Inlet Protection for Parking Lot Stormwater Runoff

Inlet Protection - Parking Lot Stormwater Runoff


Due to vehicle leaks, runoff from parking lots can contain oil, petroleum, heavy metals, dirt, and other types of pollution. Local environmental regulations in all developed countries require pre-treatment of any contaminated stormwater runoff before it is discharged into the municipal sewer system or stormwater.

  • Various types of inlet protection devices can be used to prevent grit and pollutants from escaping into the storm drains.
  • Inlet protection baskets are manufactured to be installed right beneath the inlet drop grate; the baskets filter out dirt, debris, and other types of particle pollution.
  • Additional materials such as absorbent socks can be installed to address hydrocarbon (petroleum) pollution.
  • Inlet protection baskets from stainless steel are durable, long-lasting, easy to disinfect, and can be custom-tailored to fit any inlet size.
  • Inlet protection baskets require regular maintenance (cleaning) to remain efficient. Good parking lot hygiene also helps.
  • The final price depends on the size and the features of the basket.

How Parking Lots Contribute to Environmental Pollution

Stormwater runoff, especially from urban and traffic-heavy areas, is a significant source of aquatic pollution. Water coming from precipitation or street sweeping will inevitably wash away debris, toxic compounds, and various sorts of waste.

A particular kind of pollution comes from traffic. Vehicles will inevitably leak oil, gas, and antifreeze. Particles coming from combustion include dangerous compounds such as heavy metals and accumulate on surfaces over time – and will be washed away into the stormwater if not contained.

Parking lots are usually less saturated with debris such as leaf litter and mud than an average street, especially if well maintained. In cases of guarded parking lots, there will probably be less animal waste and no trash.

However, parking lots have a distinction: a lot of motor vehicles around at all times. Even if the cars, trucks, vans, buses, or motorbikes are only parked, leaks still do occur. If the parking lot is also used for servicing vehicles, the potential for larger leaks and spills increases dramatically.

When precipitation or hosing washes it all down, the unmanaged runoff escaping through the storm sewer becomes a direct pollutant injection for our waterways.

The amount of pollution coming from stormwater runoff makes it a notable subject in environmental management, and most countries have created institutions to deal with it. The responsible subjects are usually obliged by regulations to prevent the polluted runoff from freely discharging into the municipal storm drains.

Fortunately, you can manage the runoff from your parking lot with relative ease, thanks to effective engineering solutions.

Inlet protection installationInlet Protection Baskets

Parking Lot Drain Inlets

If your business owns a parking lot, you should know that there are special devices designed to keep unsuitable material on-site and out of the stormwater stream.

Inlet protection baskets – also called grit baskets or sediment baskets – are protective devices installed just beneath the inlet grate. They catch the grit and debris but pass water, effectively filtering the runoff. To deal with hydrocarbon pollution, special add-ons such as absorbent socks can effectively capture oil and petroleum products.

Parking Lot Drain Inlet Protection Baskets – A Case Study

Installed inlet stormwater protection basketCentral Automotive Maintenance (CAM) parking lot in a large Virginia county intended for vehicles waiting to be serviced or that has just been serviced.

EPA was concerned that the parking lot’s runoff contained unmanaged grit and oil coming from vehicles. CAM required a device that could contain the pollution before it reaches any of its 11 large parking lot drop inlets (DIs).

We worked with them to design a basket to fit their inlets and successfully handle the specific type of pollution coming from the parking lot.

The result was the production and successful installation of 11 custom baskets (41″ L x 10″ D x 35″ W) made out of 304 stainless steel, equipped with small holes on the bottom and the sides so they could pass water but hold the dirt. Additionally, absorbent socks were placed inside the basket to efficiently capture hydrocarbon pollution as the water flowed through the basket.


Why is oil so bad for the environment?

Hydrocarbons – oil and all its derivatives – are especially troublesome water pollutants. Since oil and water do not mix, the oil disperses within the water stream (or column) and accumulates in natural water bodies.

Once they reach the ecosystem, hydrocarbons can disrupt photosynthesis in aquatic plants and cause die-offs and a range of acute and chronic health issues in animals – consequently endangering the water quality itself. Given that these are the waters that we humans use for drinking and irrigation, the waters we swim in and fish in, it is well worth going an extra mile to prevent pollution.

Am I required by law to take care of my parking lot runoff?

Your exact obligations will depend on where you are located. In the US, there is a program called The National Pollutant ­Discharge Elimination System (NPDES), which operates under the Clean Water Act to regulate discharge from municipal storm sewer systems, industrial localities, and construction sites. Operators may face a requirement to obtain an NPDES permit before discharging stormwater.

It is always best to consult your local EPA office or an environmental protection consultant.

How do sediment baskets exactly work?

Stated briefly, grit and sediment baskets work by utilizing mechanical filtration. The basket acts as a physical barrier that traps sediment and other particles.

How large are grit baskets for parking lot drain inlets?

Our grit traps can be custom made, tailored according to the dimensions of the drop inlets.

For how long do the baskets remain effective?

When made from a durable material, plus designed and installed well, drain inlets can last almost indefinitely.

However, there is a catch. The drain inlets operate successfully only if well maintained. When the structure is filled with debris and sediment, it loses its effectiveness. Additionally, there is a hazardous possibility of collected and unremoved dirt escaping the basket during high water input events.

Regular removal of grit and dirt from the basket and proper maintenance and sweeping of the parking lots are a must to keep drain inlets functioning normally.

What are the parking lot drain inlet devices made of?

You can find various solutions in the market, but we make our parking lot inlet baskets out of high-quality stainless steel.

Stainless steel is a material that is extremely durable, corrosion, and temperature resistant. It has high tensile strength but is still formattable. The material can also be disinfected effectively and thoroughly. Stainless steel is recyclable, so it is considered an environmentally friendly material from that point of view. By looking at its properties, it is not hard to deduce that stainless steel is the perfect material for drain inlet devices.

How much does a grit basket cost?

The basket’s final price for a parking lot drain inlet can vary due to different specifications and dimensions. The basket we designed for Central Automotive Maintenance (CAM) was made out of 304 Stainless Steel and featured absorbent socks for petroleum capture. The final cost was a small investment for solving a potential large problem and well within their budget.

Have more questions? Don’t hesitate to contact us today to get professional advice on the best drain inlet solution for your parking lot.