Inlet Protection Selector

Pick the inlet you have, then its size — we’ll show the Dandy product made for it.

Buyer's Guide

How Storm Drain Inlet Protection Works

Inlet protection is a sediment filter fitted to a storm drain or catch basin so runoff leaving a construction site drops its load before it enters the system. The devices are also known as catch basin inserts, catch basin filters or inlet filter bags. Water passes through the filter fabric; sand, silt and construction debris stay behind. Without it, sediment goes straight into the storm sewer and out to the receiving water, which is both an environmental problem and a compliance problem — inlet protection is a standard requirement on SWPPP and NPDES-permitted sites, and a missing or failed device is one of the most common findings on an inspection.

The whole specification comes down to one question: what kind of inlet are you protecting? A grate in a parking lot, a curb opening along a street, and a combination inlet that has both all take different devices. The selector above asks for the inlet type and the size, then returns the product made for it.

Matching the Device to the Inlet

Grate inlets — Dandy Bag The standard catch basin insert for a flat grate. The bag hangs beneath the grate, which drops back into place over it, so there is nothing sitting proud of the pavement to be driven over or knocked out of position. Available in rectangular sizes and in round for circular grates.

Grate inlets, heavy sediment — Dandy Sack Built for grate inlets carrying a heavier sediment load, with lifting straps so a loaded unit can be pulled and emptied, and an overflow feature so a blinded filter does not simply pond water across the site.

Grate inlets, high flow — Dandy Pop For grate inlets where flow volume is the governing concern and the device has to keep taking water once sediment has begun to accumulate.

Curb inlets — Dandy Curb A length of filter laid along the curb face, sized by the opening rather than by a grate footprint. Supplied from 4 feet to 16 feet, so the device matches the curb opening on the drawing.

Combination inlets — Dandy Curb Bag Where an inlet has both a curb opening and a grate, a combination device filters both paths. Specifying a grate-only device on a combination inlet leaves the curb opening unprotected, which is a routine inspection finding.

Combination inlets, heavy duty — Dandy Curb Sack The heavier combination device, for curb and grate inlets on sites with a higher sediment load or longer-running earthwork.

Measure the inlet, not the grate frame. Sizing is the single most common ordering error. Take the dimensions of the opening the device has to fit, check whether the inlet is square, rectangular or round, and confirm whether there is a curb opening as well as a grate before ordering.

Where Inlet Protection Is Required

Active construction sites Any disturbed site draining to a storm inlet. Protection goes in before earthwork starts and stays until the area is stabilized.

SWPPP compliance Inlet protection is a named control measure on most stormwater pollution prevention plans, and inspectors check that devices are in place and serviceable.

Roadway and utility work Curb inlets along the work zone, where trench spoil and traffic-tracked material would otherwise wash straight into the system.

Parking lots and paving Grate inlets during milling, paving and sweeping operations, when fines are generated faster than they can be swept up.

Municipal maintenance Catch basin protection during street work, keeping sediment out of basins that would otherwise need vacuum cleaning.

Landscaping and site finishing Topsoil, mulch and aggregate deliveries near an inlet are a sediment source until the surface is planted and stable.

Installation and Maintenance

1
Identify the inlet type and measure
Confirm grate, curb or combination, then measure the opening. Round grates take a round device; a combination inlet needs a combination device.
2
Install before earthwork begins
Protection goes in ahead of the disturbance it is there to control, not after the first storm has already carried sediment into the system.
3
Seat the device correctly
Grate devices hang beneath the grate, which is then replaced over them so the unit is held by the frame. Curb devices sit against the curb face across the full opening with no gap at either end.
4
Inspect after every significant rain
Check that the device is still seated, that the fabric is intact, and that sediment has not built up to the point where flow is restricted. Inspection records are part of the compliance paperwork.
5
Clean out before it blinds
Remove accumulated sediment while the device is still passing water. A filter left until it is fully blinded ponds water across the site and is the point at which devices get driven over, displaced or removed.

Removal matters too. Inlet protection stays in place until the contributing area is stabilized, then comes out along with the sediment it has collected. Pulling devices early, or leaving a loaded device in a finished street, both create problems.

Inlet Protection FAQs

What is storm drain inlet protection?

It is a sediment filter fitted to a storm drain inlet so runoff drops its sediment load before entering the system. Water passes through the filter fabric while sand, silt and debris are retained. It is a standard erosion and sediment control measure on construction sites.

Which device do I need for my inlet?

It depends on the inlet. Flat grates take a Dandy Bag, or a Dandy Sack where the sediment load is heavier and the unit needs lifting straps and overflow. Curb openings take a Dandy Curb sized to the opening. Combination inlets with both a curb opening and a grate take a Dandy Curb Bag or Curb Sack. The selector above matches them for you.

How do I size inlet protection?

Measure the inlet opening the device has to fit, not the surrounding frame or casting. Note whether it is square, rectangular or round, and whether there is a curb opening in addition to the grate. Curb devices are sized by the length of the curb opening.

Is inlet protection required by law?

On most permitted construction sites, yes. Inlet protection is a standard control measure under stormwater pollution prevention plans and NPDES construction permits, and local requirements vary on top of that. Check your permit and your jurisdiction's erosion and sediment control standards for what is specified on your project.

How often does it need to be inspected?

Follow the inspection schedule in your permit, which typically sets a regular interval plus an inspection after any significant rainfall. Check that the device is seated, the fabric is sound, and sediment has not built up enough to restrict flow.

When should I clean out the filter?

Before it blinds. Once a filter is fully loaded it stops passing water and ponds runoff across the site, which is when devices get displaced or pulled out. Removing accumulated sediment while the unit is still flowing keeps the control working and the site passable.

Can I use one on a curb inlet?

Yes, with the right device. A curb opening needs a curb device sized to the opening length rather than a grate bag. If the inlet has both a curb opening and a grate, use a combination device — a grate-only product leaves the curb opening unprotected.

What is the difference between a Dandy Bag and a Dandy Sack?

Both fit grate inlets. The Bag is the standard device, hanging beneath the grate which drops back over it. The Sack is built for heavier sediment loading, with lifting straps so a loaded unit can be removed and emptied, and an overflow feature so flow continues once the filter begins to load.

Does it work on round grates?

Yes. Round inlets take a round device sized to the grate diameter. Fitting a rectangular unit to a circular grate leaves gaps the sediment passes straight through.

When does inlet protection come out?

Once the contributing area is stabilized and no longer generating sediment. Remove the device along with the material it has collected rather than leaving a loaded unit in a completed street or lot.

Do you have sizes for a whole site?

Yes. Devices are offered across a wide range of inlet sizes in rectangular, round and curb configurations, so a site with mixed inlet types can be covered from one order. For a full site take-off, send the inlet schedule and we will put the quantities together.

Is this the same as a catch basin insert?

Yes. Catch basin insert, catch basin filter, inlet filter bag and silt sack all describe the same type of device — a sediment filter fitted into or beneath a storm drain inlet. The important distinction is not the name but whether the device suits a grate, a curb opening or a combination inlet, and whether it is sized to the opening.

What does shipping cost?

Nothing. Shipping is free on every order at Landscape Discount, across every inlet protection device and size.

Storm Drain Inlet Protection Selector | Find the Right Dandy Device