair erosion.
• Clean or replace gravel around inlets, check dams, or level spreaders.
• De-thatch and aerate (grass channel) or replace filter media (dry swale) if ponding is present.
• Replace grass or vegetation to achieve adequate coverage as necessary. Use the property’s approved landscape plan if present. Otherwise, use the bioretention plant guide. 

Bioretention Plant List(PDF, 324KB)

Underground detention facilities temporarily store large quantities of runoff underground. Designs include concrete vaults or oversized pipe made from reinforced concrete (RCP), HDPE, and corrugated metal (CMP). A weir with a small outlet slowly drains water and provides overflow capacity. Some facilities use pumps instead. These facilities are like detention tanks, but much larger. Two common designs are shown above. 

Inspection:

Follow the instructions on the inspection form. Underground facilities require a professional inspection. Fairfax County maintains a maintenance contractor list. Inspections include:

1. Examining the inflow for blockages.
2. Visually inspecting the facility’s structural integrity.
3. Inspecting the low-flow orifice and trash rack (if present) for blockages.
4. Testing the pump (if present).
5. Examining the interior for sediment accumulation.

Take the two photos below:

1. An overall photo of the vault entrance.
2. A close-up photo showing the low-flow orifice or pumps.

Maintenance: 

• Clean the interior of the vault and forebay (if present) when debris exceeds 15% of the storage capacity.
• Clean the interior of the vault after upstream chemical or oil spills.
• Remove debris from around the low-flow orifice or trash grate.
• Make structural repairs if necessary.
• Service or replace pumps. 

Several engineering companies produce “manufactured” stormwater devices which are shipped from a factory and assembled or installed onsite. Cartridge filters pass water through a media to remove sediment and chemical pollutants. Hydrodynamic separators remove debris, oil, trash, and sediment. Biofilters are prefabricated planter boxes. A few examples are shown above. 

Inspection:

Manufactured facilities generally require a professional inspection. Fairfax County maintains a maintenance contractor list. Refer to the manufacturer’s inspection and maintenance guide.

Include the three attachments below:

1. An overall photo of the facility/facility access.
2. A close-up photo showing the facility.
3. Attach a completed inspection report. Use the manufacturer sample report, if available. 

Maintenance: 

Refer to the manufacturer’s inspection and maintenance guide. 

Sand filters detain concentrated runoff and pass it through a sand bed. Physical filtering and chemical reactions within the sand remove pollutants. One design (the underground DC sand filter) is shown above.

Inspection:

Follow the instructions on the inspection form. Inspections include:

1. Examining the facility for structural deficiencies.
2. Inspecting inlets and outlets for blockages.
3. Inspecting the inlet for excessive debris, sediment, or oil.
4. Examining the sand layer for discoloration, clogging, erosion, sediment, or standing water.

Include the three attachments below:

1. An overall photo of the facility/facility access.
2. A close-up photo showing the facility.
3. Attach a completed inspection report.

Maintenance: 

• Clean sediment, debris, trash, and oil from the forebay and sand bed.
• Repair erosion and service the sand bed.
• Remove blockages from the inlet and outlet.
• Replace the sand bed after five years or when drawdown exceeds 72 hours. 

1. Review the “How to Start Your Inspection” page section above. You will need the facility IDs listed on the letter. Submit the form once for each facility.
2. View the “Inspection and Maintenance Guide” page section for what photos to take and how to inspect your facilities.
3. Go outside and inspect your facilities. If maintenance is necessary, complete the maintenance. If possible, use a mobile device to complete the inspection report so you can look at the facility while answering the questions.  If you don’t have a mobile device, photograph the facility in detail using a digital camera. Transfer the photos to your computer to complete the online inspection form.
4. Did you forget a photo? Were you interrupted before you could complete the form? You can save and exit the form to complete later.  Use the link provided in the email from donotreply@arlingtonva.us to go back to the form that you saved.
5. Any questions? Contact stormwaterinspection@arlingtonva.us

1. Go to the online form and enter the facility IDs for your property. A separate form must be submitted for each facility. The letter from the County lists the facilities that are on your property. You may also find your facilities using your address(PDF, 982KB).
2. Complete the entire online form, attach the proper photos, and sign the form. Required photos may be found on the “Inspection and Maintenance Guidance” page.
3. Submit the form. You will receive email confirmation that your form is submitted. If you need to return later, save the form. You will receive an email confirming your form is in progress, with a link to access it. After submitting or saving the form, your browser will return to the main County website.

• A “submitted” confirmation email will be sent after successful submission. County staff will review the form within a few business days.
• If the facility is acceptable, the form will be approved, and a "complete" confirmation email sent.
• If maintenance is needed, the form will be rejected, and an "incomplete" email with instructions sent. The maintenance should be completed, and the form updated and resubmitted. Another round of county review will follow.

• If inspection or maintenance are incomplete after November 30, the property will not receive credit.
• If inspection or maintenance are still incomplete in Spring the county will contract inspection/maintenance. The cost will be billed to the owner, along with an administrative fee.

Request hard copy forms by emailing stormwaterinspection@arlingtonva.us. Provide your facility IDs and your address with your request. The forms will be mailed within seven business days of the request. Please return them well before the deadline.

Please contact us at stormwaterinspection@arlingtonva.us.

• For single-family homeowners: every other year/inspection cycle.
• For commercial properties and homeowner associations: every year/inspection cycle. 

The first inspection is due in the first county fiscal year (July 1 – June 30) after new facilities are approved.

• New facilities approved between July - December will require inspection in the following calendar year.
• New facilities approved between January - June will require inspection in fall of the same calendar year.

• If you have an infiltration trench, the inspection must be performed 3 days after a 0.5-inch storm. We recommend using a USGS precipitation gauge. More information is available in the infiltration trench tab of the “Inspection and Maintenance Guidance” page.
• For all other facilities, there is no precipitation requirement.

We recommend using a USGS precipitation gauge. More information is available in the infiltration trench tab of the “Inspection and Maintenance Guide” page.

A pretreatment device removes debris, reducing maintenance and extending the facility’s lifespan. Not all facilities have pretreatment. These devices can include gutter guards, sump pits, grass filters, forebays, and gravel diaphragms. Many pretreatment devices do not require inspection. If inspection is required, the online form will request a photo. More information is available in the “Inspection and Maintenance Guide” page.

For facilities with an approved landscape plan, all plants should match the plan. For attached and detached single-family homes, use the approved bioretention plant list(PDF, 324KB) or plants listed on the plan. If you want to install native plants not on the list, contact us for approval. Do not add non-native species, fruit/herbs/vegetables, or trees (unless replacing an existing tree shown on the plan). 

Ponding depth is listed under the facility description column on your inspection notice. It is also present as an auto-filled field on the online form.

Please see the "Altering Facilities" page.

• stormwaterinspection@arlingtonva.us
•  703-228-4245